Case Studies & Application Stories

Peat Water Treatment Using Combination of Cationic Surfactant Modified Zeolite, Granular Activated Carbon, and Limestone

Posted by 17 Apr, 2013

Tweet MyronLMeters.com attempts to provide its customers with the latest in water quality research and industry updates. Find more at https://www.myronlmeters.com/. Abstract This research was conducted essentially to treat fresh peat water using a series of adsorbents. Initially, the characterization of peat water was determined and five parameters, including pH, colour, COD, turbidity, and iron ion […]

MyronLMeters.com attempts to provide its customers with the latest in water quality research and industry updates. Find more at https://www.myronlmeters.com/.

Abstract

This research was conducted essentially to treat fresh peat water using a series of adsorbents. Initially, the characterization of peat water was determined and five parameters, including pH, colour, COD, turbidity, and iron ion exhibited values that exceeded the water standard limit. There were two factors influencing the adsorption capacity such as pH, and adsorbent dosages that were observed in the batch study. The results obtained indicated that the majority of the adsorbents were very efficient in removing colour, COD, turbidity at pH range 2-4 and Fe at pH range 6-8. The optimum dosage of cationic surfactant modified zeolite (CSMZ) was found around 2 g while granular activated carbon (GAC) was exhibited at 2.5 g. In column study, serial sequence of CSMZ, GAC, and limestone showed that the optimal reduction on the 48 hours treatment were found pH = 7.78, colour = 12 TCU, turbidity = 0.23 NTU, COD = 0 mg/L, and Fe= 0.11 mg/L. Freundlich isotherm model was obtained for the best description on the adsorption mechanisms of all adsorbents.

Keywords: cationic surfactant modified zeolite, granular activated carbon, limestone, peat water

1.  Introduction

Water is essential and fundamental to all living forms and is spread over 70.9% of the earth’s surface. However, only 3% of the earth’s water is found as freshwater, of which 97% is in ice caps, glaciers and ground water (Bhatmagar & Minocha, 2006). In Malaysia, more than 90% of fresh water supply comes from rivers and streams. The demand for residential and industrial water supply has grown rapidly coupled with an increase in population and urban growth (WWF Malaysia, 2004). Water demand in affected populations such as rural areas also demands that attention is paid to providing more sustainable solutions rather than transporting bottled water (Loo et al., 2012). For this reason, it is essential to ensure availability of local sources of water supply and even develop new potential sources of water such as from peat swamp forest to overcome future water shortages.

River water surrounded by peat swamp forest is defined as peat water and is commonly available as freshwater since it has a low concentration of salinity. The previous study shows that peat swamp forest has high levels of acidity and organic material depending on its region and vegetation types (Huling et al., 2001). Under natural conditions, tropical peat lands serve as reservoirs of fresh water, moderate water levels, reduce storm-flow and maintain river flows, even in the dry season, and they buffer against saltwater intrusion (Wosten et al., 2008).

Due to the acidity and high concentration of organic material, selective treatment of peat water must be conducted prior to its use as water supply. Recently, many methods have been designed and have proven their effectiveness in treating raw water such as coagulation and flocculation (Franceschi et al., 2002; Liu et al., 2011; Syafalni et al., 2012a), absorption (Ćurković et al., 1997), filtration (Paune et al., 1998) and combining (Hidaka et al., 2003). Careful consideration of the most suitable method is important to ensure that the adsorption process is the most beneficial, economically feasible method as well as easy to operate for producing high quality of water in a particular location.

Many researchers have shown that activated carbon is an effective adsorbent for treating water with high concentrations of organic compounds (Eltekova et al., 2000; Syafalni et al., 2012b). Its usefulness derives mainly from its large micropore and mesopore volumes and the resulting high surface area (Fu & Wang, 2011). However, its high initial cost makes it less economically viable as an adsorbent. Low cost adsorbent such as zeolite nowadays has been explored for its ability in many fields especially in water treatment. Natural zeolite has negative surface charge which gives advantages in absorbing unwanted positive ions in water such heavy metal. These ions and water molecules can move within the large cavities allowing ionic exchange and reversible rehydration (Jamil et al., 2010). The effectiveness of zeolite has been improvised by modified zeolite with surfactant in order to achieve higher performance in removing organic matter (Li & Bowman, 2001). Among tested cationic surfactants, hexa-decyl-tri-methyl ammonium (HDTMA) ions adsorbed onto adsorbent surfaces are particularly useful for altering the surface charge from negative to positive (Chao & Chen, 2012). Surfactant modified zeolite has been shown to be an effective adsorbent for multiple types of contaminants (Zhaohu et al., 1999).

Zeolite is modified to improve its capability of exchanging the anion by cationic surfactants, called CSMZ. CSMZ adsorbs all major classes of water contaminants (anions, cations, organics and pathogens), thus making it reliable for a variety of water treatment applications (Bowman, 2003). Nowadays, interest in the adsorption of anions and neutral molecules by surfactant modified zeolite has increased (Zhang et al., 2002). Modification of zeolite by surfactant is commonly done by cationic or amphoteric surfactants. By introducing surfactant to the zeolite, an organic layer is developed on the external surfaces and the charge is reversed to positive (Li et al., 1998). However, the present study used zeolite that had been modified using Uniquat (QAC-50) as cationic surfactant (CSMZ) and their performance towards the removal of color, COD, turbidity and iron ion from peat water were investigated.

2. Materials

Four adsorbents were used in these experiments which are natural zeolite, zeolite modified by cationic surfactant, activated carbon and limestone. All adsorbents were prepared with equivalent sizes of 1.18 mm – 2.00 mm. Hydrochloric acid (HCl) and sodium hydroxide (NaOH) were used for polishing zeolite during the preparation phase and for pH adjustment of the sample. Furthermore, potassium dichromate (K2CrO7), silver sulphate (Ag2SO4), sulphuric acid (H2SO4) and mercury (II) sulphate (HgSO4) were used as digestion solution reagents and acid reagents for COD analysis. Lastly, Uniquat (QAC-50) was used as cationic surfactant to modify the zeolite.

2.1  Preparation of Surfactant Modified Zeolite

In these studies, 100 g of prewashed natural zeolite was contacted with 5.6 ml/l Uniquat (QAC-50) as cationic surfactant (CSMZ). The mixture was then stirred at room temperature for 4 hours at 300 rpm (Karadag et al., 2007). The zeolite then was filtered and washed with distilled water several times. After that, the absorbent was dried in an oven at a temperature of 105 °C for 15 hours.

2.2  est Procedures

2.2.1 Batch Studies

Serial batch studies were conducted at room temperature (28 ± 1 °C) to investigate the influence of pH and dosage for removing colour, COD, turbidity and iron ion from peat water. Shaking speed of 200 rpm for 20 minutes were fixed and operated respectively. A working volume of 150ml peat water sample was set up in 250 ml conical flasks. Preceding the batch studies, initial concentration for those parameters was determined. The optimum pH and dosage of absorbent were determined. Subsequently, the percentage of removal was finally determined, plotted, and compared.

2.2.2 Batch Column Studies

Column studies were carried out using a plastic column with dimensions: 5.4 cm diameter and 48 cm length. Three adsorbents were filled inside the column at a specific depth with the supporting layers of marbles, cotton wool, and perforated net. Total volume of 2000 ml peat water was pumped in the up flow mode from the vessel into the column by using a Masterflex peristaltic pump at a minimum flow rate of (30, 60, 90) ml/min. In this study, however, column studies were performed un-continuously (batch) due to limitations of time. All parameters related to the column design are summarized in the following Table 1.

Table 1. Column studies parameters

 

Parameters

Unit Value
Diameter,

cm

5.4

Horizontal Surface Area, A cm2

22.9

Column volume, V cm3 1099.3
Flowrate, Q ml/min 30, 60, 90
Surface Loading Rate, SLR= Q/A cm/min 1.31, 2.62, 3.93

 

The serial sequence arrangements of adsorbents were conducted as shown in Figure 1 below. Effluent samples were collected at various time intervals, whilst maintaining room temperature, and analysed.

 Figure 1

 

Figure 1. Schematic diagrams of lab-scale column studies

 

3. Results and Discussion

3.1 eat Water Characterization

Surface water originating from the peat swamp forest was taken from Beriah peat swamp river along the Kerian River on several occasions as the main sample. The characterization of peat water was carried out at the sampling point (in-situ measurement) using a multi-parameter probe as well as in the environmental laboratory of civil engineering, USM. Fundamentally, the characterization procedures were based on the Standard Methods for the Examination of Water and Wastewater (APHA, 1992). Table 2 represents the peat water characteristics in average value and the comparison to the standard drinking water quality in Malaysia.

Table 2. The characteristics of peat water sample from Beriah Peat Swamp Forest

 

Parameters

Unit

Average Value

pH

-

4.67 – 4.98
Temperature

°C

27.8

TDS

mg/L

20.6

DO

mg/L

3.4

Conductivity uS/cm

34.5

Salinity

Ppt

0.02

Color

TCU

224.7
Turbidity

NTU

20.8

COD

mg/L

33.3

Iron, (Fe)

mg/L

1.24

NH3-N

mg/L

0.51

 

 

 

Thirteen parameters were successfully determined where the first six parameters, including pH, temperature, TDS, DO, conductivity, and salinity were measured at the sampling point, whilst the rest of the parameters, including colour, turbidity, COD, iron ion, Ammoniacal Nitrogen, NH3-N, Ammonia (NH3), and Ammonium (NH4+) were examined from the sample brought to the environmental laboratory on the same day.

Acidic pH of the peat water was predicted due to the composition of the surrounding peat soil itself which had been formed by decaying material possessing humic substances (Rieley, 1992). Besides that, humic substances also lead to the high organic content as humic substances are comprised of numerous oxygen containing functional group and fractions (humic acid, fulvic acids and humin) with different molecular weights which mean yielding high concentration of turbidity and COD as well as coloured water (Torresday et al., 1996). Moreover, composition of peat soil may also have an impact on the iron ion concentration of peat water (Botero et al., 2010).

From the thirteen parameters, five parameters were indicated exceeding the standard limit. These parameters were pH, colour, turbidity, COD, and iron ion that showed values of 4.67 – 4.98, 224.7 TCU, 20.8 NTU, 33.3 mg/l, and

1.24 mg/l respectively while the standard limit of these parameters are 6.5 – 9.0, 15 TCU, 5 NTU, 10 mg/l, and 0.3 mg/l accordingly.

3.2  Effect of Initial pH on the Efficiency of Colour, COD, Turbidity, and Iron Ion (Fe) Removal

Influence of initial pH on the adsorption capacity for removing colour, COD, turbidity, and iron ion were investigated.

Figure 2(a) to Figure 2(d) below, displayed the percentage removal of colour, COD, turbidity, and iron ion against pH of adsorbents respectively.

Figure 2a to 2d

 

 

Figure 2(a) shows the maximum removal percentage of colour that was removed by natural zeolite, CSMZ, and granular activated carbon (GAC) which were 79%, 90%, 82% respectively. This adsorption is depended on the characteristic of adsorbents itself. For zeolite and CSMZ were related to the amount of cationic ions (Al3+) increased, resulting in high reaction activity and GAC was related to the adsorption capacity. It was observed that the adsorption capacity was highly dependent on the pH of the solution, and indicated that the colour removal efficiencies decreased with the increase of solution pH.

 

The pH of the system exerts profound influence on the adsorptive uptake of adsorbate molecules presumably due to its influence on the surface properties of the adsorbent and ionization or dissociation of the adsorbate molecule. Figure 2(b) represents the percentage removal of natural zeolite and CSMZ where they reach optimum efficiency in removing organic compound (COD) at pH 2 with efficiency of 53% and 60% respectively. Meanwhile, the highest percentage removal of COD for GAC was achieved at pH 4 with efficiency obtained about 61%. Identical trends in colour removal were exhibited in percentage removal of COD for natural zeolite, CSMZ and GAC. In fact, this result also reveals that GAC has the highest percentage removal among natural zeolite and CSMZ yet optimum in difference pH solution. Neutralization mechanism occurs in low pH makes color removal, COD removal and Turbidity removals at pH 2 are higher for most of absorbents in this process.

In Figure 2(c), percentage turbidity removal against pH for each adsorbent revealed that optimal reduction of turbidity was obtained in an acidic environment with efficiency removal of 96%, 98%, 95% for natural zeolite, CSMZ, and GAC respectively. When the pH of the solution was adjusted above pH 6 to pH 12, the tendencies of all adsorption performances were gradually decreased. Moreover, it also showed that the lowest efficiency for the three adsorbents were identified at pH 12 with percentage values removal 55%, 61%, and 59% for natural zeolite, CSMZ, and GAC respectively.

Figure 2(d) demonstrates the removal efficiencies of iron ion as a function of the influent pH. The maximum removal of iron ion was observed at pH 8 for both natural zeolite and CSMZ whereas GAC had its optimum removal at pH 6. Natural zeolite and CSMZ only yielded 73% and 62% removal efficiency while GAC had more significant removal with removal efficiency of 80% to the iron ion concentration. Further, it is evident from the graph that gradual increment of removal efficiency for natural zeolite, CSMZ, and GAC occurred when the initial pH of the solution was increased to higher values. Somehow, at pH values greater than 6 the removal efficiency of GAC reduced slightly while for natural zeolite and CSMZ the reduction occurred from pH values above 8.

3.3  Effect of Adsorbent Dosage on the Efficiency of Colour, COD, Turbidity, and Iron Ion (Fe) Removal

The effect of adsorbent dosage was studied for all adsorbents employed on colour, COD, turbidity, and iron ion removal by varying the dosage of adsorbent and keeping all other experimental conditions constant. The pH was set to acidic conditions which were most favourable in obtaining the highest removal efficiency. In this study, to find optimal adsorbent dosage of natural zeolite and CSMZ, the appropriate experiments were carried out at adsorbent dosages in the range of 0.5 g to 5.0 g while for GAC, the adsorbent dosage was varied from 0.01 g to 4.0

  1. The experimental results for all the adsorbents are represented by Figure 3(a) to Figure 4(d).

Figure 3a to 4d

 

Figure 3. Percentage of color (a), COD (b), turbidity (c), and Fe (d) removal against pH for NZ, and CSMZ

 

Figure 3(a) displays the relationship between the amount of adsorbent mass (dosage) and adsorption efficiency for natural zeolite and CSMZ in terms of removing colour. The colour removal of peat water increased from about 25% to 52% with increasing adsorbent dosage of natural zeolite from 0.5 g to 3.5 g whereas for CSMZ, removal percentage increased from 41% to 53% with increasing adsorbent dosage from 0.5 g to 2.0 g. However, further increase in adsorbent dosage to 5.0 g only led to slight degradation of removal efficiency to 50% and 41% for natural zeolite and CSMZ respectively. This degradation with further increases in adsorbent dosage was due to the unsaturated adsorption active sites during the adsorption process since the adsorbates in the vessel were only shaken for 20 minutes (insufficient time). Besides, modification of zeolite by cationic surfactant had proven to have better colour removal as presented in the graph.

Percentage removal of COD against the adsorbent dosage is shown in Figure 3(b). It was observed that the highest percentage removal for both natural zeolite and CSMZ to remove COD were 51% and 59%, achieved at adsorbent dosage 3.5 g and 2.0 g respectively.

The variations in removal of turbidity of peat water at various system pH are shown in Figure 3(c). The removal rate of turbidity was highest at the adsorbent dosage of 0.5 g with 70% and 93% removal efficiency for respective natural zeolite and CSMZ. The removal rate showed a smooth downward trend with the increase in adsorbent dosage. Concurrently, the adsorption capacity gradually decreased with the increasing adsorbent dosage. The least efficient removal of turbidity was noted at dosage 5.0 g with percentage removal recorded for natural zeolite and CSMZ only 57% and 70% respectively.

Figure 3(d) demonstrates the percentage iron ion removal of natural zeolite and CSMZ with respect to their dosage. The result shows that there was a significant difference trend in iron ion adsorption efficiencies between natural zeolite and CSMZ. For natural zeolite, it was shown that the removal percentage of iron ion had increased until it reached 1.0g of dosage with 72% of removal efficiency. On the other hands, CSMZ was only able to remove about 63% of iron ion when its dosage was increased to 2.5 g. The lowest percentage removals were 47% and 57% recognized at the adsorbent dosage 5.0 g for respective natural zeolite and CSMZ.

Figure 4

 

 

Figure 4. Percentage of color (a), COD (b), turbidity (c), and Fe (d) removal against dosage for GAC

The result illustrated in Figure 4(a) shows the maximum removal percentage of colour for GAC at 2.5 g dosage was 62%. Moderate increment in colour removal was identified along with the addition dosage of 2.5 g whilst abatement of removal efficiency began subsequently at adsorbent dosage of 3.0 g to 4.0 g.

The results from Figure 4(b) indicated that increasing the GAC dosage would increase the efficiency in removing COD respectively. The optimum dosage was recorded at 3.0 g with 72% of removal efficiency. Meanwhile, increasing the dosage above 3.0 g exhibited a slight decrease in removal efficiency with 67% to 61% for COD removal. A better result in removing COD was also shown by GAC compared to the natural zeolite and CSMZ.

The percentage of turbidity removed by GAC in different dosages is described in Figure 4(c). The highest removal was indicated at adsorbent dosage 2.5 g with removal efficiency of 70% while the minimum removal was 52% recorded at the adsorbent dosage 0.01 g. However, starting from adsorbent dosage of 3.0 to 4.0 g, removal efficiency began to decrease to 68%, 67%, and 69% respectively.

The result of percentage removal of iron ion by GAC in peat water is presented in Figure 4(d). It was found that the rate of removal was rapid in the initial dosage between 0.01 g to 3.0 g at which the removal efficiency increased from 28% to 71% accordingly. Subsequently, a few significant changes in the rate of removal were observed. Possibly, at the beginning, the solute molecules were absorbed by the exterior surface of adsorbent particles, so the adsorption rate was rapid. However, after the optimum dose was reached, the adsorption of the exterior surface becomes saturated and thereby the molecules will need to diffuse through the pores of the adsorbent into the interior surface of the particle (Ahmad & Hameed, 2009).

3.4 Batch Column Experiment

On the first running, the column was packed with natural zeolite (1st layer), limestone (2nd layer), and GAC (3rd layer) as shown in Figure 5(a). Removal efficiency for colour, COD, turbidity, and iron ion was recognized to be increased when the contact time was increased. At the time interval 1 hour to 6 hours, however, the increment was not so significant. The removal efficiency at 1 hour treatment was 39%, 21%, 54%, 36% while at 6 hours treatment was 77%, 65%, 73%, 60% recorded for respective colour, COD, turbidity, and iron ion. Poor removal efficiency at 1 hour treatment indicated that the required time to remove all parameters were insufficient. It is evident that if the adsorption process is allowed to run for 24 hours on the column, the removal efficiency shows notable removal. Percentage removals of colour, COD, turbidity, and iron ion at 24 hours were 83%, 72%, 76%, 65% respectively. Furthermore, the highest removal for respective colour, COD, turbidity, and iron ion were obtained at 48 hours treatment with 87%, 81%, 86%, and 79% of removal efficiency.

Figure 5

 

 

Figure 5. Percentage removal of color, COD, turbidity, and Fe for 1st run(a), 2nd run(b), and 3rd run (c) at flowrate 30 ml/min

On the second running, the column was packed with CSMZ (1st layer), limestone (2nd layer), and GAC (3rd layer) as presented in Figure 5(b). The removal percentages of colour, COD, turbidity, and iron ion were noticed after 1 hour to be 52%, 49%, 71%, and 30% respectively. The time of contact between adsorbate and adsorbent is proven to play an important role during the uptake of pollutants from peat water samples by adsorption process. In addition, the development of charge on the adsorbent surface was governed by contact time and hence the efficiency and feasibility of an adsorbent for its use in water pollution control can also be predicted by the time taken to attain its equilibrium (Sharma, 2003). Removal efficiency of 90% for colour, 81% for COD, 91% for turbidity, and 57% for iron ion were obtained at 24 hours of contact time.

On the third running, the column was packed with a difference sequence of CSMZ (1st layer), GAC (2nd layer), and limestone (3rd layer) demonstrated in Figure 5(c). It can be seen that the adsorption of these four parameters were slightly rapid at time interval 1 hour to 6 hours treatment. Further gradual increment with the prolongation of contact time form 24 hours to 48 hours has also occurred. Observation at 1 hour treatment recorded the removal efficiency of 62%, 58%, 87%, and 48% for respective colour, COD, turbidity, and iron ion. Whereby, 6 hours treatment had yielded higher removal percentage removal of 75%, 77%, 93%, and 58% respectively for colour, COD, turbidity, and iron ion. Further removal of colour, COD, turbidity, and iron ion was recorded when the treatment was run for 24 hours which exhibited 92%, 91%, 98%, 77% of removal efficiency respectively. Prolonged time to 48 hours indeed showed better removal of colour, COD, turbidity, iron ion with percentage removal of 95%, 100%, 99%, and 89% respectively. It can be seen that the arrangement of CSMZ, GAC, and limestone has the highest removal efficiency for all parameters at the flow rate influent of 30 ml/min.

Figure 6

 

 

Figure 6. Percentage removal of color, COD, turbidity, and Fe against contact time for 2nd run(a) at flow rate 60 mL/min and at flowrate 90 mL/min (b)

The experimental adsorption behaviour was further seen for its adsorption capacity during 60 ml/min and 90 ml/min flow rate. In addition, the flow rate adjustment had also resulted in differences in surface loading rate in which the sample going through the surface area of adsorbent bed (horizontal surface area, A= 22.9 cm2) for 30 ml/min equals to 1.31 cm/min while the flow rate of 60ml/min equals to 2.62 cm/min, and the flow rate of 90 ml/min equals to 3.93 cm/min. The percentage removal for both flow rate adjustments of CSMZ, GAC, and limestone arrangement were exhibited in Figure 6 (a) and Figure 6 (b). Based on these Figures, lower removal efficiencies were indicated at 1 hour time interval of 6 hours of contact time. The percentage removals for both 60 ml/min and 90 ml/min flow rate at 1 hour were 57%, 56%, 80%, 38% and 49%, 58%, 61%, 35% for colour, COD, turbidity, and iron ion respectively. Subsequently, when the contact time was at 6 hours, the removal percentage were 70%, 79%, 88%, 56%, and 60%, 77%, 70%, 47%. However, the maximum removal efficiency at 48 hours for both flow rates was not much different from the 30ml/min flow rate.

3.5 Adsorption Isotherm

In the present investigation, the experimental data were tested with respect to both Freundlich and Langmuir isotherms. Based on the linearized Freundlich isotherm models for natural zeolite, CSMZ, GAC in terms of adsorptive capacity to remove colour, COD, turbidity, and iron ion, the majority of them exhibited fits for all adsorbate with regression value (R2) above 0.6, except for iron ion and turbidity for respective CSMZ, and GAC. On the other hand, the linearized Langmuir isotherm models for natural zeolite, CSMZ, GAC in terms of adsorptive capacity to remove colour, COD, turbidity, and iron ion, had exhibited fits for all adsorbate with regression value (R2) was at range of 0.242 to 0.912. The Langmuir isotherm model for all adsorption mechanisms were identified to have smaller R2 values compared to the Freundlich isotherm model. Thereby, it can be concluded that the Freundlich isotherm model was more applicable in determining the adsorption mechanisms for this study.

3.6  Peat Water Quality Post Column Treatment

Peat water treatment in column with serial sequence of natural zeolite, CSMZ, and limestone had exhibited the highest removal with percentage removal at 48 hours at 95%, 100%, 99%, and 89% for colour, COD, turbidity, and iron ion respectively. Final readings at 48 hours treatment on pH, TDS, DO, conductivity, salinity, colour, turbidity, COD, and iron ion were 7.78, 74 mg/l, 4.03 mg/l, 137 uS/cm, 0.05 ppt, 12 TCU, 0.23 NTU, 0 mg/l, and 0.11 mg/l respectively (see Table 3). These findings, on the other hand, have indicated that peat water treatment had successfully produced water which satisfied the standard drinking water quality.

Table 3. The characteristics of   results of peat water treatment from Beriah Peat Swamp Forest

Table 3

 

Note: 1. *)Malaysian standard for drinking water quality;2. NA = Not analyzed.

4. Conclusions

From the results presented in this paper, the following conclusions can be drawn:

1)       The optimum removal of colour, COD, and turbidity for all adsorbents were observed to occur during acidic conditions at pH range 2 – 4 whereas for iron ion, the maximum removal was noted at pH range 6 – 8.

2)       At pH 2, CSMZ yielded the highest removal for colour and turbidity with removal efficiency of 90% and 98% respectively. Meanwhile, GAC has the highest percentage removal of COD at pH 4 with removal efficiency obtained about 61% while at pH 6, GAC exhibited the best removal of iron ion with percentage removal around 80%.

3)       CSMZ revealed stronger adsorptive capacity for colour, COD, and turbidity compared to natural zeolite.

4)       The optimal removal was achieved for the serial sequence of CSMZ (1st layer), GAC (2nd layer), and Limestone (3rd layer) with the adsorbent media at 30 ml/min of flow rate.

5)       Freundlich isotherm was more reliable to describe the adsorption mechanisms of colour, COD, turbidity, and iron ion for natural zeolite, CSMZ, and GAC.

Acknowledgement

The authors wish to acknowledge the financial support from the School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia and Universiti Sains Malaysia (Short Term Grant No. 304/PAWAM/60312015).

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Paune, F., Caixach, J., Espadaler, I., Om, J., & Riveraet, J. (1998). Assessment on the removal of organic chemicals from raw and drinking water at a Llobregat river water works plant using GAC. Water Research, 32(11), 3313-3324. http://dx.doi.org/10.1016/S0043-1354(98)00108-0

Rieley, J. O. (1992). The ecology of tropical peatswamp forest ± a South-east Asian perspective. In Tropical Peat, Proceedings of International Symposium on Tropical Peatland, Kuching, Sarawak, Malaysia, 6±10 May 1991

(B.Y.  Aminuddin, ed.) pp.  244±54. Kuching, Malaysia:  Malaysia  Agricultural Research  Development Institute & Department of Agriculture, Sarawak, Malaysia

Syafalni, S., Abustan, I., Dahlan, I., & Wah, C. K. (2012b). Treatment of Dye wastewater Using Granular Activated Carbon and  Zeolite  Filter. Modern Applied Science,  6(2), 37-51. http://dx.doi.org/10.5539/mas.v6n2p37

Syafalni, S., Abustan, I., Zakaria, S. N. F., & Zawawi, M. H. (2012a). Raw water treatment using bentonite-chitosan as a coagulant. Water Science & Technology: Water Supply, 12(4), 480-488. http://dx.doi.org/10.2166/ws.2012.016

Torresdey, J. L., Tang, L., & Salvador, J. M. (1996). Copper adsorption by esterified and unesterified fractions of sphagnum peat moss and its different humic substances. Journal of Hazardous Materials, 48,  191-206. http://dx.doi.org/10.1016/0304-3894(95)00156-5

World Wildlife Fund (WWF) Malaysia. (2004). The importance of rivers.

Wosten, J. H. M., Clymans, E., Page, S. E., Rieley, J. O., & Limin, S. H. (2008). Peat- Water interrelationships in a          Tropical Peatland Ecosystem in Southeast Asia. Catena, 73, 212-224. http://dx.doi.org/10.1016/j.catena.2007.07.010

Zhang, P., Tao, X., Li, Z., & Bowman, R. S. (2002). Enhanced Perchloroethylene Reduction in Column Systems Using Surfactant Modified Zeolite/zero-valent Iron Pellets. Environmental Science and Technology, 36, 3597-3603. http://dx.doi.org/10.1021/es015816u

Modern Applied  Science;  Vol.  7,  No.  2;  2013

ISSN 1913-1844     E-ISSN 1913-1852

Published by Canadian Center of Science and Education

S. Syafalni1, Ismail Abustan1, Aderiza Brahmana1, Siti Nor Farhana Zakaria1 & Rohana Abdullah1

1 School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Penang, Malaysia. Correspondence:  S. Syafalni,  School of Civil Engineering, Engineering Campus,  Universiti Sains Malaysia,

Nibong Tebal 14300, Penang, Malaysia. E-mail: cesyafalni@eng.usm.my

Received: December 3, 2012        Accepted: January 14, 2013        Online Published: January 22, 2013 doi:10.5539/mas.v7n2p39                                                     URL: http://dx.doi.org/10.5539/mas.v7n2p39

Shared via Creative Commons Attribution 3.0 Unported license

 

Categories : Case Studies & Application Stories, Science and Industry Updates

Conductivity as alternative measurement for WWTP inflow dynamics – MyronLMeters.com

Posted by 11 Apr, 2013

Tweet Myron L Meters Myron L Meters sells the most accurate, reliable conductivity instruments in the water treatment industry.  You can find some of our most popular meters here: http://www.myronlmeters.com/SearchResults.asp?Search=conductivity&x=-1345&y=-145 Introduction Along with the development of  more and more complex integrated models for urban water systems the need of sufficient  data  bases grows as well. […]

Myron L Meters

Myron L Meters sells the most accurate, reliable conductivity instruments in the water treatment industry.  You can find some of our most popular meters here:

http://www.myronlmeters.com/SearchResults.asp?Search=conductivity&x=-1345&y=-145

Introduction

Along with the development of  more and more complex integrated models for urban water systems the need of sufficient  data  bases grows as well. It is even complicated to measure relevant parameters,e.g. dissolved nitrogen or COD, for their use in Waste Water Treatment Plants and sewer models to describe the influence of catchments to the receiving water.

This poster presents a method regarding the possibility of substituting an online ammonia measurement by conductivity measurements in the inflow of a Waste Water Treatment Plant . The aim was the description of the dynamics in wet weather flow through storm water events for modelling purposes.

The conductivity of an aqueous solution is the measure of its ability to conduct electricity. Responsible for that phenomenon are ions of dissolved salts. In natural and drinking water these are mainly carbonates, chlorides and sulphates of calcium, magnesium, sodium and potassium. Conducted experiences and measurements in combined sewers showed a relation between conductivity in Waste Water Treatment Plant inflow and the concentration of dissolved components, e.g. ammonia, in case of rainfall events. The data for different 3 Waste Water Treatment Plant are shown in Figure 1. Rainwater has nearly no ions that cause conductivity to be measured. Therefore, diluted wastewater flowing into the Waste Water Treatment Plant can be detected by a conductivity probe. The measure and quality of linear regression between ammonia concentration and conductivity can be found in Table 1 for all data from Figure 1.

Material and Methods

With this knowledge a simple regression-based inflow model for use in activated sludge modelling of Waste Water Treatment Plant was defined to use conductivity beside available composite samples as a measure for dynamics in ammonia concentration as one of the most dynamic measure.

Results and Discussion

For one of the considered Waste Water Treatment Plants (WWTP) the resulting quality for the inflow model is shown in Figure 2 for a time series of a week.

Furthermore, the inflow model was used as a source for a retention tank model at the inlet of another Waste Water Treatment Plant to describe the impact of different management strategies (storage or flow through) on receiving water and Waste Water Treatment Plant (Figure 3).

A long-term modelling of 9 storm water events was used to show the predictive capacity of the model. The regression parameters were fitted by an optimisation routine to get best fit for all concentrations (also for COD, not presented here). Figure 3 shows the fit for all events. A good prediction of dynamics and absolute values for ammonia can be seen.

The results of different Goodness-of-fit measures are summarized in Table 2 for both presented WWTP inflows. Especially the values for the modified Coefficient of Efficiency, as a well-known and used measure for model quality in hydrological sciences, show the degree of predicting of the used method and the usability of conductivity for description of influent dynamics to Waste Water Treatment Plant in storm water cases.

 Conclusions

This simple and easy-to-use method is well suited for implementation in Waste Water Treatment Plant models to describe the inflow dynamics regarding a more realistic behavior e.g. for optimization of process control.

by Markus Ahnert*, Norbert Günther*, Volker Kuehn*, University of Dresden 

References
Ahnert, M., Blumensaat, F., Langergraber, G., Alex, J., Woerner, D., Frehmann, T., Halft, N., Hobus, I., Plattes, M., Spering, V. und Winkler, S. (2007), Goodness-of-fit measures for numerical modelling in urban water management – a summary to support practical applications., paper presented at 10th IWA Specialised Conference on “Design, Operation and Economics of Large Wastewater Treatment Plants”, 9-13 September 2007, Vienna, Austria, 9-13 September 2007.

Nash, J. E. und Sutcliffe, J. V. (1970), River flow forecasting through conceptual models part I – A discussion of principles, Journal of Hydrology, 10, 282.

IWA Water Wiki (http://www.iwawaterwiki.org) / CC BY-SA 3.0

Figure 1

Table 1

Figure 2

Figure 3

Table 2

 

Categories : Case Studies & Application Stories, Science and Industry Updates

Testing Hydroponics System’s Nutrient Solution – MyronLMeters.com

Posted by 3 Apr, 2013

TweetTDS meter Whether or not you’re a newcomer to hydroponic growing, keeping your hydroponic system’s nutrient solution properly balanced with a satisfactory nutrient concentration can be tough. Regular testing of one’s t solution is required if you want to keep the hydroponic system balanced and your plants healthy and growing. The simplest way to keep […]

TDS meter

Whether or not you’re a newcomer to hydroponic growing, keeping your hydroponic system’s nutrient solution properly balanced with a satisfactory nutrient concentration can be tough. Regular testing of one’s t solution is required if you want to keep the hydroponic system balanced and your plants healthy and growing. The simplest way to keep your nutrient solution balanced is via testing. You must check your solution’s pH level and nutrient concentration no less than every couple of days. To be able to try out your solution you need a few basic devices. You need to get a trusted pH tester and either an overall total Dissolved Solids (TDS) meter or perhaps a Conductivity (EC) meter.

pH tester

It is generally agreed that the pH of one’s nutrient solution should be kept slightly acidic using a pH range of 5.5-6.0. You will find exceptions for this generalization. If you are unsure what are the best pH range is for the plants you might be growing, there are many resources open to guide you. You can find three basic means of testing pH. The least expensive technique is paper testing strips. They’re simple to use but could be difficult to learn. Typically the most popular testing way is liquid test kits. This method is extremely accurate and easier to see than paper testing strips but it is also more expensive. An electronic digital pH meter may be the last available option. Digital pH meters are available in various shapes, sizes, and price ranges. The benefit of an electronic pH meter is that it can be really user friendly, fast, and accurate. However, they are the most costly of the testing options, they can break easily, plus they has to be calibrated frequently if you’d like them to remain accurate.

TDS tester

Both conductivity meters and TDS meters are used to look at the strength, or concentration, of your hydroponic nutrient solution. Even though it is crucial that you know the concentration of your solution, this is because measurements ought to be used being a guideline only. EC meters will almost always be measured much the same way. Two sensors they fit within the solution being tested along with a little bit of electricity is emitted by one sensor and received by the other sensor. How well the electricity travels is then based on the EC meter. The harder electricity conducted, the greater the power of solids in the solution. A TDS meter uses the EC after which calculates the amount of solids inside the solution according to among three conversion factors. Considering that the TDS is dependant on a calculation, it really is only a quote of solids in the nutrient solution.

With this particular basic comprehension of the main difference between TDS and conductivity meters you can determine which measurement process is best for you. When you use a packaged nutrient solution, browse the product label to learn which kind of meter the maker recommends. In the event the manufacturer recommends a TDS, they’ll also inform you which conversion step to use as well as the recommended concentration range for his or her product. If you use a homemade nutrient solution plus a TDS meter, a great general guideline is to keep your TDS between 800 and 1200 ppm (ppm). If you work with an EC meter to test your homemade nutrient solution, a good range is 1.0 to 3.0 mS/cm (milisiemens per centimeter).

This information will help keep your hydroponics nutrient solution balanced and your plants healthy.

Myron L Meters has the perfect solution for hydroponics testing – the Ultrapen Combo.

ULTRACOMBO – ULTRAPEN PT1  Conductivity – TDS – Salinity pen & PT2  - pH – Temp Pen

Accuracy of +/-1% of READING (+/-.2% at Calibration Point)
Accuracy of +/- 0.01 pH
Reliable Repeatable Results
Solution modes: KCl, NaCl and 442
Automatic Temperature Compensation
Autoranging
Durable, Fully Potted Circuitry
Comes with 2oz bottle of pH Storage Solution
Waterproof

Ultrapen Combo

List Price: $318.00 

Exclusive Online Price: $280.50

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Material Shared via Creative Commons Attribution-Share Alike 2.5 Croatia, original found here: http://blog.dnevnik.hr/nathanielwhite566668/2012/02/1629933596/tds-meter.html

 

 

 

 

Categories : Application Advice, Case Studies & Application Stories, Technical Tips

Testing Fountain Solution Conductivity – MyronLMeters.com

Posted by 1 Apr, 2013

Tweet WHY TEST FOUNTAIN SOLUTIONS? Accurate fountain (dampening) solution concentration control is essential for consistent, high-quality results in lithography. Low concentration can cause drying on the non-image area of the plate resulting in tinting, scumming, blanket piling, etc. High concentrations, on the other hand, bring about over-emulsification of the ink. This results in weakening of […]

WHY TEST FOUNTAIN SOLUTIONS?

Accurate fountain (dampening) solution concentration control is essential for consistent, high-quality results in lithography. Low concentration can cause drying on the non-image area of the plate resulting in tinting, scumming, blanket piling, etc. High concentrations, on the other hand, bring about over-emulsification of the ink. This results in weakening of color strength and changes in ink rheology (body and flow properties). Correct concentration will allow the non-image areas of the plate to be appropriately wetted.

 WAYS TO TEST

Traditionally, pH was the test relied on to determine fountain solution concentration. Today, however, conductivity testing is recognized as a much more accurate method. Many modern dampening solutions are pH stabilized (or buffered), so only small changes in pH are seen even when dramatic changes occur in solution strength. Conductivity measurement is a fast and easy test which is more indicative of fountain solution concentration than pH. This is true for all neutral, alkaline, and many acid type solutions.

pH is still important, however, with unbuffered acid fountain solutions. Checking both conductivity and pH can provide valuable information. Acid fountain solution is a mixture of gum arabic, wetting agents, salts, acids, buffers, etc. Conductivity will tell you if the proper amount of most ingredients are present, but pH is necessary to check acid concentrations. pH will also determine how effective one ingredient, gum arabic, will be.

 CONDUCTIVITY TESTING

What is conductivity? Conductivity is the measurement of a solution’s ability to conduct an electrical current. It is usually expressed in microsiemens (micromhos). Absolutely pure water is actually a poor electrical conductor. It is the substances dissolved in water which determine how conductive the solution will be. Therefore, conductivity is an excellent indicator of solution strength.

To properly measure the conductivity of fountain solutions:

1.   Test and write down the conductivity of the water used to prepare the solution.

  1. Mix the fountain solution concentrate with the water, using the manufacturer’s recommendations or as experience dictates.
  2. Measure the conductivity of the mixed solution.
  3. Subtract the water conductivity value obtained in step 1. This is necessary because tap water quality can change from day to day.

The resulting number is an accurate indicator of fountain solution strength. Caution: because alcohol will lower a solution’s conductivity, always test solution conductivity before and after the addition of alcohol.

Determining the best concentration of fountain solution is mostly “trial and error.” It can be very useful to make a graph, recording readings for every one-half or one ounce of concentrate added to a gallon of water. Record readings on a graph with the vertical axis representing conductivity values and the horizontal axis representing ounces/gallon. Such a graph will help “fine tune” your system during future press runs.

For “on the spot” fountain solution tests, Myron L handheld instruments are fast, accurate, and reliable. Measurements are made in seconds simply by pouring a small sample of solution into the instrument cell cup and pressing a button. Automatic temperature compensated accuracy and famous Myron L reliability have made our instruments popular in pressrooms worldwide.

 pH TESTING

Even though pH usually is not the best method to check the concentration of fountain solution, it is still very important and must be checked regularly. The pH of acid dampening solution affects sensitivity, plate-life, ink-drying, etc. Also, pH can change during a run if the paper has a high acid or alkaline content. pH, therefore, must be maintained at the proper level for good printing.

A convenient and accurate way to test pH (as well as temperature) is Myron L’s waterproof Ultrameter II™ Model 6PFCE or TechPro II™ TH1. The 6PFCE has a 100 reading memory and the TH1 has a 20 reading memory to store test results on site. The 6P also measures conductivity. All electrodes are contained in the cell cup for protection. Model M6/PH also measures pH and conductivity.

 CONTINUOUS CONTROL

 For continuous monitoring and/or control of fountain solution concentration, Myron L offers a complete series of in-line conductivity instruments. These economical, accurate, and reliable models use a remotely installed sensor and a panel/wall mount meter enclosure. Most contain an adjustable set point and heavy duty relay circuit which can be used to activate alarms, valves, feedpumps, etc. All models contain a 0-10 VDC output for a chart recorder or PLC (SCADA) input, if required, (4-20 mA output is also available).

The 750 Series II with dual set point option has become quite popular in pressrooms. The two set points allow a “safe zone” for controlling fountain solution concentration.

LITHO-KIT™

Ultrameter II 6PFCE, 512M5 and M6/PH are available with the useful LITHO-KIT™. This accessory includes a foam-lined, rugged all-plastic carry case with calibrating solutions and buffers. In addition, a syringe to simplify drawing samples and a thermometer for testing fountain solution temperature are also included.

 

PROBLEM

REMEDY

RECOMMENDED MODELS
Improperly mixed fountain solution Carefully follow manufacturer’s directions, checking both water and mixed solution with a conductivity instrument Ultrameter 4PII, 6PIIFCE and 9PTK; ULTRAPEN PT1; and TechPro II TPH1 or TP1 all test 0-9999 ppm TDS or microsiemens conductivity, and temperature. 512M5 por- table DS Meter™ with a 0-5000 microsiemens conductivity range.
Halftones sharpen and highlight dots lost during run Check pH of fountain solution to determine if it’s too acidic Ultrameter 4PII, 6PIIFCE and 9PTK; ULTRAPEN PT2; and TechPro II TH1.M6/PH portable pDS Meter. Ranges: 0-5000 microsiemens and 2-12 pH.
Reverse osmosis water treatment system monitor indicates membrane failure Test RO water quality and verify in-line instrument accuracy Ultrameter 4PII, 6PIIFCE  and 9PTK; ULTRAPEN PT1; and TechPro II TPH1 or TP1 all test 0-9999 ppm TDS or microsiemens conductivity, and temperature.
Scum streaks across plate after 10,000 – 20,000impressions Check acid/gum levels infountain solution Ultrameter 6PIIFCE and 9PTK; ULTRAPEN PT2; and TechPro II TH1.M6/PH portable pDS Meter. Ranges: 0-5000 microsiemens and 2-12 pH.
Personnel unable to test fountain solution concentration Continuously control fountain solution with conductivity Monitor/controller 758II-123 (0-5000 µS) in-lineMonitor/controller.

You can save 10% on any recommended meter at MyronLMeters.com.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Categories : Application Advice, Case Studies & Application Stories, Technical Tips

Sustainability in Water Supply – MyronLMeters.com

Posted by 27 Mar, 2013

TweetSustainability in Water Supply Sustainable water systems should provide adequate water quantity and appropriate water quality for a given need, without compromising the future ability to provide this capacity and quality. Water systems in the realm of sustainable development may not literally include the use of water, but include systems where the use of water […]

Sustainability in Water Supply

Sustainable water systems should provide adequate water quantity and appropriate water quality for a given need, without compromising the future ability to provide this capacity and quality. Water systems in the realm of sustainable development may not literally include the use of water, but include systems where the use of water has traditionally been required. Examples include waterless toilets and waterless car washes, whose use helps to alleviate water stress and secure a sustainable water supply.

Accessing the sustainability features in water supply, that is to say, the three-fold goals of economic feasibility, social responsibility and environmental integrity, is linked to the purpose of water use. Sometimes, these purposes compete when resources are limited; for example, water needed to meet the demands of an increasingly urban population and those needs of rural agriculture. Water is used (1) for drinking as a survival necessity, (2) in industrial operations (energy production, manufacturing of goods, etc.), (3) domestic applications (cooking, cleaning, bathing, sanitation), and (4) agriculture. Sustainable water supply is a component of integrated water resource management, the practice of bringing together multiple stakeholders with various viewpoints in order to determine how water should best be managed. In order to decide if a water system is sustainable, various economical, social and ecological considerations must be considered.

Surface water

Surface freshwater is unfortunately limited and unequally distributed in the world. Almost 50% of the world’s lakes are located in Canada alone (UNEP, 2002). In addition, pollution from various activities leads to surface water that is not drinking quality. Therefore, treatment systems (either large scale or at the household level) must be put in place.

Structures such as dams may be used to impound water for consumption. Dams can be used for power generation, water supply, irrigation, flood prevention, water diversion, navigation, etc. If properly designed and constructed, dams can help provide a sustainable water supply. The design should consider peak flood flows (historical and projected for climate change), earthquake faults, soil permeability, slope stability and erosion, silting, wetlands, water table, human impacts, ecological impacts (including wildlife), compensation for resettlement, and other site characteristics. There are various challenges that large-scale dam projects may present to sustainability: negative environmental impacts on wildlife habitats, fish migration, water flow and quality, and socioeconomic impacts resulting from resettled local communities. A sustainability impact assessment should therefore be performed to determine the environmental, economic and social consequences of the construction.

Groundwater

Groundwater accounts for greater than 50% of global freshwater; thus, it is critical for potable water (Lozan et al, 2007). Groundwater can be a sustainable water supply source if the total amount of water entering, leaving, and being stored in the system is conserved. There are three main factors which determine the source and amount of water flowing through a groundwater system: precipitation, location of streams and other surface-water bodies, and evapotranspiration rate; it is thus not possible to generalize a sustainable withdrawal or pumping rate for groundwater (USGS, 1999). Unsustainable groundwater use results in water-level decline, reduced streamflow, and low water quality, jeopardizing the livelihood of effected communities. Various practices of sustainable groundwater supply include changing rates or spatial patterns of ground-water pumpage, increasing recharge to the ground-water system, decreasing discharge from the groundwater system, and changing the volume of groundwater in storage at different time scales (USGS, 1999). A long-term vision is necessary when extracting groundwater since the effects of its development can take years before becoming apparent. It is important to integrate groundwater supply within adequate land planning and sustainable urban drainage systems.

Rainwater Harvesting

Collecting water from precipitation is one of the most sustainable sources of water supply since it has inherent barriers to the risk of over-exploitation found in surface and groundwater sources, and directly provides drinking water quality. However, rainwater harvesting systems must be properly designed and maintained in order to collect water efficiently, prevent contamination and use sustainable treatment systems in case the water is contaminated. A number of drinking water treatments exist at point-of-use, each with advantages and disadvantages. These include solar treatment, boiling, using filters, chlorination, combined methods such as filtration and chlorination, flocculation and chlorination. Although technically given the Earth’s surface and precipitation, rainwater harvesting can meet global water demand, the solution can most practically be a supplement to sustainable water supply systems given a level of uncertainty (especially with climate change), and competing land-use applications.

Reclaimed Water

Reclaimed water, or water recycled from human use, can also be a sustainable source of water supply. It is an important solution to reduce stress on primary water resources such as surface and groundwater. There are both centralized and decentralized systems which include greywater recycling systems and the use of microporous membranes. Reclaimed water must be treated to provide the appropriate quality for a given application (irrigation, industry use, etc.). It is often most efficient to separate greywater from blackwater, thereby using the two water streams for different uses. Greywater comes from domestic activities such as washing, whereas blackwater contains human waste. The characteristics of the two wastestreams thus differ.

Desalinization

Desalinisation has the potential to provide an adequate water quantity to those regions that are freshwater poor, including small island states. However, the energy demands of reverse osmosis, a widely-used procedure used to remove salt from water, are a challenge to the adaptation of this technology as a sustainable one. The costs of desalination average around 0.81 USD per cubic meter compared to roughly 0.16 USD per cubic meter from other supply sources (USGS, 2010). If desalination can be provided with renewable energies and efficient technologies, the sustainable features of this supply source would increase. Currently, desalination increases operational costs because of the needed energy (and also carbon dioxide emissions); this in turn raises the cost of the final product. In addition, desalination plants can have negative impacts on marine life, and cause water pollution due to the chemicals used to treat water and the discharge of brine.

Bottled Water

Bottled water is a 21st century phenomenon whereby mostly private companies provide potable water in a bottle for a cost. In some areas, bottled water is the only reliable source of safe drinking water. However, often in these same locations, the cost is prohibitively expensive for the local population to use in a sustainable manner. Bottled water is not considered an “improved drinking water source” when it is the only potable source available (UN, 2010). When sustainability metrics are used to access bottled water, it falls short in many situations of being a sustainable water supply. Economic costs, pollution associated with its manufacturing (plastic, energy, etc.) and transportation, as well as extra water use, makes bottled water an unsustainable water supply system for many regions and for many brands. It takes 3-4 liters of water to make less than 1 liter of bottled water (Pacific Institute, 2008).

Potable Water

Potable water requires some of the strictest standards of quality in terms of bacteriological and chemical pollutants. These standards are often governed by national governments; international recommendations can be found from the World Health Organization (http://www.who.int/water_sanitation_health/dwq/guidelines/en/index.html). Drinking water must be freshwater and should be free of pathogens and free of harmful chemicals.

Water in Industry

Water is used in just about every industry. Industrial water withdrawls represent 22% of total global water use (significant regional differences). Its use is notable for manufacturing, processing, washing, diluting, cooling, transporting substances, sanitation needs within a facility, incorporating water into a final product, etc. (USGS, 2010). The food, paper, chemicals, refined petroleum, and primary metal industries use large amounts of water (USGS, 2010). A sustainable water supply in industry involves limiting water use through efficient appliances and methods adapted to the particular industry. Rainwater harvesting on-site (including the creation of large pond-like structures), as well as recycling water in industrial processes, can provide a sustainable water supply for industry without straining municipal water supplies. Industry releases organic water pollutants, heavy metals, solvents, toxic sludge, and other wastes into water supply sources. Industry thus has a dual responsibility for internal sustainable water supply and the protection of external water supply sources.

Water in Agriculture

Agriculture uses the largest amount of freshwater on a global scale. It represents roughly 70% of all water withdrawal worldwide, with various regional differences. In the United States, for example, agriculture accounts for over 80% of water consumption (USDA, 2010). The productivity of irrigated land is approximately three times greater than that of rain-fed land (FAO, 2010). Thus, irrigation is an important factor for sustainable agriculture systems. In addition, global food production is expected to increase by 60% from 2000 to 2030, creating a 14% increase in water demand for irrigation (UN, 2005). Agriculture is also responsible for some of the surface and groundwater degradation because of run-off (chemical and erosion-based). It thus has a dual role in sustainable water supply: (1) using water efficiently for irrigation and (2) protecting surface and groundwater supply sources. Techniques for sustainable water supply in agriculture include organic farming practices which limit substances that would contaminate water, efficient water delivery, micro-irrigation systems, adapted water lifting technologies, zero tillage, rainwater harvesting, runoff farming, and drip irrigation (efficient method that allows water to drip slowly to plant roots by using pipes, valves, tubes and emitters).

Domestic Water Uses

The average household needs an estimated 20-50 liters of water per person per day, depending on various assumptions and practices (Gleick, 1996). Reducing water use through waterless toilets, water efficient appliances, and water quantity monitoring, is an important part of sustainability for domestic water supply. Efficient piping systems that are leak-free and well insulated provide a network that is reliable and help to limit water waste. The aforementioned potable water supply sources, with their sustainability features and sustainability challenges, are all relevant to other domestic uses. Since water quality standards are not as strict for household uses as for drinking, there is more flexibility when considering sustainable domestic water supply (including the potential for reclaimed water use).

Conclusions

A water supply system will be sustainable only if it promotes efficiencies in both the supply and the demand sides. Initiatives to meet demand for water supply will be sustainable if they prioritize measures to avoid water waste. Avoiding wastage will contribute to reducing water consumption and, consequently, to delaying the need for new resources.
On the supply side, it is fundamental to enhance operation and maintenance capabilities of water utilities, reducing non-revenue water (NRW), leakages, and energy use, as well as improving the capacity of the workforce to understand and operate the system. It is also necessary to ensure cost-recovery through a fair tariff system and “intelligent” investment planning. In addition, all alternatives to increase the water supply must be analysed considering the entire life cycle.

On the demand side, the adoption of water efficient technology can considerably reduce water consumption. Investments in less water intensive industrial processes and more efficient buildings lead to a more sustainable water supply. Concrete possibilities of economic savings, social benefits (such as the involvement of different sectors of society to reach a common objective, environmental awareness of the population, etc.) and a range of environmental gains make the adoption of water efficient technologies viable.
Sustainable water supply involves a sequence of combined actions and not isolated strategies. It depends on the individual’s willingness to save water, governmental regulations, changes in the building industry, industrial processes reformulation, land occupation, etc. The challenge is to create mechanisms of regulation, incentives and affordability to ensure the sustainability of the system.

Waite1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References

Food and Agriculture Organization of the United Nations (FAO). (2010). Water Use in Agriculture. Retrieved from http://www.fao.org/ag/magazine/0511sp2.htm

Gleick, Peter H. (1996). Basic Water Requirements for Human Activities: Meeting Basic Needs.” Water International 21, 2: 83-92.

US Geological Survey. (2010). Industrial Water Use. Retrieved from http://ga.water.usgs.gov/edu/wuin.html

United States Department of Agriculture. (2010). Irrigation and Water Use. Retrieved from http://www.ers.usda.gov/Briefing/WaterUse/

Lozan, Grassl, et al. (2007). The water problem of our Earth: From climate and the water cycle to the human right for water.

UN Water for Life Decade. (2005). United Nations Department of Public Information (32948—DPI/2378—September 2005—10M).

UNEP. (2002). Vital Water Graphics: An Overview of the State of the World’s Fresh and Marine Waters. Retrieved from http://www.unep.org/dewa/assessments/ecosystems/water/vitalwater/.

Pacific Institute. Water Content of Things. The World’s Water 2008-2009.

United Nations (WHO and UNICEF). (2010). Progress on Sanitation and Drinking Water Update 2010. Retrieved from http://www.unicef.org/media/files/JMP-2010Final.pdf.

USGS. (2010). Thirsty? How ’bout a cool, refreshing cup of seawater? Retrieved from http://ga.water.usgs.gov/edu/drinkseawater.html.

USGS. (1999). Sustainability of Ground-Water Resources. Retrieved from http://pubs.usgs.gov/circ/circ1186/pdf/circ1186.pdf.

Waite, Marilyn. (2010). Sustainable Water Resources in the Built Environment. IWA Publishing: London.

Resources

Many of the issues in this article are covered in the book, Sustainable Water Resources in the Built Environment, published in 2010, written by Marilyn Waite.

Sustainable Water Resources in the Built Environment covers elements of water engineering and policy making in the sustainable construction of buildings with a focus on case studies from Panama and Kenya. It provides comprehensive information based on case studies, experimental data, interviews, and in-depth research.

The book focuses on the water aspects of sustainable construction in less economically developed environments. It covers the importance of sustainable construction in developing country contexts with particular reference to what is meant by the water and wastewater aspects of sustainable buildings, the layout, climate, and culture of sites, the water quality tests performed and results obtained, the design of rainwater harvesting systems and policy considerations.

The book is a useful resource for practitioners in the field working on the water aspects of sustainable construction (international aid agencies, engineering firms working in developing contexts, intergovernmental organizations and NGOs). It is also useful as a text for water and sanitation practices in developing countries.

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Management of Change in Water Companies – Joaquim Pocas Martins
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Arsenic in Groundwater: Poisoning and Risk Assessment – M. Manzurul Hassan, Peter J. Atkins
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Categories : Case Studies & Application Stories, Science and Industry Updates

Recent Papers in Adsorption and Ion Exchange Processes – MyronLMeters.com

Posted by 21 Feb, 2013

TweetContent Table Recent Papers in Adsorption and Ion Exchange Processes Magnetic ion exchange resin treatment for drinking water production Removal of radiocobalt from EDTA-complexes using oxidation and selective ion exchange Ammonium removal from anaerobic digester effluent by ion exchange A hybrid ion exchange-nanofiltration (HIX-NF) process for energy efficient desalination of brackish/seawater Adsorption kinetics and isotherm […]

Content Table

Magnetic ion exchange resin treatment for drinking water production

Journal of Water Supply: Research and Technology—AQUA Vol 58 No 1 pp 41–50 © IWA Publishing 2009 doi:10.2166/aqua.2009.081

Link to Summary Page

B. Sani, E. Basile, L. Rossi and C. Lubello

Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, I-50139, Florence, Italy Tel.: +39 55 479 6317 E-mail: beatrice.sani@dicea.unifi.it
Publiacqua SpA, Via Villamagna 39, I-50126, Florence, Italy

Abstract

Italian drinking water treatment plants (DWTP) generally use chlorine-based chemicals to achieve the oxidation/disinfection phases of their treatment trains. The main problem related to the application of such disinfectants consists in the formation of disinfection by-products (DBPs) as a result of the reaction with organic substances in the water. Italian regulations set very strict limits for the maximum concentration of chlorine DBPs and, for many DWTPs, the compliance with such a regulation is difficult. Non-oxidative pre-treatments, able to remove organic substances from the water prior to chlorination, could be a suitable solution to overcome this problem. These treatments could increase the water quality, decrease the oxidant demand and, hence, reduce the formation of DBPs. This paper presents an experimental investigation of ion exchange processes for the dissolved organic carbon (DOC) removal by using MIEX® resin. The process was studied as a pre-treatment on raw river water. The DOC removal efficiency and the effects on downstream processes of the treatment train were evaluated.

Removal of radiocobalt from EDTA-complexes using oxidation and selective ion exchange

Water Science & Technology—WST Vol 60 No 4 pp 1097–1101 © IWA Publishing 2009 doi:10.2166/wst.2009.458

org.xwiki.gwt.dom.client.Element#placeholderhttp://www.iwaponline.com/wst/06004/wst060041097.htm“>Link to Summary Page

L. K. Malinen, R. Koivula and R. Harjula

Laboratory of Radiochemistry, Department of Chemistry, University of Helsinki, P.O. Box 55 (A. I. Virtasen aukio 1), FI-00014, Finland E-mail: leena.k.malinen@helsinki.fi; risto.koivula@helsinki.fi; risto.harjula@helsinki.fi

Abstract

Methods for the removal of radiocobalt from an ethylenediaminetetraacetic acid (EDTA) complex of Co(II) (aqueous solution containing 10 mM Co(II) and 10 mM or 50 mM EDTA traced with 57Co) are presented. The studies examined a combination of different oxidation methods and the sorption of 57Co on a selective inorganic ion exchange material, CoTreat. The oxidation methods used were ultraviolet (UV) irradiation with and without hydrogen peroxide (H2O2), as well as ozonation alone or in combination with UV irradiation. Also, the possible contribution of Degussa P25 TiO2 photocatalyst to degradation of EDTA was studied. The best results for the equimolar solution of Co(II) and EDTA were achieved by combining ozonation, UV irradiation, Degussa P25 TiO2 and CoTreat, with approximately 94% sorption of 57Co. High values for the 57Co sorption were also achieved by ozonation (~88%) and UV irradiation (~90%) in the presence of CoTreat and Degussa P25 TiO2. A surplus of EDTA over Co(II) was also tested using 10 mM Co(II) and 50mM EDTA. Only a slight decrease, to ~88% sorption of 57Co, was detected compared to the value (~90%) obtained with 10 mM EDTA.

Ammonium removal from anaerobic digester effluent by ion exchange

Water Science & Technology—WST Vol 60 No 1 pp 201–210 © IWA Publishing 2009 doi:10.2166/wst.2009.317

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T. Wirthensohn, F. Waeger, L. Jelinek and W. Fuchs

Department of IFA-Tulln, Institute for Environmental Biotechnology, University of Natural Resources and Applied Life Sciences—Vienna, Konrad Lorenz Strasse 20, 3430 Tulln, Austria E-mail: thomas.wirthensohn@boku.ac.at; frank.waeger@boku.ac.at; werner.fuchs@boku.ac.at
Department of Power Engineering, Faculty of Environmental Technology, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6, Czech Republic E-mail: Ludek.Jelinek@vscht.cz

Abstract

The effluent of a 500 kW biogas plant is treated with a solid separation, a micro filtration and a reverse osmosis to achieve nutrient recovery and an effluent quality which should meet disposal quality into public water bodies. After the reverse osmosis, the ammonium concentration is still high (NH4-N = 467 mg/l), amongst other cations (K+=85 mg/l; Na+=67 mg/l; Mg2 + =0.74 mg/l; Ca2 + =1.79 mg/l). The aim of this study was to remove this ammonium by ion exchange. Acidic gel cation exchange resins and clinoptilolite were tested in column experiments to evaluate their capacity, flow rates and pH. Amberjet 1,500 H was the most efficient resin, 57 BV of the substrate could be treated, 1.97 mol NH4-N/l resin were removed. The ammonium removal was more than 99% and the quality of the effluent was very satisfactory (NH4-N < 2 mg/l). The breakthrough of the observed parameters happened suddenly, the order was sodium—pH—ammonium—potassium. The sharp increase of the pH facilitates the online control, while the change in conductivity is less significant. A regeneration with 3 bed volumes of 2  M HCl recovered 91.7% of the original cation exchange capacity.

A hybrid ion exchange-nanofiltration (HIX-NF) process for energy efficient desalination of brackish/seawater

Water Science & Technology: Water Supply—WSTWS Vol 9 No 4 pp 369–377 © IWA Publishing 2009 doi:10.2166/ws.2009.634

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S. Sarkar and A. K. SenGupta

Department of Civil and Environmental Engineering, Lehigh University, Fritz Engineering Laboratory, 13 E Packer Avenue, Bethlehem PA, 18015, USA E-mail: sus9@lehigh.edu;arup.sengupta@lehigh.edu

Abstract

This study reports a new hybrid ion exchange-nanofiltration (HIX-NF) process for desalination of sea and brackish water that can attain significant energy economy over the conventional membrane-based pressure driven processes. In this hybrid process, an ion exchange step converts monovalent chloride ions of saline water to divalent sulfate ions and the resulting solution, having a reduced osmotic pressure than the feed, is desalinated using a nanofiltration (NF) membrane. The sulfate rich reject stream from the NF process is used to regenerate the anion exchanger. Results validate that NF membranes can desalinate sodium sulfate solution at a much lower transmembrane pressure compared to RO membranes as well as yield a higher permeate flux. The sulfate-chloride selectivity of the anion exchangers plays important role in sustainability of the process. Laboratory studies have revealed that a single type of anion exchanger cannot sustain the process for saline water with different salt concentrations. However, anion exchangers with different sizes of amine functional groups (e.g. quaternary-, tertiary-, secondary- and primary amine) hold the promise that the process can be tailored to achieve sustainability. Laboratory studies have validated the basic premise of the hybrid process including greater than two times less energy requirement than RO process for the same feed water and same permeate recovery condition.

Adsorption kinetics and isotherm characteristics of selected endocrine disrupting compounds on activated carbon in natural waters

Water Science & Technology: Water Supply—WSTWS Vol 9 No 1 pp 51–58 © IWA Publishing 2009 doi:10.2166/ws.2009.063

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A. Assoumani, L. Favier-Teodorescu and D. Wolbert

Ecole Nationale Supérieure de Chimie de Rennes,CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35700, Rennes Cedex 4, France E-mail: azziz.assoumani@ensc-rennes.fr

Abstract

Bisphenol A (BPA) and ethynylestradiol (EE2), two representative endocrine disrupting compounds (EDCs), were tested for their adsorbabilities onto two powdered activated carbons (PACs). The main aim of the study was to create a prediction tool for the determination of the EDCs adsorbabilities at low ng.L-1 level. Single solute solution adsorption isotherms at high concentrations, for prediction purposes, and low concentrations, for verification of the prediction, were performed for one EDC/PAC couple. Over the whole range of concentration, results showed that the Langmuir-Freundlich model better suits the adsorption phenomenon than the Freundlich or Langmuir model. Kinetics experiments were carried out on the same EDC/PAC couple. HSDM modelling of single solute adsorption kinetics at high concentration allowed determining the kinetic coefficients kf and Ds; both were shown to dominate the mass transfer mechanism. Competitive adsorption isotherms at high and low concentrations showed that downward extrapolation of low concentration adsorption capacities from solely high concentration information results in acceptable error compared to the total range isotherm. The IAST-EBC approach combined with the Langmuir-Freundlich single solute model, for the target compound, and the Langmuir model, for the EBC, appears as an acceptable global model.

Influence of hybrid coagulation-ultrafiltration pretreatment on trace organics adsorption in drinking water treatment

Journal of Water Supply: Research and Technology—AQUA Vol 58 No 3 pp 170–180 © IWA Publishing 2009 doi:10.2166/aqua.2009.071

Link to Summary Page

S. Müller and W. Uhl

Institute of Urban Water Management (ISI), Chair of Water Supply Engineering, Technische Universität Dresden, Dresden, 01062, Germany Tel.:             +49-(0)351-46333126       Fax: +49-(0)351-46337204 E-mail: wolfgang.uhl@tu-dresden.de

Abstract

The treatment of raw water by hybrid coagulation-ultrafiltration was investigated. Coagulation-ultrafiltration removed high molecular weight organics, preferentially humics. Adsorption of the trace compound cis-1,2-dichloroethene, present in raw water, on granular activated carbon was improved considerably as compounds competing for adsorption space had been removed. This was shown in isotherms and breakthrough curves. Aeration during filtration did not affect membrane performance as expressed in permeability. However, aeration in the submerged membrane container resulted in a release of organic matter from the flocs, which resulted in higher concentrations of dissolved organic carbon in the filtrate.

Phosphorus adsorption on water treatment residual solids

Journal of Water Supply: Research and Technology—AQUA Vol 58 No 1 pp 1–10 © IWA Publishing 2009 doi:10.2166/aqua.2009.017

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Meaghan K. Gibbons, Md. Maruf Mortula and Graham A. Gagnon

Department of Civil and Resource Engineering, Dalhousie University, Halifax, Nova Scotia, B3J 1X1, Canada Tel.:             +1 902 494 3268       Fax:+1 902 494 3108 E-mail: graham.gagnon@dal.ca
Department of Civil Engineering, American University of Sharjah, Sharjah, PO Box, 26666, UAE

Abstract

The treatment and disposal of water treatment plant residual solids has become an increasingly important environmental priority for drinking water utilities. This study examines water treatment residual solids (WTRSs) from four North American water treatment plants to determine the role that coagulant types play in phosphate adsorption by the residual solids. In total, two alum residual solids (one solid from a plant that has a raw water with low alkalinity and one solid from a plant that has a raw water with high alkalinity), one lime residual solid and one ferric residual solid were used in batch adsorption experiments with deionized water at a pH of 6.2±0.2 and secondary municipal wastewater effluent at a pH of 6.8. Langmuir isotherm modeling showed that ferric residuals had the highest adsorptive capacity for phosphate (Qmax=2,960 mg/kg), followed by lime (Qmax=1,390 mg/kg) and alum (Qmax=1,110 mg/kg and 1,030 mg/kg) for adsorption experiments with P-spiked deionized water. Of the two alum residuals, the residual with a higher weight percent of metal oxides had a higher adsorptive capacity. The ferric residuals were less affected by competing species in the wastewater effluent, while the lime and alum residuals had a higher rate of phosphate removal from the deionized water compared to the wastewater effluent. Overall, ferric water treatment residuals were the best adsorbent for phosphate adsorption, followed by lime and alum residuals.

Influence of surface chemistry and structure of activated carbon on adsorption of fulvic acids from water solution

Water Science & Technology—WST Vol 60 No 2 pp 441–447 © IWA Publishing 2009 doi:10.2166/wst.2009.344

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L. A. Savchyna, I. P. Kozyatnyk, T. V. Poliakova and N. A. Klymenko

Institute of Colloid Chemistry and Chemistry of Water, Ukrainian National Academy of Sciences, 42 Vernadsky Avenue, Kiev 03680, Ukraine E-mail: klimenko@carrier.kiev.ua

Abstract

The adsorption of fulvic acids (FA) from aqueous solutions on activated carbon (AC) with different characteristics of surface chemical state has been investigated. To characterize the adsorbability of FA with complex fractional composition, a method of estimation of modified Freundlich equation constants was employed, and “conventional component” was used to evaluate the change in Gibbs free adsorption energy. It has been shown that change in activated carbon surface energy in-homogeneity due to oxidation leads mainly to a decrease in the adsorption energy of fulvic acids and to an increase of the concentration range of the conventional portion of the low adsorbable fraction. Decrease in the adsorption energy of organic substrate may result in higher degree of spontaneous bioregeneration of activated carbon and hence in its longer life in the processes of FA solutions filtration.

Synthesis of carboxylated chitosan and its adsorption properties for cadmium (II), lead (II) and copper (II) from aqueous solutions

Water Science & Technology—WST Vol 60 No 2 pp 467–474 © IWA Publishing 2009 doi:10.2166/wst.2009.369

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K. L. Lv, Y. L. Du and C. M. Wang

Department of Chemistry, Lanzhou University, Lanzhou 730000, China E-mail: wangcm@lzu.edu.cn

Abstract

Carboxylated chitosan (CKCTS) was prepared for the removal of Cd(II), Pb(II), and Cu(II) from aqueous solutions. The effects of experimental parameters such as pH value, initial concentration, contact time and temperature on the adsorption were studied. From the results we can see that the adsorption capacities of Cd(II), Pb(II), and Cu(II) increase with increasing pH of the solution. The kinetic rates were best fitted to the pseudo-second-order model. The adsorption equilibrium data were fitted well with the Langmuir isotherm, which revealed that the maximum adsorption capacities for monolayer saturation of Cd(II), Pb(II), and Cu(II) were 0.555, 0.733 and 0.827 mmol/g, respectively. The adsorption was an exothermic process.

Competitive adsorption of heavy metals in soil underlying an infiltration facility installed in an urban area

Water Science & Technology—WST Vol 59 No 2 pp 303–310 © IWA Publishing 2009 doi:10.2166/wst.2009.865

Link to Summary Page

M. A. Hossain, H. Furumai and F. Nakajima

Institute of Water and Flood Management, Bangladesh University of Engineering and Technology, Dhaka, 1000, Bangladesh E-mail: abed@iwfm.buet.ac.bd; abed.hossain@gmail.com
Research Center for Water Environment Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan E-mail: furumai@env.t.u-tokyo.ac.jp
Environmental Science Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan E-mail- nakajima@esc.u-tokyo.ac.jp

Abstract

Accumulation of heavy metals at elevated concentration and potential of considerable amount of the accumulated heavy metals to reach the soil system was observed from earlier studies in soakaways sediments within an infiltration facility in Tokyo, Japan. In order to understand the competitive adsorption behaviour of heavy metals Zn, Ni and Cu in soil, competitive batch adsorption experiments were carried out using single metal and binary metal combinations on soil samples representative of underlying soil and surface soil at the site. Speciation analysis of the adsorbed metals was carried out through BCR sequential extraction method. Among the metals, Cu was not affected by competition while Zn and Ni were affected by competition of coexisting metals. The parameters of fitted ‘Freundlich’ and ‘Langmuir’ isotherms indicated more intense competition in underlying soil compared to surface soil for adsorption of Zn and Ni. The speciation of adsorbed metals revealed less selectivity of Zn and Ni to soil organic matter, while dominance of organic bound fraction was observed for Cu, especially in organic rich surface soil. Compared to underlying soil, the surface soil is expected to provide greater adsorption to heavy metals as well as provide greater stability to adsorbed metals, especially for Cu.

 

Categories : Case Studies & Application Stories, Science and Industry Updates

Study of Physico-Chemical Characteristics of Wastewater in an Urban Agglomeration in Romania – MyronLMeters.com

Posted by 11 Feb, 2013

TweetStudy of Physico-Chemical Characteristics of Wastewater in an Urban Agglomeration in Romania Abstract This study investigates the level of wastewater pollution by analyzing its chemical characteristics at five wastewater collectors. Samples are collected before they discharge into the Danube during a monitoring campaign of two weeks. Organic and inorganic compounds, heavy metals, and biogenic compounds […]

Study of Physico-Chemical Characteristics of Wastewater in an Urban Agglomeration in Romania

Abstract

This study investigates the level of wastewater pollution by analyzing its chemical characteristics at five wastewater collectors. Samples are collected before they discharge into the Danube during a monitoring campaign of two weeks. Organic and inorganic compounds, heavy metals, and biogenic compounds have been analyzed using potentiometric and spectrophotometric methods. Experimental results show that the quality of wastewater varies from site to site and it greatly depends on the origin of the wastewater. Correlation analysis was used in order to identify possible relationships between concentrations of various analyzed parameters, which could be used in selecting the appropriate method for wastewater treatment to be implemented at wastewater plants.

1. Introduction

Sources of wastewater in the selected area are microindustries (like laundries, hotels, hospitals, etc.), macroindustries (industrial wastewater) and household activities (domestic wastewater). Wastewater is collected through sewage systems (underground sewage pipes) to one or more centralized Sewage Treatment Plants (STPs), where, ideally, the sewage water is treated. However, in cities and towns with old sewage systems treatment stations sometimes simply do not exist or, if they exist, they might not be properly equipped for an efficient treatment. Even when all establishments are connected to the sewage system, the designed capacities are often exceeded, resulting in a less efficient sewage system and occasional leaks.

Studies of water quality in various effluents revealed that anthropogenic activities have an important negative impact on water quality in the downstream sections of the major rivers. This is a result of cumulative effects from upstream development but also from inadequate wastewater treatment facilities. Water quality decay, characterized by important modifications of chemical oxygen demand (COD), total suspended solids (TSSs), total nitrogen (TN), total phosphorous (TP), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), and so forth [11] are the result of wastewater discharge in rivers. Water-related environmental quality has been shown to be far from adequate due to unknown characteristics of wastewater . Thus an important element in preventing and controlling river pollution by an effective management of STP is the existence of reliable and accurate information about the concentrations of pollutants in wastewater. Studies of wastewater in Danube basins can be found, for instance, in central and eastern European countries, but we are not aware of extensive studies of wastewater quality at regional/national level in Romania.

This paper analyses the chemical composition of wastewater at several collectors/stations in an important Romanian city, Galati, before being discharged into natural receptors, which in this case are the Danube and Siret Rivers. No sewage treatment existed when the monitoring campaign took place, except the mechanical separation. The study presented here is part of a larger project aiming at establishing the best treatment technology of wastewater at each station. Presently this project is in the implementation stage at all stations. Possible relationships between concentrations of various chemical residues in wastewater and with pollution sources are also investigated. The study is based on daily measurements of chemical parameters at five city collectors in Galati, Romania, during a two-week campaign in February 2010.

2. Experimental Analysis

2.1. Location of Sampling Sites

Galati-Braila area is the second urban agglomeration in Romania after Bucharest, which is located in Romania at the confluence of three major rivers: Danube, Siret, and Prut. The wastewater average flow is about 100000 m3/day . The drainage system covers an area of 2300 ha, serving approximately 99% of the population (approximately 300000 habitants). The basic drainage system is very old, dating back to the end of the 19th century, and was extended along with the expansion of the city due to demographic and industrial evolution. There are several collectors that collect wastewater and rainwater from various areas with very different characteristics, according to the existing water-pipe drainage system. There is no treatment at any station, except for simple mechanical separation. However, industrial wastewater is pretreated before being discharged in the city system. The five wastewater collectors are denoted in the following as S 1 , S 2 , … , S 5. Four of them discharge in the Danube River and the fifth discharges in the Siret River (which is an affluent of Danube River). Figure 1 shows the distribution of the monitoring sites and highlights the type of collecting area (domestic, industrial, or mixed). For the sake of brevity, these stations will be named in the present paper as “domestic,” “mixed,” and “industrial” stations, according to the type of collected wastewater. The mixture between domestic and industrial water at the two mixed collectors is the result of changes in city planning and various transformations of small/medium enterprises.

Figure 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1: Monitoring sampling sites of wastewater from Galati city.

Technical details about each collector/station can be found in Table 1. The first station, S1, collects 10% of the total quantity of wastewater. A high percentage of the water collected at this station comes from domestic sources from the south part of the city (more than 96%). Station S2 collects 64% of the total daily flow of wastewater, out of which 30% comes from domestic sources and the rest (70%) is industrial. Most of the industrial sources in this area are food-production units (milk, braid, wine) while the domestic sources include 20 schools, 4 hospitals, and important social objectives. Station S3 is located in the old part of the city and collects 5% of the total wastewater and has domestic sources. At the fourth station, S4, 11% of the quantity of wastewater is collected from domestic (70%) and industrial (30%) sources. The last collector, S5, collects wastewater from the industrial area of the city, where the most important objectives are a shipyard, metallurgical, and mechanical plants and transport stations.

Table 1

Table 1: Characteristics of collectors S 1 , … , S 5.

2.2. Physico-Chemical Parameters and Methods of Analysis

The physico-chemical parameters which were measured are the following:(i)pH;(ii)chemical oxygen demand (COD) and dissolved oxygen (DO);(iii)nutrients such as nitrate (N-NO3) and phosphate (P-PO4) (these were included due to their impact on the eutrophication phenomenon);(iv)metals such as aluminum (Al+3), soluble iron (Fe+2), and cadmium (Cd+2).

The pH and DO were determined in situ using a portable multiparameter analyzer. Other chemical parameters such as COD, metals and nutrients were determined according to the standard analytical methods for the examination of water and wastewater .

The COD values reflect the organic and inorganic compounds oxidized by dichromate with the following exceptions: some heterocyclic compounds (e.g., pyridine), quaternary nitrogen compounds, and readily volatile hydrocarbons. The concentration of metals (Al+3, Cd+2, Fe+2) was determined as a result of their toxicity.

The value of pH was analyzed according to the Romanian Standard using a portable multiparameter analyzer, Consort C932.

COD parameter was measured using COD Vials (COD 25–1500 mg/L, Merck, Germany). The digestion process of 3 mL aliquots was carried out in the COD Vials for 2 h at 148°C. The absorbance level of the digested samples was then measured with a spectrophotometer at λ = 605 nm (Spectroquant NOVA 60, Merck, Germany), the method being analogous to EPA methods [20], US Standard Methods, and Romanian Standard Methods.

The DO parameter was analyzed according to Romanian Standard using a portable multiparameter analyzer, Consort C932.

Aluminum ions (Al+3) were determined using Al Vials (Aluminum Test 0.020–1.20 mg/L, Merck, Germany) in a way analogous to US Standard Methods. The absorbance levels of the samples were then measured with a spectrophotometer (Spectroquant NOVA 60; Merck, Germany) at λ = 550 nm. The method was based on reaction between aluminum ions and Chromazurol S, in weakly acidic-acetate buffered solution, to form a blue-violet compound that is determined spectrophotometrically. The pH of the sample must be within range 3–10. Where necessary, the pH will be adjusted with sodium hydroxide solution or sulphuric acid.

Iron concentration (Fe+2) was determined using Iron Vials (Iron Test 0.005–5.00 mg/L, Merck, Germany) and their absorbance levels were then measured using a spectrophotometer (Spectroquant NOVA 60; Merck, Germany) at λ = 565 nm. The method was based on reducing all iron ions (Fe+3) to iron ions (Fe+2). In a thioglycolate-buffered medium, these react with a triazine derivative to form a red-violet complex which is spectrophotometrically determined. The pH must be within range 3–11. Where necessary the pH was adjusted with sodium hydroxide solution or sulphuric acid.

Cadmium ions (Cd+2) were determined using Cadmium Vials (Cadmium Test 0.005–5.00 mg/L, Merck, Germany), their absorbance levels being measured with a spectrophotometer (Spectroquant NOVA 60; Merck, Germany) at λ = 525 nm. The method was based on the reaction of cadmium ions with a cadion derivative (cadion-trivial name for 1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazene), in alkaline solution, to form a red complex that is determined spectrophotometrically. The pH must be within the range 3–11, and, if not, the pH will be adjusted with sodium hydroxide solution or sulphuric acid.

Nitrogen content was determined using Nitrate Vials (Nitrate Cell test in seawater 0.10–3.00 mg/L NO3-N or 0.4–13.3 mg/L N O3 −, Merck, Germany). The method being based on the reaction of nitrate ions with resorcinol, in the presence of chloride, in a strongly sulphuric acid solution, to form a red-violet indophenols dye that is determined spectrophotometrically. The absorbance levels of the samples were then measured with a spectrophotometer (Spectroquant NOVA 60; Merck, Germany) at λ = 500 nm.

Phosphorous content was determined using Phosphate Vials (Phosphate Cell Test 0.5–25.0 mg/L PO4-P or 1.5–76.7 mg/L P O4 − 3, Merck, Germany) with a method that was analogous to the US Standard Methods [17]. The method was based on the reaction of orthophosphate anions, in a sulphuric solution, with ammonium vanadate and ammonium heptamolybdate to form orange-yellow molybdo-vanado-phosphoric acid that is determined spectrophotometrically (“VM” method). The absorbance levels of the samples were then measured with a spectrophotometer (Spectroquant NOVA 60; Merck, Germany) at λ = 410 nm.

All results were compared with standardized levels for wastewater quality found in accordance with European Commission Directive [23] and Romanian law [24].

3. Results and Discussion

3.1. The Acidity (pH)

The results for pH for all the investigated five collectors are shown in Figure 2.

Figure 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2: Daily variation of pH at all sites.

Generally, the wastewater collected at the monitored sites is slightly alkaline. The pH varies between 6.8 and 8.3—average value 7.82—thus the pH values are within the accepted range for Danube River according to the Romanian law, which is between 6.5 and 9.0. The pH variation is relatively similar at collectors S1–S4 (domestic and/or mixed domestic-industrial contribution). Lower pH values are observed at S5, which is dominated by industrial wastewater, originating from major enterprises and heavy industry. However, these values are not too low, since usually pH values for industrial wastewater are smaller than 6.5.

A significant decrease in the pH value was observed during the 8th day of the analyzed period at each station. Interestingly, a heavy snowfall took place at that particular time, thus the decrease could be attributed to the mixing between wastewater and a high quantity of low pH water, resulted from the melting of snow . One could speculate that the snowfall, which has an acidic character, might have affected the pH of the wastewater through “run off” phenomena.

No other snowfall took place during the monitoring campaign, thus no definite conclusion can be drawn for a possible relationship between pH and snowfalls.

3.2. Results for Chemical Oxygen Demand (COD)

Detection of COD values in each sampling site of wastewater is presented in Figure 3.

Figure 3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3: Daily variation of COD at all sites.

All COD values are higher than the maximum accepted values (125 mg O2/L) of the Romanian Law . Both organic and inorganic compounds have an effect on urban wastewater’s oxidability since COD represents not only oxidation of organic compounds, but also the oxidation of reductive inorganic compounds. That means some inorganic compounds interfere with COD determination through the consumption of C r2O7 − 2. Two different behaviors can be observed, which are associated with the type of the collected wastewater as follows.(i)The first group consists of stations S2, S4 and S5 where the wastewater has an important industrial component. At these stations, COD values are approximately between 150 and 300 mg O2/L, smaller, for instance, than COD values found by in the raw wastewater produced by an industrial coffee plant where COD values were between 4000 and 4600 mg O2/L. Also, the temporal variation of COD values at all three stations is similar with no significant deviations from the average value, which is about 250 mg O2/L. Interestingly, the lowest COD level can be seen, on the average, at S5, which has the highest percentage of industrial wastewater. The second group comprises the “domestic” stations S1 and S3. The COD levels are higher, with values of 500 mg O2/L or more. Also, the variability is clearly higher than at the industrial-type stations. No clear association between the variations at the two sites can be seen. A peak in COD was measured in the 14th day of the study at site S1 (1160 mg O2/L). Since S1 is a domestic type station, it is unlikely that some major discharge led to such a high variation of COD. Unfortunately, no other information exists that might indicate a possible cause for this increase.

3.3. Results for Dissolved Oxygen (DO)

The amount of DO, which represents the concentration of chemical or biological compounds that can be oxidized and that might have pollution potential, can affect a sum of processes that include re-aeration, transport, photosynthesis, respiration, nitrification, and decay of organic matter. Low DO concentrations can lead to impaired fish development and maturation, increased fish mortality, and underwater habitat degradation . No standards are given by Romanian or European Law for DO in wastewater. The DO values for the analyzed wastewater at all five sites are shown in Figure 4.

Figure 4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4: Daily variation of DO at all sites.

Concentration of DO varies at all sampling sites and has values between 0.96 (at S2) and 11.33 (at S4) mg O2/L with a mean value of 6.39 mg O2/L. These are clearly higher than DO values measured, for instance, in surface natural waters in China, where the Taihu watershed had the lowest DO level (2.70 mg/L), while in other rivers DO varied from 3.14 to 3.36 mg O2/L [34]. On the other hand, such high values of DO (9.0 mg O2/L) could be found, for instance, in the Santa Cruz River , who argued that discharging industry and domestic wastewater induced serious organic pollution in rivers, since the decrease of DO was mainly caused by the decomposition of organic compounds. Extremely low DO content (DO < 2 mg O2/L) usually indicates the degradation of an aquatic system .

The DO levels vary similarly for all selected sampling sites. The DO levels cover a wide range, with a minimum value of 1.0 mg O2/L at S1 and S3 and a maximum value of 11.33 mg O2/L at S4. There is a drop in DO at all stations, observed is in the 8th day of the monitoring interval, which coincides with the day when a similar decrease in pH took place. The lowest values of DO are observed for S1, one of the two “domestic” stations. It is interesting to note that DO at S5 is low although the wastewater here comes only from industry sources.

3.4. Metals

The variation of Al+3, Fe+2, and Cd+2 concentrations in wastewater are shown in Figures 5, 6, and 7. Al+3 concentrations (Figure 5) were mostly within the 0.05–0.20 mg/L range at all the sampling sites. However, during the beginning and the end of the monitoring campaign, Al+3 concentration at station S2 is high (reaching even 0.65 mg/L), nonetheless below the limit imposed by the Romanian law, which is 5 mg/L . The fact that in the beginning of the time interval, the concentration of Al+3 is high at two neighboring stations (S1 and S2) suggests that some localized discharge affecting both runaway and waste water, might have happened in the southern part of the city, which led to the increase of Al+3concentration in the collected wastewater. This is supported by the fact that the concentration gradually decreases at S2.

 

Figure 5: Daily variation of Al at all sites.

Figure 5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6: Daily variation of Fe at all sites.

Figure 6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 7: Daily variation of Cd at all sites.

Figure 7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The variation of Fe+2 concentrations is shown in Figure 6. Fe+2 concentration is within the 0.07–0.4 mg/L interval, below 5.0 mg/L, which is the maximum accepted value of the Romanian law . Two higher values were observed at S2 and S4 (both with industrial component) during the third and fourth days of the monitoring campaign.

Besides Al+3 and Fe+2, concentrations of Cd+2 were determined and the variations at the five stations are shown in Figure 7. Cd+2 is a rare pollutant, originating from heavy industry. Leakages in the sewage systems can also lead to Cd+2. Except for two days, Cd+2 varies between 0.005 and 0.04 mg/L. The two high values of 0.11 mg/L were observed in the first and fourth days at S5, which collects industrial wastewater. However, Cd+2 concentrations do not exceed the maximum accepted values of the Romanian law [24] for the monitoring interval which is 0.2 mg/L.

3.5. Nutrients

Water systems are very vulnerable to nitrate pollution sources like septic systems, animal waste, commercial fertilizers, and decaying organic matter [37]. Important quantities of nutrients, which are impossible to be removed naturally, can be found in rivers and this leads to the eutrophication of natural water (like Danube River). As a result, an increase in the lifetime of pathogenic microorganisms is expected. Measurement of nutrient (different forms of nitrogen (N) or phosphorous (P)) variations in domestic wastewater is strongly needed in order to maintain the water quality of receptors [36]. Nitrogen by nitrate (Figure 8) and phosphorous by phosphate (Figure 9) are considered as representative for nutrients.

Figure 8: Daily variation of N-NO3 at all sites.

Figure 8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 9: Daily variation of P-PO4 at all sites.

Figure 9

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 8 shows that N-NO3 concentrations vary, on the average, between 0 and 5.0 mg/L.

At all four stations with a domestic component, S1, S2, S3 and S4, the concentration of N-NO3 is low (between 0 and 1.5 mg/L) and the daily variation is relatively similar at all sites. Noticeable drops of the N-NO3 concentration are observed at all stations in the 8th day of the monitoring interval, coinciding with pH (Figure 2) and DO strong variations (Figure 4). This supports the conclusion that the heavy snowfall recorded at that period had an important impact on wastewater quality most likely due to the runoff joining the sewage system.

The behavior of N-NO3 clearly differs at station S5, which collects only industrial wastewater. Significantly higher values of N-NO3, ranging from 2.0 to 5.0 mg/L, were detected. However, the mean concentration of N-NO3 remained below the maximum concentration given by the Romanian law [24]. Obviously, if treatment stations have to be set up, the priority for this particular nutrient component should concentrate on stations where industrial wastewater is collected.

Another nutrient that was analyzed for our study was orthophosphate expressed by phosphorous. The P-PO4 concentration varies, on the average, between 1.0 and 6.0 mg/L (Figure 9). For this component, concentrations are higher at domestic stations, S1 and S3, than at the other three stations. P-PO4 is expected to increase in domestic wastewater because of food, more precisely meat, processing, washing, and so forth. The lowest values were observed at S5, which has a negligible domestic component. Peaks in the P-PO4 concentration are observed at S1. Interestingly enough, P-PO4 temporal variations correlated pretty well at stations S2, S4, and S5 (which collect industrial wastewater). Unlike most of the other analyzed compounds, for which the concentrations were within the accepted ranges, the maximum level of P-PO4 is exceeded at all five collectors. Both Romanian law  and the European law  stipulate 2.0 mg/L total phosphorous for 10000–100000 habitants, and for more than 100000 habitants (as in Galati City’s case) 1.0 mg/L total phosphorus. Interestingly, domestic stations seem to require more attention with respect to the quality of water then industrial stations.

Our results regarding the variation and levels of the analyzed parameters are grouped below as the following.(1)The values of pH are within the accepted range for Danube, and their daily variations are relatively similar for both domestic and mixed wastewater. Significantly smaller pH values were measured in the wastewater with a high industrial load. A clear minimum was observed at all sites in the 8th day of the monitoring period, when a heavy snowfall took place. One could speculate that the snowfall, which has an acidic character, might have affected the pH of the wastewater through “run off” phenomena. However, a clear connection cannot be established relying on one event only.(2)The COD level clearly depends on the type of wastewater. Higher values were observed for domestic wastewater, while “pure” industrial wastewater has the lowest COD. This might be explained by the fact that industrial wastewater benefits from some treatment before being discharged into the city sewage system. However, COD does exceed the maximum accepted values according to the Romanian law [24] at all sites thus additional treatment is required at all stations.(3)Concentrations of all analysed metals, Al+3, Cd+2 and Fe+2, are within the limit of the Romanian law. No association with the type of wastewater could be inferred. Isolated peaks could not be linked with any specific polluting factors, except for Cd+2, for which accidental concentration increases are observed for pure industrial wastewater.(4)The level of P-PO4, one of the two nutrients that were analyzed, was high at all stations; however, the highest concentrations are associated with domestic loads.(5)Opposingly, the N-NO3 level is the highest, by far, in wastewater with a high industrial contribution.

3.6. Possible Relationships between Various Parameters

The experimental results have shown that some parameters might be related and that their behavior greatly depends on the type of collected wastewater. Differences between the behavior of physico-chemical parameters at the domestic sites (S1 and S3), on one hand, and at the other sites, on the other, was observed. Pearson correlation coefficients have been calculated between all parameters at all the selected five sites and corresponding significances. Although most of correlations were not significant, some interesting connections between various parameters at sites with similar characteristics were revealed. Table 2 shows correlation coefficients between various parameters for all five stations. Significant correlations at different types of stations are denoted as follows: italicized fonts for domestic stations, boldface italicized fonts for the industrial station and boldface fonts for mixed stations.

Table 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2: Correlation coefficients calculated for station S1 to S5. Significant correlations at each type of stations are identified as follows: boldface italicized fonts for industrial station (S5), italicized fonts for domestic stations (S1 and S3) and boldface fonts for mixed stations (S2 and S4).

An important relationship seems to exist between pH and N-NO3 at all stations except for the industrial wastewater collecting site, S5 (i.e., at all stations collecting wastewater resulting from domestic activities). Similarly, pH correlates well with DO at all stations except the industrial one.

COD correlates with two metals, Cd+2 and soluble Fe+2, which is expected [30], but only at S1 and S3, where the daily variations of the concentration for these two metals (Cd+2 and soluble Fe+2) were similar.

No conclusion can be drawn for the industrial wastewater collector that was analyzed, where both positive and negative correlations were observed. The lack of correlation between the two metals and COD at the industrial wastewater collectors suggests that other processes, that alter the chemical equilibrium between the two chemical compounds, must be taken into account. For example some metals are complexed by organic compounds that are present in the water and the pH values can influence these phenomena.

DO correlates with pH and N-NO3 at all four sampling stations with domestic component (S1–S4) but the relationship vanish at S5 (industrial). There is also a negative correlation between DO and Fe+2 and Cd+2 only for domestic wastewater, which is expected because of the natural oxidation of metals. The correlation vanishes at the other three stations which collect wastewater from industrial areas.

Heavy metals, Fe+2 and Cd+2 correlate only at domestic stations and no relationships can be defined to link the concentration of Al+3 with other components.

The P-PO4 variation is linked to the variation of soluble Fe+2 at the two stations that collect domestic wastewater. Interestingly, these two elements exist together in reductive domestic systems because these are dominated by proteins, lipids, degradation products. This relationship disappears at the other stations, where the industrial load is significant. The other metals, Al+3, seems to be linked with P-PO4at stations S5 and S2, which collect wastewater with the highest industrial load. No link is observed for the rest of stations and for Cd+2 which can be explained by a higher probability of iron (II) orthophosphate to form in wastewater compared to Al+3 or Cd+2 orthophosphates.

Positive correlations can also be seen between P-PO4 and COD for all sampling sites except S1, where the relationship is still positive but less significant. The other nutrient, N-NO3, is anticorrelated with COD but only at S3 and is well correlated with pH and DO at all four stations with domestic component. The only exception is station S5, which collects mostly industrial wastewater.

Concluding, positive correlations were observed between the following parameters.(1)pH and N-NO3 everywhere except “purely” industrial water.(2)COD and soluble Fe+2 at domestic stations.(3)DO and pH, on the one hand, and DO and N-NO3 at domestic stations.(4)P-PO4 and soluble Fe+2 at domestic stations.(5)P-PO4 and COD everywhere, which, taking into account the high level of P-PO4 at domestic stations, might suggest that one important contributor to water quality degradation are household discharges.(6)Al+3 and P-PO4.

4. Conclusions

In the present paper we have analyzed the daily variation of several physico-chemical parameters of the wastewater (pH, COD, DO, Al+3, Fe+2, Cd+2, N-NO3, and P-PO4) at five collectors that have been characterized as domestic, industrial and mixed, according to the type of collecting area. Different results have been obtained for domestic and industrial wastewater. Most of the chemical parameters are within accepted ranges. Nevertheless, their values as well as their behavior depend significantly on the type of collected wastewater.

The overall conclusion is that wastewater with a high domestic load has the highest negative impact on water quality in a river. On the other hand, industrial wastewater brings an important nutrient load, with potentially negative effect on the basins where it is discharged. Our results suggested that meteorological factors (snow) might modify some characteristics of wastewater, but a clear connection cannot be established relying on one event only.

Significantly smaller pH values were measured in the wastewater with a high industrial load. The COD level clearly depends on the type of wastewater. Higher values were observed for wastewater with domestic sources, while “pure” industrial wastewater has the lowest COD. This might be explained by the fact that industrial wastewater benefits from some treatment before being discharged into the city sewage system. COD does exceed the maximum accepted values according to the Romanian law at all sites thus additional treatment is required at all stations. Accidental increases of Cd+2 concentrations are observed for pure industrial wastewater. The highest concentrations of P-PO4 are associated with domestic loads. Opposing, the N-NO3 level is clearly the highest in wastewater with a high industrial contribution.

Correlation analysis has been used in order to identify possible relationships between various parameters for wastewater of similar origin.

Positive correlations between various physico-chemical parameters exist for the domestic wastewater (DO, pH and N-NO3, on the one hand, and P-PO4, COD and soluble Fe+2, on the other hand). Except for two cases, these relationships break when the industrial load is high. Some of the existing correlations are expected as discussed above, thus any removal treatment should be differentiated according to the type of collector, before discharging it into the natural receptors in order to be costly efficient. Correlations between DO and COD and nutrient load suggest that the most important threat for natural basins in the studied area, are domestic sources for the wastewater.

The different percentages of industrial and domestic collected wastewater vary at each station, which has a clear impact on concentrations of the selected chemical components. Our results show that domestic wastewater has a higher negative impact on water quality than wastewater with a high industrial load, which, surprisingly, seems to be cleaner. This might be related to the fact that most industries are forced, by law, to apply a pretreatment before discharging wastewater into the city sewage system. Industrial wastewater affects the nutrient content of natural water basins. Although the time period was relatively short, our study identified specific requirements of chemical treatment at each station. An efficient treatment plan should take into account the type of wastewater to be processed at each station. Results presented here are linked with another research topic assessing the level of water quality in the lower basin of the Danube before and after implementing the complete biochemical treatment plants.

Acknowledgment

The work of Catalin Trif was supported by Project SOP HRD-EFICIENT 61445/2009.

Copyright © 2012 Paula Popa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited – original found here: http://www.hindawi.com/journals/tswj/2012/549028/

 

 

Categories : Case Studies & Application Stories, Science and Industry Updates

Application Bulletin: POOL & SPA Water – MyronLMeters.com

Posted by 31 Jan, 2013

Tweet                 Anyone responsible for operating and maintaining a swimming pool or spa has to test, monitor, and control complex, interdependent chemical factors that affect the quality of water. Additionally, aquatic facilities operators must be familiar with all laws, regulations, and guidelines governing what these parameters should be. […]

DH-PS9-TK-2T

 

 

 

 

 

 

 

 

Anyone responsible for operating and maintaining a swimming pool or spa has to test, monitor, and control complex, interdependent chemical factors that affect the quality of water. Additionally, aquatic facilities operators must be familiar with all laws, regulations, and guidelines governing what these parameters should be.

Why? Because the worst breeding ground for any kind of microorganism is a warm (enough) stagnant pool of water. People plus stagnant water equals morbid illness. That’s why pools have to be circulated, filtered, and sanitized –  with any number of chemicals or methods, but most frequently with chlorine compounds. However, adding chemicals that kill the bad microorganisms can also make the water uncomfortable, and in some cases unsafe, for swimmers. Additionally, if all the chemical factors of the water are not controlled, the very structures and equipment that hold the water and keep it clean are ruined.

So the pool professional must perform a delicate balancing act with all the factors that affect both the health and comfort of bathers and the equipment and structures that support this. Both water balance – or mineral saturation control – and sanitizer levels must constantly be maintained. This is achieved by measuring pertinent water quality factors and adding chemicals or water to keep the factors within acceptable parameters.

 WATER BALANCE

Water is constantly changing. Anything and everything directly and indirectly affects the relationship of its chemical parameters to each other: sunlight, wind, rain, oil, dirt, cosmetics, other bodily wastes, and any chemicals you add to it. Balanced water not only keeps swimmers comfortable, but also protects the pool shell, plumbing, and all other related equipment from damage by etching or build-up and stains.

The pool professional is already well acquainted with pH, Total Alkalinity (TA), and Calcium Hardness (CH); along with Total Dissolved Solids (TDS) and Temperature, these are the factors that influence water balance. Water that is in balance is neither aggressive nor oversaturated. Aggressive water lacks sufficient calcium to saturate the water, so it is hungry for more. It will eat anything it comes into contact with to fill its need, including the walls of your pool or spa or the equipment it touches. Over-saturated water cannot hold any more minerals, so dissolved minerals come out of solution and form scale on pool and equipment surfaces.

The pH of pool water is critical to the effectiveness of the sanitizer as well as the water balance. pH is determined by the concentration of Hydrogen ions in a specific volume of water. It is measured on a scale of 0-14, 0-7 being acidic and 7-14 being basic.

You must maintain the pH of the water at a level that assures the sanitizer works effectively and at the same time protects the pool shell and equipment from corrosion or scaling and the bathers from discomfort or irritation. If the pH is too high, the water is out of balance, and the sanitizer’s ability to work decreases. More and more sanitizer is then needed to maintain the proper level to kill off germs. Additionally, pH profoundly affects what and how much chemical must be added to control the balance. A pH of between 7.2 – 7.6 is desirable in most cases.*

As one of the most important pool water balance and sanitation factors, pH should be checked hourly in most commercial pools.* Even if you have an automatic chemical monitor/controller on your system, you need to double- check its readings with an independent pH test. With salt- water pools, pH level goes up fast, so you need to check it more often. Tests are available that require reagents and subjective evaluation of color depth and hue to judge their pH. But different users interpret these tests differently, and results can vary wildly. The PooLPRo and ULTRAPEN PT2 give instant lab-accurate, precise, easy-to-use, objective pH measurements, invaluable in correctly determining what and how much chemical to add to maintain water balance and effective sanitizer residuals.

Total Alkalinity (TA) is the sum of all the alkaline minerals in the water, primarily in bicarbonate form in swimming pools, but also as sodium, calcium, magnesium, and potassium carbonates and hydroxides, and affects pH directly through buffering. The greater the Total Alkalinity, the more stable the pH. In general, TA should be maintained at 80 – 120 parts per million (ppm) for concrete pools to keep the pH stable.* Maintaining a low TA not only causes pH bounce, but also corrosion and staining of pool walls and eye irritation. Maintaining a high TA causes overstabilization of the water, creating high acid demands, formation of bicarbonate scale, and may result in the formation of white carbonate particles (suspended solids), which clouds the water. Reducing TA requires huge amounts of effort. So the best solution to TA problems is prevention through close monitoring and controlling. The PoolPro PS9 Titration Kit features an in-cell conductometric titration for determining alkalinity.

 Calcium Hardness (CH) is the other water balance parameter pool professionals are most familiar with. CH represents the calcium content of the water and is measured in parts per million. Low CH combined with a low pH and low TA significantly increases corrosivity of water. Under these conditions, the solubility of calcium carbonate also increases. Because calcium carbonate is a major component of both plaster and marcite, these types of pool finishes will deteriorate quickly. Low CH also leads to corrosion of metal components in the pool plant, particularly in heat exchangers. Calcium carbonate usually provides a protective film on the surface of copper heat exchangers and heat sinks, but does not adversely affect the heating process. Without this protective layer, heat exchangers and associated parts can be destroyed prematurely. At the other extreme, high CH can lead to the precipitation of calcium carbonate from solution, resulting in cloudy water, the staining of structures and scaling of equipment. The recommended range for most pools is 200 – 400 ppm.* Calcium hardness should be tested at least monthly. The PoolPro  PS9 Titration Kit features an in-cell conductometric titration for determining hardness.

Total Dissolved Solids (TDS) is the sum of all solids dissolved in water. If all the water in a swimming pool was allowed to evaporate, TDS would be what was left on the bottom of the pool – like the white deposits left in a boiling pot after all the water has evaporated. Some of this dissolved material includes hardness, alkalinity, cyanuric acid, chlorides, bromides, and algaecides. TDS also includes bather wastes, such as perspiration, urine, and others. TDS is often confused with Total Suspended Solids (TSS). But TDS has no bearing on the turbidity, or cloudiness, of the water, as all the solids are truly in solution. It is TSS, or undissolved, suspended solids, present in or that precipitate out of the water that make the water cloudy.

High TDS levels do affect chlorine efficiency, algae growth, and aggressive water, but only minimally. TDS levels have the greatest bearing on bather comfort and water taste – a critical concern for commercial pool operators. At levels of over 5,000 ppm, people can taste it. At over 10,000 ppm bather towels are scratchy and mineral salts accumulate around the pool and equipment. Still some seawater pools comfortably operate with TDS levels of 32,000 ppm or more.

As methods of sanitization have changed, high TDS levels have become more and more of a problem. The best course of action is to monitor and control TDS by measuring levels and periodically draining and replacing some of your mature water with new, lower TDS tap water. This is a better option than waiting until you must drain and refill your pool, which is not allowed in some areas where water conservation is required by law. However, you can also decrease TDS with desalinization equipment as long as you compensate with Calcium Hardness. (Do not adjust water balance by moving pH beyond 7.8.)*

Regardless, you do need to measure and compensate for TDS to get the most precise saturation index and adjust your pH and Calcium Hardness levels accordingly. It is generally recommended that you adjust for TDS levels by subtracting one tenth of a saturation index unit (.1) for every 1,000 ppm TDS over 1,000 to keep your water properly balanced. When TDS levels exceed 5,000 ppm, it is recommended that you subtract half of a tenth, or one twentieth of unit (.05) per 1,000 ppm.* And as the TDS approaches that of seawater, the effect is negligible.

Hot tubs and spas have a more significant problem with TDS levels than pools. Because the bather load is relatively higher, more chemicals are added for superchlorination and sudsing along with a higher concentration of bather wastes. The increased electrical conductance that high TDS water promotes can also result in electrolysis or galvanic corrosion. Every hot water pool operator should consider a TDS analyzer as a standard piece of equipment.

A TDS analyzer is required to balance the water of any pool or spa in the most precise way. PoolPro, PoolMeter and ULTRAPEN PT1 instantly display accurate TDS levels giving you the information you need to take corrective action before TDS gets out of hand.

Temperature is the last and least significant factor in maintaining water balance. As temperature increases, the water balance tends to become more basic and scale- producing. Calcium carbonate becomes less soluble, causing it to precipitate out of solution. As temperature drops, water becomes more corrosive.

 In addition to helping determine water balance, temperature also affects bather comfort, evaporation, chlorination, and algae growth (warmer temperatures encourage growth). Myron L’s PooLPRo also precisely measures temperature to one tenth of a degree at the same time any other parameter is measured.

In the pool and spa industry water balance is calculated using the Langelier Saturation Index (LSI) formula:

SI = (pH + TF + CF + AF ) – 12.1

Where:

PH = pH value

TF = 0.0117 x Temperature value – 0.4116 CF = 0.4341 x ln(Hardness value) – 0.3926 AF = 0.4341 x ln(Alkalinity value) – 0.0074

The following is a general industry guideline for interpreting LSI values:

•   An index between -0.5 and +0.5 is acceptable pool water.

  • An index of more than +0.5 is scale-forming.
  • An index below -0.5 is corrosive.

pH, Total Alkalinity, and Calcium Hardness are the largest contributors to water balance. Pool water will often be balanced if these factors are kept within the recommended ranges.

The PoolPro PS9 Titration Kit features an LSI function that steps you through alkalinity & hardness titrations and pH & temperature measurements to quickly and accurately determine LSI. An LSI calculator allows you to manipulate pH, alkalinity, hardness and temperature values in the equation to determine water balance adjustments on the spot.

SANITATION

The most immediate concern of anyone monitoring and maintaining a pool is the effectiveness of the sanitizer – the germ-killer. There are many types of sanitizers, the most common being chlorine in swimming pools and bromine in hot tubs and spas. The effectiveness of the sanitizer is directly related to the pH and, to a lesser degree, the other factors influencing water balance.

To have true chemical control, you need to monitor both the sanitizer residual and the pH and use that information to chemically treat the water. To check chlorine residual, free chlorine measurements are made. For automatic chlorine dosing systems, ORP must also be monitored to ensure proper functioning.

Free Chlorine is the amount of chlorine available as hypochlorous acid (HOCl-) and hypochlorite ion (OCl-), the concentrations of which are directly dependent on pH and temperature. pH is maintained at the level of greatest concentration of HOCl- because hypochlorous acid is a much more powerful sanitizer than hypochlorite ion. Free chlorine testing is usually required before and after opening of commercial pools. Samples should be taken at various locations to ensure even distribution. Residual levels are generally kept between 1-2 mg/L or ppm.* PooLPRo V.4.03 and later features the ability to measure ppm free chlorine in pools and spas sanitized by chlorine only. With this feature PoolPro can measure a dynamic range of chlorine concentrations wider than that of a colorimetric test kit with a greater degree of accuracy.

ORP stands for Oxidation Reduction Potential (or REDOX ) of the water and is measured in millivolts (mV). The higher the ORP, the greater the killing power of all sanitizers, not just free chlorine, in the water. ORP is the only practical method available to monitor sanitizer effectiveness. Thus, every true system of automatic chemical control depends on ORP to work.

The required ORP for disinfection will vary slightly between disinfecting systems and is also dependent on the basic water supply potential, which must be assessed and taken into account when the control system is initialized. 650 mV to 700 – 750 mV is generally considered ideal.*

Electronic controllers can  be inaccurate and inconsistent when confronted with certain unique water qualities, so it is critical to perform manual testing with separate instrumentation. For automatic control dosing, it is generally recommended that you manually test pH and ORP prior to opening and then once during the day to confirm automatic readings.*

Samples for confirming automatic control dosing should be taken from a sample tap strategically located on the return line as close as possible to the probes in accordance with the manufacturer’s instructions. If manual and automatic readings consistently move further apart or closer together, you should investigate the reason for the difference.*

ORP readings can only be obtained with an electronic instrument. PoolPro provides the fastest, most precise, easy-to-use method of obtaining ORP readings to check the effectiveness of the sanitizer in any pool or spa. This is the best way to determine how safe your water is at any given moment.

SALTWATER SANITATION

A relatively new development, saltwater pools use regular salt, sodium chloride, to form chlorine with an electrical current much in the same way liquid bleach is made. As chlorine – the sanitizer – is made from the salt in the water, it is critical to maintain the salt concentration at the appropriate levels to produce an adequate level of sanitizer. It is even more important to test water parameters frequently in these types of pools and spas, as saltwater does not have the ability to respond adequately to shock loadings (superchlorination treatments).

Most saltwater chlorinators require a 2,500 – 3,000 ppm salt concentration in the water (though some may require as high as 5,000-7,000 ppm).* This can barely be tasted, but provides enough salt for the system to produce the chlorine needed to sanitize the water.

(It is important to have a good stabilizer level – 30 – 50 ppm* – in the pool, or the sunlight will burn up the chlorine. Without it, the saltwater system may not be able to keep up with the demand regardless of salt concentration.)

Taste and salt shortages are of little concern to seawater systems that maintain an average of 32,000 ppm. In these high-salt environments, you need to beware of corrosion to system components that can distort salt level and other parameter readings.

Additionally, incorrect salt concentration readings can occur in any saltwater system. The monitoring/controlling components can and do fail or become scaled— sometimes giving a false low salt reading. Thus, you must test manually for salt concentration with separate instrumentation before adding salt.

You must also test salt concentration manually with separate instrumentation to re-calibrate your system. This is critical to system functioning and production of required chlorine. Both the PoolPro and PT1 conveniently test for salt concentration at the press of a button as a check against automatic controller systems that may have disabled equipment or need to be re-calibrated.

Though no one instrument or method can be used to determine ALL of the factors that affect the comfort and sanitation of pool and spa water, PoolPro is a comprehensive water testing instrument that is reliable durable, easy-to-use and easy-to-maintain and calibrate. As a pool professional, a PoolPro will not only simplify your life, it will save you time and money.

 RECORD KEEPING – WHAT TO DO WITH ALL THOSE MEASUREMENTS …

Data handling should be done objectively, and data recorded in a common format in the most accurate way. Also, data should be stored in more than one permanent location and made available for future analysis. Most municipalities require commercial aquatic facilities to keep permanent records on site and available for inspection at any time.

PoolPro makes it easy to comply with record keeping requirements. The PoolPro is an objective means to test free chlorine, ORP, pH, TDS, temperature and the mineral/salt content of any pool or spa. You just rinse and fill the cell cup by submerging the waterproof unit and press the button of the parameter you wish to measure. You immediately get a standard, numerical digital readout –  no interpretation required – eliminating all subjectivity. And model PS9TK features the added ability to perform in-cell conductometric titrations for Alkalinity, Hardness and LSI on the spot. Up to 100 date-time-stamped readings can be stored in memory and then later transferred directly to a computer wirelessly using the bluDock™ accessory package. Simply pair the bluDock with your computer, then open the U2CI software application to download data. The user never touches the data, reducing the potential for human error in transcription. The data can then be imported into any program necessary for record-keeping and analysis. The bluDock is a quick and easy way to keep records that comply with governing standards.*

*Consult your governing bodies for specific testing, chemical concentrations, and all other guidelines and requirements. The ranges and methods suggested here are meant as general examples.

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Categories : Case Studies & Application Stories, Product Updates

The Septage Management System of the Baliwag Water District, Philippines – MyronLMeters.com

Posted by 23 Jan, 2013

TweetThe Municipality of Baliwag is located in the Province of Bulacan in the Philippines, just about an hour’s drive north of Metro Manila. The urban LGU has a population of over 160,000 and is the financial, commercial, and educational center of the Province of Bulacan, with the majority of these residents receiving their water supply – and soon their sanitation – […]

The Municipality of Baliwag is located in the Province of Bulacan in the Philippines, just about an hour’s drive north of Metro Manila. The urban LGU has a population of over 160,000 and is the financial, commercial, and educational center of the Province of Bulacan, with the majority of these residents receiving their water supply – and soon their sanitation – from the Baliwag Water District (BWD).

The BWD, like other water districts in the Philippines, is a government owned and controlled corporation (GOCC) focused on providing water and sanitation service on a baliwag1.JPGcost-recovery basis. Water districts around the country are coordinated by the Local Water Utilities Administration (LWUA), a unique GOCC itself that is tasked to promote and oversee the development of WatSan systems outside of the Metro Manila area.

In the Philippines, sewerage is rare / mainly non-existent outside of the Metro Manila area, with most residents in urban areas relying on septic tanks, most of which – in absence of any formal sanitation program – are often poorly designed and rarely desludged. This results in widespread groundwater contamination and polluted rivers from the discharges of septic tank effluent directly to drainage canals.

Awareness is rapidly rising around the country about the seriousness of this sanitation problem though, and a wide variety of both donor-driven and locally-driven sanitation programs are now underway, including a variety of septage management programs. However, to date, these existing septage management programs have been undertaken by the LGU/private sector (e.g. in San Fernando City, La Union), by an LGU-water district partnership (e.g. in Dumaguete City, Negros Oriental), or by a mainly private sector ‘build-operate-transfer’ style of arrangement (e.g. the programs of Manila Water Company Inc. & Maynilad Water Services Inc. in the Metro Manila area).

baliwag2.JPGThe BWD, though, decided to try a different arrangement with its new septage management program: one led entirely by the water district, with very little LGU/government collaboration. The BWD, led by its dynamic and learned General Manager since 1995, Mr Artemio Baylosis, has rapidly grown from an insignificant, 1000-connection provider to the significant and respected provider it is today, ISO-9001 certified and with over 25,000 connections accounting for about 80% of the total population of Baliwag, which is better coverage than many other water districts in other urban areas around the country.

Through the initiative of Mr Baylosis and the BWD team, the BWD, in 2008, secured the support of the USAID-funded Philippine Water Revolving Fund (PWRF) to fund a feasibility study on septage management for the water district. From the data and analysis gathered by this study, the BWD was then able to pursue their own program without any further donor assistance, the planning for which began in 2009.

The next step after the feasibility study was to ensure a suitable regulatory environment for the program. The BWD worked with the local government of Baliwag to help them pass an ordinance in 2009 that allowed the establishment of the BWD septage and (future) sewerage management program. This was not a particularly comprehensive nor proactive ordinance for the LGU, but was sufficient to allow the BWD to be proactive on their own initiative. In addition, the BWD and LGU signed an MoA in 2010 to provide further details on the sharing of responsibilities for the septage management program. Most of these responsibilities were taken on by the BWD, with the LGU simply in charge of levying fines where necessary and in supporting the outreach efforts of the BWD about the program.

The BWD then required a source of funds to manage this program. Rather than rely on donor assistance, the BWD simply secured a 60M Peso (~$1.5M USD) loan from thebaliwag3.JPG Philippine National Bank, with a 10-year repayment period and 7% interest.

With these funds, the BWD could then launch into the program planning and consultations. They conducted a thorough public information drive across the entire LGU, to discuss and seek feedback on the program’s legality, guidelines, and proposed tariff structure. During this time, the BWD also engaged in a ‘Water Operators Partnership’, through the USAID-sponsored Waterlinks program, which linked them up with Indah Water Company in Malaysia, for joint trainings, site visits, and consultations on technical aspects of Indah’s already successful program.

Through this, the BWD was able to design their program to incorporate elements already proven to be successful, and build off of the unsuccessful elements of other programs. On desludging, the BWD decided to split their service area into 5 zones, with the goal of desludging one zone each year, so as to achieve a regular, once-every-5-years desludging cycle for its customers. However, they also do not plan on charging any additional fees if customers want to avail of additional desludgings within this 5-year period; if they desire 2 or 3 desludgings during this time, the BWD hopes to be able to do this for them without any additional fee.

baliwag4.JPGThe BWD is able to make this offer because, unlike a private company, they do not need to make a profit, only to recover their costs. This also allows them to offer a low water tariff, with the subsidised price of the first 10 cubic meters at only ~145 Pesos (just over $3USD), with average monthly water consumption in the community at approximately 20 cubic meters. And because of their 80% water supply coverage, they thus decided to use this water tariff as the basis for financing their septage management costs. Their financial models determined that a fixed charge of 10% of the user’s total water bill would collect enough to recover the costs. Thus, the previously mentioned 145 Peso bill, as of June 2012, became a 160 Peso bill. The community was consulted on this tariff structure and were agreeable to it. So far, as of Dec. 2012, no one has complained about the new fee, even though the desludging service has not yet begun.

In addition to the desludging service that the BWD will offer, they also plan on taking responsibility for enforcing properly-designed septic tanks in the LGU, both for old tanks and new constructions. For the former, they hope to inspire maintenance/upgrading via consultation with customers and fines if necessary, while for the latter, they plan on visiting new construction sites to ensure that the septic tanks are properly designed. They have also already begun collecting data on every septic tank of their customers. Currently, they have just noted the number of household users of the tank and its general location on the property (e.g. on the left side / right side / inside / etc.), but they soon hope to begin mapping each of these tanks into their GIS/GPS database, for easy reference and route planning for desludging. Properly-designed septic tanks (i.e. 2 or 3 chambers and sealed at the bottom) are important, since many of the country’s existing tanks are sized too small for their daily flow rate and are not sealed at the bottom, resulting in widespread groundwater pollution.

A problem that has faced previous septage management programs is that of availment rates. Even if customers are paying (e.g. through the water tariff) for the desludging service, availment rates of this service have often been as low as 50%, due mainly to the desludgers’ rules about the lifting of the septic tank lid. In previous programs, the desludger required residents to lift the septic tank lid if they wanted to avail of the service (to avoid any liability related to potentially damaging the lid), but this was often complicated by the fact that many septic tanks here are built without a lid and/or are built in a difficult-to-access location, such as under the kitchen.

Learning from this, the BWD will try a different approach. In the first 5-year cycle, the BWD will lift all of the lids themselves, a day or two in advance of the planned baliwag5.JPGdesludging, and if there is no lid, the BWD will drill one themselves by breaking a hole through the floor. Then, in the second 5-year cycle, the customers will be responsible for lifting their own lids. They are not concerned about liability, as their activities are supported by the LGU’s ordinance, though it remains to be seen whether this will be enough to prevent any complaints on potential damage. If successful, though, this approach could greatly increase availment rates, and thus greatly reduce the amount of ground/surface water pollution from overflowing septic tanks.

Turning now to the technology, the BWD purchased two, 5 cubic meter desludging trucks (at a cost of 17.4M Pesos (~$420,000 USD), which they hope to run at 3 loads per day, 5 days per week. These trucks will bring the septage to the new septage treatment plant (SpTP), which is currently under construction in the LGU. The BWD purchased the land for this plant itself, even though the LGU is supposed to be legally obligated to provide it, thus showing the BWD’s desire to do it themselves. The construction of their SpTP and the office / laboratory building that will rise beside it were contracted out to two different local engineering companies. The SpTP will have a capacity of 30 cubic meters per day and will cost 32.7M Pesos (~$800,000 USD) to build. In addition to their regular desludging, the BWD also hopes that this capacity will allow the acceptance of some septage from neighboring LGUs or from small private desludgers, with a tipping fee applied. In theory, the site could also be upgraded to accept sewage one day, as they chose a location in a lower elevation area as compared with the rest of the LGU. The site is also strategically located in terms of odor – it is beside a smelly pig farm and duck farm, so it is unlikely that these neighbors will complain about odors from the plant!

baliwag6.JPGThe SpTP uses a highly mechanised technology package, which was chosen by the BWD so as to minimise the exposure of its staff to raw septage, even though this option is more expensive than a less mechanised version. Their technology process is as follows:

1) Macerator and/or bar screen – These will be able to run in series or parallel. The use of the macerator will depend on how much electricity it consumes.
2) A joint garbage screen / sand screen / FOG (fats/oils/grease) screen unit
3) Holding tank (with mixer) – 2 tanks, each with 2 days of holding time
4) Pump line, with cationic polymer injection, leading to the dewatering screw press (solids from this and the aforemention garbage / sand will fall into a pickup truck)
5) Equalisation Tank
6) Sequencing Batch Reactor (SBR) (Consisting of: a – Equalisation tank {aerobic} , b – SBR {aerobic} , c – Chlorine contact tank (Cl will drip in in liquid form), d – Effluent holding tank -> Discharge to storm drain. e – Sludge from tank B will get pumped to a sludge digestion tank, for further holding time, which will overflow back into tank A)

The aerobic portions are serviced by 2 blower motors. The site will also have 2 big water tanks for drinking water and recycled/rain water for use on site. The effluent can also be recirculated after the screw press back into the holding tank if so desired for further treatment time. The biosolids/sludge from this SpTP will be composted for local use around the LGU.

baliwag7.JPG

As of this writing (Dec. 2012), construction of the SpTP was nearly complete, with testing and commissioning to follow from Jan. to Aug. 2013, with the goal of project turn over and full operation by Sept. 2013. Even though it has not yet begun, the innovative design being used here by the BWD is already being mimicked by neighboring water districts in their septage planning, and it thus stands to serve as a model for water district-led septage management in the Philippines, with its lessons being applicable to septage management programs around the world as well.

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Categories : Case Studies & Application Stories, Science and Industry Updates

Recent Papers in Water Treatment for Small/Decentralized Systems – MyronLMeters.com

Posted by 12 Jan, 2013

TweetRecent Papers in Water Treatment for Small/Decentralized Systems Content Table Recent Papers in Water Treatment for Small/Decentralized Systems  Turbidity and chlorine demand reduction using locally available physical water clarification mechanisms before household chlorination in developing countries Appropriate wastewater treatment systems for developing countries: criteria and indictor assessment in Thailand A new paradigm for low-cost urban […]

Recent Papers in Water Treatment for Small/Decentralized Systems

Content Table

Turbidity and chlorine demand reduction using locally available physical water clarification mechanisms before household chlorination in developing countries

Journal of Water and Health Vol 07 No 3 pp 497–506 © IWA Publishing 2009 doi:10.2166/wh.2009.071

Link to Summary Page

Nadine Kotlarz, Daniele Lantagne, Kelsey Preston and Kristen Jellison

Department of Civil and Environmental Engineering, Lehigh University, 13 East Packer Avenue, Bethlehem, PA 18015, USA
Enteric Diseases Epidemiology Branch, US Centers for Disease Control and Prevention, 1600 Clifton Road, MS-A38, Atlanta, GA 30333, USA Tel.:             +1 404 639 0231       Fax: +1 404 639 2205 E-mail: dlantagne@cdc.gov

Abstract

Over 1.1 billion people in the world lack access to improved drinking water. Diarrhoeal and other waterborne diseases cause an estimated 1.9 million deaths per year. The Safe Water System (SWS) is a proven household water treatment intervention that reduces diarrhoeal disease incidence among users in developing countries. Turbid waters pose a particular challenge to implementation of SWS programmes; although research shows that a 3.75 mg l-1 sodium hypochlorite dose effectively treats turbid waters, users sometimes object to the strong chlorine taste and prefer to drink water that is more aesthetically pleasing. This study investigated the efficacy of three locally available water clarification mechanisms—cloth filtration, settling/decanting and sand filtration—to reduce turbidity and chlorine demand at turbidities of 10, 30, 70, 100 and 300 NTU. All three mechanisms reduced turbidity (cloth filtration -1–60%, settling/decanting 78–88% and sand filtration 57–99%). Sand filtration (P=0.002) and settling/decanting (P=0.004), but not cloth filtration (P=0.30), were effective at reducing chlorine demand compared with controls. Recommendations for implementing organizations based on these results are discussed.

Appropriate wastewater treatment systems for developing countries: criteria and indictor assessment in Thailand

Water Science & Technology—WST Vol 59 No 9 pp 1873–1884 © IWA Publishing 2009 doi:10.2166/wst.2009.215

Link to Summary Page

W. Singhirunnusorn and M. K. Stenstrom

Faculty of Environment and Resource Studies, Mahasarakham University, Kantharawichai District, Maha Sarakham Province 44150, Thailand E-mail: swichitra@gmail.com
Department of Civil and Environmental Engineering, UCLA, Los Angeles CA 90095, USA E-mail: stenstro@seas.ucla.edu

Abstract

This paper presents a comprehensive approach with factors to select appropriate wastewater treatment systems in developing countries in general and Thailand in particular. Instead of focusing merely on the technical dimensions, the study integrates the social, economic, and environmental concerns to develop a set of criteria and indicators (C&I) useful for evaluating appropriate system alternatives. The paper identifies seven elements crucial for technical selection: reliability, simplicity, efficiency, land requirement, affordability, social acceptability, and sustainability. Variables are organized into three hierarchical elements, namely: principles, criteria, and indicators. The study utilizes a mail survey to obtain information from Thai experts—academicians, practitioners, and government officials—to evaluate the C&I list. Responses were received from 33 experts on two multi-criteria analysis inquiries—ranking and rating—to obtain evaluative judgments. Results show that reliability, affordability, and efficiency are among the most important elements, followed by sustainability and social acceptability. Land requirement and simplicity are low in priority with relatively inferior weighting. A number of criteria are then developed to match the contextual environment of each particular condition. A total of 14 criteria are identified which comprised 64 indicators. Unimportant criteria and indicators are discarded after careful consideration, since some of the indicators are local or site specific.

A new paradigm for low-cost urban water supplies and sanitation in developing countries

Water Policy Vol 10 No 2 pp 119–129 © IWA Publishing 2008 doi:10.2166/wp.2008.034

Link to Summary Page

Duncan Maraa and Graham Alabasterb

aCorresponding author. School of Civil Engineering, University of Leeds, Leeds LS2 9JT UK. Fax: +44-113-343-2243 E-mail: d.d.mara@leeds.ac.uk
bUnited Nations Human Settlements Programme, PO Box 30300, Nairobi, Kenya

Abstract

To achieve the Millennium Development Goals for urban water supply and sanitation ~300,000 and ~400,000 people will have to be provided with an adequate water supply and adequate sanitation, respectively, every day during 2001–2015. The provision of urban water supply and sanitation services for these numbers of people necessitates action not only on an unprecedented scale, but also in a radically new way as “more of the same” is unlikely to achieve these goals. A “new paradigm” is proposed for low-cost urban water supply and sanitation, as follows: water supply and sanitation provision in urban areas and large villages should be to groups of households, not to individual households. Groups of households would form (even be required to form, or pay more if they do not) water and sanitation cooperatives. There would be standpipe and yard-tap cooperatives served by community-managed sanitation blocks, on-site sanitation systems or condominial sewerage, depending on space availability and costs and, for non-poor households, in-house multiple-tap cooperatives served by condominial sewerage or, in low-density areas, by septic tanks with on-site effluent disposal. Very poor households (those unable to afford to form standpipe cooperatives) would be served by community-managed standpipes and sanitation blocks.

Faecal bacterial indicators removal in various wastewater treatment plants located in Almendares River watershed (Cuba)

Water Science & Technology—WST Vol 58 No 4 pp 773–779 © IWA Publishing 2008 doi:10.2166/wst.2008.440

Link to Summary Page

Tamara Garcia-Armisen, Josué Prats, Yociel Marrero and Pierre Servais

Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Brussels, Belgium *Present address: MINT, Vrije Universiteit Brussel, Building E, Pleinlaan 2, 1050, Brussels, Belgium Tel.:            +3226291918       E-mail: tgarciaa@vub.ac.be
Dpto. de Microbiología, Facultad de Biología, Universidad de La Habana, La Habana, Cuba
Instituto Superior Politécnico José Antonio Echeverría, La Habana, Cuba

Abstract

The Almendares River, located in Havana city, receives the wastewaters of more than 200,000 inhabitants. The high abundance of faecal bacterial indicators (FBIs) in the downstream stretch of the river reflects the very poor microbiological water quality. In this zone, the Almendares water is used for irrigation of urban agriculture and recreational activities although the microbiological standards for these uses are not met. Improvement of wastewater treatment is absolutely required to protect the population against health risk. This paper compares the removal of FBIs in three wastewater treatment plants (WWTPs) located in this watershed: a conventional facility using trickling filters, a constructed wetland (CW) and a solar aquatic system (SAS). The results indicate better removal efficiency in the two natural systems (CW and SAS) for all the measured parameters (suspended matters, biological oxygen demand, total coliforms, E. coli and enterococci). Removals of the FBIs were around two log units higher in both natural systems than in the conventional one. A longitudinal profile of the microbiological quality of the river illustrates the negative impact of the large conventional WWTP. This case study confirms the usefulness of small and natural WWTPs for tropical developing countries, even in urban and periurban areas.

Treatment of low and medium strength sewage in a lab-scale gradual concentric chambers (GCC) reactor

Water Science & Technology—WST Vol 57 No 8 pp 1155–1160 © IWA Publishing 2008 doi:10.2166/wst.2008.093

Link to Summary Page

L. Mendoza, M. Carballa, L. Zhang and W. Verstraete

Experimental Reproduction Centre (CEYSA), Agricultural Faculty, Technical University of Cotopaxi, Latacunga, Ecuador E-mail: lauramen_2000@yahoo.com
Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, B-9000, Ghent, Belgium E-mail: willy.verstraete@ugent.be; marta.carballa@ugent.be; lezhanghua@hotmail.com

Abstract

One of the major challenges of anaerobic technology is its applicability for low strength wastewaters, such as sewage. The lab-scale design and performance of a novel Gradual Concentric Chambers (GCC) reactor treating low (165±24 mg COD/L) and medium strength (550 mg COD/L) domestic wastewaters were studied. Experimental data were collected to evaluate the influence of chemical oxygen demand (COD) concentrations in the influent and the hydraulic retention time (HRT) on the performance of the GCC reactor. Two reactors (R1 and R2), integrating anaerobic and aerobic processes, were studied at ambient (26°C) and mesophilic (35°C) temperature, respectively. The highest COD removal efficiency (94%) was obtained when treating medium strength wastewater at an organic loading rate (OLR) of 1.9 g COD/L·d (HRT = 4 h). The COD levels in the final effluent were around 36 mg/L. For the low strength domestic wastewater, a highest removal efficiency of 85% was observed, producing a final effluent with 22 mg COD/L. Changes in the nutrient concentration levels were followed for both reactors.

Use of modelling for optimization and upgrade of a tropical wastewater treatment plant in a developing country

Water Science & Technology Vol 56 No 7 pp 21–31 © IWA Publishing 2007 doi:10.2166/wst.2007.675

Link to Summary Page

D. Brdjanovic*, M. Mithaiwala** , M.S. Moussa*** , G. Amy* and M.C.M. van Loosdrecht**** 

*Department of Urban Water and Sanitation, UNESCO-IHE Institute for Water Education, Westvest 7, PO Box 3015, 2061 DA , Delft, The Netherlands (E-mail: d.brjanovic@unesco-ihe.org)
**Drainage Department, Surat Municipal Corporation, Muglisara, Surat , Gujarat, 395003, India (Email: mayank_heena6143@yahoo.com)
***Civil Engineering Department, Faculty of Engineering Mataria, Helwan , University, Egypt (Email: m.moussa@delft-environment.com)
****Department of Biochemical Engineering, Delft University of Technology, Julianalaan 67, 2628 BC , Delft, The Netherlands (Email: m.c.m.vanloosdrecht@tudelft.nl)

Abstract

This paper presents results of a novel application of coupling the Activated Sludge Model No. 3 (ASM3) and the Anaerobic Digestion Model No.1 (ADM1) to assess a tropical wastewater treatment plant in a developing country (Surat, India). In general, the coupled model was very capable of predicting current plant operation. The model proved to be a useful tool in investigating various scenarios for optimising treatment performance under present conditions and examination of upgrade options to meet stricter and upcoming effluent discharge criteria regarding N removal. It appears that use of plant-wide modelling of wastewater treatment plants is a promising approach towards addressing often complex interactions within the plant itself. It can also create an enabling environment for the implementations of the novel side processes for treatment of nutrient-rich, side-streams (reject water) from sludge treatment.

Ceramic silver-impregnated pot filters for household drinking water treatment in developing countries: material characterization and performance study

Water Science & Technology: Water Supply Vol 7 No 5-6 pp 9–17 © IWA Publishing 2007 doi:10.2166/ws.2007.142

Link to Summary Page

D. van Halem*, S.G.J. Heijman* , A.I.A. Soppe** , J.C. van Dijk* and G.L. Amy*** 

*Delft University of Technology, Stevinweg 1, 2628 CN , Delft, The Netherlands (E-mail: d.vanhalem@tudelft.nl; j.c.vandijk@tudelft.nl)
**Delft University of Technology & Kiwa Water Research, Groningenhaven 7, 3433 PE , Nieuwegein, The Netherlands (E-mail: s.g.j.heijman@tudelft.nl)
***Aqua for All Foundation, Groningenhaven 7, 3433 PE , Nieuwegein, The Netherlands (E-mail: gsoppe@planet.nl)
****UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX , Delft, The Netherlands (E-mail: g.amy@unesco-ihe.org)

Abstract

The ceramic silver-impregnated pot filter (CSF) is a low-cost drinking water treatment system currently produced in many factories worldwide. The objective of this study is to gather performance data to provide a scientific basis for organisations to safely scale-up and implement the CSF technology. Filters from three production locations are included in this study: Cambodia, Ghana and Nicaragua. The microstructure of the filter material was studied using mercury intrusion porosimetry and bubble-point tests. Effective pores were measured with a mean of 40 mm, which is larger than many pathogenic microorganisms. The removal efficiency of these microorganisms was measured by using indicator organisms; total coliforms naturally present in canal water, sulphite reducing Clostridium spores, E.coli K12 and MS2 bacteriophages. The removal of these organisms was monitored during a long-term study of several months in the laboratory. Ceramic silver impregnated pot filters successfully removed total coliforms and sulphite reducing Clostridium spores. High concentrations of Escherichia coli K12 were also removed, with log(10) reduction values consistently higher than 2. MS2 bacteriophages were only partially removed from the water, with significantly better results for filters without an impregnation of colloidal silver. During this study the main deficiency of the filter system proved to be the low water production; after 12 weeks of use all filter discharges were below 0.5 Lh-1, which is insufficient to provide drinking water for a family

Ceramic membranes for direct river water treatment applying coagulation and microfiltration

Water Science & Technology: Water Supply Vol 6 No 4 pp 89–98 © IWA Publishing 2006 doi:10.2166/ws.2006.906

Link to Summary Page

A. Loi-Brügger*, S. Panglisch*, P. Buchta*, K. Hattori**, H. Yonekawa**, Y. Tomita** and R. Gimbel*,***

*IWW Water Center, Moritzstr. 26, 45476 Mülheim, , Germany (E-mail: a.loi@iww-online.de)
**NGK Insulators Ltd., 2-56 Suda-cho, Nagoya, Aichi, , 467-8530, Japan (E-mail: kohji-h@ngk.co.jp)
***Institut für Energie- und Umweltverfahrenstechnik, Universität Duisburg-Essen Bismarckstr. 90, 47057 Duisburg, , Germany (E-mail: gimbel@uni-duisburg.de)

Abstract

A new ceramic membrane has been designed by NGK Insulators Ltd., Japan, to compete in the drinking water treatment market. The IWW Water Centre, Germany, investigated the operational performance and economical feasibility of this ceramic membrane in a one year pilot study of direct river water treatment with the hybrid process of coagulation and microfiltration. The aim of this study was to investigate flux, recovery, and DOC retention performance and to determine optimum operating conditions of NGK’s ceramic membrane filtration system with special regards to economical aspects. Temporarily, the performance of the ceramic membrane was challenged under adverse conditions. During pilot plant operation river water with turbidities between 3 and 100 FNU was treated. Membrane flux was increased stepwise from 80–300 l/m2h resulting in recoveries between 95.9 and 98.9%. A DOC removal between about 20–35% was achieved. The pilot study and the subsequent economical evaluation showed the potential to provide a reliable and cost competitive process option for water treatment. The robustness of the ceramic membrane filtration process makes it attractive for a broad range of water treatment applications and, due to low maintenance requirements, also suitable for drinking water treatment in developing countries.

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Categories : Case Studies & Application Stories, Science and Industry Updates