Science and Industry Updates
Reverse Osmosis and Measurement for Home and Commercial Systems
Tweet OSMOSIS Osmosis is the phenomenon of lower dissolved solids in water passing through a semi-permeable membrane into higher dissolved solids water until a near equilibrium is reached. Reverse Osmosis (RO) is a membrane process of purification which removes most of the total dissolved solids (TDS) in water by reversing the natural process of osmosis. [...]
OSMOSIS
Osmosis is the phenomenon of lower dissolved solids in water passing through a semi-permeable membrane into higher dissolved solids water until a near equilibrium is reached. Reverse Osmosis (RO) is a membrane process of purification which removes most of the total dissolved solids (TDS) in water by reversing the natural process of osmosis. Pressure is applied to a TDS-concentrated solution against a semi-permeable membrane, causing pure water to diffuse through the membrane. RO has become an important process for a wide variety of applications including: medical, laboratory, desalination, industrial wastewater, Deionized (Dl) pretreatment, and drinking water.
TESTING RO WATER QUALITY
Electrical conductivity is the most convenient method for testing RO water quality and membrane performance. Pure water is actually a poor electrical conductor. The amount of ionized substances (salts, acids, or bases) dissolved in water determines its conductivity. Normally, the vast majority of the dissolved minerals in tap, surface or ground water are conductive impurities. Myron L Company has conducted extensive research relating conductivity to TDS, resulting in instrumentation and calibration solutions which have become the standard of the RO industry.
When calibrating your conductivity instrument for testing fresh water, the “442 Natural Water Standard™” solutions are the best choice. These solutions are available in various concentrations.
442 solutions contain the following salts diluted in pure water: 40% sodium bicarbonate, 40% sodium sulfate and 20% sodium chloride. These are the most common salt compounds in surface and ground water. A sodium chloride solution provides better results in brackish or sea water because the predominant salt in these waters is sodium chloride.
ORP
ORP (Oxidation Reduction Potential/REDOX) and pH are important parameters in measuring the success and useful life of an RO membrane. The ORP may be used to determine the activity of an oxidizer. RO membranes are susceptible to attack by oxidizers such as chlorine, bromine, ozone and hydrogen peroxide. The activity of the oxidizer is more informative than the chemical residual because it determines the ability and speed of oxidation. A high ORP reading would indicate a need for pretreatment. A low ORP may indicate biological activity which may cause fouling of the membranes.
ORP can also be used to determine an overfeed of sodium bisulfite, which is used to reduce chlorine. If the ORP reading is under 200 mV, you have a reducing condition. This overfeed costs extra money and can lead to environmental discharge problems. It is best to check the reject water, where the concentration is highest. This will show even minute quantities of oxidizers or reducers.
pH
pH is very useful in predicting membrane life and the scaling potential of feedwater. The higher the pH and calcium, the more likely it is that scale will form on the membranes. However, with silicon based compounds, a low pH will increase the tendency for scaling. Membranes also have a pH range where operation is optimal. It is often useful to check the pH of the reject water to help determine scaling potential.
HOME SYSTEMS
Myron L Meters carries single and multiple range handheld instruments. Model RO-1 and RO-1NC are reliable, single range instruments used to demonstrate the RO process to a prospective buyer. The color coding of the model RO-1 dial dramatizes the difference between high TDS (red- above EPA recommended limits for drinking water), medium TDS (orange – within EPA recommended standards for drinking water), and low TDS RO water (blue-high purity water). Installers prefer the three range 532 models or TechPro II™ TP1 or TPH1 because they are ideal for accurately testing both feed and product water.
COMMERCIAL/INDUSTRIAL
Larger RO systems such as those found in bottled water plants, hospitals, industrial process, or seawater desalination require continuous monitoring to verify water quality and membrane condition. For continuous measurement of water quality, Myron L Meters carries the 720 and 750 Series II Monitor/ controllers. Monitor only, and monitor/controller models are available. Monitor/controller models contain an adjustable set point and a heavy-duty 10 amp relay which can be used to activate alarms, valves, autodialers, etc. A variety of options and outputs are available to cost-effectively tailor the monitor to the particular RO application.
The Ultrameter™ 9PTK, 6PII and 4PII are preferred by water treatment professionals for calibrating and checking Commercial/industrial RO systems. They appreciate the waterproof case, ability to store and record 100 memory data records, and three preprogrammed solution curves. Ultrameters are compact, but their multiple parameters give them the versatility of several instruments.
Myron L Meters also carries pen style meterss for dip or scoop sampling. The ULTRAPEN PT1 delivers stable, lab-accurate readings of Conductivity, TDS, Salinity and Temperature. The PT2 pH and Temperature pen is also available for spot checks and pretreatment screening. Both pens are waterproof, durable, and easy to use with one-button functioning.
Visit us here to save 10% on any of our Myron L meters: http://www.myronlmeters.com/Digital-Multiparameter-Meters-s/48.htm
Deionized water
Tweet Today, deionized (Dl) water has become an essential ingredient in hundreds of applications including: medical, laboratory, pharmaceutical, cosmetics, electronics manufacturing, food processing, plating, countless industrial processes – even the final rinse at the local car wash. THE DEIONIZATION PROCESS Most dissolved impurities in modern water supplies are ions like calcium, sodium, chlorides, [...]
Today, deionized (Dl) water has become an essential ingredient in hundreds of applications including: medical, laboratory, pharmaceutical, cosmetics, electronics manufacturing, food processing, plating, countless industrial processes – even the final rinse at the local car wash.
THE DEIONIZATION PROCESS
Most dissolved impurities in modern water supplies are ions like calcium, sodium, chlorides, etc. The deionization process removes ions from water via ion exchange. Positively charged ions (cations) and negatively charged ions (anions) are exchanged for hydrogen (H+) and hydroxyl (OH-) ions, respectively, due to the resin’s greater affinity for other ions. The ion exchange process occurs on the binding sites of the resin beads. Once depleted of exchange capacity, the resin bed is regenerated with concentrated acid and caustic which strips away accumulated ions through physical displacement, leaving hydrogen or hydroxyl ions in their place.
DEIONIZER TYPES
Deionizers exist in four basic forms: disposable cartridges, portable exchange tanks, automatic units, and continuous units. A two-bed system employs separate cation and anion resin beds. Mixed-bed deionizers utilize both resins in the same vessel. The highest quality water is produced by mixed-bed deionizers, while two-bed deionizers have a larger capacity. Continuous deionizers, mainly used in labs for polishing, do not require regeneration.
TESTING Dl WATER QUALITY
Water quality from deionizers varies with the type of resins used, feed water quality, flow, efficiency of regeneration, remaining capacity, etc. Because of these variables, it is critical in many Dl water applications to know the precise quality. Resistivity/ conductivity is the most convenient method for testing Dl water quality. Deionized pure water is a poor electrical conductor, having a resistivity of 18.2 million ohm-cm (18.2 megohm) and conductivity of 0.055 microsiemens. It is the amount of ionized substances (or salts) dissolved in the water which determines water’s ability to conduct electricity. Therefore, resistivity and its inverse, conductivity, are good general purpose quality parameters.
Because temperature dramatically affects the conductivity of water, conductivity measurements are internationally referenced to 25°C to allow for comparisons of different samples. With typical water supplies, temperature changes the conductivity an average of 2%/°C, which is relatively easy to compensate. Deionized water, however, is much more challenging to accurately measure since temperature effects can approach 10%/°C! Accurate automatic temperature compensation, therefore, is the heart of any respectable instrument.
RECOMMENDED INSTRUMENTATION
Portable instruments are typically used to measure Dl water quality at points of use, pinpoint problems in a Dl system confirm monitor readings, and test the feed water to the system. The handheld Myron L meters have been the first choice of Dl water professionals for many years. For two-bed Dl systems, there are several usable models with displays in either microsiemens or ppm (parts per million) of total dissolved solids. The most versatile instruments for Dl water is the Ultrameter II 4P or Ultrameter II 6PFCE , which can measure both ultrapure mixed-bed quality water and unpurified water. It should be noted that once Dl water leaves the piping, its resistivity will drop because the water absorbs dissolved carbon dioxide from the air. Measuring of ultrapure water with a hand-held instrument requires not only the right instrument, but the right technique to obtain accurate, repeatable readings. Myron L meters offer the accuracy and precision necessary for ultrapure water measurements.
In-line Monitor/controllers are generally used in the more demanding Dl water applications. Increased accuracy is realized since the degrading effect of carbon dioxide on high purity water is avoided by use of an in-line sensor (cell). This same degradation of ultrapure water is the reason there are no resistivity calibration standard solutions (as with conductivity instruments). Electronic sensor substitutes are normally used to calibrate resistivity Monitor/controllers.
Myron L Meters carries a variety of in-line instruments, including resistivity Monitor/controllers which are designed specifically for Dl water. Seven resistivity ranges are available to suit any Dl water application: 0-20 megohm, 0-10 megohm,
0-5 megohm, 0-2 megohm, 0-1 megohm, 0-500 kilohm, and 0-200 kilohm. Temperature compensation is automatic and achieved via a dual thermistor circuit. Monitor/controller models contain an internal adjustable set point, Piezo alarm connectors and a heavy-duty 10 amp relay circuit which can be used to control an alarm, valves, pump, etc. Available options include 4-20 milliamp output, 3 sensor input, 3 range capability and temperature. Internal electronic sensor substitutes are standard on all Monitor/controllers.
Forest Byproducts, Shells May Be Key to Removing Radioactive Contaminants from Drinking Water
Tweet ScienceDaily (Apr. 15, 2011) — A combination of forest byproducts and crustacean shells may be the key to removing radioactive materials from drinking water, researchers from North Carolina State University have found. Complete story below: http://www.sciencedaily.com/releases/2011/04/110413111319.htm There’s always more at MyronLMeters.com.
ScienceDaily (Apr. 15, 2011) — A combination of forest byproducts and crustacean shells may be the key to removing radioactive materials from drinking water, researchers from North Carolina State University have found.
Complete story below:
http://www.sciencedaily.com/releases/2011/04/110413111319.htm
There’s always more at MyronLMeters.com.
Could the California Aqueduct Turn Into a Solar Farm?
Tweet by TODD WOODY In Wednesday’s Times, I wrote about start-up companies developing solar panel arrays that float on water. The companies see a potentially large market to generate electricity from building floating arrays for irrigation and mining ponds, hydroelectric reservoirs and canals. But the great white whale for some of these solar developers is deploying floating photovoltaic arrays [...]
by TODD WOODY In Wednesday’s Times, I wrote about start-up companies developing solar panel arrays that float on water. The companies see a potentially large market to generate electricity from building floating arrays for irrigation and mining ponds, hydroelectric reservoirs and canals. But the great white whale for some of these solar developers is deploying floating photovoltaic arrays on the California Aqueduct, the 400-mile long canal that irrigates much of the state’s agricultural heartland and delivers water to Southern California. Read the whole story here: http://green.blogs.nytimes.com/2011/04/20/could-the-california-aqueduct-turn-into-a-solar-farm/ There’s always more at MyronLMeters.com.
Antibiotic-Resistant Bacteria in Indian Public Water Supply
Tweet ScienceDaily (Apr. 7, 2011) — Disease-causing bacteria carrying the new genetic resistance to antibiotics, NDM-1, have been discovered in New Delhi’s drinking water supply. Click below for the whole story. http://www.sciencedaily.com/releases/2011/04/110406214332.htm There’s always more at MyronLMeters.com
ScienceDaily (Apr. 7, 2011) — Disease-causing bacteria carrying the new genetic resistance to antibiotics, NDM-1, have been discovered in New Delhi’s drinking water supply.
Click below for the whole story.
http://www.sciencedaily.com/releases/2011/04/110406214332.htm
There’s always more at MyronLMeters.com
Arctic Ocean hosts weird freshwater pond
Tweet Odd, persistent winds prevent river inputs from mixing with the sea By Janet Raloff As rivers empty into seas, freshwater mixes into the vast briny depths to replace water lost to evaporation. Or that’s what’s supposed to happen. But for the past dozen years, scientists now report, a large share of river inflows and sea-ice [...]
Click below for more.
http://www.sciencenews.org/view/generic/id/72214/title/Arctic_Ocean_hosts_wei…
There’s always more at MyronLMeters.com
River Water and Salty Ocean Water Used to Generate Electricity
Tweet http://www.sciencedaily.com/releases/2011/03/110329134254.htm ScienceDaily (Mar. 30, 2011) — Stanford researchers have developed a battery that takes advantage of the difference in salinity between freshwater and seawater to produce electricity.
http://www.sciencedaily.com/releases/2011/03/110329134254.htm
ScienceDaily (Mar. 30, 2011) — Stanford researchers have developed a battery that takes advantage of the difference in salinity between freshwater and seawater to produce electricity.
Unusual Park Saves Millions, Prevents Floods
Tweet ATLANTA—In October 2008, as the economy became a gray expanse of toxic rubble, this spot in the historic Fourth Ward was a gray expanse of toxic rubble. The neighborhood flooded often. Broken concrete and tainted soil buried ironically named Clear Creek. A hundred or so optimists gathered on a hot fall day and broke ground for a park. [...]
ATLANTA—In October 2008, as the economy became a gray expanse of toxic rubble, this spot in the historic Fourth Ward was a gray expanse of toxic rubble. The neighborhood flooded often. Broken concrete and tainted soil buried ironically named Clear Creek. A hundred or so optimists gathered on a hot fall day and broke ground for a park. On March 27, many of the same people ate cake on the banks of a lake surrounded by green space.
http://www.theepochtimes.com/n2/united-states/unusual-park-saves-millions-prevents-floods-53745.html
There’s more at blog.MyronLMeters.com
Potential for CO2 Fixation by Chlorella pyrenoidosa Grown in Oil Sands Tailings Water
Tweet Discharge of process water into tailings ponds is associated with many mining operations, including that of bitumen. These tailings ponds can be used to grow organisms, such as algae, which, in turn, fix CO2 and degrade unwanted dissolved components. After processing, algae can be used for the production of fuels (for example, biodiesel or methane). [...]
Discharge of process water into tailings ponds is associated with many mining operations, including that of bitumen. These tailings ponds can be used to grow organisms, such as algae, which, in turn, fix CO2 and degrade unwanted dissolved components. After processing, algae can be used for the production of fuels (for example, biodiesel or methane). In this work, we explored the potential for growth of a unicellular algae, Chlorella pyrenoidosa, in tailings water from an oil sands mining and upgrading operation. Once we determined that it was possible to grow algae in the tailings water, we designed and optimized minimal growth media for biomass (algae) production and did a preliminary engineering estimate of the potential for CO2 fixation. The medium components required for growth of C. pyrenoidosa in 95% oil sands tailings water (OSTW) were screened using a two-level full factorial experiment. Sodium nitrate, phosphate, and Fe-ethylenediaminetetraacetic acid (EDTA) were the most important medium components. After this work, response surface methodology (RSM) was used to find the optimum concentrations of these nutrients. The optimum concentrations of sodium nitrate, phosphate, Fe-EDTA, and trace metal solution were 11.9 mM, 9.4 mM, 49.5 μM, and 2 mL/L, respectively. On the basis of an optimized specific growth rate of 0.085 g L−1 day−1, it was estimated that 12 million tons/year of CO2 could be fixed by C. pyrenoidosa growing in the tailings ponds in the Athabasca region of Canada. This value has to be considered optimistic because of fluctuations in temperature, light, and other growing conditions, which would be experienced in the full-scale system.
Full text here: http://pubs.acs.org/stoken/campaign/acs/full/10.1021/ef101503h
More at http://www.myronlmeters.com
Social class makes no difference to water contamination risk from chemicals formed in chlorinated water, Spanish study suggests
Tweet http://www.sciencedaily.com/releases/2011/03/110316084423.htm ScienceDaily (2011-03-15) — Wealthy, well-educated people who choose to drink bottled water rather than water from public supplies may be no less exposed to potentially cancer-causing water contaminants, according to new research. More at blog.MyronLMeters.com
http://www.sciencedaily.com/releases/2011/03/110316084423.htm
ScienceDaily (2011-03-15) — Wealthy, well-educated people who choose to drink bottled water rather than water from public supplies may be no less exposed to potentially cancer-causing water contaminants, according to new research.
More at blog.MyronLMeters.com