Science and Industry Updates

A Book On Desalination Plant Concentrate Management by Nikolay Voutchkov

Tweet           A Book On Desalination Plant Concentrate Management by Nikolay Voutchkov, PE, BCEE of Water Globe Consulting and one of Myron L Meters valued customers This book provides an overview of the alternatives for management of concentrate generated by brackish water and seawater desalination plants, as well as site specific [...]

A Book On Desalination Plant Concentrate Management by Nikolay Voutchkov, PE, BCEE of Water Globe Consulting and one of Myron L Meters valued customers

This book provides an overview of the alternatives for management of concentrate generated by brackish water and seawater desalination plants, as well as site specific factors involved in the selection of the most viable alternative for a given project, and the environmental permitting requirements and studies associated with their implementation. The book focuses on widely used alternatives for disposal of concentrate, including discharge to surface water bodies; disposal to the wastewater collection system; deep well injection; land application; evaporation; and zero liquid discharge. Direct discharge through new outfall; discharge through existing wastewater treatment plant outfall; and co-disposal with the cooling water of existing coastal power plant are thoroughly described and design guidance for the use of these concentrate disposal alternatives is presented with engineers and practitioners in the field of desalination in mind. Key advantages, disadvantages, environmental impact issues and possible solutions are presented for each discharge alternative. Easy-to-use graphs depicting construction costs as a function of concentrate flowrate are provided for all key concentrate management alternatives.

Mr. Voutchkov is a registered professional engineer and a board certified environmental engineer (BCEE) by the American Academy of Environmental Engineers. He has over 25 years of experience in planning, environmental review, permitting and implementation of large seawater desalination, water treatment and water reclamation projects in the US and abroad. Mr. Voutchkov has extensive expertise with all phases of seawater desalination project delivery: from conceptual scoping, pilot testing and feasibility analysis; to front-end and detailed project design; environmental review and permitting; contractor procurement; project construction and operations oversight/asset management. Mr. Voutchkov is President of Water Globe Consulting a private company specialized in providing expert advisory services in the field of seawater desalination and reuse. For over 11 years prior to establishing his project advisory firm, Mr. Voutchkov was a Chief Technology Officer and Corporate Technical Director for Poseidon Resources, a private company involved in the development of the largest seawater desalination projects in the USA. In recognition of his outstanding efforts and contribution to the field of seawater desalination, Mr. Voutchkov has received a number of prestigious awards from the International Desalination Association, the International Water Association and the American Academy of Environmental Engineers. He is one of the principal authors of the American Water Works Association s Manual of Water Supply Practices on Reverse Osmosis and Nanofiltration and of the World Health Organization s Guidance for the Health and Environmental Aspects Applicable to Desalination. Mr. Voutchkov has published over 40 technical articles in the field of water and wastewater treatment and reuse, and is co-author of several books and manuals of practice on membrane treatment and desalination. He wrote a book on “Seawater Pretreatment”, which was published by Water Treatment Academy in 2010.

Desalination Plant Concentrate Management

By Nikolay Voutchkov, PE, BCEE

ISBN: 978-974-496-357-4, 181 pages, Hardcover, Published by Technobiz Communications

CONTENTS

PREFACE

Ch. 1. Introduction to Concentrate Management

Ch. 2. Desalination Plant Discharge Characterization

2.1. Desalination Plant Waste Streams

2.2. Concentrate

2.3. Spent Pretreatment Backwash Water

2.4. Chemical Cleaning Residuals

Ch. 3. Surface Water Discharge of Concentrate

3.1. New Surface Water Discharge

3.2. Potential Environmental Impacts

3.3. Concentrate Treatment Prior to Surface Water Discharge

3.4. Design Guidelines for Surface Water Discharges

3.5. Costs for New Surface Water Discharge

3.6. Case Studies of New Surface Water Discharges

3.7. Co-Disposal with Wastewater Effluent

3.8. Co-Disposal with Power Plant Cooling Water

Ch. 4. Discharge to Sanitary Sewer

4.1. Description

4.2. Potential Environmental Impacts

4.3. Effect on Sanitary Sewer Operations

4.4. Effect on Wastewater Treatment Operations

4.5. Effect on Water Reuse

4.6. Design and Configuration Guidelines

4.7. Costs for Sanitary Sewer Discharge

Ch. 5. Deep Well Injection

5.1. Description

5.2. Potential Environmental Impacts

5.3. Criteria and Methods for Feasibility Assessment

5.4. Design and Configuration Guidelines

5.5. Injection Well Costs

Ch. 6. Land Application

6.1. Description

6.2. Potential Environmental Impacts

6.3. Criteria and Methods for Feasibility Assessment

6.4. Design and Configuration Guidelines

6.5. Land Application Costs

Ch. 7. Evaporation Ponds

7.1. Description

7.2. Potential Environmental Impacts

7.3. Criteria and Methods for Feasibility Assessment

7.4. Design and Configuration Guidelines

7.5. Evaporation Pond Costs

Ch. 8. Zero Liquid Discharge Concentrate Disposal Systems

8.1. Description

8.2. Potential Environmental Impacts

8.3. Criteria and Methods for Feasibility Assessment

8.4. Design and Configuration Guidelines

8.5. Zero Liquid Discharge Costs

Ch. 9. Beneficial Use of Concentrate

9.1. Technology Overview

9.2. Feasibility of Beneficial Concentrate Use

Ch. 10. Regional Concentrate Management

10.1. Types of Regional Concentrate Management Systems

10.2. Use of Brackish Water Concentrate in SWRO Plants

Ch. 11. Non-Concentrate Residuals Management

11.1. Spent Pretreatment Backwash Water

11.2. Chemical Cleaning Residuals

Ch. 12. Comparison of Concentrate Management Alternatives

12.1. Selection of Concentrate Management Approach

12.2. Costs

12.3. Environmental Impacts

12.4. Regulatory Acceptance

12.5. Ease of Implementation

12.6. Site Footprint

12.7. Reliability and Operational Constraints

12.8. Energy Use

You can order your book here: http://talloaks.com/Zencart/index.php?main_page=product_info&cPath=1_9&products_id=85

Environmental Applications Bulletin – MyronLMeters.com

TweetEnvironmental Applications Keeping the water in our lakes, rivers, and streams clean requires monitoring of water quality at many points as it gradually makes its way from its source to our oceans. Over the years ever-increasing environmental concerns and regulations have heightened the need for increased diligence and tighter restrictions on wastewater quality. Control of [...]

Environmental Applications
Keeping the water in our lakes, rivers, and streams clean requires monitoring of water quality at many points as it gradually makes its way from its source to our oceans. Over the years ever-increasing environmental concerns and regulations have heightened the need for increased diligence and tighter restrictions on wastewater quality. Control of water pollution was once concerned mainly with treating wastewater before it was discharged from a manufacturing facility into the nation’s waterways. Today, in many cases, there are restrictions on wastewater that is discharged to city sewer systems or to other publicly owned treatment facilities. Many jurisdictions even restrict or regulate the runoff of storm water — affecting not only industrial and commercial land, but also residential properties as well.

In its simplest form, water pollution management requires impoundment of storm water runoff for a specified period of time before being discharged. Normally, a few simple tests such as pH and suspended solids must be checked to verify compliance before release. If water is used in any way prior to discharge, then the monitoring requirements can expand significantly. For example, if the water is used for once-through cooling, testing may include temperature, pH, total dissolved solids (TDS), chemical oxygen demand (COD), and biochemical oxygen demand (BOD), to name a few.

Once water is used in a process, some form of treatment is often required before it can be discharged to a public waterway. If wastewater is discharged to a city sewer or publicly owned facility, and treatment is required, the quality is often measured and the cost is based not only on the quantity discharged, but also the amount of treatment required. As a minimum requirement suspended solids must be removed. Filtering or using clarifiers often accomplishes such removal. Monitoring consists of measuring total suspended solids (TSS) or turbidity.

If inorganic materials have been introduced into the water, their concentration must be reduced to an acceptable level. Inorganics, such as heavy metals, typically are removed by raising the pH to form insoluble metal oxides or metal hydroxides. The precipitated contaminants are filtered or settled out. Afterward, the pH must be adjusted back into a “normal” range, which often requires continuous monitoring of pH.

Organic materials by far require the most extensive treatment. Many different methods have been devised to convert soluble organic compounds into insoluble inorganic matter. Most of these involve some form of biological oxidation treatment. Bacteria are used to metabolize the organic materials into carbon dioxide and solids, which can be easily removed. To insure that these processes work smoothly and efficiently requires regular monitoring of the health of the biological organisms. The level of food (organic material), nutrients (nitrogen and phosphorous), dissolved oxygen, and pH are some of the parameters that must be controlled. After bio-oxidation the wastewater is filtered or clarified. Often the final effluent is treated with an oxidizing compound such as chlorine to kill any remaining bacterial agents, but any excess oxidant normally must be removed prior to discharge. Oxidation Reduction Potential (ORP)/Redox is ideal for monitoring the level of oxidants before and after removal. The final effluent stream must be monitored to make sure it meets all regulatory requirements.

The monitoring of wastewater pollution does not end there. Scientists are continuously testing water in streams, ground water, lakes, lagoons, and other bodies of water to determine if and what effects any remaining contamination is having on the receiving waters and its associated aquatic life. Measurements may include pH, conductivity, TDS, temperature, dissolved oxygen, TSS and organic levels (COD and BOD).

Environmental testing is not limited to monitoring of wastewater systems. Control of air emissions often includes gas-cleaning systems that involve the use of water. Wet scrubbers and wet electrostatic precipitators are included in this group. A flue gas desulfurization (FGD) system is one type of wet scrubber that uses slurry of lime, limestone, or other caustic material to react with sulfur compounds in the flue gas. The key to reliable operation of these units is proper monitoring of solids levels and pH. After use, the water in these systems must be treated or added to other wastewater from the plant, where it is treated by one of the methods previously discussed.
With proper monitoring, systems that maintain cleaner air and water can be operated efficiently and effectively. Such operation will go a long way toward maintaining a cleaner environment for future generations.

Myron L Meters offers a full line of handheld instruments and in-line monitor/controllers that can be used to measure or monitor many of the parameters previously mentioned. The following table lists some of the model numbers for measuring, monitoring, or controlling pH, conductivity, TDS and ORP. For additional information, please refer to our data sheets or Ask An Expert at MyronLMeters.com.

Note: When using a monitor/controller to measure pH in streams that contain heavy metals, sulfides, or other materials that react with silver, Myron L Meters recommends using a double junction pH sensor with a potassium nitrate (KNO3) reference gel to avoid fouling the silver electrode. See our 720II Sensor Selection Guide for pH and ORP Monitor/controllers for more information.
Recommended handheld:

Ultrameter II 6P

http://www.myronlmeters.com/Ultrameter-II-6P-Multiparameter-Meter-p/dh-umii-6pii.htm

Multi-Parameter: Conductivity, TDS, Resistivity, pH, ORP, Temperature, Free Chlorine (FC^E)
+/-1% Accuracy of Reading
Memory Storage: Save up to 100 samples w/ Date & Time stamp
Wireless Download Module Optional
Waterproof

TDS (Total Dissolved Solids) and TDS Meters – MyronLMeters.com

TweetA TDS Meter indicates the Total Dissolved Solids (TDS) of a solution (the concentration of dissolved solids in it). Since dissolved ionized solids such as salts and minerals increase the conductivity of a solution, a TDS meter measures the conductivity of the solution and estimates the TDS from that. Dissolved organic solids such as sugar [...]

A TDS Meter indicates the Total Dissolved Solids (TDS) of a solution (the concentration of dissolved solids in it). Since dissolved ionized solids such as salts and minerals increase the conductivity of a solution, a TDS meter measures the conductivity of the solution and estimates the TDS from that.
Dissolved organic solids such as sugar and colloids don’t affect the conductivity of a solution much so a TDS meter does not include them in its reading.

Units of TDS

A TDS meter usually displays TDS in parts per million (ppm). For example, a TDS reading of 1 ppm would indicate there is 1 milligram of dissolved solids in each kilogram of water.

Measurement

The two chief methods of measuring total dissolved solids are gravimetry and conductivity. Gravimetric methods are the most accurate and involve evaporating the liquid solvent and measuring the mass of residues left. This method is generally the best but time-consuming. If inorganic salts comprise the majority of TDS, gravimetric methods are recommended.

Electrical conductivity of water is directly related to the concentration of dissolved ionized solids in the water. Ions from the dissolved solids in water create the water’s ability to conduct an electrical current, which can be measured using a conventional conductivity meter or TDS meter. When correlated with laboratory TDS measurements, conductivity provides an approximate value for the TDS concentration.

TDS

Total Dissolved Solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in: molecular, ionized or micro-granular (colloidal sol) suspended form. The operational definition is that the solids must be small enough to survive filtration through a two micrometer sieve. Total dissolved solids are normally discussed only for freshwater systems, as salinity comprises some of the ions constituting the definition of TDS. The principal application of TDS is in the study of water quality for streams, rivers and lakes, although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants.
Primary sources for TDS in receiving waters are agricultural and residential runoff, leaching of soil contamination and point source water pollution discharge from industrial or sewage treatment plants. The most common chemical constituents are calcium, phosphates, nitrates, sodium, potassium and chloride, which are found in nutrient runoff, storm water runoff and runoff from snowy climates where road de-icing salts are applied. The chemicals may be cations, anions, molecules or agglomerations on the order of one thousand or fewer molecules, so long as a soluble micro-granule is formed. More exotic and harmful elements of TDS are pesticides arising from surface runoff. Certain naturally occurring total dissolved solids arise from the weathering and dissolution of rocks and soils. The United States has established a secondary water quality standard of 500 mg/l to provide for palatability of drinking water.

TDS Measurement Applications

High TDS levels indicate hard water, which can cause scale buildup in pipes, valves, and filters, reducing performance and adding to system maintenance costs. These effects can be seen in aquariums, spas, swimming pools, and reverse osmosis water treatment systems. Typically, in these applications, total dissolved solids are tested frequently, and filtration membranes are checked in order to prevent adverse effects.
In the case of hydroponics and aquaculture, TDS is often monitored in order to create a water quality environment favorable for organism productivity. For freshwater oysters, trouts, and other high value seafood, highest productivity and economic returns are achieved by mimicking the TDS and pH levels of each species’ native environment. For hydroponic uses, TDS is considered one of the best indices of nutrient availability for the aquatic plants being grown.

Because the threshold of acceptable aesthetic criteria for human drinking water is 500 mg/l, there is no general concern for odor, taste, and color at a level much lower than is required for harm. A number of studies have been conducted and indicate various species’ reactions range from intolerance to outright toxicity due to elevated TDS. The numerical results must be interpreted cautiously, as true toxicity outcomes will relate to specific chemical constituents. Nevertheless, some numerical information is a useful guide to the nature of risks in exposing aquatic organisms or terrestrial animals to high TDS levels. Most aquatic ecosystems involving mixed fish fauna can tolerate TDS levels of 1000 mg/l.

Applications
Boilers & cooling towers, Deionization, Reverse osmosis, Chemical concentrations, Printing fountain solutions, Swimming pools & spas, Water pollution control, Wastewater & more…
Myron L Meters Top-selling TDS Meters

Ultrapen PT1 Conductivity, TDS, Salinity pen

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ULTRAPEN PT1 Conductivity – TDS – Salinity Pen
Accuracy of +/-1% of READING (+/-.2% at Calibration Point)
Reliable Repeatable Results
Solution modes: KCl, NaCl and 442
Automatic Temperature Compensation
Autoranging
Durable, Fully Potted Circuitry
Waterproof

http://www.myronlmeters.com/Analog-Conductivity-Multirange-Meter-p/ah-ds-ep-10.htm

EP-10: 0-10, 100, 1000, 10,000 micromhos/microsiemens
Instant and accurate TDS tests
Electronic Internal Standard for easy field calibration
Fast Auto Temperature Compensation
Rugged design for years of trouble-free testing
Simple to use

Multi-Parameter: Conductivity, TDS, Resistivity, Temperature

http://www.myronlmeters.com/Ultrameter-II-4P-Multiparameter-Meter-p/dh-umii-4pii.htm

Multi-Parameter: Conductivity, TDS, Resistivity, Temperature
+/-1% Accuracy of Reading
Memory Storage: Save up to 100 samples w/ Date & Time stamp
Wireless Download Module Optional
Waterproof

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Reverse Osmosis and RO Meters – MyronLMeters.com

TweetReverse Osmosis and RO Meters – MyronLMeters.com               Schematics of a reverse osmosis system (desalination) using a pressure exchanger. 1: Sea water inflow, 2: Fresh water flow (40%), 3: Concentrate flow (60%), 4: Sea water flow (60%), 5: Concentrate (drain), A: Pump flow (40%), B: Circulation pump, C: Osmosis unit [...]

Reverse Osmosis and RO Meters – MyronLMeters.com

Schematics of a reverse osmosis system (desalination) using a pressure exchanger.
1: Sea water inflow,
2: Fresh water flow (40%),
3: Concentrate flow (60%),
4: Sea water flow (60%),
5: Concentrate (drain),
A: Pump flow (40%),
B: Circulation pump,
C: Osmosis unit with membrane,
D: Pressure exchanger

Reverse osmosis (RO) is a membrane-technology filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be “selective,” this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as the solvent) to pass freely.

In normal osmosis, the solvent naturally moves from an area of low solute concentration (High Water Potential), through a membrane to an area of high solute concentration (Low Water Potential). The movement of a pure solvent to equalize solute concentrations on each side of a membrane generates osmotic pressure. Applying an external pressure to reverse the natural flow of pure solvent, thus, is reverse osmosis. The process is similar to other membrane technology applications. However, there are key differences between reverse osmosis and filtration. The predominant removal mechanism in membrane filtration is straining, or size exclusion, so the process can theoretically achieve perfect exclusion of particles regardless of operational parameters such as influent pressure and concentration. Reverse osmosis, however, involves a diffusive mechanism so that separation efficiency is dependent on solute concentration, pressure, and water flux rate. Reverse osmosis is most commonly known for its use in drinking water purification from seawater, removing the salt and other substances from the water molecules.

Reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a semipermeable membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. The largest and most important application of reverse osmosis is to the separation of pure water from seawater and brackish waters; seawater or brackish water is pressurized against one surface of the membrane, causing transport of salt-depleted water across the membrane and emergence of potable drinking water from the low-pressure side.

The membranes used for reverse osmosis have a dense layer in the polymer matrix — either the skin of an asymmetric membrane or an interfacially polymerized layer within a thin-film-composite membrane — where the separation occurs. In most cases, the membrane is designed to allow only water to pass through this dense layer, while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2–17 bar (30–250 psi) for fresh and brackish water, and 40–82 bar (600–1200 psi) for seawater, which has around 27 bar (390 psi)[3] natural osmotic pressure that must be overcome. This process is best known for its use in desalination (removing the salt and other minerals from sea water to get fresh water), but since the early 1970s it has also been used to purify fresh water for medical, industrial, and domestic applications.

Osmosis describes how solvent moves between two solutions separated by a permeable membrane to reduce concentration differences between the solutions. When two solutions with different concentrations of a solute are mixed, the total amount of solutes in the two solutions will be equally distributed in the total amount of solvent from the two solutions. Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semipermeable membrane. The semipermeable membrane does not allow the solutes to move from one compartment to the other, but allows the solvent to move. Since equilibrium cannot be achieved by the movement of solutes from the compartment with high solute concentration to the one with low solute concentration, it is instead achieved by the movement of the solvent from areas of low solute concentration to areas of high solute concentration. When the solvent moves away from low concentration areas, it causes these areas to become more concentrated. On the other side, when the solvent moves into areas of high concentration, solute concentration will decrease. This process is termed osmosis. The tendency for solvent to flow through the membrane can be expressed as “osmotic pressure”, since it is analogous to flow caused by a pressure differential. Osmosis is an example of diffusion.

In reverse osmosis, in a similar setup as that in osmosis, pressure is applied to the compartment with high concentration. In this case, there are two forces influencing the movement of water: the pressure caused by the difference in solute concentration between the two compartments (the osmotic pressure) and the externally applied pressure.

Around the world, household drinking water purification systems, including a reverse osmosis step, are commonly used for improving water for drinking and cooking.

Such systems typically include a number of steps:

a sediment filter to trap particles, including rust and calcium carbonate

optionally, a second sediment filter with smaller pores

an activated carbon filter to trap organic chemicals and chlorine, which will attack and degrade TFC reverse osmosis membranes

a reverse osmosis (RO) filter, which is a thin film composite membrane (TFM or TFC)

optionally, a second carbon filter to capture those chemicals not removed by the RO membrane

optionally an ultra-violet lamp for sterilizing any microbes that may escape filtering by the reverse osmosis membrane

In some systems, the carbon prefilter is omitted, and cellulose triacetate membrane (CTA) is used. The CTA membrane is prone to rotting unless protected by chlorinated water, while the TFC membrane is prone to breaking down under the influence of chlorine. In CTA systems, a carbon postfilter is needed to remove chlorine from the final product, water.

Portable reverse osmosis (RO) water processors are sold for personal water purification. To work effectively, the water feeding to these units should be under some pressure (40 psi or greater is the norm). Portable RO water processors can be used by people who live in rural areas without clean water, far away from the city’s water pipes. Rural people filter river or ocean water themselves, as the device is easy to use (saline water may need special membranes). Some travelers on long boating, fishing, or island camping trips, or in countries where the local water supply is polluted or substandard, use RO water processors coupled with one or more UV sterilizers. RO systems are also now extensively used by marine aquarium enthusiasts. In the production of bottled mineral water, the water passes through an RO water processor to remove pollutants and microorganisms. In European countries, though, such processing of Natural Mineral Water (as defined by a European Directive) is not allowed under European law. In practice, a fraction of the living bacteria can and do pass through RO membranes through minor imperfections, or bypass the membrane entirely through tiny leaks in surrounding seals. Thus, complete RO systems may include additional water treatment stages that use ultraviolet light or ozone to prevent microbiological contamination.

Membrane pore sizes can vary from 0.1 nanometres (3.9×10−9 in) to 5,000 nanometres (0.00020 in) depending on filter type. “Particle filtration” removes particles of 1 micrometre (3.9×10−5 in) or larger. Microfiltration removes particles of 50 nm or larger. “Ultrafiltration” removes particles of roughly 3 nm or larger. “Nanofiltration” removes particles of 1 nm or larger. Reverse osmosis is in the final category of membrane filtration, “hyperfiltration”, and removes particles larger than 0.1 nm.

Water and waste water purification

Rain water collected from storm drains is purified with reverse osmosis water processors and used for landscape irrigation and industrial cooling in Los Angeles and other cities, as a solution to the problem of water shortages.

In industry, reverse osmosis removes minerals from boiler water at power plants. The water is boiled and condensed repeatedly. It must be as pure as possible so that it does not leave deposits on the machinery or cause corrosion. The deposits inside or outside the boiler tubes may result in under-performance of the boiler, bringing down its efficiency and resulting in poor steam production, hence poor power production at turbine.

It is also used to clean effluent and brackish groundwater. The effluent in larger volumes (more than 500 cu. meter per day) should be treated in an effluent treatment plant first, and then the clear effluent is subjected to reverse osmosis system. Treatment cost is reduced significantly and membrane life of the RO system is increased.

The process of reverse osmosis can be used for the production of deionized water.

RO process for water purification does not require thermal energy. Flow through RO system can be regulated by high pressure pump. The recovery of purified water depends upon various factors including membrane sizes, membrane pore size, temperature, operating pressure and membrane surface area.

In 2002, Singapore announced that a process named NEWater would be a significant part of its future water plans. It involves using reverse osmosis to treat domestic wastewater before discharging the NEWater back into the reservoirs.

Food industry

In addition to desalination, reverse osmosis is a more economical operation for concentrating food liquids (such as fruit juices) than conventional heat-treatment processes. Research has been done on concentration of orange juice and tomato juice. Its advantages include a lower operating cost and the ability to avoid heat-treatment processes, which makes it suitable for heat-sensitive substances like the protein and enzymes found in most food products.

Reverse osmosis is extensively used in the dairy industry for the production of whey protein powders and for the concentration of milk to reduce shipping costs. In whey applications, the whey (liquid remaining after cheese manufacture) is concentrated with RO from 6% total solids to 10–20% total solids before UF (ultrafiltration) processing. The UF retentate can then be used to make various whey powders, including whey protein isolate used in bodybuilding formulations. Additionally, the UF permeate, which contains lactose, is concentrated by RO from 5% total solids to 18–22% total solids to reduce crystallization and drying costs of the lactose powder.

Although use of the process was once avoided in the wine industry, it is now widely understood and used. An estimated 60 reverse osmosis machines were in use in Bordeaux, France in 2002. Known users include many of the elite classed growths.

Car washing

Because of its lower mineral content, reverse osmosis water is often used in car washes during the final vehicle rinse to prevent water spotting on the vehicle. Reverse osmosis is often used to conserve and recycle water within the wash/pre-rinse cycles, especially in drought stricken areas where water conservation is important. Reverse osmosis water also enables the car wash operator to reduce the demands on the vehicle drying equipment, such as air blowers.

Maple syrup production

In 1946, some maple syrup producers started using reverse osmosis to remove water from sap before the sap is boiled down to syrup. The use of reverse osmosis allows approximately 75-90% of the water to be removed from the sap, reducing energy consumption and exposure of the syrup to high temperatures. Microbial contamination and degradation of the membranes has to be monitored.

Hydrogen production

For small-scale production of hydrogen, reverse osmosis is sometimes used to prevent formation of minerals on the surface of electrodes.

Reef aquariums

Many reef aquarium keepers use reverse osmosis systems for their artificial mixture of seawater. Ordinary tap water can often contain excessive chlorine, chloramines, copper, nitrogen, phosphates, silicates, or many other chemicals detrimental to the sensitive organisms in a reef environment. Contaminants such as nitrogen compounds and phosphates can lead to excessive, and unwanted, algae growth. An effective combination of both reverse osmosis and deionization (RO/DI) is the most popular among reef aquarium keepers, and is preferred above other water purification processes due to the low cost of ownership and minimal operating costs. Where chlorine and chloramines are found in the water, carbon filtration is needed before the membrane, as the common residential membrane used by reef keepers does not cope with these compounds.

Desalination

Areas that have either no or limited surface water or groundwater may choose to desalinate seawater or brackish water to obtain drinking water. Reverse osmosis is a common method of desalination, although 85 percent of desalinated water is produced in multistage flash plants.[5]

Large reverse osmosis and multistage flash desalination plants are used in the Middle East, especially Saudi Arabia. The energy requirements of the plants are large, but electricity can be produced relatively cheaply with the abundant oil reserves in the region. The desalination plants are often located adjacent to the power plants, which reduces energy losses in transmission and allows waste heat to be used in the desalination process of multistage flash plants, reducing the amount of energy needed to desalinate the water and providing cooling for the power plant.

Sea water reverse osmosis (SWRO) is a reverse osmosis desalination membrane process that has been commercially used since the early 1970s. Its first practical use was demonstrated by Sidney Loeb and Srinivasa Sourirajan from UCLA in Coalinga, California. Because no heating or phase changes are needed, energy requirements are low in comparison to other processes of desalination, but are still much higher than those required for other forms of water supply (including reverse osmosis treatment of wastewater).

The Ashkelon seawater reverse osmosis (SWRO) desalination plant in Israel is the largest in the world. The project was developed as a BOT (Build-Operate-Transfer) by a consortium of three international companies: Veolia water, IDE Technologies and Elran.

The typical single-pass SWRO system consists of the following components:

Intake

Pretreatment

High pressure pump

Membrane assembly

Remineralization and pH adjustment

Disinfection

Alarm/control panel

Pretreatment

Pretreatment is important when working with RO and nanofiltration (NF) membranes due to the nature of their spiral wound design. The material is engineered in such a fashion as to allow only one-way flow through the system. As such, the spiral wound design does not allow for backpulsing with water or air agitation to scour its surface and remove solids. Since accumulated material cannot be removed from the membrane surface systems, they are highly susceptible to fouling (loss of production capacity). Therefore, pretreatment is a necessity for any RO or NF system. Pretreatment in SWRO systems has four major components:

Screening of solids: Solids within the water must be removed and the water treated to prevent fouling of the membranes by fine particle or biological growth, and reduce the risk of damage to high-pressure pump components.

Cartridge filtration: Generally, string-wound polypropylene filters are used to remove particles of 1–5 µm diameter.

Dosing: Oxidizing biocides, such as chlorine, are added to kill bacteria, followed by bisulfite dosing to deactivate the chlorine, which can destroy a thin-film composite membrane. There are also biofouling inhibitors, which do not kill bacteria, but simply prevent them from growing slime on the membrane surface and plant walls.

Prefiltration pH adjustment: If the pH, hardness and the alkalinity in the feedwater result in a scaling tendency when they are concentrated in the reject stream, acid is dosed to maintain carbonates in their soluble carbonic acid form.

CO32– + H3O+ = HCO3– + H2O

HCO3– + H3O+ = H2CO3 + H2O

Carbonic acid cannot combine with calcium to form calcium carbonate scale. Calcium carbonate scaling tendency is estimated using the Langelier saturation index (LSI). Adding too much sulfuric acid to control carbonate scales may result in calcium sulfate, barium sulfate or strontium sulfate scale formation on the RO membrane.

Antiscalants: Scale inhibitors (also known as antiscalants) prevent formation of all scales compared to acid, which can only prevent formation of calcium carbonate and calcium phosphate scales. In addition to inhibiting carbonate and phosphate scales, antiscalants inhibit sulfate and fluoride scales, disperse colloids and metal oxides. Despite claims that antiscalants can inhibit silica formation, there is no concrete evidence to prove that silica polymerization can be inhibited by antiscalants. Antiscalants can control acid soluble scales at a fraction of the dosage required to control the same scale using sulfuric acid.

Some small scale desalination units use Beach wells, they are usually drilled on the seashore in close vicinity to the ocean. These intake facilities are relatively simple to build and the seawater they collect is pretreated via slow filtration through the subsurface sand/seabed formations in the area of source water extraction. Raw seawater collected using beach wells is often of better quality in terms of solids, silt, oil and grease, natural organic contamination and aquatic microorganisms, compared to open seawater intakes. Sometimes, beach intakes may also yield source water of lower salinity.

High pressure pump

The pump supplies the pressure needed to push water through the membrane, even as the membrane rejects the passage of salt through it. Typical pressures for brackish water range from 225 to 375 psi (15.5 to 26 bar, or 1.6 to 2.6 MPa). In the case of seawater, they range from 800 to 1,180 psi (55 to 81.5 bar or 6 to 8 MPa). This requires a large amount of energy.

Membrane assembly

The layers of a membrane

The membrane assembly consists of a pressure vessel with a membrane that allows feed water to be pressed against it. The membrane must be strong enough to withstand whatever pressure is applied against it. RO membranes are made in a variety of configurations, with the two most common configurations being spiral-wound and hollow-fiber.

Remineralization and pH adjustment

The desalinated water is very corrosive and is “stabilized” to protect downstream pipelines and storages, usually by adding lime or caustic to prevent corrosion of concrete lined surfaces. Liming material is used to adjust pH between 6.8 and 8.1 to meet the potable water specifications, primarily for effective disinfection and for corrosion control.

Disinfection

Post-treatment consists of preparing the water for distribution after filtration. Reverse osmosis is an effective barrier to pathogens, however post-treatment provides secondary protection against compromised membranes and downstream problems. Disinfection by means of UV lamps (sometimes called germicidal or bactericidal) may be used to sterilize pathogens which bypassed the reverse osmosis process. Chlorination or chloramination (chlorine and ammonia) protects against pathogens which may have lodged in the distribution system downstream, such as from new construction, backwash, compromised pipes, etc.[citation needed]

Disadvantages

Household reverse osmosis units use a lot of water because they have low back pressure. As a result, they recover only 5 to 15 percent of the water entering the system. The remainder is discharged as waste water. Because waste water carries with it the rejected contaminants, methods to recover this water are not practical for household systems. Waste water is typically connected to the house drains and will add to the load on household septic systems. An RO unit delivering 5 gallons of treated water a day may discharge anywhere between 20 and 90 gallons of waste water a day. For household use, however, and based on consumption of half a gallon per day, this may amount to less than a toilet-flush per day.

Large-scale industrial/municipal systems have a production efficiency of 75% – 80%, or as high as 90%, because they can generate the high pressure needed for more efficient RO filtration. On the other hand, as efficiency of waste water rates increases in commercial operations effective removal rates tend to become reduced, as evidenced by TDS counts.

Reverse Osmosis Removes Minerals

Reverse Osmosis (RO) removesd more than 90-99.99% of all the contaminants including minerals from the drinking water supply. RO removes minerals because they have larger molecules than water. The subject of minerals and RO created controversy and disagreement among water and health professionals.  The World Health Organization (WHO) stated that most of healthy minerals needed by the human body come from food or dietary supplementary sources and not from drinking tap water. In addition, some minerals found in water can be harmful to human health.  The evidence is strong that calcium and magnesium are essential elements for human body.  However, this is not to suggest that we should make up this deficiency through water consumption. Tap water presents a variety of inorganic minerals which human body has difficulty absorbing. Their presence is suspect in a wide array of degenerative diseases, such as hardening of the arteries, arthritis, kidney stones, gall stones, glaucoma, cataracts, hearing loss, emphysema, diabetes, and obesity. What minerals are available, especially in “hard” tap water, are poorly absorbed, or rejected by cellular tissue sites, and, if not evacuated, their presence may cause arterial obstruction, and internal damage (Dennison, 193; Muehling, 1994; Banik, 1989).

A number of studies have looked at the long term health effects of drinking demineralized water. However, demineralized water can be remineralized, and this process has been done in instances when processing demineralized water for consumption. Dasani water uses this process.

Water filtered or treated by RO is generally pure, clean, and healthy.  RO treatment is currently the only technology that can remove emerging contaminants (prescription drugs and perchlorate) and some others (i.e., arsenic, cyanide, and fluoride) that are difficult to remove by other methods. Consumers should not be concerned about the removal of minerals by RO system.  WHO (2009) and WQA (2011) pointed out, that the human body obtains most minerals from food or supplements, not from drinking water.

Popular RO Meters

RO Meter – RO-1: 0-1250 ppm with color band

Instant and accurate TDS tests
Electronic Internal Standard for easy field calibration
Fast Auto Temperature Compensation
Rugged design for years of trouble-free testing
Simple to use

758II: Conductivity Digital Monitor/Controller

The choice of professionals for years, this compact instrument has been designed specifically to demonstrate and test Point of Use (POU) reverse osmosis or distillation systems. By measuring electrical conductivity, it will quickly determine the parts per million/Total Dissolved Solids (ppm/TDS) of any drinking water.

With a single ‘before and after’ test, this handy device effectively demonstrates how your RO or distillation system eliminates harmful dissolved solids. It will also service test systems, including membrane evaluation programs.

The unique circuitry of the 750 Series II Conductivity Monitor/controllers guarantees accurate and reliable measurements. Drift-free performance is assured by “field proven” electronics, including automatic DC offset compensation and highly accurate drive voltage.

Since temperature compensation is at the heart of accurate water measurement, all Myron L Monitor/controllers feature a highly refined and precise TC circuit. This feature perfectly matches the water temperature coefficient as it changes. All models corrected to 25′C. The TC may be disabled to conform with USP requirements.

Built-in electronic calibration allows for fast quality checks without standard solutions. (Note: for maximum system accuracy standard solutions are recommended).

Aquaswitch I 

For use with any two-bank supply systems (DI banks, RO systems, etc)

Must use with Inline Monitor/Controller

The AQUASWITCH I is a special purpose dedicated instrument which automatically “switches” from an exhausted DI or RO bank to a fresh stand-by bank. LEDs continually give the condition of both banks. An alarm output is activated as each bank is depleted.

Ultrameter III – 9PTK

pH and pH Meters – MyronLMeters.com

TweetWhat is pH? pH measures the activity of the (solvated) hydrogen ion. Pure water has a pH very close to 7 at 25°C. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic or alkaline. The pH scale is traceable to a set of standard solutions [...]

What is pH?

pH measures the activity of the (solvated) hydrogen ion. Pure water has a pH very close to 7 at 25°C. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic or alkaline. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Measuring pH for aqueous solutions can be done with a glass electrode and a pH meter, or using indicators.

Measuring pH is important in water treatment, medicine, biology, chemistry, agriculture, forestry, food science, environmental science, oceanography, civil engineering, chemical engineering, and many other applications.

p[H] was first introduced by Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells.  According to the Carlsberg Foundation pH stands for “power of hydrogen”.

pH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, a_H+, in a solution.

pH Meters

A pH meter is an electronic device used for measuring the pH (acidity or alkalinity) of a liquid (though special probes are sometimes used to measure the pH of semi-solid substances). A typical pH meter consists of a special measuring probe (a glass electrode) connected to an electronic meter that measures and displays the pH reading.

The probe

The pH probe measures pH as the activity of the hydrogen cations surrounding a thin-walled glass bulb at its tip. The probe produces a small voltage (about 0.06 volt per pH unit) that is measured and displayed as pH units by the meter. For more information about pH probe care or replacement, please consult your Myron L meter operations manual.

Calibration and use

*Please consult your Myron L meter operations manual before calibrating.

For very precise work the pH meter should be calibrated before each measurement. For normal use calibration should be performed at the beginning of each day. The reason for this is that the glass electrode does not give a reproducible e.m.f. over longer periods of time. Calibration should be performed with at least two standard buffer solutions that span the range of pH values to be measured. For general purposes buffers at pH 4 and pH 10 are acceptable. The pH meter has one control (calibrate) to set the meter reading equal to the value of the first standard buffer and a second control (slope) which is used to adjust the meter reading to the value of the second buffer. A third control allows the temperature to be set. Standard buffer solutions, which can be obtained from MyronLMeters.com here:

http://www.myronlmeters.com/pH-Buffer-Calibration-Solutions-s/82.htm

usually state how the buffer value changes with temperature. For more precise measurements, a three buffer solution calibration is preferred. As pH 7 is essentially, a “zero point” calibration (akin to zeroing a scale), calibrating at pH 7 first, calibrating at the pH closest to the point of interest ( e.g. either 4 or 10) second and checking the third point will provide a more linear accuracy to what is essentially a non-linear problem. Some meters will allow a three point calibration and that is the preferred scheme for the most accurate work, and is recommended by Myron L Meters. Higher quality meters will have a provision to account for temperature coefficient correction, and high-end pH probes have temperature probes built in. The calibration process correlates the voltage produced by the probe (approximately 0.06 volts per pH unit) with the pH scale. After each single measurement, the probe is rinsed with distilled water or deionized water to remove any traces of the solution being measured, blotted with a scientific wipe to absorb any remaining water which could dilute the sample and thus alter the reading, and then quickly immersed in another solution.

Storage conditions of the glass probes

When not in use, the glass probe tip must be kept wet at all times to avoid the pH sensing membrane dehydration and the subsequent dysfunction of the electrode. You can get your sensor storage solution here:

http://www.myronlmeters.com/pH-Storage-Solution-p/s-ssq.htm

A glass electrode alone (i.e., without combined reference electrode) is typically stored immersed in an acidic solution of around pH 3.0. In an emergency, acidified tap water can be used, but distilled or deionised water must never be used for longer-term probe storage as the relatively ionless water “sucks” ions out of the probe membrane through diffusion, which degrades it.

Combined electrodes (glass membrane + reference electrode) are better stored immersed in the bridge electrolyte (often KCl  3 M) to avoid the diffusion of the electrolyte (KCl) out of the liquid junction.

Cleaning and troubleshooting of the glass probes

Occasionally (about once a month), the probe may be cleaned using pH-electrode cleaning solution; generally a 0.1 M solution of hydrochloric acid (HCl) is used, having a pH of one.

In case of strong degradation of the glass membrane performance due to membrane poisoning, diluted hydrofluoric acid (HF < 2 %) can be used to quickly etch (< 1 minute) a thin damaged film of glass. Alternatively a dilute solution of ammonium fluoride (NH4F) can be used. To avoid unexpected problems, the best practice is however to always refer to the electrode manufacturer recommendations or to a classical textbook of analytical chemistry.

Types of pH meters

A pH meter for every industry

pH meters range from simple and inexpensive pen-like devices to complex and expensive laboratory instruments with computer interfaces and several inputs for indicator and temperature measurements to be entered to adjust for the slight variation in pH caused by temperature. Specialty meters and probes are available for use in special applications, harsh environments, etc. Myron L Meters offers a simple pen-style pH meter, analog handheld meters, digital handheld multiparameter meters, and inline monitor/controllers.

https://www.myronlmeters.com/Ultrapen-PT2-Multiparameter-Meter-p/dh-up-pt2-ss.htm

ULTRAPEN PT2 pH and Temperature Pen

Accuracy of +/- 0.01 pH

Reliable Repeatable Results

Easy Calibration

Automatic Temperature Compensation

Measures Temperature

Durable, Fully Potted Circuitry

Waterproof

Comes with 2oz bottle of pH Storage Solution

http://www.myronlmeters.com/Analog-pH-Conductivity-Meter-p/ah-ds-ag6-fslash-ph.htm

Agri-Meter – Ag-6: 0-5 millimhos; 2-12 pH

Instant and accurate TDS tests

Electronic Internal Standard for easy field calibration

Fast Auto Temperature Compensation

Rugged design for years of trouble-free testing

Simple to use

http://www.myronlmeters.com/Ultrameter-II-6P-Multiparameter-Meter-p/dh-umii-6pii.htm

Multi-Parameter: Conductivity, TDS, Resistivity, pH, ORP, Temperature, Free Chlorine (FCE)

+/-1% Accuracy of Reading

Memory Storage: Save up to 100 samples w/ Date & Time stamp

Wireless Download Module Optional

Waterproof

http://www.myronlmeters.com/Inline-pH-Digital-Monitor-Controller-p/i-dmc-723ii.htm

The advanced “isolated” circuitry of the 720 Series II pH/ORP Monitor/ controllers guarantees accurate and reliable measurements — completely eliminating ground-loop and noise issues.

The unique sensor preamp allows for longer distances between the sensor and the Monitor/controller without the loss of accuracy or reliability.

All Myron L Monitor/controllers feature a highly refined and precise Temperature Compensation circuit. This feature perfectly matches the NERNST equation correcting the displayed reading to 25′C. The TC may be disabled to conform to USP requirements.

Groundbreaking Research Proves Easier Measurements of Free Chlorine

TweetNew studies have discovered a new, easier way to measure free chlorine using a digital handheld water quality instrument. This exhaustive research study resulted in the engineering of a brand new measurement feature on the Ultrameter II 6P. This new feature is the Free Chlorine Equivalent (FCE) using value from other parameters to compute accurate [...]

New studies have discovered a new, easier way to measure free chlorine using a digital handheld water quality instrument. This exhaustive research study resulted in the engineering of a brand new measurement feature on the Ultrameter II 6P.

This new feature is the Free Chlorine Equivalent (FCE) using value from other parameters to compute accurate free chlorine values. Check out the full story that breaks down all of the technical details with facts, figures, charts and more.

Read the study or download the research paper here: Free Chlorine Research Paper

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.