Reverse osmosis uses pressure to force water through a semi-permeable membrane that allows water molecules to pass but blocks most other contaminants. Feed water is pumped into a reverse osmosis system, producing two outputs - purified permeate water with 95-99% of dissolved salts removed, and a reject concentrate containing the contaminants unable to pass through the membrane. By applying pressure greater than osmotic pressure, reverse osmosis is able to "reverse" natural osmosis and produce purified drinking water from brackish or seawater.
This document provides an overview of reverse osmosis systems, including:
- Osmosis is the natural process by which water moves through a semi-permeable membrane from an area of high water concentration to low. Reverse osmosis forces water through a membrane from a low to high concentration area using pressure.
- Reverse osmosis membranes filter out dissolved ions and particles as small as 0.0001 microns to produce purified water. Factors like temperature, pressure, and contaminants affect production rates.
- Proper maintenance of pre-filters, post-filters, and membranes is required to maximize system performance and lifespan. Troubleshooting guidance addresses common issues like low flow rates or continuous running.
Reverse osmosis uses pressure to force water through a semi-permeable membrane, allowing pure water to pass through while retaining dissolved salts and other contaminants. It is a highly effective purification process that can remove pollutants from tap water to produce pure water. A basic reverse osmosis system consists of a cold water line, pre-filter, reverse osmosis membrane, post-filter, automatic shut-off valve, check valve, flow restrictor, storage tank, and faucet. Reverse osmosis systems are commonly used to purify water for industrial, medical, and bottled water applications.
This document provides an introduction to reverse osmosis, a membrane-based process for desalination and water purification. It begins by explaining osmosis and how reverse osmosis works by applying pressure to force water through a semi-permeable membrane from a higher solute concentration to a lower one. The document then discusses different types of reverse osmosis membranes, including cellulosic, aromatic polyamide, and thin film composite membranes. It also outlines several applications of reverse osmosis water purification and explains how reverse osmosis can remove over 90% of various dissolved solids and contaminants from water.
This document discusses zero liquid discharge (ZLD) systems. It provides background on the need for ZLD due to water scarcity issues. It then describes the key steps in a ZLD process, which involves pre-treatment, evaporation, and crystallization to separate water for reuse from solids for disposal. Common technologies used are reverse osmosis, mechanical vapor recompression, and multiple effect evaporators. The document concludes with two case studies of industries that have implemented ZLD systems successfully.
Operation & maintenance aspects of a Water treatment plant.Home
Operation and maintenance of a treatment plant is task. This is done to expand the life time of the treatment plant. So its necessary to keep the water treatment plant with a good look after on the hand of operation and also in maintenance both simultaneously. The given slides show some operation and maintenance processes to carry out a water treatment plant.
This document provides an overview of water issues and sewage treatment processes. It discusses the global water crisis, reasons for water scarcity in India like increasing demand and decreasing supply. It then describes the various unit processes involved in sewage treatment like bar screens, neutralization, activated sludge process using aeration tanks and secondary clarifiers, and tertiary treatment using processes like filtration and UV disinfection. The importance of proper operation and maintenance of sewage treatment plants is also emphasized.
This document provides an overview of reverse osmosis systems, including:
- Osmosis is the natural process by which water moves through a semi-permeable membrane from an area of high water concentration to low. Reverse osmosis forces water through a membrane from a low to high concentration area using pressure.
- Reverse osmosis membranes filter out dissolved ions and particles as small as 0.0001 microns to produce purified water. Factors like temperature, pressure, and contaminants affect production rates.
- Proper maintenance of pre-filters, post-filters, and membranes is required to maximize system performance and lifespan. Troubleshooting guidance addresses common issues like low flow rates or continuous running.
Reverse osmosis uses pressure to force water through a semi-permeable membrane, allowing pure water to pass through while retaining dissolved salts and other contaminants. It is a highly effective purification process that can remove pollutants from tap water to produce pure water. A basic reverse osmosis system consists of a cold water line, pre-filter, reverse osmosis membrane, post-filter, automatic shut-off valve, check valve, flow restrictor, storage tank, and faucet. Reverse osmosis systems are commonly used to purify water for industrial, medical, and bottled water applications.
This document provides an introduction to reverse osmosis, a membrane-based process for desalination and water purification. It begins by explaining osmosis and how reverse osmosis works by applying pressure to force water through a semi-permeable membrane from a higher solute concentration to a lower one. The document then discusses different types of reverse osmosis membranes, including cellulosic, aromatic polyamide, and thin film composite membranes. It also outlines several applications of reverse osmosis water purification and explains how reverse osmosis can remove over 90% of various dissolved solids and contaminants from water.
This document discusses zero liquid discharge (ZLD) systems. It provides background on the need for ZLD due to water scarcity issues. It then describes the key steps in a ZLD process, which involves pre-treatment, evaporation, and crystallization to separate water for reuse from solids for disposal. Common technologies used are reverse osmosis, mechanical vapor recompression, and multiple effect evaporators. The document concludes with two case studies of industries that have implemented ZLD systems successfully.
Operation & maintenance aspects of a Water treatment plant.Home
Operation and maintenance of a treatment plant is task. This is done to expand the life time of the treatment plant. So its necessary to keep the water treatment plant with a good look after on the hand of operation and also in maintenance both simultaneously. The given slides show some operation and maintenance processes to carry out a water treatment plant.
This document provides an overview of water issues and sewage treatment processes. It discusses the global water crisis, reasons for water scarcity in India like increasing demand and decreasing supply. It then describes the various unit processes involved in sewage treatment like bar screens, neutralization, activated sludge process using aeration tanks and secondary clarifiers, and tertiary treatment using processes like filtration and UV disinfection. The importance of proper operation and maintenance of sewage treatment plants is also emphasized.
- Osmosis is the natural movement of water across a semi-permeable membrane from an area of high water concentration to low concentration. Reverse osmosis (RO) works in the opposite direction, using pressure to force water across a membrane from a more concentrated solution to a less concentrated one.
- A typical home RO system uses prefilters, an RO membrane, and postfilters to produce clean water for drinking. Key factors that affect RO performance include water temperature, pressure, and contaminant levels. Regular maintenance like replacing filters every 6 months helps the membrane last 1-3 years. Issues like slow flow or no water could be due to fouling, pressure problems, or installation errors.
- RO
Reverse osmosis uses semi-permeable membranes to purify water by separating dissolved solids. It has various applications in water treatment and is used along with demineralization plants. A reverse osmosis system consists of pre-treatment, high-pressure pumps, membrane systems, and post-treatment. It produces permeate water while concentrating impurities in reject water. Demineralization uses ion exchange resins to remove mineral ions, producing very high purity water. Together, reverse osmosis and demineralization can purify water for various industrial and medical uses.
Reverse osmosis systems use semi-permeable membranes to filter water and remove salts and other contaminants. They work by applying pressure to reverse the natural process of osmosis, allowing pure water to pass through the membrane while retaining salts. Reverse osmosis systems are commonly used in homes to produce drinking water and in industry to provide high-quality feed water to boilers and other systems. They provide benefits such as producing quality water at low cost with limited space requirements.
This document provides information about reverse osmosis (RO) technology. It defines RO as a water purification process that uses semi-permeable membranes to remove molecules and ions from water by applying pressure. RO can be used to purify drinking water, treat wastewater, and produce deionized water. It is effective at removing pesticides, salt, microorganisms, suspended solids, and other contaminants. RO has advantages such as low energy requirements, compact size, easy maintenance and modular design allowing for expansion. However, it does not remove hardness, gases or some beneficial minerals and the waste concentrate requires disposal.
Reverse osmosis uses pressure to force water through a semi-permeable membrane, leaving dissolved salts and other contaminants behind. It works by applying pressure greater than natural osmotic pressure to the more concentrated side of the membrane. This forces water molecules through the membrane while preventing 95-99% of dissolved salts from passing. The filtered water is called permeate, while the concentrated waste is the reject stream. Reverse osmosis can remove particles, bacteria, and other contaminants over 200 molecular weight from water and is widely used for desalination, wastewater treatment, and producing ultrapure water.
This document describes the effluent treatment plant (ETP) of Delta Knit Composite Ltd. The ETP uses a biological treatment process to treat 120 m3/hr of industrial wastewater. The treatment process includes screening, equalization, pH correction, aeration, sedimentation, sludge thickening, and recycling of sludge. The ETP is able to reduce pollutants in the wastewater and produce treated effluent that can be safely discharged and dried sludge.
This document provides an overview of cleaning reverse osmosis and nanofiltration membrane elements. It discusses common types of fouling and scaling like carbonate, sulfate, organic and biological, and recommends appropriate cleaning methods. Cleaning solutions may include acids, bases, chelating agents and detergents. The document outlines the cleaning process, safety procedures, and recommends feed flow rates during cleaning based on element size and pressure. The goal of cleaning is to remove buildup and restore membrane performance by reducing pressure and increasing permeate flow.
The document discusses key terms and processes used in effluent treatment plants (ETPs). It defines terms like pH, BOD, COD, DO and explains their significance. It also summarizes different treatment stages in ETPs like preliminary treatment involving screening and grit removal, primary treatment using equalization, coagulation and flocculation, and biological treatment using activated sludge process. The document provides an overview of the various unit operations and treatment mechanisms involved in ETPs.
Lecture note of Industrial Waste Treatment (Elective -III) as per syllabus of Solapur university for BE Civil
Prepared by
Prof S S Jahagirdar,
Associate Professor,
N K ORchid College of Engg and Tech,
Solapur
The document discusses various techniques for demineralizing water for high pressure boilers, including distillation, electrodialysis, reverse osmosis, and ion exchange. It provides details on the processes of reverse osmosis and ion exchange, which are the most common techniques used. Reverse osmosis uses pressure to force water through a semi-permeable membrane, leaving dissolved ions behind. Ion exchange involves the reversible exchange of ions between a solid resin and water, allowing contaminated water to be treated by replacing its ions with more desirable ones like hydrogen or hydroxide ions. The document outlines the components and operation of typical reverse osmosis and ion exchange systems used for demineralization.
Reverse osmosis uses pressure to force water through a semi-permeable membrane that allows water to pass but blocks dissolved salts and other molecules. In reverse osmosis, a pressurized saline solution is pumped through a membrane, separating it into a purified water stream and a concentrated brine stream. Higher pressure increases water flux through the membrane while lowering salt passage. Reverse osmosis is used to desalinate seawater, purify water, and separate dissolved materials in industrial processes.
Reverse osmosis is a process where water molecules pass through a semipermeable membrane from a high concentration solution to a low concentration solution when sufficient pressure is applied against the flow of osmosis. It works in the reverse direction of natural osmosis and can remove dissolved particles like ions and bacteria from water. Spiral wound, thin film composite, and stainless steel membranes are commonly used, with each having advantages like high packing density or chemical stability but also limitations such as susceptibility to fouling or high costs. Reverse osmosis has benefits of producing clean drinking water without chemicals but uses significant amounts of water and energy during processing.
Effluent treatment plant - design, operation and analysis of waste water trea...Shubham Hydrosys Pvt. Ltd
The Effluent Treatment Plants [ETP] plant is designed to treat the effluent coming from various areas of the plant. The treatment of different effluents varies with the type of effluent. Industrial wastewater contains a diversity of impurities and therefore for this reason alone, its treatment establishes a special task. Shubham Inc. offers comprehensive range of Effluent Treatment Plants that is highly effective.
The complete treatment solution works at many levels and comprises of different physical, chemical, biological and membrane processes. For reducing the BOD, COD, color, nitrogen and toxic level of the effluent, SHUBHAM is offeringa various solutions from ASP (activated sludge process) to advance Membrane technologies as per treated water uses.Shubham OffersCustomized systems to suit the extensive variety of effluents and to maintain efficiency are provided to industries.
We provide innovative and economical systems for waste withexpertise is advantageously employed for the technical and economic optimization of every subsequent facility.
SHUBHAM INC use the best-in-class technology and cutting-edge tools to foster high-quality, sustainable, community-level water supply sewage treatment plant and Effluent Treatment Plants projects in Gujarat, India across the ahmedabad, Surat, Rajkot and Baroda.
Some processes followed by us are:
• Aerobic Biological Process
• Anaerobic Biological Process
• Chemical-physical process
TREATMENT REQUIREMENTS:
1. Oil & grease Separation
2. Neutralization of Acids and Alkali
3. Removal of Suspended Solids
4. Reduction & Removal of metallic impurities
5. Reduction of high organic content: BOD, COD, P, TKN, etc.
6. Dissolve impurities for ZLD system.
TREATMENT METHODS
• Primary clarifications
• Biological process
• Secondary clarifications.
• Tertiary treatment
• Polishing units i.e. UF, RO and DM (Optional for recycling or ZLD)
Applications:
• Textile Industries
• Distilleries
• Pharmacy Industries.
• Chemical Industries
• Paper Industries
• Tannery Industries
• Dye & Dye Intermediaries
• Edible Oil Refineries
• Electroplating Industries
Features:
• Sturdy construction
• Resistant to corrosion
• Superior performance
• Rapid installation
• Less civil work involved
• Flexible in reworking
1) The document describes the key physical, chemical, and biological characteristics used to analyze industrial wastewater quality.
2) It covers 4 categories - physical, chemical, microbiological, and radiological - and describes parameters like turbidity, temperature, pH, and toxic substances.
3) Measurement methods for parameters like BOD, COD, and solids are also outlined to analyze wastewater contaminants and inform treatment.
Installing non-compatible Zero Liquid Discharge System to comply with Prescribed Norms imposed by State Pollution Control Board is simply equal to non-compliance of the same. To get the best possible solution for actual ZLD, Contact Us www.envirochemservices.in
Reverse osmosis is a process where an applied pressure is used to force a concentrated solution through a semi-permeable membrane to separate out water molecules. It works by allowing water molecules to pass through the membrane while preventing dissolved salts, particles, organics, bacteria, and other contaminants from passing. Factors like temperature, pressure, and salt concentration affect the performance and permeate flow rate, with higher temperatures and pressures increasing flow. Reverse osmosis has applications in industries like food/beverage processing for concentrating liquids, drinking water purification, and dairy for milk concentration.
This document provides information about the wastewater treatment process at Renata Limited, a pharmaceutical manufacturer in Bangladesh. Renata has water treatment plants and effluent treatment plants at each of its five manufacturing facilities. The effluent treatment plant uses a physico-chemical treatment process including equalization, coagulation, flocculation, sedimentation, sand filtration, activated carbon filtration, and aeration to treat wastewater and reduce pollutants before discharging to the municipal sewer system. Plant staff monitor influent and effluent water quality parameters regularly to evaluate the treatment system's performance.
Zero liquid discharge (ZLD) refers to systems that enable absolute recycling of treated wastewater and conversion of dissolved solids into solid residue through concentration and thermal evaporation. ZLD certification is based on water consumption, wastewater recycled, and solids recovered. Conventional ZLD uses multi-effect evaporation, but this requires high steam consumption. A new technology called polymeric film evaporation uses polymer films as the heat transfer surface, achieving lower operating costs than multi-effect evaporation through reduced steam and power usage. This polymeric film evaporation technology provides benefits like low maintenance and scaling resistance.
This document discusses water demineralization using ion exchange. It explains that demineralization removes inorganic salts by using cation exchange resins to convert dissolved salts to acids and anion exchange resins to remove these acids. The purpose is to reduce conductivity and control pH. It describes how cation resins exchange hydrogen for raw water cations and anion resins exchange hydroxyl for anions. Together this forms water and embeds the anions in the resin, removing other weak acids. Cation resins are regenerated with acid then washing, and anion resins are regenerated with sodium hydroxide then washing.
Reverse osmosis uses semipermeable membranes to separate salt from water by applying pressure greater than the osmotic pressure. It is used to desalinate seawater and brackish water by producing fresh water with low salt content. Common applications include meeting water needs where surface water is limited, and purifying water for industrial uses. Proper membrane cleaning and maintenance is important to prevent contamination and extend membrane lifespan for continued effective desalination.
1. Reverse osmosis uses semipermeable membranes and pressure to separate solvent molecules like water from solutes like salt, forcing the pure solvent to pass through the membrane and retaining the solute.
2. It is used in desalination plants worldwide to produce fresh water from seawater and in various industrial and domestic water purification applications.
3. Key applications include purifying drinking water, water and wastewater treatment, producing deionized water, and concentrating food liquids like fruit juices and milk.
- Osmosis is the natural movement of water across a semi-permeable membrane from an area of high water concentration to low concentration. Reverse osmosis (RO) works in the opposite direction, using pressure to force water across a membrane from a more concentrated solution to a less concentrated one.
- A typical home RO system uses prefilters, an RO membrane, and postfilters to produce clean water for drinking. Key factors that affect RO performance include water temperature, pressure, and contaminant levels. Regular maintenance like replacing filters every 6 months helps the membrane last 1-3 years. Issues like slow flow or no water could be due to fouling, pressure problems, or installation errors.
- RO
Reverse osmosis uses semi-permeable membranes to purify water by separating dissolved solids. It has various applications in water treatment and is used along with demineralization plants. A reverse osmosis system consists of pre-treatment, high-pressure pumps, membrane systems, and post-treatment. It produces permeate water while concentrating impurities in reject water. Demineralization uses ion exchange resins to remove mineral ions, producing very high purity water. Together, reverse osmosis and demineralization can purify water for various industrial and medical uses.
Reverse osmosis systems use semi-permeable membranes to filter water and remove salts and other contaminants. They work by applying pressure to reverse the natural process of osmosis, allowing pure water to pass through the membrane while retaining salts. Reverse osmosis systems are commonly used in homes to produce drinking water and in industry to provide high-quality feed water to boilers and other systems. They provide benefits such as producing quality water at low cost with limited space requirements.
This document provides information about reverse osmosis (RO) technology. It defines RO as a water purification process that uses semi-permeable membranes to remove molecules and ions from water by applying pressure. RO can be used to purify drinking water, treat wastewater, and produce deionized water. It is effective at removing pesticides, salt, microorganisms, suspended solids, and other contaminants. RO has advantages such as low energy requirements, compact size, easy maintenance and modular design allowing for expansion. However, it does not remove hardness, gases or some beneficial minerals and the waste concentrate requires disposal.
Reverse osmosis uses pressure to force water through a semi-permeable membrane, leaving dissolved salts and other contaminants behind. It works by applying pressure greater than natural osmotic pressure to the more concentrated side of the membrane. This forces water molecules through the membrane while preventing 95-99% of dissolved salts from passing. The filtered water is called permeate, while the concentrated waste is the reject stream. Reverse osmosis can remove particles, bacteria, and other contaminants over 200 molecular weight from water and is widely used for desalination, wastewater treatment, and producing ultrapure water.
This document describes the effluent treatment plant (ETP) of Delta Knit Composite Ltd. The ETP uses a biological treatment process to treat 120 m3/hr of industrial wastewater. The treatment process includes screening, equalization, pH correction, aeration, sedimentation, sludge thickening, and recycling of sludge. The ETP is able to reduce pollutants in the wastewater and produce treated effluent that can be safely discharged and dried sludge.
This document provides an overview of cleaning reverse osmosis and nanofiltration membrane elements. It discusses common types of fouling and scaling like carbonate, sulfate, organic and biological, and recommends appropriate cleaning methods. Cleaning solutions may include acids, bases, chelating agents and detergents. The document outlines the cleaning process, safety procedures, and recommends feed flow rates during cleaning based on element size and pressure. The goal of cleaning is to remove buildup and restore membrane performance by reducing pressure and increasing permeate flow.
The document discusses key terms and processes used in effluent treatment plants (ETPs). It defines terms like pH, BOD, COD, DO and explains their significance. It also summarizes different treatment stages in ETPs like preliminary treatment involving screening and grit removal, primary treatment using equalization, coagulation and flocculation, and biological treatment using activated sludge process. The document provides an overview of the various unit operations and treatment mechanisms involved in ETPs.
Lecture note of Industrial Waste Treatment (Elective -III) as per syllabus of Solapur university for BE Civil
Prepared by
Prof S S Jahagirdar,
Associate Professor,
N K ORchid College of Engg and Tech,
Solapur
The document discusses various techniques for demineralizing water for high pressure boilers, including distillation, electrodialysis, reverse osmosis, and ion exchange. It provides details on the processes of reverse osmosis and ion exchange, which are the most common techniques used. Reverse osmosis uses pressure to force water through a semi-permeable membrane, leaving dissolved ions behind. Ion exchange involves the reversible exchange of ions between a solid resin and water, allowing contaminated water to be treated by replacing its ions with more desirable ones like hydrogen or hydroxide ions. The document outlines the components and operation of typical reverse osmosis and ion exchange systems used for demineralization.
Reverse osmosis uses pressure to force water through a semi-permeable membrane that allows water to pass but blocks dissolved salts and other molecules. In reverse osmosis, a pressurized saline solution is pumped through a membrane, separating it into a purified water stream and a concentrated brine stream. Higher pressure increases water flux through the membrane while lowering salt passage. Reverse osmosis is used to desalinate seawater, purify water, and separate dissolved materials in industrial processes.
Reverse osmosis is a process where water molecules pass through a semipermeable membrane from a high concentration solution to a low concentration solution when sufficient pressure is applied against the flow of osmosis. It works in the reverse direction of natural osmosis and can remove dissolved particles like ions and bacteria from water. Spiral wound, thin film composite, and stainless steel membranes are commonly used, with each having advantages like high packing density or chemical stability but also limitations such as susceptibility to fouling or high costs. Reverse osmosis has benefits of producing clean drinking water without chemicals but uses significant amounts of water and energy during processing.
Effluent treatment plant - design, operation and analysis of waste water trea...Shubham Hydrosys Pvt. Ltd
The Effluent Treatment Plants [ETP] plant is designed to treat the effluent coming from various areas of the plant. The treatment of different effluents varies with the type of effluent. Industrial wastewater contains a diversity of impurities and therefore for this reason alone, its treatment establishes a special task. Shubham Inc. offers comprehensive range of Effluent Treatment Plants that is highly effective.
The complete treatment solution works at many levels and comprises of different physical, chemical, biological and membrane processes. For reducing the BOD, COD, color, nitrogen and toxic level of the effluent, SHUBHAM is offeringa various solutions from ASP (activated sludge process) to advance Membrane technologies as per treated water uses.Shubham OffersCustomized systems to suit the extensive variety of effluents and to maintain efficiency are provided to industries.
We provide innovative and economical systems for waste withexpertise is advantageously employed for the technical and economic optimization of every subsequent facility.
SHUBHAM INC use the best-in-class technology and cutting-edge tools to foster high-quality, sustainable, community-level water supply sewage treatment plant and Effluent Treatment Plants projects in Gujarat, India across the ahmedabad, Surat, Rajkot and Baroda.
Some processes followed by us are:
• Aerobic Biological Process
• Anaerobic Biological Process
• Chemical-physical process
TREATMENT REQUIREMENTS:
1. Oil & grease Separation
2. Neutralization of Acids and Alkali
3. Removal of Suspended Solids
4. Reduction & Removal of metallic impurities
5. Reduction of high organic content: BOD, COD, P, TKN, etc.
6. Dissolve impurities for ZLD system.
TREATMENT METHODS
• Primary clarifications
• Biological process
• Secondary clarifications.
• Tertiary treatment
• Polishing units i.e. UF, RO and DM (Optional for recycling or ZLD)
Applications:
• Textile Industries
• Distilleries
• Pharmacy Industries.
• Chemical Industries
• Paper Industries
• Tannery Industries
• Dye & Dye Intermediaries
• Edible Oil Refineries
• Electroplating Industries
Features:
• Sturdy construction
• Resistant to corrosion
• Superior performance
• Rapid installation
• Less civil work involved
• Flexible in reworking
1) The document describes the key physical, chemical, and biological characteristics used to analyze industrial wastewater quality.
2) It covers 4 categories - physical, chemical, microbiological, and radiological - and describes parameters like turbidity, temperature, pH, and toxic substances.
3) Measurement methods for parameters like BOD, COD, and solids are also outlined to analyze wastewater contaminants and inform treatment.
Installing non-compatible Zero Liquid Discharge System to comply with Prescribed Norms imposed by State Pollution Control Board is simply equal to non-compliance of the same. To get the best possible solution for actual ZLD, Contact Us www.envirochemservices.in
Reverse osmosis is a process where an applied pressure is used to force a concentrated solution through a semi-permeable membrane to separate out water molecules. It works by allowing water molecules to pass through the membrane while preventing dissolved salts, particles, organics, bacteria, and other contaminants from passing. Factors like temperature, pressure, and salt concentration affect the performance and permeate flow rate, with higher temperatures and pressures increasing flow. Reverse osmosis has applications in industries like food/beverage processing for concentrating liquids, drinking water purification, and dairy for milk concentration.
This document provides information about the wastewater treatment process at Renata Limited, a pharmaceutical manufacturer in Bangladesh. Renata has water treatment plants and effluent treatment plants at each of its five manufacturing facilities. The effluent treatment plant uses a physico-chemical treatment process including equalization, coagulation, flocculation, sedimentation, sand filtration, activated carbon filtration, and aeration to treat wastewater and reduce pollutants before discharging to the municipal sewer system. Plant staff monitor influent and effluent water quality parameters regularly to evaluate the treatment system's performance.
Zero liquid discharge (ZLD) refers to systems that enable absolute recycling of treated wastewater and conversion of dissolved solids into solid residue through concentration and thermal evaporation. ZLD certification is based on water consumption, wastewater recycled, and solids recovered. Conventional ZLD uses multi-effect evaporation, but this requires high steam consumption. A new technology called polymeric film evaporation uses polymer films as the heat transfer surface, achieving lower operating costs than multi-effect evaporation through reduced steam and power usage. This polymeric film evaporation technology provides benefits like low maintenance and scaling resistance.
This document discusses water demineralization using ion exchange. It explains that demineralization removes inorganic salts by using cation exchange resins to convert dissolved salts to acids and anion exchange resins to remove these acids. The purpose is to reduce conductivity and control pH. It describes how cation resins exchange hydrogen for raw water cations and anion resins exchange hydroxyl for anions. Together this forms water and embeds the anions in the resin, removing other weak acids. Cation resins are regenerated with acid then washing, and anion resins are regenerated with sodium hydroxide then washing.
Reverse osmosis uses semipermeable membranes to separate salt from water by applying pressure greater than the osmotic pressure. It is used to desalinate seawater and brackish water by producing fresh water with low salt content. Common applications include meeting water needs where surface water is limited, and purifying water for industrial uses. Proper membrane cleaning and maintenance is important to prevent contamination and extend membrane lifespan for continued effective desalination.
1. Reverse osmosis uses semipermeable membranes and pressure to separate solvent molecules like water from solutes like salt, forcing the pure solvent to pass through the membrane and retaining the solute.
2. It is used in desalination plants worldwide to produce fresh water from seawater and in various industrial and domestic water purification applications.
3. Key applications include purifying drinking water, water and wastewater treatment, producing deionized water, and concentrating food liquids like fruit juices and milk.
1. The document describes a reverse osmosis system for desalination using a pressure exchanger. It involves sea water flowing into an osmosis unit containing a semipermeable membrane, with fresh water flowing out and concentrated brine flowing out.
2. Reverse osmosis uses pressure to force solvent through a semipermeable membrane from an area of high solute concentration to low solute concentration. It is commonly used to purify drinking water from seawater and other sources.
3. Key applications of reverse osmosis include drinking water purification, water and wastewater treatment, food processing, and desalination of seawater. It removes particles, molecules and ions from
This document discusses various water treatment processes used in the pharmaceutical industry, including reverse osmosis (RO), demineralization (DM), and ultrafiltration. RO uses semipermeable membranes to remove dissolved solids, particles, and microorganisms from water. DM removes mineral salts using ion exchange resins. Ultrafiltration uses membranes to retain suspended solids and high molecular weight substances. The document also describes different types of treated water used in pharmaceutical applications, such as water for injection and sterile water, and their production processes.
This document discusses various water treatment processes used in the pharmaceutical industry, including reverse osmosis (RO), demineralization (DM), and ultrafiltration. RO uses semipermeable membranes to remove dissolved solids, organic pyrogens, and microbes from water. DM removes mineral salts using ion exchange resins. Ultrafiltration uses membranes to retain suspended solids and high molecular weight substances while allowing water and low molecular solutes to pass through. The document also describes different types of treated pharmaceutical water like water for injection and their uses.
Reverse osmosis (RO) is a membrane separation process that uses pressure to force a solvent like water through a semi-permeable membrane that blocks solutes like salt. RO works in reverse of natural osmosis by applying pressure to overcome osmotic pressure. Key applications of RO include producing clean drinking water, boiler feed water, and rinse water. RO membranes are made of materials like cellulose acetate and polyamide and are configured in modules like spiral-wound, plate and frame, hollow fiber, and tubular. Factors that impact RO performance include applied pressure, temperature, solute concentration, and membrane characteristics. RO is effective at removing 95-99% of dissolved solids but requires pre-
Reverse osmosis uses semi-permeable membranes to purify water by separating dissolved solids. It has various applications in water treatment and is used along with demineralization plants. A reverse osmosis system consists of pre-treatment, high-pressure pumps, membrane systems, and post-treatment. It produces permeate water while concentrating impurities in reject water. Demineralization uses ion exchange resins to remove mineral ions, producing very high purity water. Together, reverse osmosis and demineralization can purify water for various industrial and medical uses.
Reverse osmosis is a water purification process that uses a semi-permeable membrane under pressure to separate dissolved impurities from water molecules. It can remove over 99% of ions, particles, bacteria and other contaminants by allowing water to pass through the membrane while blocking dissolved salts and unwanted molecules. Some key benefits of reverse osmosis include effectively removing many types of chemical and biological impurities from water, enabling water desalination and purification for medical and other uses.
RO PLANT OF PHARMACEUTICAL INDUSTRY BY AMIT KUMAR.pptxAmitKumar829430
Reverse osmosis (RO) is a water treatment process that uses a semi-permeable membrane to remove ions, molecules, and larger particles from drinking water. The basic components of an RO system include pre-filters, an RO membrane, a storage tank, and a faucet. RO is effective at removing 95% of total dissolved solids and purifying water, but it wastes a large portion of the incoming water and is more expensive than other treatments due to the costs of installation and maintenance.
The document discusses various aspects of water treatment systems for pharmaceutical processes, including different types of water used, common water contaminants, functions of equipment in a treatment system like filtration and reverse osmosis, performance calculations for reverse osmosis, and desired water parameters. It provides schematics of sample water treatment systems and discusses topics like pre-treatment solutions, common problems in reverse osmosis systems, and the difference between single-pass and double-pass or single-stage and double-stage reverse osmosis configurations.
This document provides information about Guangzhou KangYang Seawater Desalination Equipment Co., Ltd., including their address, contact information, and answers to frequently asked questions about reverse osmosis water treatment systems. Reverse osmosis systems can treat various water sources, including tap water, groundwater, and seawater. Pretreatment is necessary to protect the reverse osmosis membranes and proper water analysis is required to determine the appropriate pretreatments. Reverse osmosis systems have many commercial and industrial applications wherever high-purity water is needed.
Water treatment and quality control of dialysate.Vishal Golay
The document discusses water treatment and quality control for dialysate used in hemodialysis. It describes the various components of a water treatment system, including backflow preventers, temperature blending valves, filters, softeners, carbon tanks, reverse osmosis membranes, and ultraviolet irradiation. The water treatment system aims to remove contaminants and achieve a composition similar to extracellular fluid for the dialysate. Proper functioning and monitoring of the water treatment system is important for patient safety and preventing toxic effects of contaminants.
Treatment of water using reversed osmosisनिखिल आहिर
The document discusses reverse osmosis, which uses pressure to force water through a semi-permeable membrane, allowing pure water to pass while retaining dissolved salts and other contaminants. It explains key terms like osmosis, solvent, solute, and membrane types. The history and basic components of a reverse osmosis system are outlined, including pre-filters, membrane, post-filter, storage tank, and faucet. Advantages of reverse osmosis water filtration are removing particles, long-lasting membranes, being eco-friendly and eliminating heavy metals and bacteria.
Singapore produces NEWater by treating used water through advanced purification processes like reverse osmosis. NEWater provides 7% of Singapore's water supply. Reverse osmosis uses pressure to force water through a semi-permeable membrane, removing impurities. It has allowed Singapore to recycle its used water into a clean, safe source to supplement its other water sources and ensure long-term water security.
Newer technologies have gained popularity and expanded over the last one decade.
Effective separation is crucial in the operation of processes of any industry. A major question is how best can these processes solve the problems and what are the edges which we can push these new technologies. Achievements have been made in (waste) water treatment. Some of the successes are; low cost of operation, high efficiency, less energy consumption and smaller spaces of operation.
Membrane separation processes have been adopted throughout the world. They are
divided based on the size of particles they can let to pass through and the driving force that is used. Talking of pressure driven processes like microfiltration, ultrafiltration and reverse osmosis, they are processes which changed the whole history of water treatment. For example, reverse osmosis has been used in the desalination of brackish water.
Advantages of reverse osmosis in drinking water treatment include: physically removal
of pathogens, effective removal of substrates in the treated water, less biofilm growth, less disinfectant chemical requirement and less disinfection of the byproduct. However, there are some unanswered questions like the exact dosage of the disinfectants we can use and since the disinfectants will be of less amount, how can we compare it to classic technologies? What are the other advantages of using the reverse osmosis?
This document discusses different membrane separation techniques including reverse osmosis, dialysis, and electrodialysis. Reverse osmosis uses pressure to force purified water through a semi-permeable membrane, leaving dissolved ions behind. Dialysis relies on diffusion across a semi-permeable membrane to remove low molecular weight solutes from fluids. Electrodialysis transports ions through ion exchange membranes under an applied electric potential to purify solutions.
This document discusses various membrane processes used in industrial water and wastewater treatment. It defines membrane processes as including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, and electrodialysis. These processes are used to desalinate seawater, treat brackish groundwater, soften water, recover wastewater, and remove contaminants. The document provides details on the applications and operating principles of ultrafiltration and reverse osmosis membrane processes. It also discusses other wastewater treatment methods like freezing, elutriation, and the removal of color, odor, taste, iron and manganese.
This document discusses the process of water purification. It begins by defining potable water and outlining the basic 6 step process of water treatment which includes coagulation, flocculation, sedimentation, filtration, disinfection and aeration. It then provides more details on coagulation and flocculation where chemicals are added to remove particles from water. Sedimentation allows floc to settle in basins. Filtration through sand or other media further removes particles. Chlorine is commonly used for disinfection to kill pathogens, though it can form harmful byproducts. The entire process aims to produce safe drinking water.
The document proposes a business partnership between DTS Inc. and a water shop in Karachi to provide high-quality RO water filtering systems called Water Heart. Water Heart can filter water to different quality levels depending on usage, such as reducing seawater salt levels to safe drinking levels. It uses advanced filtration technology including RO, NF, MF and carbon filters. The proposal offers an on-site maintenance service and 10-year purchase agreement.
1.
Basics of Reverse Osmosis
1
What is Reverse Osmosis?
Reverse Osmosis is a technology that is used to remove a large majority of contaminants from water by
pushing the water under pressure through a semi-‐permeable membrane. This paper is aimed towards
an audience that has little of no experience with Reverse Osmosis and will attempt to explain the basics
in simple terms that should leave the reader with a better overall understanding of Reverse Osmosis
technology and its applications.
This paper covers the following topics:
1. Understanding Osmosis and Reverse Osmosis
2. How does Reverse Osmosis (RO) work?
3. What contaminants does Reverse Osmosis (RO) remove?
4. Performance and design calculations for Reverse Osmosis (RO) systems
a. Salt Rejection %
b. Salt Passage %
c. Recovery %
d. Concentration Factor
e. Flux Rate
f. Mass Balance
5. Understanding the difference between passes and stages in a Reverse Osmosis (RO) system
a. 1 stage vs 2 stage Reverse Osmosis (RO) system
b. Array
c. Reverse Osmosis (RO) system with a concentrate recycle
d. Single Pass vs Double Pass Reverse Osmosis (RO) systems
6. Pre-‐treatment for Reverse Osmosis (RO)
a. Fouling
b. Scaling
c. Chemical Attack
d. Mechanical Damage
7. Pre-‐treatment Solutions for Reverse Osmosis (RO)
a. Multi Media Filtration
b. Micro Filtration
c. Antiscalants and scale inhibitors
d. Softening by ion exchange
e. Sodium Bisulfite (SBS) injection
f. Granular Activated Carbon (GAC)
8. Reverse Osmosis (RO) performance trending and data normalization
9. Reverse Osmosis (RO) membrane cleaning
10. Summary
2.
Basics of Reverse Osmosis
2
Understanding Reverse Osmosis
Reverse osmosis, commonly referred to as RO, is a process where you demineralize or deionize water by pushing it
under pressure through a semi permeable reverse osmosis membrane.
Osmosis
To understand the purpose and process of Reverse Osmosis you must first understand the naturally occurring
process of Osmosis.
Osmosis is a naturally occurring phenomenon and one of the most important processes in nature. It is a process
where a weaker saline solution will tend to migrate to a strong saline solution. Examples of osmosis are when plant
roots absorb water from the soil and our kidneys absorb water from our blood.
Below is a diagram which shows how osmosis works. A solution that is less concentrated will have a natural
tendency to migrate to a solution with a higher concentration. For example, if you had a container full of water
with a low salt concentration and another container full of water with a high salt concentration and they were
separated by a semi-‐permeable membrane, then the water with the lower salt concentration would begin to
migrate towards the water container with the higher salt concentration.
A semi-‐permeable membrane is a membrane that will allow some atoms or molecules to pass but not
others. A simple example is a screen door. It allows air molecules to pass through but not pests or
anything larger than the holes in the screen door. Another example is Gore-‐tex clothing fabric that
contains an extremely thin plastic film into which billions of small pores have been cut. The pores are big
enough to let water vapor through, but small enough to prevent liquid water from passing.
Reverse Osmosis is the process of Osmosis in reverse. Whereas Osmosis occurs naturally without energy
required, to reverse the process of osmosis you need to apply energy to the more saline solution. A
reverse osmosis membrane is a semi-‐permeable membrane that allows the passage of water molecules
but not the majority of dissolved salts, organics, bacteria and pyrogens. However, you need to ‘push’ the
water through the reverse osmosis membrane by applying pressure that is greater than the naturally
occurring osmotic pressure in order to desalinate (demineralize or deionize) water in the process,
allowing pure water through while holding back a majority of contaminants.
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Basics of Reverse Osmosis
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Below is a diagram outlining the process of Reverse Osmosis. When pressure is applied to the
concentrated solution, the water molecules are forced through the semi-‐permeable membrane and the
contaminants are not allowed through.
How does Reverse Osmosis work?
Reverse osmosis works by using a high pressure pump to increase the pressure on the salt side of the RO and force
the water across the semi-‐permeable RO membrane, leaving almost all (around 95% to 99%) of dissolved salts
behind in the reject stream. The amount of pressure required depends on the salt concentration of the feed water.
The more concentrated the feed water, the more pressure is required to overcome the osmotic pressure.
In very simple terms, feed water is pumped into a Reverse Osmosis (RO) system and you end up with two types of
water coming out of the RO system: good water and bad water. The good water that comes out of an RO system
has the majority of contaminants removed and is called permeate. Another term for permeate water is product
water – they mean the same thing. Permeate is the water that was pushed through the RO membrane and
contains very little contaminants.
The ‘bad’ water is the water that contains all of the contaminants that were unable to pass through the RO
membrane and is known as the concentrate, reject, or brine. All three terms (concentrate, reject, and brine) are
used interchangeably and mean the same thing. Below is a simple schematic that shows how an RO system works.
As the feed water enters the RO membrane under pressure (enough pressure to overcome osmotic pressure) the
water molecules pass through the semi-‐permeable membrane and the salts and other contaminants are not
allowed to pass and are discharged through the concentrate stream, which goes to drain or can be fed back into
the feed water supply in some circumstances to be recycled through the RO system to save water. The water that
makes it through the RO membrane is called permeate or product water and usually has around 95% to 99% of the
dissolved salts removed from it.
RO Membrane
Permeate Water
Pump (Low Concentration of Salts)
Reject Stream
(High Concentration of salts)
Feed Water
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Basics of Reverse Osmosis
4
It is important to understand that an RO system employs cross filtration rather than standard filtration where the
contaminants are collected within the filter media. With cross filtration, the solution passes through the filter, or
crosses the filter, with two outlets: the filtered water goes one way and the contaminated water goes a different
route. To avoid build up of contaminants, cross flow filtration allows water to sweep away contaminant build up
and also allow enough turbulence to keep the membrane surface clean.
What will Reverse Osmosis remove from water?
Reverse Osmosis is capable of removing up to 99%+ of the dissolved salts (ions), particles, colloids,
organics, bacteria and pyrogens from the feed water (although an RO system should not be relied upon
to remove 100% of bacteria and viruses). An RO membrane rejects contaminants based on their size and
charge. Any contaminant that has a molecular weight greater than 200 is likely rejected by a properly
running RO system. Likewise, the greater the ionic charge of the contaminant, the more likely it will be
unable to pass through the RO membrane. For example, a sodium ion has only one charge (monovalent)
and is not rejected by the RO membrane as well as calcium for example, which has two charges.
Likewise, this is why an RO system does not remove gases such as CO2 very well because they are not
highly ionized (charged) while in solution and have a very low molecular weight. Because an RO system
does not remove gases, the permeate water can have a slightly lower than normal pH level depending
on CO2 levels in the feed water as the CO2 is converted to carbonic acid.
Reverse Osmosis is very effective in treating brackish, surface and ground water for both large and small
flows applications. Some examples of industries that use RO water include pharmaceutical, boiler feed
water, food and beverage, metal finishing and semiconductor manufacturing to name a few.
Reverse Osmosis Performance & Design Calculations
There are a handful of calculations that are used to judge the performance of an RO system and also for
design considerations. An RO system has instrumentation that displays quality, flow, pressure and
sometimes other data like temperature or hours of operation. In order to accurately measure the
performance of an RO system you need the following operation parameters at a minimum:
1. Feed pressure
2. Permeate pressure
3. Concentrate pressure
4. Feed conductivity
5. Permeate conductivity
6. Feed flow
7. Permeate flow
8. Temperature
Salt Rejection %
This equation tells you how effective the RO membranes are removing contaminants. It does not tell you
how each individual membrane is performing, but rather how the system overall on average is
performing. A well-‐designed RO system with properly functioning RO membranes will reject 95% to 99%
of most feed water contaminants (that are of a certain size and charge). You can determine effective the
RO membranes are removing contaminants by using the following equation:
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Basics of Reverse Osmosis
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Salt Rejection % = Conductivity of Feed Water – Conductivity of Permeate Water x 100
Conductivity of Feed
The higher the salt rejection, the better the system is performing. A low salt rejection can mean that the
membranes require cleaning or replacement.
Salt Passage %
This is simply the inverse of salt rejection described in the previous equation. This is the amount of salts
expressed as a percentage that are passing through the RO system. The lower the salt passage, the
better the system is performing. A high salt passage can mean that the membranes require cleaning or
replacement.
Salt Passage % = (1-‐ Salt Rejection%)
Recovery %
Percent Recovery is the amount of water that is being ‘recovered’ as good permeate water. Another
way to think of Percent Recovery is the amount of water that is not sent to drain as concentrate, but
rather collected as permeate or product water. The higher the recovery % means that you are sending
less water to drain as concentrate and saving more permeate water. However, if the recovery % is too
high for the RO design then it can lead to larger problems due to scaling and fouling. The % Recovery for
an RO system is established with the help of design software taking into consideration numerous factors
such as feed water chemistry and RO pre-‐treatment before the RO system. Therefore, the proper %
Recovery at which an RO should operate at depends on what it was designed for. By calculating the %
Recovery you can quickly determine if the system is operating outside of the intended design. The
calculation for % Recovery is below:
% Recovery = Permeate Flow Rate (gpm) x 100
Feed Flow Rate (gpm)
For example, if the recovery rate is 75% then this means that for every 100 gallons of feed water that
enter the RO system, you are recovering 75 gallons as usable permeate water and 25 gallons are going
to drain as concentrate. Industrial RO systems typically run anywhere from 50% to 85% recovery
depending the feed water characteristics and other design considerations.
Concentration Factor
The concentration factor is related to the RO system recovery and is an important equation for RO
system design. The more water you recover as permeate (the higher the % recovery), the more
concentrated salts and contaminants you collect in the concentrate stream. This can lead to higher
potential for scaling on the surface of the RO membrane when the concentration factor is too high for
the system design and feed water composition.
Concentration Factor = (1 / (1-‐Recovery %)
The concept is no different than that of a boiler or cooling tower. They both have purified water exiting
the system (steam) and end up leaving a concentrated solution behind. As the degree of concentration
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increases, the solubility limits may be exceeded and precipitate on the surface of the equipment as
scale.
For example, if your feed flow is 100 gpm and your permeate flow is 75 gpm, then the recovery is
(75/100) x 100 = 75%. To find the concentration factor, the formula would be 1 ÷ (1-‐75%) = 4.
A concentration factor of 4 means that the water going to the concentrate stream will be 4 times more
concentrated than the feed water is. If the feed water in this example was 500 ppm, then the
concentrate stream would be 500 x 4 = 2,000 ppm.
Flux
Gfd = gpm of permeate x 1,440 min/day s
# of RO elements in system x square footage of each RO element
For example, you have the following:
The RO system is producing 75 gallons per minute (gpm) of permeate.
You have 3 RO vessels and each vessel holds 6 RO membranes. Therefore you have a total of 3 x 6 = 18
membranes.
The type of membrane you have in the RO system is a Dow Filmtec BW30-‐365. This type of RO
membrane (or element) has 365 square feet of surface area.
To find the flux (Gfd):
Gfd = 75 gpm x 1,440 min/day s
18 elements x 365 sq ft
= 108,000
6,570
The flux is 16 Gfd.
This means that 16 gallons of water is passed through each square foot of each RO membrane per day.
This number could be good or bad depending on the type of feed water chemistry and system design.
Below is a general rule of thumb for flux ranges for different source waters and can be better
determined with the help of RO design software. If you had used Dow Filmtec LE-‐440i RO membranes in
the above example, then the flux would have been 14. So it is important to factor in what type of
membrane is used and to try and keep the type of membrane consistent throughout the system.
Feed Water Source Gfd
Sewage Effluent 5-‐10
Sea Water 8-‐12
Brackish Surface Water 10-‐14
Brackish Well Water 14-‐18
RO Permeate Water 20-‐30
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Basics of Reverse Osmosis
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Mass Balance
A Mass Balance equation is used to help determine if your flow and quality instrumentation is reading
properly or requires calibration. If your instrumentation is not reading correctly, then the performance
data trending that you are collecting is useless.
You will need to collect the following data from an RO system to perform a Mass Balance calculation:
1. Feed Flow (gpm)
2. Permeate Flow (gpm)
3. Concentrate Flow (gpm)
4. Feed Conductivity (µS)
5. Permeate Conductivity (µS)
6. Concentrate Conductivity (µS)
The mass balance equation is:
(Feed flow
1
x Feed Conductivity) = (Permeate Flow x Permeate Conductivity) + (Concentrate Flow*Concentrate Conductivity)
1
Feed Flow equals Permeate Flow + Concentrate Flow
For example, if you collected the following data from an RO system:
Permeate Flow 5 gpm
Feed Conductivity 500 µS
Permeate Conductivity 10 µS
Concentrate Flow 2 gpm
Concentrate Conductivity 1200 µS
Then the Mass Balance Equation would be:
(7 x 500) = (5 x 10) + (2*1200)
3,500 2,450
Then find the difference:
Difference
Sum
100
, ,
, ,
100
= 18%
A difference of +/-‐ 5% is ok. A difference of +/-‐ 5% to 10% is generally adequate. A difference of > +/-‐
10% is unacceptable and calibration of the RO instrumentation is required to ensure that you are
collecting useful data. In the example above, the RO mass balance equation falls out of range and
requires attention.
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Basics of Reverse Osmosis
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Understanding the difference between passes and stages in a Reverse Osmosis (RO) system
The term ‘stage’ and ‘pass’ are often mistaken for the same thing in an RO system and can be confusing
termonology for an RO operator. It is important to understand the difffernce between a 1 and 2 stage
RO and a 1 and 2 pass RO.
Difference between a 1 and 2 stage RO System
In a one stage RO system, the feed water enters the RO system as one stream and exits the RO as either
concentrate or permeate water.
In a two-‐stage system the concentrate (or reject) from the first stage then becomes the feed water to
the second stage. The permeate water is collected from the first stage is combined with permeate water
from the second stage. Additional stages increase the recovery from the system.
1 stage RO system
Feed Water
Permeate Water
Concentrate Water
RO MEMBRANE
2 stage RO system
Feed Water
Permeate Water
Concentrate Water
RO MEMBRANE
RO MEMBRANE
RO MEMBRANE
1st
Stage 2nd
Stage
Feed
Permeate
Water
Concentrate
Water
Feed
Permeate
Water
Concentrate
Water
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Basics of Reverse Osmosis
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Array
In a reverse osmosis system an array describes the physical arrangement of the pressure vessels in a 2
stage system. Pressure vessels contain RO membranes (usually from 1 to 6 RO membranes are in a
pressure vessel). Each stage can have a certain amount of pressure vessels with RO membranes. The
reject of each stage then becomes the feed stream for the next successive stage. The 2 stage RO system
displayed on the previous page is a 2:1 array which means that the concentrate (or reject) of the first 2
RO vessels is fed to the next 1 vessel.
RO System with Concentrate Recycle
With an RO system that can’t be properly staged and the feed water chemistry allows for it, a
concentrate recycle setup can be utilized where a portion of the concentrate stream is fed back to the
feed water to the first stage to help increase the system recovery.
Feed Water
Permeate Water
Concentrate Water
RO MEMBRANE
RO MEMBRANE
RO MEMBRANE
Concentrate Recycle Stream
Permeate
Water
Concentrate
Water
Feed Water
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Basics of Reverse Osmosis
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Single Pass RO vs Double Pass RO
Think of a ‘pass’ as a stand alone RO system. With this in mind, the difference between a single pass RO
system and a double pass RO system is that with a double pass RO, the permeate from the first pass
becomes the feed water to the second pass (or second RO) which ends up producing a much higher
quality permeate because it has essentially gone through two RO systems.
Besides producing a much higher quality permeate, a double pass system also allows the opportunity to
remove carbon dioxide gas from the permeate by injecting caustic between the first and second pass.
C02 is undesirable when you have mixed bed ion exchange resin beds after the RO. By adding caustic
after the first pass, you increase the pH of the first pass permeate water and convert C02 to bicarbonate
(HCO3
-‐
) and carbonate (CO3
-‐2
) for better rejection by the RO membranes in the second pass. This can’t
be done with a single pass RO because injecting caustic and forming carbonate (CO3
-‐2
) in the presence of
cations such as calcium will cause scaling of the RO membranes.
Single Pass RO
Feed Water
Permeate Water
Concentrate Water
RO MEMBRANE
Double Pass RO
Feed Water
Permeate Water
Concentrate Water
RO MEMBRANE RO MEMBRANE
Concentrate Recycle back to feed water
Feed Water
Concentrate
Water
Feed
Permeate
Water
Concentrate
Water
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RO Pretreatment
Proper pretreatment using both mechanical and chemical treatments is critical for an RO system to
prevent fouling, scaling and costly premature RO membrane failure and frequent cleaning requirements.
Below is a summary of common problems an RO system experiences due to lack of proper
pretreatment.
Fouling
Fouling occurs when contaminants accumulate on the membrane surface effectively plugging the
membrane. There are many contaminants in municipal feed water that are naked to the human eye and
harmless for human consumption, but large enough to quickly foul (or plug) an RO system. Fouling
typically occurs in the front end of an RO system and results in a higher pressure drop across the RO
system and a lower permeate flow. This translates into higher operating costs and eventually the need
to clean or replace the RO membranes. Fouling will take place eventually to some extent given the
extremely fine pore size of an RO membrane no matter how effective your pretreatment and cleaning
schedule is. However, by having proper pretreatment in place, you will minimize the need to address
fouling related problems on a regular basis.
Fouling can be caused by the following:
1. Particulate or colloidal mater (dirt, silt, clay, etc.)
2. Organics (humic/fulvic acids, etc)
3. Microorganisms (bacteria, etc). Bacteria present one of the most common fouling problems
since RO membranes in use today cannot tolerate a disinfectant such as chlorine and thefore
microorganisms are often able to thrive and multiply on the membrane surface. They may
product biofilms that cover the membrane surface and result in heavy fouling.
4. Breakthrough of filter media upstream of the RO unit. GAC carbon beds and softener beds may
develop an under drain leak and if there is not adequate post filtration in place the media can
foul the RO system.
By performing analytical tests, you can determine if the feed water to your RO has a high potential for
fouling. To prevent fouling of an RO system, mechanical filtration methods are used. The most popular
methods to prevent fouling are the use of multi-‐media filters (MMF) or microfiltration (MF). In some
cases cartridge filtration will suffice.
Scaling
As certain dissolved (inorganic) compounds become more concentrated (remember discussion on
concentration factor) then scaling can occur if these compounds exceed their solubility limits and
precipitate on the membrane surface as scale. The results of scaling are a higher pressure drop across
the system, higher salt passage (less salt rejection), low permeate flow and lower permeate water
quality. An example of a common scale that tends to form on an RO membrane is calcium carbonate
(CaCO3).
Chemical Attack
Modern thin film composite membranes are not tolerant to chlorine or chloramines. Oxidizers such as
chlorine will ‘burn’ holes in the membrane pores and can cause irreparable damage. The result of
chemical attack on an RO membrane is a higher permeate flow and a higher salt passage (poorer quality
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12
permeate water). This is why microorganism growth on RO membranes tends to foul RO membranes so
easily since there is no biocide to prevent its growth.
Mechanical Damage
Part of the pretreatment scheme should be pre and post RO system plumbing and controls. If ‘hard
starts’ occur mechanical damage to the membranes can occur. Likewise, if there is too much
backpressure on the RO system then mechanical damage to the RO membranes can also occur. These
can be addressed by using variable frequency drive motors to start high pressure pumps for RO systems
and by installing check valve(s) and/or pressure relief valves to prevent excessive back pressure on the
RO unit that can cause permanent membrane damage.
Pretreatment Solutions
Below are some pretreatment solutions for RO systems that can help minimize fouling, scaling and
chemical attack.
Multi Media Filter (MMF)
A Multi-‐Media Filter is used to help prevent fouling of an RO system. A MMF typically contains three
layers of media consisting of anthracite coal, sand and garnet, with a supporting layer of gravel at the
bottom. These are the medias of choice because of the differences in size and density. The larger (but
lighter) anthracite coal will be on top and the heavier (but smaller) garnet will remain on the bottom.
The filter media arrangement allows the largest dirt particles to be removed near the top of the media
bed with the smaller dirt particles being retained deeper and deeper in the media. This allows the entire
bed to act as a filter allowing much longer filter run times between backwash and more efficient
particulate removal.
A well-‐operated Multi-‐Media Filter can remove particulates down to 15-‐20 microns. A Multi-‐Media Filter
that uses a coagulant addition (which induces tiny particles to join together to form particles large
enough to be filtered) can remove particulates down to 5-‐10 microns. To put this in perspective, the
width of a human hair is around 50 microns.
A multi media filter is suggested when the Silt Density Index (SDI) value is greater than 3 or when the
turbidity is greater than 0.2 NTU. There is no exact rule, but the above guidelines should be followed to
prevent premature fouling of RO membranes.
It is important to have a 5 micron cartridge filter placed directly after the MMF unit in the event that the
under drains of the MMF fail. This will prevent the MMF media from damaging downstream pumps and
fouling the RO system.
Microfiltration (MF)
Microfiltration is effective in removing colloidal and bacteria matter and has a pore size of only 0.1-‐
10µm. MF is helpful in reducing fouling potential for an RO unit. Membrane configuration can vary
between manufacturers, but the "hollow fiber" type is the most commonly used. Typically, the water is
pumped from the outside of the fibers, and the clean water is collected from the inside of the fibers.
Microfiltration membranes used in potable water applications usually operate in "dead-‐end" flow. In
dead-‐end flow, all of the water fed to the membrane is filtered through the membrane. A filter cake that
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13
must be periodically backwashed from the membrane surface forms. Recovery rates are normally
greater than 90 percent on feed water sources which have fairly high quality and low turbidity feeds.
Antiscalants/Scale Inhibitors
Antiscalants and scale inhibitors, as their name suggests, are chemicals that can be added to feed water
before an RO unit to help reduce the scaling potential of the feed water. Antiscalants and scale
inhibitors increase the solubility limits of troublesome inorganic compounds. By increasing the solubility
limits, you are able to concentrate the salts further than otherwise would be possible and therefore
achieve a higher recovery rate and run at a higher concentration factor. Antiscalants and scale inhibitors
work by interfering with scale formation and crystal growth. The choice of antiscalant or scale inhibitor
to use and the correct dosage depends on the feed water chemistry and RO system design.
Water Softening
A water softener can be used to help prevent scaling in an RO system by exchanging scale forming ions
with non scale forming ions. As with a MMF unit, it is important to have a 5 micron cartridge filter
placed directly after the water softener in the event that the under drains of the softener fail.
Sodium Bisulfite
By adding sodium bisulfite (SBS or SMBS), which is a reducer, to the water stream before an RO at the
proper dose you can remove residual chlorine and chloramines.
Granular Activated Carbon (GAC)
GAC is used for both removing organic constituents and residual disinfectants (such as chlorine and
chloramines) from water. GAC media is made from coal, nutshells or wood. Activated carbon removes
residual chlorine and chloramines by a chemical reaction that involves a transfer of electrons from the
surface of the GAC to the residual chlorine or chloramines. The chlorine or chloramines ends up as a
chloride ion that is no longer an oxidizer.
The disadvantage of using a GAC before the RO unit is that the GAC will remove chlorine quickly at the
very top of the GAC bed. This will leave the remainder of the GAC bed without any biocide to kill
microorganisms. A GAC bed will absorb organics throughout the bed, which is potential food for
bacteria, so eventually a GAC bed can become a breeding ground for bacteria growth which can pass
easily to the RO membranes. Likewise, a GAC bed can produce very small carbon fines under some
circumstances that have the potential to foul an RO.
RO Data Trending and Normalization
The RO membranes are the heart of the RO system and certain data points need to be collected to
determine the health of the RO membranes. These data points include the system pressures, flows,
quality and temperature. Water temperature is directly proportional to pressure. As the water
temperature decreases it becomes more viscous and the RO permeate flow will drop as it requires more
pressure to push the water through the membrane. Likewise, when the water temperature increases
the RO permeate flow will increase. As a result, performance data for an RO system must be normalized
so that flow variations are not interpreted as abnormal when no problem exists. The normalized flows,
pressures and salt rejection should be calculated, graphed and compared to the baseline data (when the
RO was commissioned or after the membranes were cleaned or replaced) to help troubleshoot any
problems and also determine when to clean or inspect the membranes for damage. Data normalization
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helps display the true performance of the RO membranes. As a general rule of thumb, when the
normalized change is +/-‐ 15% from the baseline data then you need to take action. If you don’t follow
this rule then RO membrane cleanings may not be very effective at brining the membranes back to near
new performance.
RO Cleaning
RO membranes will inevitably require periodic cleaning, anywhere from 1 to 4 times a year depending
on the feed water quality. As a general rule, if the normalized pressure drop or the normalized salt
passage has increased by 15%, then it is time to clean the RO membranes. If the normalized permeate
flow has decreased by 15% then it is also time to clean the RO membranes. You can either clean the RO
membranes in place or have them removed from the RO system and cleaned off site by a service
company that specializes in this service. It has been proven that offsite membrane cleaning is more
effective at providing a better cleaning than onsite cleaning skids.
RO membrane cleaning involves low and high pH cleaners to remove contaminants from the membrane.
Scaling is addressed with low pH cleaners and organics, colloidal and biofouling are treated with a high
pH cleaner. Cleaning RO membranes is not only about using the appropriate chemicals. There are many
other factors involved such as flows, water temperature and quality, properly designed and sized
cleaning skids and many other factors that an experienced service group must address in order to
properly clean RO membranes.
Summary
Reverse Osmosis is an effective and proven technology to produce water that is suitable for many
industrial applications that require demineralized or deionized water. Further post treatment after the
RO system such as mixed bed deionization can increase the quality of the RO permeate and make it
suitable for the most demanding applications. Proper pretreatment and monitoring of an RO system is
crucial to preventing costly repairs and unscheduled maintenance. With the correct system design,
maintenance program, and experienced service support, your RO system should provide many years of
high purity water.