Water Desalination & RO
Desalination Course – Lecture 10 Reverse Osmosis (7)
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Desalination Course – Lecture 10 Reverse Osmosis (7)
Presented by: Dr. Abeer Moneer
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Water Desalination & RO
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Desalination and Water Treatment
Abstract:
This study proposes a simple design method of the Reverse osmosis (RO) system in RO brackish water desalination plants. This method is based on the application of maximum available recovery without scaling of any of the compounds present in the water as silica, calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, and calcium fluoride, and membrane manufacturer design guidelines, and the plant production. Although the method was originally
conceived for application to subterranean brackish waters in the Canary Islands, Spain (principally Gran Canaria, Fuerteventura and Tenerife), it can be extrapolated to other types of region and water treatable with RO systems. The required input data are the chemical composition of the feed water, pH, temperature, silt density index membrane manufacturer design guidelines, and the plant production. The programmed method then determines the design of the RO system. The method whose procedure is described graphically and analytically can be used as an aid in design optimization of RO brackish water desalination plants with acid-free pretreatment processes and only the use of scale inhibitor using spiral wound membranes. Practical applications are presented. The final results for different types of feed water and capacities are showed.
Desalination and Water Treatment
Abstract:
This study proposes a simple design method of the Reverse osmosis (RO) system in RO brackish water desalination plants. This method is based on the application of maximum available recovery without scaling of any of the compounds present in the water as silica, calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, and calcium fluoride, and membrane manufacturer design guidelines, and the plant production. Although the method was originally
conceived for application to subterranean brackish waters in the Canary Islands, Spain (principally Gran Canaria, Fuerteventura and Tenerife), it can be extrapolated to other types of region and water treatable with RO systems. The required input data are the chemical composition of the feed water, pH, temperature, silt density index membrane manufacturer design guidelines, and the plant production. The programmed method then determines the design of the RO system. The method whose procedure is described graphically and analytically can be used as an aid in design optimization of RO brackish water desalination plants with acid-free pretreatment processes and only the use of scale inhibitor using spiral wound membranes. Practical applications are presented. The final results for different types of feed water and capacities are showed.
Cleaning Procedures for Composite Polyamide RO Membrane Elements
Note: The Composite Polyamide type of RO membrane elements may not be
exposed to chlorinated water under any circumstances. Any such exposure may
cause irreparable damage to the membrane. Absolute care must be taken
following any disinfection of piping or equipment or the preparation of cleaning or
storage solutions to ensure that no trace of chlorine is present in the feedwater to
the RO membrane elements. If there is any doubt about the presence of chlorine,
perform chemical testing. Neutralize any chlorine residual with a sodium bisulfite
solution, and ensure adequate mixing and contact time to accomplish complete
dechlorination. Dosing rate is 1.8 to 3.0 ppm sodium bisulfite per 1.0 ppm of free
chlorine
Cleaning Procedures for Composite Polyamide RO Membrane Elements
Note: The Composite Polyamide type of RO membrane elements may not be
exposed to chlorinated water under any circumstances. Any such exposure may
cause irreparable damage to the membrane. Absolute care must be taken
following any disinfection of piping or equipment or the preparation of cleaning or
storage solutions to ensure that no trace of chlorine is present in the feedwater to
the RO membrane elements. If there is any doubt about the presence of chlorine,
perform chemical testing. Neutralize any chlorine residual with a sodium bisulfite
solution, and ensure adequate mixing and contact time to accomplish complete
dechlorination. Dosing rate is 1.8 to 3.0 ppm sodium bisulfite per 1.0 ppm of free
chlorine
Database Of Permitting Practices For Seawater Desalination Concentrate
Abstract:
The purpose of this research project was to identify the discharge information that permitting agencies need and the decision-making process they go through to permit discharge methods in order to help desalination project proponents focus and expedite their permitting efforts.
The project documented seawater reverse osmosis (SWRO) discharge regulatory issues and provided a critical overview of facility discharge-related information required for permitting desalination projects in the United States and selected countries with advanced environmental regulations and experience in implementing seawater desalination projects. Information was gathered from the three key U.S. states (California, Florida, Texas) where interest in SWRO desalination has been highest. Due to the more extensive international experience with SWRO desalination, information was also obtained from the countries of Australia, Israel, and Spain – all countries of significant recent large-scale SWRO desalination projects. Case studies of 11 SWRO plants and analysis of regulatory systems and permitting processes supported detailed definition of the decision-making process to set discharge permit limits, as well as defining environmental and other regulatory issues associated with concentrate regulation.
Database Of Permitting Practices For Seawater Desalination Concentrate
Abstract:
The purpose of this research project was to identify the discharge information that permitting agencies need and the decision-making process they go through to permit discharge methods in order to help desalination project proponents focus and expedite their permitting efforts.
The project documented seawater reverse osmosis (SWRO) discharge regulatory issues and provided a critical overview of facility discharge-related information required for permitting desalination projects in the United States and selected countries with advanced environmental regulations and experience in implementing seawater desalination projects. Information was gathered from the three key U.S. states (California, Florida, Texas) where interest in SWRO desalination has been highest. Due to the more extensive international experience with SWRO desalination, information was also obtained from the countries of Australia, Israel, and Spain – all countries of significant recent large-scale SWRO desalination projects. Case studies of 11 SWRO plants and analysis of regulatory systems and permitting processes supported detailed definition of the decision-making process to set discharge permit limits, as well as defining environmental and other regulatory issues associated with concentrate regulation.
Tailoring Advanced Desalination Technologies for 21st Century Agriculture
Abstract: Substantial parts of the U.S., particularly drier landlocked regions, are facing acute water shortages and water quality issues that decrease agricultural productivity. Reduced crop yields cause billions of dollars in losses annually, affecting the livelihoods of thousands. A combination of population growth, inefficient agricultural practices, and resource demanding consumption trends is only expected to increase pressure on our water supplies. This research proposal seeks to address water and food security issues by cost-effectively and energy-efficiently enhancing water quality and water supply in greenhouses; a $22.93 billion dollar industry in 2017 that is rapidly growing at an annual rate of 8.92%. Greenhouses widely practice desalination of salty irrigation water to improve their operations. However, currently used desalination methods do not tailor greenhouse waters based on crop requirements. This work investigates a fully integrated desalination solution that treats and tailors brackish source waters ingreenhouses to save fertilizer and water. Specifically, this project experimentally studies multi-ion transport in and assesses the economic viable of monovalent selective electrodialysis (MSED). MSED allows for the selective removal of monovalent ions damaging to crops and the retention of divalent ions beneficial for crops, unlike the widely used reverse osmosis (RO), which removes all ions from greenhouse source water. First, we evaluate the techno-economic feasibility of MSED compared to other brackish desalination technologies for agricultural applications, based on primary market research we conduct with over 70 greenhouses.
These include conventional technologies, such as reverse osmosis (RO) and electrodialysis (ED), and advanced technologies, such as closed circuit reverse osmosis (CCRO). The analysis determines the levelized costs of water, the capital costs and energy requirements of these technologies, and how these vary with feed salinity, system capacity and recovery ratio. Then, we build a bench-scale setup to experientially characterize MSED membrane properties, including monovalent selectivity, ion transport, limiting current and resistance, for multiple brackish feedwaters and for two sets of MSED membranes: the widely used Neosepta ACS/CMS membranes and the new Fujifilm Type 16 membranes. Both MSED membranes show notable monovalent selectivity for all tested compositions, reflecting the potential of the technology for selective desalination in greenhouses. The measurements are compared to a model for MSED in multi-ion solutions. The model predicts multi-ion transport for the Neosepta and Fujifilm MSED systems within 6% and 8%, respectively.
Tailoring Advanced Desalination Technologies for 21st Century Agriculture
Abstract: Substantial parts of the U.S., particularly drier landlocked regions, are facing acute water shortages and water quality issues that decrease agricultural productivity. Reduced crop yields cause billions of dollars in losses annually, affecting the livelihoods of thousands. A combination of population growth, inefficient agricultural practices, and resource demanding consumption trends is only expected to increase pressure on our water supplies. This research proposal seeks to address water and food security issues by cost-effectively and energy-efficiently enhancing water quality and water supply in greenhouses; a $22.93 billion dollar industry in 2017 that is rapidly growing at an annual rate of 8.92%. Greenhouses widely practice desalination of salty irrigation water to improve their operations. However, currently used desalination methods do not tailor greenhouse waters based on crop requirements. This work investigates a fully integrated desalination solution that treats and tailors brackish source waters ingreenhouses to save fertilizer and water. Specifically, this project experimentally studies multi-ion transport in and assesses the economic viable of monovalent selective electrodialysis (MSED). MSED allows for the selective removal of monovalent ions damaging to crops and the retention of divalent ions beneficial for crops, unlike the widely used reverse osmosis (RO), which removes all ions from greenhouse source water. First, we evaluate the techno-economic feasibility of MSED compared to other brackish desalination technologies for agricultural applications, based on primary market research we conduct with over 70 greenhouses.
These include conventional technologies, such as reverse osmosis (RO) and electrodialysis (ED), and advanced technologies, such as closed circuit reverse osmosis (CCRO). The analysis determines the levelized costs of water, the capital costs and energy requirements of these technologies, and how these vary with feed salinity, system capacity and recovery ratio. Then, we build a bench-scale setup to experientially characterize MSED membrane properties, including monovalent selectivity, ion transport, limiting current and resistance, for multiple brackish feedwaters and for two sets of MSED membranes: the widely used Neosepta ACS/CMS membranes and the new Fujifilm Type 16 membranes. Both MSED membranes show notable monovalent selectivity for all tested compositions, reflecting the potential of the technology for selective desalination in greenhouses. The measurements are compared to a model for MSED in multi-ion solutions. The model predicts multi-ion transport for the Neosepta and Fujifilm MSED systems within 6% and 8%, respectively.
Desalination & Water Purification Technologies
Introduction:
The world’s water consumption rate is doubling every 20 years, outpacing by two times the rate of population growth. The availability of good quality water is on the decline and water demand is on the rise. Worldwide availability of fresh water for industrial needs and human consumption is limited.
Various industrial and developmental activities in recent times have resulted in increasing the pollution level and deteriorating the water quality. Water shortages and unreliable water quality are considered major obstacles to achieve sustainable development and improvement in the quality of life. The water
demand in the country is increasing fast due to progressive increase in the demand of water for irrigation, rapid industrialization, and population growth and improving life standards. The existing water resources are diminishing (i) due to unequal distribution of rain water and occasional drought, (ii) excessive exploitation of ground water sources and its insufficient recharge, (iii) deterioration of water quality due to the discharge of domestic and industrial effluents without adequate treatment. This is resulting into water stress/ scarcity. Country is currently passing through social and economic transition.
The proportion of the population which is urban has doubled over the last thirty years (and is now about 30%), agriculture now accounts for about 25% of GDP and the economy has been growing at around 7-9% a year. Country has a highly seasonal pattern of rainfall, with 50% of precipitation falling
in just 15 days and over 90% of river flows in just four months
Desalination & Water Purification Technologies
Introduction:
The world’s water consumption rate is doubling every 20 years, outpacing by two times the rate of population growth. The availability of good quality water is on the decline and water demand is on the rise. Worldwide availability of fresh water for industrial needs and human consumption is limited.
Various industrial and developmental activities in recent times have resulted in increasing the pollution level and deteriorating the water quality. Water shortages and unreliable water quality are considered major obstacles to achieve sustainable development and improvement in the quality of life. The water
demand in the country is increasing fast due to progressive increase in the demand of water for irrigation, rapid industrialization, and population growth and improving life standards. The existing water resources are diminishing (i) due to unequal distribution of rain water and occasional drought, (ii) excessive exploitation of ground water sources and its insufficient recharge, (iii) deterioration of water quality due to the discharge of domestic and industrial effluents without adequate treatment. This is resulting into water stress/ scarcity. Country is currently passing through social and economic transition.
The proportion of the population which is urban has doubled over the last thirty years (and is now about 30%), agriculture now accounts for about 25% of GDP and the economy has been growing at around 7-9% a year. Country has a highly seasonal pattern of rainfall, with 50% of precipitation falling
in just 15 days and over 90% of river flows in just four months
Desalination: A National Perspective
NOTICE:
The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the panel responsible for the report were chosen for their special competences and with regard for appropriate balance.
Support for this study was provided by the U.S. Bureau of Reclamation under Grant No. 06CS811198. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided
support for the project.
Desalination: A National Perspective
NOTICE:
The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the panel responsible for the report were chosen for their special competences and with regard for appropriate balance.
Support for this study was provided by the U.S. Bureau of Reclamation under Grant No. 06CS811198. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided
support for the project.
Basics of Reverse Osmosis
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.
Basics of Reverse Osmosis
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.
Concentrating Solar Power For Seawater Desalination
Introduction:
The general perception of “solar desalination” today comprises only small scale technologies for decentralized water supply in remote places, which may be quite important for the development of rural areas, but do not address the increasing water deficits of the quickly growing urban centers of demand. Conventional large scale desalination is perceived as expensive, energy consuming and limited to rich countries like those of the Arabian Gulf, especially in view of the quickly escalating cost of fossil fuels like oil, natural gas and coal. The environmental impacts of large scale desalination due to airborne emissions of pollutants from energy consumption and to the discharge of brine and chemical additives to the sea are increasingly considered as critical. For those reasons, most contemporary strategies against a “Global Water Crisis” consider seawater desalination only as a marginal element of supply. The focus of most recommendations lies on more efficient use of water, better accountability, re-use of waste water, enhanced distribution and advanced irrigation systems. To this adds the recommendation to reduce agriculture and rather import food from other places. On the other hand, most sources that do recommend seawater desalination as part of a solution to the water crisis usually propose nuclear fission and fusion as indispensable option.
Concentrating Solar Power For Seawater Desalination
Introduction:
The general perception of “solar desalination” today comprises only small scale technologies for decentralized water supply in remote places, which may be quite important for the development of rural areas, but do not address the increasing water deficits of the quickly growing urban centers of demand. Conventional large scale desalination is perceived as expensive, energy consuming and limited to rich countries like those of the Arabian Gulf, especially in view of the quickly escalating cost of fossil fuels like oil, natural gas and coal. The environmental impacts of large scale desalination due to airborne emissions of pollutants from energy consumption and to the discharge of brine and chemical additives to the sea are increasingly considered as critical. For those reasons, most contemporary strategies against a “Global Water Crisis” consider seawater desalination only as a marginal element of supply. The focus of most recommendations lies on more efficient use of water, better accountability, re-use of waste water, enhanced distribution and advanced irrigation systems. To this adds the recommendation to reduce agriculture and rather import food from other places. On the other hand, most sources that do recommend seawater desalination as part of a solution to the water crisis usually propose nuclear fission and fusion as indispensable option.
California Desalination Planning Handbook
Introduction:
Desalination is receiving increased attention as a means for addressing the water supply challenges of California. Growing population, much of which is located in semi-arid regions of the state, and various other water demands pose increased pressure on existing water supplies. Much of California’s water supply depends on snow accumulation in the winter, providing spring runoff that flls reservoirs and replenishes often depleted groundwater supplies. But in periods of drought, water supply shortages can be encountered throughout the state, particularly in the central valley and southern portion of the state. All indications suggest the impacts of global warming will include a change in the timing of runoff and less snowfall. This will put more pressure on existing supplies, and exacerbate the impacts of drought. As the implications of global warming become clearer, more emphasis will likely be given to developing
new sources of water supply to meet existing and projected demand. While conservation and recycling are recommended as the frst course of action, other alternatives (such as desalination and increased surface and groundwater storage) are receiving increased attention.
California Desalination Planning Handbook
Introduction:
Desalination is receiving increased attention as a means for addressing the water supply challenges of California. Growing population, much of which is located in semi-arid regions of the state, and various other water demands pose increased pressure on existing water supplies. Much of California’s water supply depends on snow accumulation in the winter, providing spring runoff that flls reservoirs and replenishes often depleted groundwater supplies. But in periods of drought, water supply shortages can be encountered throughout the state, particularly in the central valley and southern portion of the state. All indications suggest the impacts of global warming will include a change in the timing of runoff and less snowfall. This will put more pressure on existing supplies, and exacerbate the impacts of drought. As the implications of global warming become clearer, more emphasis will likely be given to developing
new sources of water supply to meet existing and projected demand. While conservation and recycling are recommended as the frst course of action, other alternatives (such as desalination and increased surface and groundwater storage) are receiving increased attention.
Desalination Plant Basis Of Design
Overview:
The project potable water requirements will be provided using single desalination plant with the Grand Bahama Port Authority water supply serving as the backup source. The overall desalination treatment process will consist of feedwater pumping, bag filtration, optional media filtration, the addition of a scale
inhibitor, cartridge filtration, membrane separation, forced air degasification, re-pumping, and post treatment. Provisions have been included to bypass the post treatment systems for the production of irrigation water. The post aeration re-pump station will be designed to transfer either type of water to the
appropriate storage tanks located within the project. Membrane concentrate will be disposed via an injection well to be constructed as part of this project.
The desalination process will consist of a dual treatment units or “trains” each equipped with a positive displacement axial piston first pass membrane feed pump, first pass membrane array, energy recovery system, second pass membrane feed pump, second pass membrane array, high- and low-pressure
piping and instrumentation. The second pass system is designed to treat up to 60 percent of the first pass permeate. A membrane cleaning/flush system will be provided. The membrane post treatment will be designed to receive the flow from both units and consists of a forced air degasified, repumping, recarbonation, calcium carbonate up flow contactors to boost finished water hardness and alkalinity concentrations; and three chemical feed systems for the metering of a corrosion inhibitor, dilute hydrochloric acid for pH adjustment and sodium hypochlorite for residual disinfection. The final pH and chlorine residual will be controlled and recorded by a separate system. The following sections describe the various aspects of the facility in greater detail. Process flow
schematics are presented in Appendix A.
Desalination Plant Basis Of Design
Overview:
The project potable water requirements will be provided using single desalination plant with the Grand Bahama Port Authority water supply serving as the backup source. The overall desalination treatment process will consist of feedwater pumping, bag filtration, optional media filtration, the addition of a scale
inhibitor, cartridge filtration, membrane separation, forced air degasification, re-pumping, and post treatment. Provisions have been included to bypass the post treatment systems for the production of irrigation water. The post aeration re-pump station will be designed to transfer either type of water to the
appropriate storage tanks located within the project. Membrane concentrate will be disposed via an injection well to be constructed as part of this project.
The desalination process will consist of a dual treatment units or “trains” each equipped with a positive displacement axial piston first pass membrane feed pump, first pass membrane array, energy recovery system, second pass membrane feed pump, second pass membrane array, high- and low-pressure
piping and instrumentation. The second pass system is designed to treat up to 60 percent of the first pass permeate. A membrane cleaning/flush system will be provided. The membrane post treatment will be designed to receive the flow from both units and consists of a forced air degasified, repumping, recarbonation, calcium carbonate up flow contactors to boost finished water hardness and alkalinity concentrations; and three chemical feed systems for the metering of a corrosion inhibitor, dilute hydrochloric acid for pH adjustment and sodium hypochlorite for residual disinfection. The final pH and chlorine residual will be controlled and recorded by a separate system. The following sections describe the various aspects of the facility in greater detail. Process flow
schematics are presented in Appendix A.
Chemical Cleaning Effects On Properties And Separation Efciency Of An RO Membrane
Abstract: This study aims to investigate the impacts of chemical cleaning on the performance of a reverse osmosis
membrane. Chemicals used for simulating membrane cleaning include a surfactant (sodium dodecyl sulfate, SDS), a
chelating agent (ethylenediaminetetraacetic acid, EDTA), and two proprietary cleaning formulations namely MC3
and MC11. The impact of sequential exposure to multiple membrane cleaning solutions was also examined. Water
permeability and the rejection of boron and sodium were investigated under various water fluxes, temperatures and
feedwater pH. Changes in the membrane performance were systematically explained based on the changes in the
charge density, hydrophobicity and chemical structure of the membrane surface. The experimental results show that
membrane cleaning can significantly alter the hydrophobicity and water permeability of the membrane; however, its
impacts on the rejections of boron and sodium are marginal. Although the presence of surfactant or chelating agent
may cause decreases in the rejection, solution pH is the key factor responsible for the loss of membrane separation
and changes in the surface properties. The impact of solution pH on the water permeability can be reversed by
applying a subsequent cleaning with the opposite pH condition. Nevertheless, the impacts of solution pH on boron
and sodium rejections are irreversible in most cases
Chemical Cleaning Effects On Properties And Separation Efciency Of An RO Membrane
Abstract: This study aims to investigate the impacts of chemical cleaning on the performance of a reverse osmosis
membrane. Chemicals used for simulating membrane cleaning include a surfactant (sodium dodecyl sulfate, SDS), a
chelating agent (ethylenediaminetetraacetic acid, EDTA), and two proprietary cleaning formulations namely MC3
and MC11. The impact of sequential exposure to multiple membrane cleaning solutions was also examined. Water
permeability and the rejection of boron and sodium were investigated under various water fluxes, temperatures and
feedwater pH. Changes in the membrane performance were systematically explained based on the changes in the
charge density, hydrophobicity and chemical structure of the membrane surface. The experimental results show that
membrane cleaning can significantly alter the hydrophobicity and water permeability of the membrane; however, its
impacts on the rejections of boron and sodium are marginal. Although the presence of surfactant or chelating agent
may cause decreases in the rejection, solution pH is the key factor responsible for the loss of membrane separation
and changes in the surface properties. The impact of solution pH on the water permeability can be reversed by
applying a subsequent cleaning with the opposite pH condition. Nevertheless, the impacts of solution pH on boron
and sodium rejections are irreversible in most cases
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