Water Desalination & RO
Evaluation of Membrane Pretreatment for Seawater Reverse Osmosis Desalination
Evaluation of Membrane Pretreatment for Seawater Reverse Osmosis Desalination
Credit to: https://www.usbr.gov/
Desalination and Water Purification Research and Development Program Report No. 106
Abstract:
This project was undertaken to better understand the technical and cost implications of the use of membrane filtration as pretreatment for seawater reverse osmosis (RO). The pilot study was conducted using raw feed water from the Corpus Christi Bay in Texas, at the San Patricio Municipal Water District facility. The pilot study consisted of a side-by-side comparison of membrane filtration and conventional filtration, both followed by separate RO pilot systems, testing over an approximate 1-year period. The results indicate that membrane filtration produced far superior water quality for pretreatment, measured by reduced turbidity and by the silt density index (SDI). The resulting impact on the RO performance was a significantly lower RO cleaning frequency. The economic evaluation indicates that on a life-cycle cost analysis, the total water cost (TWC) for a plant using membrane filtration is 4-8% less than a plant using media filtration.
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Cleaning Your RO
Eventually the day comes when your RO system will require cleaning. Cleaning is recommended when your RO shows evidence of fouling, just prior to a long term shutdown, or as a matter of scheduled routine maintenance. Fouling characteristics that signal you need to clean are a 10-15% decrease in normalized permeate flow, a 10-15% decrease in normalized permeate quality, or a 10-15% increase in normalized pressure drop as measured between the feed and concentrate headers
Cleaning Your RO
Eventually the day comes when your RO system will require cleaning. Cleaning is recommended when your RO shows evidence of fouling, just prior to a long term shutdown, or as a matter of scheduled routine maintenance. Fouling characteristics that signal you need to clean are a 10-15% decrease in normalized permeate flow, a 10-15% decrease in normalized permeate quality, or a 10-15% increase in normalized pressure drop as measured between the feed and concentrate headers
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.
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
Desalination As An Alternative To Alleviate Water Scarcity And a Climate Change Adaptation Option In The MENA Region
This report has been prepared by Dr. Jauad El Kharraz at MEDRC with the support of Eng. Ayisha Al-Hinaai, Eng. Riadh Dridi, Ms. Elsa Andrews, Ms. Jackie Allison, and Eng. Georges Geha. This study was peer reviewed by three international experts. We would like to thank them for their reviewing work
Desalination As An Alternative To Alleviate Water Scarcity And a Climate Change Adaptation Option In The MENA Region
This report has been prepared by Dr. Jauad El Kharraz at MEDRC with the support of Eng. Ayisha Al-Hinaai, Eng. Riadh Dridi, Ms. Elsa Andrews, Ms. Jackie Allison, and Eng. Georges Geha. This study was peer reviewed by three international experts. We would like to thank them for their reviewing work
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 For Safe Water Supply
Preface:
Access to sufficient quantities of safe water for drinking and domestic uses and also for commercial and industrial applications is critical to health and well being, and the opportunity to achieve human and economic development. People in many areas of the world have historically suffered from inadequate access to safe water. Some must walk long distances just to obtain sufficient water to sustain life. As a result they have had to endure health consequences and have not had the opportunity to develop their resources and capabilities to achieve major improvements in their well being. With growth of world population the availability of the limited quantities of fresh water decreases. Desalination technologies were introduced about 50 years ago at and were able to expand access to water, but at high cost. Developments of new and improved technologies have now significantly broadened the opportunities to access major quantities of safe water in many parts of the world. Costs are still significant but there has been a reducing cost trend, and the option is much more widely available. When the alternative is no water or inadequate water greater cost may be endurable in many circumstances.
Desalination For Safe Water Supply
Preface:
Access to sufficient quantities of safe water for drinking and domestic uses and also for commercial and industrial applications is critical to health and well being, and the opportunity to achieve human and economic development. People in many areas of the world have historically suffered from inadequate access to safe water. Some must walk long distances just to obtain sufficient water to sustain life. As a result they have had to endure health consequences and have not had the opportunity to develop their resources and capabilities to achieve major improvements in their well being. With growth of world population the availability of the limited quantities of fresh water decreases. Desalination technologies were introduced about 50 years ago at and were able to expand access to water, but at high cost. Developments of new and improved technologies have now significantly broadened the opportunities to access major quantities of safe water in many parts of the world. Costs are still significant but there has been a reducing cost trend, and the option is much more widely available. When the alternative is no water or inadequate water greater cost may be endurable in many circumstances.
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.
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.
Desalination At A Glance
Introduction:
By desalination, we will be referring to the production of a useful product water from a feed
water that is too high in inorganic materials (salts) to be useful. The feed water may be
seawater, brackish water, or other “impaired” water that cannot be used directly for potable
or general industrial purposes. Notice that this definition includes the treatment of certain
wastewaters for subsequent reuse.
The principal technologies used in desalination are based on concepts that are fairly easy to
grasp by those with a modest amount of scientific training and/or technical experience. In
practice, however, choices of technology and plant design are usually determined by factors
that might appear minor to the inexperienced. Similarly, new technologies that show great
promise in the laboratory frequently fail for reasons that were earlier overlooked or dismissed
as trivial. Indeed, professional fascination with specific technical elegance has, in some
cases, led researchers to remain oblivious to inherent limitations of a process. Nonetheless,
attention to detail over the past five decades has resulted in dramatic reductions in capital
and operating costs as well as greatly increased plant reliability and performance
Desalination At A Glance
Introduction:
By desalination, we will be referring to the production of a useful product water from a feed
water that is too high in inorganic materials (salts) to be useful. The feed water may be
seawater, brackish water, or other “impaired” water that cannot be used directly for potable
or general industrial purposes. Notice that this definition includes the treatment of certain
wastewaters for subsequent reuse.
The principal technologies used in desalination are based on concepts that are fairly easy to
grasp by those with a modest amount of scientific training and/or technical experience. In
practice, however, choices of technology and plant design are usually determined by factors
that might appear minor to the inexperienced. Similarly, new technologies that show great
promise in the laboratory frequently fail for reasons that were earlier overlooked or dismissed
as trivial. Indeed, professional fascination with specific technical elegance has, in some
cases, led researchers to remain oblivious to inherent limitations of a process. Nonetheless,
attention to detail over the past five decades has resulted in dramatic reductions in capital
and operating costs as well as greatly increased plant reliability and performance
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