A Cost-Effective and Environmentally Friendly Desalination Option
The problem of supplying drinking water to the masses still survives, and desalination continues to be one of the most sought-after solutions.
Humans have always tried to control their environment, especially when it comes to water. The Romans, ancient masters of irrigation, used a system of complex aqueducts to supply their citizens with a steady supply of potable water. Massive, unwieldy, and demanding, the empire undoubtedly asked for more water than was readily available.
According to the World Health Organization, 97% of the world’s water is undrinkable, 2% of the fresh water is frozen, and “less than 1% of the world’s water supply is fresh water and available for human consumption.” Constantly threatened by pollution and waste, the remaining 1% cannot adequately support the world’s population, and as a result, more than 2.7 billion people, most of who live in developing countries, do not have access to safe drinking water. Water consumption continues to increase exponentially, and experts anticipate that demand for water will increase by 22% by 2025.
In the past, desalination lurked in the shadows because of its prohibitive cost and detrimental environmental effect. Currently there are approximately 12,000 desalination plants worldwide, more than 60% of which are located in the Middle East. By contrast, fewer than 2,000 desalination plants exist in the United States, with the majority located in the Caribbean and Florida. A smaller number of plants sit along the California coastline, but in the face of diminished supply and increased population, the idea of desalination as a viable alternative is gaining popularity.
In 1996, the Los Angeles Department of Water and Power (LADWP), in a joint effort with the US Bureau of Land Management, initiated the creation of a desalination research and development project in Long Beach, CA. By September 2005, a 300,000-gallon-per-day research facility was up and running, completing the second phase of the Long Beach Seawater Desalination Project. Officials anticipate fulfilling the third and final phase of the project by 2010, at which time the Long Beach project will have morphed into a fully operational facility able to provide up to10% of the region’s drinking water. With recent California Coastal Commission approval and an influx of grant funding from California State Proposition 50, the project is poised to become the most efficient and environmentally sound desalination program in the country.
Desalination: A Brief History
The process of desalination involves the removal of dissolved solids (such as salts) from seawater, treated wastewater, or brackish water in order to produce fresh water. Desalination methods fall into two major categories: distillation and membrane filtration. Distillation involves heating seawater in order to collect the resulting freshwater vapor. With membrane filtration, also known as reverse osmosis, water passes through membranes that separate dissolved solids. Sidney Loeb and Srinivasa Sourirajan (University of California–Los Angeles) developed the first reverse osmosis membrane in 1959. These membranes, made of cellulose acetate, allow for the application of high pressure to “specific ionic water molecules,” thereby producing fresh water from a salt solution. In order to ensure that the membranes are kept in a pristine condition, the seawater gets pretreated using a cleaning process similar to the filtration methods used at water treatment plants. Currently more than 60% of the world’s desalination systems use some form of reverse osmosis.
High costs have thwarted the expansion of desalination. According to the American Water Works Association, in the 1950s, when the US first began to focus on desalination technologies, the price hovered around $16 per 1,000 gallons. Because of the high cost associated with the technology, the US focused primarily on research and development in an attempt to make the method more economically viable. The massive economical expenditures associated with desalination can be attributed to technological expenditures and the enormous amounts of energy required to run a desalination facility. A. Judson Hill, managing director with the Halifax Group, states, “Currently 40% of desalination costs comes from energy,” but change is on the horizon. According to Hill, “Desalination is getting more competitive as the price for natural source water is going up due to pretreatment costs.”
In addition, current technologies have helped reduce the price of desalination drinking water to approximately $3 per 1,000 gallons. Hill summarizes the effect of technological advances on costs. “Overall the market has been good about deploying new technologies,” he says. “Desalination has become substantially less expensive because membranes are now much more energy efficient.”
Environmental Impact and Regulatory Compliance
The environmental impact of desalination plants can also be blamed for the reticence shown by municipalities to explore the option of desalination. Currently, desalination plants require energy via fossil fuels in order to operate, resulting in air pollution. Desalination also adversely affects the marine ecosystem due to a fear of incidental killing of sea life inadvertently sucked into intake pipes. Brine, desalination’s salty byproduct, also triggers concerns about adverse environmental impacts and is another obstacle that facilities must overcome. In order to build and operate a desalination plant, the project must comply with federal and state regulations governing water pretreatment, drinking water processing, and brine disposal.
 |
| Of the 12,000-plus desalination plants in the world, fewer than 2,000 exist in the US. |
In California, the Coastal Commission controls coastal development and enforces the California Coastal Act passed in 1976. The Coastal Act requires local jurisdictions to work with state government to create and regulate development plans along the coast. The act covers an area that extends 3 miles up from the shoreline and 5 miles from the shoreline out to sea. Pam Emerson of the Coastal Commission in Long Beach summarizes its mission as follows: “Our concerns would be the location—if it were close to a biological function and displaced something like a wetland—and to make sure that the discharge does not pollute.”
Currently many older facilities transfer seawater into pipes using the “once-through cooling” method utilized by older power plants. Once-through cooling draws water directly from the ocean using pumps that then run it through the system. Unfortunately, the pumps suck up more than just water, inevitably killing a variety of marine life. Larger organisms, such as adult fish, get trapped in the intake screens, while smaller organisms, like eggs or larvae, make it through the intake screens only to be trapped and killed inside the treatment facility. Protecting coastal resources and promoting sustainable development are the twin concerns of coastal protection in California. As a result, the Coastal Commission and the Coastal Act significantly influence the construction and operation of desalination facilities.
Construction of desalination plants impacts dune and surf zones, air quality, and seafloor ecology. In addition, the pipelines needed for intake and discharge can affect tidal pools and lagoons. The possible catastrophic outcome of desalination construction and operation on California’s fragile coastline elicits concern from environmental organizations, local governments, and such state agencies as the Coastal Commission. As Emerson states, the Coastal Commission must ensure “the work doesn’t adversely impact coastal areas. [The Coastal Commission must also maintain] public access to coastal areas.”
Federal regulations also govern the operation of desalination plants. The Clean Water Act and the Safe Drinking Water Act are two powerful federal laws that empower the EPA to enforce standards aimed at protecting water resources and the water supplies from various forms of contamination. Working under the authority of these federal statutes, the EPA requires all desalination plants to comply with specific guidelines and protocols.
The Clean Water Act limits the amount of pollutants discharged into surface waters. According to the EPA, pretreatment guidelines help “ensure that pollutants do not pass through or interfere with the safe and effective operation of treatment plants.” The act not only gives the EPA authority to implement pollution control programs, it also sets water quality standards and National Pollutant Discharge Elimination System (NPDES) permit requirements: “It is unlawful for any person to discharge any pollutant from a point source into navigable waters, unless a permit was obtained under its provisions.”
The Clean Water Act also discusses desalination’s non-drinking-water byproduct: brine. Water treated by reverse osmosis splits into two categories: 50% of it becomes drinking water, and the remaining 50% becomes brine. Brine contains twice the salt content of saltwater. Currently classified as an industrial waste by the EPA, brine requires an involved and complex disposal process. “The real issue when you have large volumes of water is how you discharge brine,” says Hill.
Brine can be dealt with either by subsurface injection or surface-water discharge. Subsurface injection is primarily utilized by landlocked facilities and involves the placement of liquid waste into a porous geological formation such as sandstone or limestone. Coastal facilities commonly use subsurface discharge because the byproduct can be easily diluted into coastal waters. The main purpose of the Clean Water Act is to control water contamination via the NPDES permit process. The NPDES permits control manufacturing discharge and water runoff by focusing primarily on contaminant control. Discharge from manufacturing or from point sources and nonpoint sources, such as agricultural or water runoff, are measured and regulated. One of the biggest challenges for desalination plants is developing a brine disposal method that meets the requirements set by the NPDES permit process.
 |
| The Long Beach plant processes 3000,000 gallons of water per day. |
The purpose of desalination is to provide potable water, so facilities must also comply with the Safe Drinking Water Act, passed by congress in 1974. The Safe Drinking Water Act calls for the implementation and enforcement of health standards for contaminants in drinking water. The act also authorizes the EPA to “set enforceable health standards for contaminants in drinking water.” The EPA established the standard for safe drinking water at less than 500 milligrams of dissolved substance per liter of water. The drinking water produced by desalination plants must meet this standard. Additional aspects of the act include a requirement for public notification of water system violations and annual reports for consumers detailing the contaminants in their drinking water. In order to operate, a desalination facility must comply with all of these provisions.
In summary, in order to produce a viable source of municipal drinking water, desalination must minimally impact its local environment and comply with state and federal law. The Clean Water Act, the Safe Drinking Water Act and individual state regulations require protection of marine ecosystems, pollution control, and untainted drinking water. In order for desalination to become a predominant source of drinking water in this country, a project must be created that can balance the environmental issues with fiscally viable operating procedures. The Long Beach Desalination Project aims to do exactly that.
The Long Beach Project
Economically efficient and environmentally friendly, the Long Beach project can easily clear the hurdles that have stalled the expansion of desalination projects in the US. The project’s ultimate goal, according to Ryan Alsop, director of government and public affairs for the Long Beach Water Department, is to prove the feasibility of an “economically and environmentally responsive method of collecting seawater, producing potable water, and disposing of brine.”
Although Long Beach desalination plant currently “is not a full scale production facility,” according to Alsop, the project “is an all inclusive seawater desalination plant that is only focused on reducing energy requirements and improving the water-quality requirements.”
The focus of the project made clearing the permitting process easy. Alsop says, “There were no regulatory and permitting problems. They like our project.”
It took almost 10 years and $15 million in funding from the state, the federal government, and the Long Beach Water Department ratepayers, but in September 2005, the highly anticipated Long Beach Desalination Research and Demonstration Program opened its 300,000-gallon-per-day research facility. Located at the LADWP generation center, the facility currently processes 300,000 gallons of water per day. Because the facility operates only as a research and development project, the drinking water produced is remixed with brine and released back through the intake system. According to Alsop, the facility is “the largest of its kind in the nation.”
“Water quality is an issue. With seawater, we’re going to use this facility to perfect the water quality,” says Alsop, who goes on to explain, “Desalination is expensive, so we are using this facility to try and bring the cost down.”
Alsop sums up the focus of the project by explaining that the LADWP “constructed the facility in order to conduct research. We built the project to find out what the Demonstration program began with the 1996 passage of Public Law 104-266 by the House of Representatives authorizing the initiation of the program. By October 2001, a 9,000-gallon-per-day pilot plant was fully operational, with initial research already indicating an energy savings of between 20% and 30%. In September 2001, the Long Beach Water Department signed a cooperative agreement with the US Bureau of Reclamation to begin the design and construction of a $15 million research prototype.
The Long Beach Water Department ultimately awarded the construction contract for the prototype plant to Pascal & Ludwig. Jeff McDonnell of Pascal & Ludwig says that the major challenges faced by the company were “a tight schedule and the fact that it was a design/build project, being designed and built concurrently.”
In the past, Pascal & Ludwig have overseen the construction of several desalination facilities; those projects have been focused on treating brackish groundwater. The Long Beach contract, on the other hand, was Pascal & Ludwig’s “first raw seawater facility” according to McDonnell, who goes on say that the facility was “built from the ground up as a brand-new facility. Everybody worked together to bring the project up and running.”
McDonnell expresses optimism about the project. “The opportunity this presents is determining whether desalination on a large scale is economically feasible,” he says.
 |
| Energy efficiency is a key focus of the Long Beach Desalination Project. |
In November 2003, after receiving all the necessary permits and additional funding, construction started on the 300,000-gallon-per-day research facility, which finally began operations in September 2005. At the Long Beach facility, water is taken from the Haynes intake channel and passes through a pretreatment process that filters out silt and other larger particles. After the pretreatment process has been completed, the next step involves side-by-side testing of different desalination technologies: one-pass reverse osmosis and two-pass nano-filtration.
Half of the pretreated water goes through one-pass reverse osmosis while the other half is subjected to two-pass nano-filtration. Also known as the Long Beach Method, the two-pass nano-filtration method is a low-pressure, two-stage filtration process developed by Long Beach engineers that sends seawater through two sets of membranes. Nano-filtration removes 90% of the salinity from seawater. Various tests are then performed, allowing for a comparison and contrast of each process. The purpose of this dual testing, according to Alsop, is to “use different membranes, water temperatures, distribution integration, et cetera, in order to generate a lot of data that currently doesn’t exist.”
Part of the research conducted at the Long Beach facility includes the testing of all aspects of the desalination process, including the effectiveness of the desalination equipment. In order to collect relevant data and determine efficiency, explains Alsop, “We’re also using different types of membranes.” The types of filtration membranes tested by the facility include those manufactured by TriSep Corp. (located in Goleta, CA), FilmTec Corp. (a subsidiary of The Dow Chemical Co.), and Saehan Industries (a multinational corporation). By comparing the different materials available, the project aims to create a databank that can provide materials manufacturers with the information necessary to improve their product and technologies, the ultimate goal being a long-lasting, inexpensive, and energy-efficient filtration membrane.
After collecting the information generated by these processes, the water is combined, mixed with brine, and discharged back into the intake channel. By the time the water is flushed through the second set of membranes, the water contains less than 500 milligrams of dissolved substances per liter of water, thereby complying with EPA drinking-water standards. The Long Beach facility has demonstrated that the nano-filtration technique is potentially 20% to 30% more efficient than other desalination techniques. The energy savings, says Alsop, are the result of “utilizing nano-filtration, which is different from reverse osmosis. We’re using a two-stage process as opposed to a single-pass process, and that’s the essence of the savings.”
The Long Beach project focuses on energy efficiency, but, states Alsop, “This plant is also more than that.” Energy efficiency is “ the core focus of the prototype that we built, but over the next two years we’re going to be doing all sorts of research.”
Part of that research involves an innovative filtration technique, the Under Ocean Floor Seawater Intake and Discharge Demonstration System. This research and development project was eased along by a $3 million grant from funds created by Proposition 50. Covering water quality, water supply, safe drinking-water projects, and coastal wetlands purchase and protection, Proposition 50 supplies $3.4 billion in bonds to fund water projects. In April 2006, the California Coastal Commission approved a coastal development permit for the Under Ocean Floor Desalination Demonstration System, clearing one more hurdle. Alsop sums up the significance of Under Sea Floor innovation. “It demonstrates that desalination can be cost-effective and environmentally responsible,” he says.
This portion of the Long Beach project, according to Alsop, focuses “on demonstrating an alternative to open ocean intake and discharge practices with an under-ocean-floor intake and discharge systems.”
Traditionally, intake and discharge pipes sit on the ocean floor with significant environmental impacts. The Under Ocean Floor Seawater Intake and Discharge Demonstration project involves the installation of permeable intake and discharge pipes underneath, rather than on top of, the ocean floor. Placing the pipes underneath the ocean floor adds yet another level of filtration. What is most exciting about this under-ocean-floor system is that it eliminates two of the biggest environmental problems associated with desalination: inadvertent killing of marine life and brine byproduct disposal. By using the ocean floor as a barrier between the intake pipes and the ocean, the system eliminates the danger of sea life inadvertently being sucked into the pipes and killed. The ocean floor also serves as an added filter for the brine byproduct. The Under Sea Floor innovations are an “environmentally responsive method of collecting seawater and disposing of brine,” says Alsop.
The Southern California Metropolitan Water District currently provides the City of Long Beach with 42% of its water via the State Water Project and the Colorado River Aqueduct. Another 38% is supplied from groundwater that is locally treated and pumped. Conservation and water reuse supplies the final 20%. Alsop predicts that eventually desalination will be a significant source of water for the city. “We see it making up 10% of the city’s water resources portfolio,” he says.
Ultimately the Long Beach desalination plant involves a three-step plan that will span 15 years. The first step was the small-scale 9,000-gallon-per-day pilot plant that began operations in October 2001. The second step was the construction and operation of the 300,000-gallon-per-day plant in September 2005. By 2015, Long Beach officials anticipate commencement of the final stage of the program: a full-scale, fully operational plant that applies all of the knowledge acquired from the prototype projects.
Elaborating on the future of the facility, Alsop states, “Over the next two years we’re going to be doing all sorts of research. We’re going to be looking at the life of membranes because that’s a big expense on desal plants, to have to go out and replace membranes. We’re looking at different types of membranes. We’re looking again at water quality, pretreatment technologies, distribution system integration—all of those things are going to be part of research over the next couple of years.”
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A View to the Future
There are currently over 12,000 desalination plants in the world, supplying between 5 billion and 7 billion gallons of water per day. These systems also create between 2 billion and 3 billion gallons of byproduct per day. Two issues have hindered the expansion of desalination from a secondary water-supply source to a primary water-supply source: high cost and adverse environmental impact. Technological advances continue to fine-tune desalination with the goal to make it more cost-effective and environmentally friendly. Once a desalination project can clear these twin hurdles, it will be poised to become a significant source of drinking water for the US. With desalination in the mix, municipalities and water facilities will be able to reduce their dependence on such finite freshwater sources as groundwater and spring-fed reservoirs.
The technological advances created at the Long Beach desalination facility cast desalination in a new and more favorable light. The dual issues of high cost and environmental impact are being conquered, and desalination is poised to significantly contribute to the world’s water supply. Alsop predicts, “If our research goes the way we think it will go, the data will be very valuable and influential” for other agencies and organizations, freeing them to pursue desalination as a viable and important supplement to their water supplies.
January-February 2007
A Cost-Effective and Environmentally Friendly Desalination Option
The problem of supplying drinking water to the masses still survives, and desalination continues to be one of the most sought-after solutions.
Humans have always tried to control their environment, especially when it comes to water. The Romans, ancient masters of irrigation, used a system of complex aqueducts to supply their citizens with a steady supply of potable water. Massive, unwieldy, and demanding, the empire undoubtedly asked for more water than was readily available.
According to the World Health Organization, 97% of the world’s water is undrinkable, 2% of the fresh water is frozen, and “less than 1% of the world’s water supply is fresh water and available for human consumption.” Constantly threatened by pollution and waste, the remaining 1% cannot adequately support the world’s population, and as a result, more than 2.7 billion people, most of who live in developing countries, do not have access to safe drinking water. Water consumption continues to increase exponentially, and experts anticipate that demand for water will increase by 22% by 2025.
In the past, desalination lurked in the shadows because of its prohibitive cost and detrimental environmental effect. Currently there are approximately 12,000 desalination plants worldwide, more than 60% of which are located in the Middle East. By contrast, fewer than 2,000 desalination plants exist in the United States, with the majority located in the Caribbean and Florida. A smaller number of plants sit along the California coastline, but in the face of diminished supply and increased population, the idea of desalination as a viable alternative is gaining popularity.
In 1996, the Los Angeles Department of Water and Power (LADWP), in a joint effort with the US Bureau of Land Management, initiated the creation of a desalination research and development project in Long Beach, CA. By September 2005, a 300,000-gallon-per-day research facility was up and running, completing the second phase of the Long Beach Seawater Desalination Project. Officials anticipate fulfilling the third and final phase of the project by 2010, at which time the Long Beach project will have morphed into a fully operational facility able to provide up to10% of the region’s drinking water. With recent California Coastal Commission approval and an influx of grant funding from California State Proposition 50, the project is poised to become the most efficient and environmentally sound desalination program in the country.
Desalination: A Brief History
The process of desalination involves the removal of dissolved solids (such as salts) from seawater, treated wastewater, or brackish water in order to produce fresh water. Desalination methods fall into two major categories: distillation and membrane filtration. Distillation involves heating seawater in order to collect the resulting freshwater vapor. With membrane filtration, also known as reverse osmosis, water passes through membranes that separate dissolved solids. Sidney Loeb and Srinivasa Sourirajan (University of California–Los Angeles) developed the first reverse osmosis membrane in 1959. These membranes, made of cellulose acetate, allow for the application of high pressure to “specific ionic water molecules,” thereby producing fresh water from a salt solution. In order to ensure that the membranes are kept in a pristine condition, the seawater gets pretreated using a cleaning process similar to the filtration methods used at water treatment plants. Currently more than 60% of the world’s desalination systems use some form of reverse osmosis.
High costs have thwarted the expansion of desalination. According to the American Water Works Association, in the 1950s, when the US first began to focus on desalination technologies, the price hovered around $16 per 1,000 gallons. Because of the high cost associated with the technology, the US focused primarily on research and development in an attempt to make the method more economically viable. The massive economical expenditures associated with desalination can be attributed to technological expenditures and the enormous amounts of energy required to run a desalination facility. A. Judson Hill, managing director with the Halifax Group, states, “Currently 40% of desalination costs comes from energy,” but change is on the horizon. According to Hill, “Desalination is getting more competitive as the price for natural source water is going up due to pretreatment costs.”
In addition, current technologies have helped reduce the price of desalination drinking water to approximately $3 per 1,000 gallons. Hill summarizes the effect of technological advances on costs. “Overall the market has been good about deploying new technologies,” he says. “Desalination has become substantially less expensive because membranes are now much more energy efficient.”
Environmental Impact and Regulatory Compliance
The environmental impact of desalination plants can also be blamed for the reticence shown by municipalities to explore the option of desalination. Currently, desalination plants require energy via fossil fuels in order to operate, resulting in air pollution. Desalination also adversely affects the marine ecosystem due to a fear of incidental killing of sea life inadvertently sucked into intake pipes. Brine, desalination’s salty byproduct, also triggers concerns about adverse environmental impacts and is another obstacle that facilities must overcome. In order to build and operate a desalination plant, the project must comply with federal and state regulations governing water pretreatment, drinking water processing, and brine disposal.
|
| Of the 12,000-plus desalination plants in the world, fewer than 2,000 exist in the US. |
In California, the Coastal Commission controls coastal development and enforces the California Coastal Act passed in 1976. The Coastal Act requires local jurisdictions to work with state government to create and regulate development plans along the coast. The act covers an area that extends 3 miles up from the shoreline and 5 miles from the shoreline out to sea. Pam Emerson of the Coastal Commission in Long Beach summarizes its mission as follows: “Our concerns would be the location—if it were close to a biological function and displaced something like a wetland—and to make sure that the discharge does not pollute.”
Currently many older facilities transfer seawater into pipes using the “once-through cooling” method utilized by older power plants. Once-through cooling draws water directly from the ocean using pumps that then run it through the system. Unfortunately, the pumps suck up more than just water, inevitably killing a variety of marine life. Larger organisms, such as adult fish, get trapped in the intake screens, while smaller organisms, like eggs or larvae, make it through the intake screens only to be trapped and killed inside the treatment facility. Protecting coastal resources and promoting sustainable development are the twin concerns of coastal protection in California. As a result, the Coastal Commission and the Coastal Act significantly influence the construction and operation of desalination facilities.
Construction of desalination plants impacts dune and surf zones, air quality, and seafloor ecology. In addition, the pipelines needed for intake and discharge can affect tidal pools and lagoons. The possible catastrophic outcome of desalination construction and operation on California’s fragile coastline elicits concern from environmental organizations, local governments, and such state agencies as the Coastal Commission. As Emerson states, the Coastal Commission must ensure “the work doesn’t adversely impact coastal areas. [The Coastal Commission must also maintain] public access to coastal areas.”
Federal regulations also govern the operation of desalination plants. The Clean Water Act and the Safe Drinking Water Act are two powerful federal laws that empower the EPA to enforce standards aimed at protecting water resources and the water supplies from various forms of contamination. Working under the authority of these federal statutes, the EPA requires all desalination plants to comply with specific guidelines and protocols.
The Clean Water Act limits the amount of pollutants discharged into surface waters. According to the EPA, pretreatment guidelines help “ensure that pollutants do not pass through or interfere with the safe and effective operation of treatment plants.” The act not only gives the EPA authority to implement pollution control programs, it also sets water quality standards and National Pollutant Discharge Elimination System (NPDES) permit requirements: “It is unlawful for any person to discharge any pollutant from a point source into navigable waters, unless a permit was obtained under its provisions.”
The Clean Water Act also discusses desalination’s non-drinking-water byproduct: brine. Water treated by reverse osmosis splits into two categories: 50% of it becomes drinking water, and the remaining 50% becomes brine. Brine contains twice the salt content of saltwater. Currently classified as an industrial waste by the EPA, brine requires an involved and complex disposal process. “The real issue when you have large volumes of water is how you discharge brine,” says Hill.
Brine can be dealt with either by subsurface injection or surface-water discharge. Subsurface injection is primarily utilized by landlocked facilities and involves the placement of liquid waste into a porous geological formation such as sandstone or limestone. Coastal facilities commonly use subsurface discharge because the byproduct can be easily diluted into coastal waters. The main purpose of the Clean Water Act is to control water contamination via the NPDES permit process. The NPDES permits control manufacturing discharge and water runoff by focusing primarily on contaminant control. Discharge from manufacturing or from point sources and nonpoint sources, such as agricultural or water runoff, are measured and regulated. One of the biggest challenges for desalination plants is developing a brine disposal method that meets the requirements set by the NPDES permit process.
|
| The Long Beach plant processes 3000,000 gallons of water per day. |
The purpose of desalination is to provide potable water, so facilities must also comply with the Safe Drinking Water Act, passed by congress in 1974. The Safe Drinking Water Act calls for the implementation and enforcement of health standards for contaminants in drinking water. The act also authorizes the EPA to “set enforceable health standards for contaminants in drinking water.” The EPA established the standard for safe drinking water at less than 500 milligrams of dissolved substance per liter of water. The drinking water produced by desalination plants must meet this standard. Additional aspects of the act include a requirement for public notification of water system violations and annual reports for consumers detailing the contaminants in their drinking water. In order to operate, a desalination facility must comply with all of these provisions.
In summary, in order to produce a viable source of municipal drinking water, desalination must minimally impact its local environment and comply with state and federal law. The Clean Water Act, the Safe Drinking Water Act and individual state regulations require protection of marine ecosystems, pollution control, and untainted drinking water. In order for desalination to become a predominant source of drinking water in this country, a project must be created that can balance the environmental issues with fiscally viable operating procedures. The Long Beach Desalination Project aims to do exactly that.
The Long Beach Project
Economically efficient and environmentally friendly, the Long Beach project can easily clear the hurdles that have stalled the expansion of desalination projects in the US. The project’s ultimate goal, according to Ryan Alsop, director of government and public affairs for the Long Beach Water Department, is to prove the feasibility of an “economically and environmentally responsive method of collecting seawater, producing potable water, and disposing of brine.”
Although Long Beach desalination plant currently “is not a full scale production facility,” according to Alsop, the project “is an all inclusive seawater desalination plant that is only focused on reducing energy requirements and improving the water-quality requirements.”
The focus of the project made clearing the permitting process easy. Alsop says, “There were no regulatory and permitting problems. They like our project.”
It took almost 10 years and $15 million in funding from the state, the federal government, and the Long Beach Water Department ratepayers, but in September 2005, the highly anticipated Long Beach Desalination Research and Demonstration Program opened its 300,000-gallon-per-day research facility. Located at the LADWP generation center, the facility currently processes 300,000 gallons of water per day. Because the facility operates only as a research and development project, the drinking water produced is remixed with brine and released back through the intake system. According to Alsop, the facility is “the largest of its kind in the nation.”
“Water quality is an issue. With seawater, we’re going to use this facility to perfect the water quality,” says Alsop, who goes on to explain, “Desalination is expensive, so we are using this facility to try and bring the cost down.”
Alsop sums up the focus of the project by explaining that the LADWP “constructed the facility in order to conduct research. We built the project to find out what the Demonstration program began with the 1996 passage of Public Law 104-266 by the House of Representatives authorizing the initiation of the program. By October 2001, a 9,000-gallon-per-day pilot plant was fully operational, with initial research already indicating an energy savings of between 20% and 30%. In September 2001, the Long Beach Water Department signed a cooperative agreement with the US Bureau of Reclamation to begin the design and construction of a $15 million research prototype.
The Long Beach Water Department ultimately awarded the construction contract for the prototype plant to Pascal & Ludwig. Jeff McDonnell of Pascal & Ludwig says that the major challenges faced by the company were “a tight schedule and the fact that it was a design/build project, being designed and built concurrently.”
In the past, Pascal & Ludwig have overseen the construction of several desalination facilities; those projects have been focused on treating brackish groundwater. The Long Beach contract, on the other hand, was Pascal & Ludwig’s “first raw seawater facility” according to McDonnell, who goes on say that the facility was “built from the ground up as a brand-new facility. Everybody worked together to bring the project up and running.”
McDonnell expresses optimism about the project. “The opportunity this presents is determining whether desalination on a large scale is economically feasible,” he says.
|
| Energy efficiency is a key focus of the Long Beach Desalination Project. |
In November 2003, after receiving all the necessary permits and additional funding, construction started on the 300,000-gallon-per-day research facility, which finally began operations in September 2005. At the Long Beach facility, water is taken from the Haynes intake channel and passes through a pretreatment process that filters out silt and other larger particles. After the pretreatment process has been completed, the next step involves side-by-side testing of different desalination technologies: one-pass reverse osmosis and two-pass nano-filtration.
Half of the pretreated water goes through one-pass reverse osmosis while the other half is subjected to two-pass nano-filtration. Also known as the Long Beach Method, the two-pass nano-filtration method is a low-pressure, two-stage filtration process developed by Long Beach engineers that sends seawater through two sets of membranes. Nano-filtration removes 90% of the salinity from seawater. Various tests are then performed, allowing for a comparison and contrast of each process. The purpose of this dual testing, according to Alsop, is to “use different membranes, water temperatures, distribution integration, et cetera, in order to generate a lot of data that currently doesn’t exist.”
Part of the research conducted at the Long Beach facility includes the testing of all aspects of the desalination process, including the effectiveness of the desalination equipment. In order to collect relevant data and determine efficiency, explains Alsop, “We’re also using different types of membranes.” The types of filtration membranes tested by the facility include those manufactured by TriSep Corp. (located in Goleta, CA), FilmTec Corp. (a subsidiary of The Dow Chemical Co.), and Saehan Industries (a multinational corporation). By comparing the different materials available, the project aims to create a databank that can provide materials manufacturers with the information necessary to improve their product and technologies, the ultimate goal being a long-lasting, inexpensive, and energy-efficient filtration membrane.
After collecting the information generated by these processes, the water is combined, mixed with brine, and discharged back into the intake channel. By the time the water is flushed through the second set of membranes, the water contains less than 500 milligrams of dissolved substances per liter of water, thereby complying with EPA drinking-water standards. The Long Beach facility has demonstrated that the nano-filtration technique is potentially 20% to 30% more efficient than other desalination techniques. The energy savings, says Alsop, are the result of “utilizing nano-filtration, which is different from reverse osmosis. We’re using a two-stage process as opposed to a single-pass process, and that’s the essence of the savings.”
The Long Beach project focuses on energy efficiency, but, states Alsop, “This plant is also more than that.” Energy efficiency is “ the core focus of the prototype that we built, but over the next two years we’re going to be doing all sorts of research.”
Part of that research involves an innovative filtration technique, the Under Ocean Floor Seawater Intake and Discharge Demonstration System. This research and development project was eased along by a $3 million grant from funds created by Proposition 50. Covering water quality, water supply, safe drinking-water projects, and coastal wetlands purchase and protection, Proposition 50 supplies $3.4 billion in bonds to fund water projects. In April 2006, the California Coastal Commission approved a coastal development permit for the Under Ocean Floor Desalination Demonstration System, clearing one more hurdle. Alsop sums up the significance of Under Sea Floor innovation. “It demonstrates that desalination can be cost-effective and environmentally responsible,” he says.
This portion of the Long Beach project, according to Alsop, focuses “on demonstrating an alternative to open ocean intake and discharge practices with an under-ocean-floor intake and discharge systems.”
Traditionally, intake and discharge pipes sit on the ocean floor with significant environmental impacts. The Under Ocean Floor Seawater Intake and Discharge Demonstration project involves the installation of permeable intake and discharge pipes underneath, rather than on top of, the ocean floor. Placing the pipes underneath the ocean floor adds yet another level of filtration. What is most exciting about this under-ocean-floor system is that it eliminates two of the biggest environmental problems associated with desalination: inadvertent killing of marine life and brine byproduct disposal. By using the ocean floor as a barrier between the intake pipes and the ocean, the system eliminates the danger of sea life inadvertently being sucked into the pipes and killed. The ocean floor also serves as an added filter for the brine byproduct. The Under Sea Floor innovations are an “environmentally responsive method of collecting seawater and disposing of brine,” says Alsop.
The Southern California Metropolitan Water District currently provides the City of Long Beach with 42% of its water via the State Water Project and the Colorado River Aqueduct. Another 38% is supplied from groundwater that is locally treated and pumped. Conservation and water reuse supplies the final 20%. Alsop predicts that eventually desalination will be a significant source of water for the city. “We see it making up 10% of the city’s water resources portfolio,” he says.
Ultimately the Long Beach desalination plant involves a three-step plan that will span 15 years. The first step was the small-scale 9,000-gallon-per-day pilot plant that began operations in October 2001. The second step was the construction and operation of the 300,000-gallon-per-day plant in September 2005. By 2015, Long Beach officials anticipate commencement of the final stage of the program: a full-scale, fully operational plant that applies all of the knowledge acquired from the prototype projects.
Elaborating on the future of the facility, Alsop states, “Over the next two years we’re going to be doing all sorts of research. We’re going to be looking at the life of membranes because that’s a big expense on desal plants, to have to go out and replace membranes. We’re looking at different types of membranes. We’re looking again at water quality, pretreatment technologies, distribution system integration—all of those things are going to be part of research over the next couple of years.”
A View to the Future
There are currently over 12,000 desalination plants in the world, supplying between 5 billion and 7 billion gallons of water per day. These systems also create between 2 billion and 3 billion gallons of byproduct per day. Two issues have hindered the expansion of desalination from a secondary water-supply source to a primary water-supply source: high cost and adverse environmental impact. Technological advances continue to fine-tune desalination with the goal to make it more cost-effective and environmentally friendly. Once a desalination project can clear these twin hurdles, it will be poised to become a significant source of drinking water for the US. With desalination in the mix, municipalities and water facilities will be able to reduce their dependence on such finite freshwater sources as groundwater and spring-fed reservoirs.
The technological advances created at the Long Beach desalination facility cast desalination in a new and more favorable light. The dual issues of high cost and environmental impact are being conquered, and desalination is poised to significantly contribute to the world’s water supply. Alsop predicts, “If our research goes the way we think it will go, the data will be very valuable and influential” for other agencies and organizations, freeing them to pursue desalination as a viable and important supplement to their water supplies.