INTRODUCTION
As a public health graduate student, I frequently reflect on the impact of individual actions and their broader societal implications Public health focuses on the collective behaviors of society and their consequences, systematically overseeing large-scale initiatives aimed at enhancing community well-being This field plays a crucial role in implementing strategies that ensure our safety and health, particularly in recent years.
I have become more interested in our oceans as an advocate to keep the oceans clean & healthy.
The world's oceans are vital for providing food and sustaining populations globally, but their health is increasingly at risk due to human activity Significant events like the Deepwater Horizon oil spill in 2010 and the Fukushima Daiichi nuclear disaster in 2011 highlight the potential for catastrophic impacts on marine ecosystems, despite efforts to protect them Additionally, our reliance on plastic products contributes to pollution, as waste often ends up in the oceans, harming marine life and disrupting the delicate balance of oceanic environments.
Being married to a former Surfrider Foundation volunteer has heightened my awareness of public concerns regarding ocean health A recent article by the Surfrider Foundation titled “Carlsbad Desalination Plant Opening: The Wrong Solution at the Wrong Time” sparked my interest in desalination, a topic I was previously unfamiliar with The article highlighted California's plan to open a desalination plant to address its water needs, but it raised significant concerns about the negative impacts on marine habitats, increased water bills, and heightened greenhouse gas emissions While my initial reaction was skepticism, I recognize my limited perspective as a non-native Californian My passion for ocean preservation and background in public health motivated me to further explore the implications of desalination in California.
To grasp the essentials of desalination and its implications for Southern California, it is crucial to examine its effects on marine ecosystems This article explores the history of desalination, evaluates existing and former desalination facilities, and analyzes relevant case studies while considering future prospects Through a synthesis of literature and media sources, this analysis aims to highlight the significance of desalination in addressing the growing public health issue of drinking water scarcity in Southern California.
HISTORY & BACKGROUND
Desalination is the process of removing salts and minerals from water, particularly ocean water, to meet safe drinking standards This technique operates on the principle that salt can be separated from water, a concept recognized since ancient times Notably, Aristotle accurately described the water cycle and demonstrated that evaporating saltwater produces fresh water Over a millennium later, the development of alchemical stills in the 16th Century, and Giovani Batista Della Porta's advancements in distillation, furthered the quest for potable water Despite the understanding of distillation, its energy-intensive nature limited its practicality until the late 1800s when alternative energy sources made desalination more feasible, leading to the US's copyright of a solar distillation plan around 1870.
In 2003, the use of solar energy for desalination emerged as an effective solution to address drinking water shortages The first solar desalination plant was established in Chile, operating until around 1912 to meet the fresh water needs of mine operators.
The necessity for drinking water has historically driven the exploration and implementation of desalination In the United States, it became a viable alternative during the severe drought in the Southwest during the Great Depression The urgency for reliable water sources was further amplified by World War II, as naval troops required fresh drinking water This led to Congress, under President Harry S Truman, supporting legislation for research and development in ocean desalination Consequently, advancements in desalination technology were propelled by the Office of Saline Water (OSW).
Research on solar distillation emerged globally in the 1950s and 60s, particularly in regions like the Caribbean, India, Australia, the USSR, and the USA (Delyannis, 2003) Under President Dwight D Eisenhower, who served from 1953 to 1961, desalination received increased political backing, leading to enhanced federal programs and technology collaboration (Jorgensen, 2005) Eisenhower's 1957 Peace Plan for the Middle East promoted desalination efforts, fostering partnerships between the US and Israel, as well as with Saudi Arabia and Japan, which facilitated significant data sharing on water issues (Jorgensen, 2005) Although reverse osmosis technology was developed in the 1950s, the membranes at that time did not meet commercial standards (Wikipedia, 2016) The establishment of the National Water Supply Improvement Association in 1973 aimed to advance desalination, water reclamation, and the sharing of water science knowledge (Jorgensen, 2005).
US based RO desalination plant in 1977 at Cape Coral Florida, (Wikipedia, 2016).
Improvements in reverse osmosis (RO) membranes progressed significantly from the 1970s to the 1990s, evolving from polyetherurea to more advanced polyamide membranes These advancements in premium polyamide membranes led to enhanced salt rejection rates, resulting in greater efficiency for water purification processes.
In the 1980s, interest in desalination in the US waned, leading to the phasing out of many programs, which were then transitioned to the US Bureau of Reclamation The 1990s saw the establishment of the National Water Research Institute, which promoted water research and initiated several desalination projects (Jorgensen, 2005) As technology evolved, newer initiatives began to prioritize desalination through reverse osmosis due to its lower energy demands compared to traditional distillation methods.
Globally, desalination technologies, including membrane and multi-stage flash (MSF), are widely employed, particularly in the Middle East, where a 2008 assessment indicated the production of over 24 million cubic meters of fresh water daily from oceans (Lattemann & Hửpner, 2008) The distribution of ocean desalination varies by continent, with 6% from Asia-Pacific, 7% from the Americas, 10% from Europe, and a significant 77% from the Middle East and Africa Leading countries in desalinated water production include the United Arab Emirates (26%), Saudi Arabia (23%), Kuwait (7%), and Spain (7%) (Lattemann & Hửpner, 2008) Notably, Spain initially adopted MSF technology in the 1960s but now utilizes modern reverse osmosis (RO) technology in approximately 95% of its desalination plants, while around 90% of desalination in the Arabian Gulf relies on the distillation/MSF method (Sadhwani, Veza, & Santana, 2005; Lattemann & Hửpner, 2008).
MSF (Multi-Stage Flash) and RO (Reverse Osmosis) are two distinct desalination technologies MSF utilizes heat to evaporate seawater, transforming it into steam, which is then condensed into pure water In contrast, RO employs pressure to push seawater through semi-permeable membranes, allowing water molecules to pass while separating them from salts and minerals These fundamental differences in their operational mechanics highlight the unique approaches each technology takes to produce fresh water.
The primary distinction between Reverse Osmosis (RO) and Multi-Stage Flash (MSF) desalination technologies lies in their energy consumption and the characteristics of the brine they discharge MSF plants can consume up to six times more energy than RO systems (Medeazza, 2005) Additionally, the concentrated brine produced varies in several factors, including salinity, temperature, plume density, dissolved oxygen levels, toxicity of biocides and their by-products, anti-scalants, anti-foaming agents, heavy metals from corrosion, and the pH of cleaning agents (Lattemann & Hửpner, 2008) It is important to note that while these differences provide a general overview, individual desalination sites may exhibit variability in these parameters.
Scientists have found that the sensitivity of marine environments to brine discharge varies significantly, depending on factors such as ocean geography and water mixing dynamics (Einav, Hamssib, & Periyb, 2002) Generally, areas with less water movement, like bays, reefs, marshes, and mangrove flats, are more vulnerable to the adverse effects of brine discharge In contrast, oceans characterized by strong wave action tend to be less sensitive to such discharges, as better mixing can mitigate harmful impacts on marine life (Einav, Hamssib, & Periyb, 2002).
Ocean desalination plants utilize intakes to draw in seawater, which is essential for both Multi-Stage Flash (MSF) and Reverse Osmosis (RO) processes These intakes can be categorized as direct or indirect, with direct intakes posing a greater risk to marine life due to their location in open water This exposure can lead to both large and small organisms becoming trapped on filters or entrained in the water flow, ultimately resulting in their destruction at the plant Direct intakes may be positioned at the ocean's surface, floating, or even at greater depths, highlighting the need for careful consideration of their environmental impact.
Indirect intakes are buried pipes or wells located beneath the ocean floor, minimizing their impact on marine life (Cooley, Ajami, & Heberber, 2013) These systems include various types such as Vertical, Horizontal Radial, Horizontal Directionally Drilled, Slant, and Infiltration Galleries (Cooley, Ajami, & Heberber, 2013) However, the primary marine impacts associated with indirect intakes arise from the invasive construction processes at offshore or onshore sites, which can disrupt seabed habitats (Cooley, Ajami, & Heberber, 2013).
A 2012 white paper identified reverse osmosis (RO) as the preferred desalination technology in the USA, supported by the Environmental Protection Agency's assertion that it is the best available method for purifying water from inorganic and pharmaceutical contaminants This technology is noted for its potential to be self-sufficient and "drought proof." Furthermore, ongoing advancements in RO technology are leading to decreasing costs, emphasizing its critical role in seawater desalination In California, all proposed and operational ocean desalination plants exclusively utilize RO technology.
This essay examines the environmental impacts of reverse osmosis (RO) technology, specifically regarding seawater intake systems and the brine discharges from RO plants, while noting that California will not adopt this technology in the future.
POTENTIAL DISCHARGE AND INTAKE MARINE IMPACTS WITH RO TECHNOLOGY
Intakes
Open ocean intakes pose greater potential marine impacts compared to indirect intakes, which are situated below the seabed and offer several environmental advantages These subsurface intakes are more cost-efficient, reliable, and have reduced effects on marine life, resulting in running and performance costs that can be 5-30% lower due to less water pre-treatment and decreased energy usage Additionally, they experience fewer operational interruptions since they lack screens that could trap fish or be affected by algal blooms, with sand acting as a natural filter for organisms While the initial construction costs for indirect intakes may be higher, the long-term savings from reduced pretreatment chemicals and enhanced efficiency can offset these expenses, making them a more sustainable choice for marine intake systems.
Discharges
After the reverse osmosis (RO) plant treats seawater, it generates brine, which is a byproduct containing concentrated ocean water constituents This brine also includes any pretreatment chemicals, cleaning agents, or heavy metals that may have been introduced during the water processing or as contaminants.
Brine salinity is a critical consideration in reverse osmosis (RO) desalination, as non-diluted brine can be nearly twice as concentrated as the source ocean water (Einav, Hamssib, & Periyb, 2002) The salinity of discharged brine varies based on pre-dilution measures implemented at the facility Elevated salinity levels pose a significant threat to marine life, as many species cannot adapt to these changes, potentially altering the natural marine habitat and disrupting the local ecosystem (Lattemann & Hửpner, 2008).
Temperature significantly influences the mixing of brine and ocean water, with discharged brine from reverse osmosis (RO) plants typically increasing by about 2°F (Cooley, Ajami, & Heberber, 2013) However, when brine interacts with nearby power plants' once-through cooling (OTC) system water, temperatures can rise by approximately 10-30°F (Lattemann & Hửpner, 2008) This warmed OTC water, which is a byproduct of cooling power generators, affects the density of the discharged brine plume Concentrated brine that is not mixed with OTC water tends to be denser and sinks, while brine mixed with warmer OTC water can either become buoyant or match the surrounding ocean water (Lattemann & Hửpner, 2008) Mixing brine with OTC discharge facilitates dilution and natural blending The outcome of whether the discharged brine sinks or remains buoyant can have significant implications for the seabed or open ocean, with the open ocean likely able to mix the brine effectively, while sinking brine may form a plume that expands as more brine is discharged.
Discharged brine from desalination plants exhibits varying levels of dissolved oxygen (DO), which depend on the source of the ocean water In the case of open ocean intakes, the DO levels match those of the surrounding environment, while indirect subsurface intakes may result in different DO concentrations.
Dissolved oxygen (DO) levels are typically slightly lower than their surrounding environment (Lattemann & Hửpner, 2008) Maintaining adequate oxygen levels is essential for the survival of living organisms, as fluctuations in DO can adversely impact local species' diversity and abundance A significant decline in DO levels may disrupt the operations of reverse osmosis (RO) plants, particularly when environmental regulations are enforced to mitigate marine impacts.
Brine discharge from reverse osmosis (RO) desalination plants raises concerns regarding the toxicity of biocides and by-products used to prevent biofouling A significant issue is the formation of hypobromous acid when chlorine is added to seawater, due to the high levels of naturally occurring bromide This leads to the production of brominated organic by-products, which can pose risks to marine life (Lattemann & Hửpner, 2008) To mitigate these effects, sodium bisulfite is employed to neutralize hypobromous and hypochlorous acids, converting them into harmless chloride and bromide ions This process effectively reduces the levels of hypochlorite in brine discharge to below the EPA's long-term exposure limit of 7.5 µg/L (Lattemann & Hửpner, 2008).
In reverse osmosis (RO) desalination, the release of heavy metals through corrosion is minimal compared to multi-stage flash (MSF) plants, as RO systems experience less corrosion and do not rely heavily on anti-corrosion chemicals However, slight increases in heavy metals such as iron, chromium, nickel, and molybdenum can occur in the discharged brine due to stainless steel corrosion (Cooley, Ajami, & Heberber, 2013) The toxicity of these heavy metals poses a risk primarily due to their potential for bioaccumulation in marine organisms (Lattemann & Hửpner, 2008).
Antiscalants, anti-foaming agents, coagulants, and cleaning agents are essential components in reverse osmosis (RO) membrane fouling prevention, but their discharge with brine can pose risks to marine life, even at low concentrations (Cooley, Ajami, & Heberber, 2013) While most antiscalants are low in toxicity and biodegradable, some persist in the environment and can affect marine ecosystems by altering the availability of divalent ions like calcium and magnesium, which are crucial for various biological processes In contrast, anti-foaming agents used in multi-stage flash (MSF) plants are not commonly applied in RO systems, reducing their environmental impact.
RO plants serve as primary filtration systems for intake water and are generally non-toxic However, backwashing filters can increase murkiness at discharge sites, potentially attracting marine organisms or entombing seabed creatures (Lattemann & Hửpner, 2008) Additionally, the use of cleaning agents, including detergents and oxidants with both alkaline and acidic properties, poses risks to marine life (Lattemann & Hửpner, 2008).
A 2008 report by the National Academy of Sciences highlighted that insufficient funding has hindered significant advancements in desalination, particularly regarding the understanding of its environmental impacts Federal funding for desalination dropped dramatically in the 21st century, plummeting from $24 million in 2005 to approximately $10 million in 2007 To effectively improve knowledge of environmental effects and reduce the financial costs of desalination, an estimated annual funding of $25 million is needed In contrast, the private sector has been more proactive, particularly in California, where companies are launching pilot projects to assess environmental impacts and comply with state regulations.
In recent years, growing awareness of our actions has led to heightened concerns about the environmental impacts on marine ecosystems As our understanding of marine life has improved, the significance of Environmental Impact Assessments (EIA) has increased, especially compared to the past when Reverse Osmosis (RO) and Multi-Stage Flash (MSF) desalination technologies were being developed Examining these studies is crucial for grasping the true consequences of ocean desalination, as demonstrated by various case studies highlighting these impacts.
CASE STUDIES
Canary Islands, Spain
Since 1986, Spain has implemented regulations aimed at preserving natural resources and addressing the environmental impacts of seawater reverse osmosis (RO) desalination plants (Sadhwani, Veza, & Santana, 2005) In the 1990s, these regulations were amended to require mandatory ecological assessments for desalination facilities producing over 5,000 cubic meters of fresh water daily A 2005 study examined environmental impact assessments (EIAs) from five RO plants in the Canary Islands, revealing several environmental concerns despite the plants being relatively small, with outputs under 8,000 cubic meters per day While the EIAs primarily focused on discharge and chemical concentrations related to cleaning and scale prevention, they offered valuable insights into marine effects The studied plants included locations at Bocabarranco Beach, Arucas, Rogue Prieto, La Aldea, and Maspalomas, with Bocabarranco Beach showing significant ocean intake water constituents such as Calcium (450 mg/L), Magnesium (1520 mg/L), Sodium (11,415 mg/L), and Potassium.
The analysis of brine discharge from various desalination plants, including Arucas, Rogue Prieto, and La Aldea, revealed significant concentrations of total dissolved solids (TDS), with values reaching up to 90,000 mg/L in Maspalomas due to a 15% increase in freshwater recovery (Sadhwani, Veza, & Santana, 2005) Discharged brine was approximately twice the volume of the intake water, and while most plants released their brine along the ocean coast, La Aldea opted for open ocean discharge Notably, two species, a sea grass and a red algae, were adversely affected by the coastal brine deposits, with some populations completely eradicated downstream (Sadhwani, Veza, & Santana, 2005).
CypruS
A 2002 study highlighted the environmental concerns associated with ocean desalination, specifically focusing on the impact of open ocean brine discharges (Einav, Hamssib, & Periyb, 2002) For instance, the Dhkelia desalination plant in Cyprus featured a brine discharge pipe that extended approximately 150 meters into the ocean, raising awareness about the ecological implications of such practices.
Increased salinity levels from discharge sites have been found to negatively impact marine biota, leading to the complete loss of several species within a 200-meter radius.
A study conducted at a Maspalomas plant, which processes over 15,000 cubic meters of fresh water daily, revealed that its brine discharge pipeline extends 300 meters into the ocean, perpendicular to the coast The pipeline's location on the ocean shelf has led to the plume retaining more than 50% of its original brine concentration, indicating limited dispersal and dilution Additionally, the assessment highlighted observable effects on marine life in proximity to the discharge site (Einav, Hamssib, & Periyb, 2002).
Spain’s Posidonia grasslands in the Mediterranean Sea
Seawater salinity naturally ranges from 35,000-38,000 ppm A paper citing a 2003 study about
Research indicates that increased salinity from RO brine significantly affects marine species in a short timeframe Specifically, the crustacean genus Leptomysis and sea urchins experienced notable mortality, while Posidonia grasslands showed a marked decline as salinity levels rose from 40,000 to 45,000 ppm Alarmingly, over 50% of marine plant populations perished within just two weeks due to these elevated salinity levels (Medeazza, 2005).
Florida
In 2003, a seawater desalination plant commenced operations, producing 25 million gallons per day (MGD) and generating 19 million gallons of brine daily at maximum capacity To mitigate environmental impact, the plant's brine discharge is mixed with water from a nearby power plant in a ratio of 1:70 before being released into a nearby bay The Shannon diversity index was utilized to assess potential environmental and marine impacts, revealing that changes remained below the 25% reference point Consequently, the study concluded that the desalination plant has not significantly affected marine biota (Cooley, Ajami, & Heberber, 2013).
California (Santa Cruz and San Francisco Bay)
Here 2 small studies noted in a California report about ocean desalination, portray the possible effects at intake sites The study that took place in Santa Cruz lasted for a little over 1 year and monitored a small scale pilot RO plant producing 07 MGD Based on estimated entrainment amounts from sampling and video surveillance for impingement at the intake, they found that no significant effects would impact the marine biota This was based on the fact that the level of affects are below the levels where mitigation would be required by California law Another reason was that no endangered species were found during their testing, which would have had caused mitigation steps to take place The study that took place in the San Francisco Bay area was the same size plant but only lasted for 6 months Conversely, this pilot plant’s intake was located in an estuary, rather than an open ocean It also found a high population of delta smelt, an endangered species Due to the increased number of marine biota in the vicinity compared to the open ocean and the presence of Delta smelt, the assessment concluded a high degree of marine impact and noted mitigation procedures would be needed due to California law, (Cooley,Ajami, & Heberber, 2013).
Perth, Australia
In 2006, a 38 MGD reverse osmosis desalination plant commenced operations in Cockburn Sound, utilizing a 1,500-foot long brine disposal pipeline with diffusers positioned 18 inches above the seabed, achieving a minimum 45-fold dilution of brine within a 50-meter radius This method of brine disposal, rather than landfill, significantly reduced sediment and murkiness, thereby protecting seabed ecosystems Baseline assessments of marine habitat and water quality were conducted six months prior to the plant's opening, revealing that dissolved oxygen levels along the seabed fell below permissible limits twice within the first year of operation, leading to decreased water production as a response to mitigate the low dissolved oxygen levels (Cooley, Ajami, & Heberber, 2013).
The availability of environmental assessments for large-scale operating plants in Saudi Arabia and Kuwait is notably limited, primarily due to national policies and regulations at the time these plants began operations (Einav, Hamssib, & Periyb, 2002) Consequently, many Environmental Impact Assessments (EIAs) are incomplete and rely on anecdotal evidence, often presenting limited data Recent studies tend to utilize laboratory testing or small pilot projects to simulate conditions of full-scale plants, revealing that even minor salinity fluctuations, such as a 3 parts per thousand increase, can be lethal to aquatic organisms (Cooley, Ajami, & Heberber, 2013) Furthermore, it is crucial to recognize that many EIAs primarily focus on mortality rates while neglecting potential sub-lethal effects (Cooley, Ajami, & Heberber, 2013).
CALIFORNIA PERSPECTIVE
California's water shortages have prompted municipalities to explore additional sources, raising the question of whether desalination is the only viable solution for Southern California Many arid cities in the western US rely on imported water or long-distance conveyance from the Colorado River Recent advancements in ocean desalination technology offer new possibilities that could complement or replace existing methods, with ocean reverse osmosis (RO) desalination proving to be approximately 5% more energy efficient As RO costs decrease, this technology becomes increasingly feasible Southern California has already implemented strategies such as water reclamation, recycling, and conservation, but the potential for ocean desalination to provide a drought-proof water source presents a promising outlook for the region's water supply challenges.
Recent trends indicate a significant reduction in reverse osmosis (RO) costs, contrasting with the rising municipal water costs in cities like San Diego, Monterey, Perth, Sydney, and Barcelona, which have increased approximately 300% since the 1970s While municipal water expenses have steadily climbed, RO plants have experienced a remarkable 50% decrease in production costs from the 1980s to the early 21st century This decline in RO costs is attributed to improved water production efficiency and reduced emphasis on construction expenses for these plants.
Desalination is gaining traction in California due to advancements in technology that lower reverse osmosis (RO) costs and the rising expense of existing municipal water resources A 2009 report indicated that ocean desalination plants require approximately 4,000 kWh of energy per acre-foot, with 1 million gallons per day (MGD) equating to 1,120 acre-feet annually Collaborative efforts suggested that energy requirements could potentially be reduced by 50% through innovative energy recovery devices and membranes Furthermore, integrating renewable energy sources could lead to even greater cost reductions, underscoring significant progress in desalination technologies.
Since 2002, California has actively pursued ocean desalination through various initiatives, including the establishment of the California Water Desalination Task Force under the Department of Water Resources The Water Security, Clean Drinking Water, Coastal and Beach Protection Act allocated over $50 million in grants to advance desalination science, leading to significant progress in over 45 projects within two years By 2009, the state operated 20 water reclaiming desalination plants and six ocean water desalination plants, with three additional projects, such as the Carlsbad plant, in development.
As of December 2015, California had 10 ocean desalination plants, but only 7 are currently operational, with 2 built in the last decade, including the Carlsbad plant, one of the largest in North America Opened in December 2015, the Carlsbad plant has a capacity of 50 million gallons per day (MGD) but requires double that amount of seawater for operation, resulting in significant brine disposal challenges This raises concerns about the environmental impact of such large facilities and highlights the need for improved brine disposal methods The Carlsbad plant serves as a critical example for California's desalination efforts, emphasizing the importance of setting industry standards for environmental safeguards.
The Carlsbad plant relies on the nearby Encina Power Station for its ocean intake and discharge systems, with upgrades pending since June 2016 to address environmental regulations aimed at reducing marine organism entrapment (Cooley & Donnelly, 2012; San Diego County Water Authority, 2016) Its pretreatment process features sand and anthracite filtration before membrane filtration, which helps minimize biofouling and chemical use The reverse osmosis (RO) process produces water that is re-mineralized and transported 10 miles into the regional aqueduct, supplying approximately 42-50 million gallons per day (MGD) to serve around 400,000 residents, or 30% of San Diego County’s water supply (San Diego County Water Authority, 2016) Households can expect an average increase of over $5 on their water bills, with a projected annual inflation rate of 2.5% for this water, significantly lower than the nearly 10% inflation for imported water, making it a more efficient and cost-effective solution (San Diego County Water Authority, 2016).
The Carlsbad desalination plant adheres to California's environmental regulations concerning marine life, implementing necessary mitigation measures like habitat restoration based on the volume of marine organisms affected during the desalination process The facility is currently engaged in efforts to rehabilitate over [insert specific area or quantity if available].
The plant owners are responsible for the maintenance of 60 acres of wetlands in San Diego Bay and more than 35 acres within the 400-acre Agua Hedionda Lagoon, as outlined by the San Diego County Water Authority in 2016.
In the US, specifically California, laws around RO ocean desalination keep changing The
The 1967 California Water Code established standards for waste discharge and disposal in industrial facilities, incorporating the Ocean Plan to protect ocean waters, in alignment with the Federal Clean Water Act Early 21st-century updates introduced stricter policies for ocean protection, including a ban on mixing brine discharge with ocean water for dilution, akin to the phase-out of power plant OTC systems to mitigate open ocean impacts In 2007, the State Water Board launched a significant project to identify future legal requirements for desalination, involving an expert panel and regional stakeholders to create a Desalination Amendment under the Ocean Plan The 2014 draft of this amendment outlined four key components designed to safeguard marine life throughout the desalination process, including initial construction.
“Clarify the State Water Board’s authority over desalination facility intakes and discharges
The regional water boards are directed to assess the criteria outlined in Water Code section 13142.5, subdivision (b), focusing on the evaluation of the most effective site, design, technology, and mitigation strategies to reduce the intake and mortality of marine life at new or expanded seawater desalination facilities.
To protect marine life, a salinity limit will be established for brine discharges from all desalination facilities This regulation aims to prevent adverse environmental impacts in marine discharge areas.
Monitoring and reporting obligations necessitate the assessment of effluent, sediments, and the well-being of bottom-dwelling organisms to confirm that the effluent plume does not adversely affect marine life outside the brine mixing zone (California Water Boards, 2015).
This Amendment was signed into law on January 28, 2016
In California, reverse osmosis (RO) plants dispose of brine directly into the ocean, following state regulations that require dilution before disposal For instance, the Carlsbad plant dilutes each gallon of brine with four gallons of ocean water, ensuring compliance with environmental standards.
As of May 2016, California law mandates that at discharge sites, salinity levels must not exceed 2 parts per thousand above ambient levels within a 100-meter radius Additionally, the law encourages the use of active diffusers or the mixing of discharges with municipal wastewater to ensure that the combined impact is less harmful than that of separate discharges.
The amendment emphasizes the need for environmentally sound practices to protect ocean marine life, particularly concerning intake methods While not legally mandated, strategies such as physical barriers and behavioral deterrents can help reduce the entrapment and impingement of marine biota Various barrier types, including barrier nets, traveling screens, Ristroph screens, and wedgewire screens, exhibit differing levels of effectiveness Wedgewire screens, which combine fine mesh with low-velocity intakes, have shown a 20% increase in marine organism survival, though they are prone to clogging and may not suit larger desalination plants Behavioral deterrents like air-bubble curtains, strobe lights, and sound waves have limited effectiveness, with velocity caps emerging as a more promising option by altering water flow to encourage avoidance However, small organisms may still be entrained Despite California's preference for subsurface intakes as of May 2016, these are not legally required, and "after-the-fact mitigation" for entrained organisms' deaths is mandated.
CONCLUDING REMARKS
San Diego County exemplifies Southern California's critical water needs, highlighting the effectiveness of water conservation programs that have reduced total water consumption by approximately 12% over the past 25 years Despite a 30% population increase and 80% economic growth in the region, the demand for water continues to rise, making conservation efforts insufficient to meet future needs (Little, 2016) While ocean desalination presents a promising solution, further development of best practices is essential for producing fresh water effectively.
Of the total water on the Earth, less than 3% of it is fresh water, (Lattemann & Hửpner,
The availability of fresh water is limited, with only a small fraction of the 3% of the world's water being accessible for use, as highlighted by the National Academy of Sciences (2008) This scarcity, coupled with rising global population and agricultural demands, has led to increased water demand, particularly in Southern California Drought and resource depletion have prompted the exploration of desalination as a viable alternative Advances in technology have made desalination methods more energy-efficient, and while reverse osmosis (RO) desalination remains more expensive and energy-intensive than traditional sources, costs are trending downward However, the environmental impact of RO desalination plants, particularly concerning marine ecosystems due to brine discharge and marine life entrapment, raises concerns In response, California is implementing protective measures, as evidenced by the January 28, 2016 Amendment to the Ocean Plan, which aims to ensure that future desalination plants utilize the best available technology for energy efficiency, intake methods, and discharge processes.
To enhance ocean protection and mitigate the lethal impacts on marine life, it is essential to improve existing measures, particularly by mandating subsurface intakes for open ocean intake mortality Addressing the long-term effects of brine on marine organisms is crucial, as minimizing brine contact is the most effective way to alleviate the burden on the marine environment Exploring alternative brine discharge options, such as zero liquid discharge, could be beneficial This approach not only presents potential commercialization opportunities but also offers financial advantages that could help offset the costs of ocean desalination, making such projects more viable for smaller communities.
Concerns regarding the use of chemicals in reverse osmosis (RO) plants need to be addressed, as these substances are often believed to enhance efficiency by minimizing scale formation and preventing membrane biofouling, which can lead to increased energy costs (Katebian et al., 2016) However, chemicals like biocides and cleaning agents can produce brominated organic by-products similar to chlorinated compounds (Lattemann & Hửpner, 2008) Ideally, the use of these chemicals should be limited or replaced with safer alternatives, and advancements in membrane materials could help reduce chemical dependency Research indicates that inhibiting quorum sensing pathways in bacteria may reduce biofouling through natural, non-toxic inhibitors (Katebian et al., 2016), although practical application remains challenging due to the large quantities required in ocean water intake A more feasible solution involves modifying membrane surfaces to prevent biofouling, as demonstrated by Jee et al., who showed that increasing membrane hydrophilicity could mitigate biofouling attributed to hydrophobicity and rough surfaces (Jee et al.).
Laboratory experiments have shown that treated membranes experience significantly less fouling compared to untreated membranes (Jee, Shin, & Lee, 2016) Furthermore, implementing indirect intakes as a legal requirement could decrease the volume of chemicals utilized in the process, thereby minimizing the chemical composition of the resulting brine.
Advancements in technology and industry standards are essential for the future of ocean water desalination, but effective environmental safeguards can only be implemented with the appropriate laws Seawater desalination has significant global impacts on oceans, and in California, mitigation measures are being introduced to protect marine environments However, there is a crucial distinction between prevention and mitigation; unfortunately, prevention has not been prioritized, and current efforts fall short in addressing marine effects While desalination is a viable solution for Southern California's urgent water needs, it may not be the optimal approach at this time, as technological improvements are still ongoing.
California Water Boards (2015) Fact Sheet, Proposed Desalination Amendment: Creating a
California Water Plan (2009) Resource Management Strategies Sacramento.
Cooley, H., & Donnelly, K (2012) Key Issues in Seawater Desalination in California: Proposed
Seawater Desalination Facilities Oakland: Pacific Institute.
Cooley, H., Ajami, N., & Heberger, M (2013) Key Issues in Seawater Desalination in
California: Marine Impacts Oakland: Pacific Institute Retrieved from www.pacinst.org/publication/desal-marine-impacts
Delyannis, E (2003) Historic Background of desalination and renewable energies Solar Energy,
Einav, R., Hamssib, K., & Periyb, D (2002) The footprint of the desalination processes on the environment Desalination, 152, 141-154.
Freeman, S (2016, July 18) How Water Works Retrieved from How Stuff Works: https://science.howstuffworks.com/environmental/earth/geophysics/h2o1.htm
Jee, K Y., Shin, D H., & Lee, Y T (2016) Surface modification of polyamide RO membrane for improved fouling resistance Desalination, 131-137.
Jorgensen, J C (2005) A history of the federal involvment in water desalination and the related water improvement research and development Desalination, 180, 1-3.
Katebian, L., Gomez, E., Skillman, L., Li, D., & Ho, G (2016) Inhibiting quorum sensing pathways to mitigate seawater desalination RO membrane biofouling Desalination, 393, 135-143.
Khamis, I., & El-Emam, R S (2016) , IAEA coordinated research activity on nuclear desalination: the quest for new technologies and techno-economic assessment