August 2007, Vol. 19, No.8
As water professionals know, managing water supply and demand can be a delicate balance, especially in the drier regions of the world. Recent data show this challenge is not getting any easier.
As drought conditions and water shortages escalate, regions from the U.S. West Coast to northeastern Australia are turning to innovative water reuse solutions
As water professionals know, managing water supply and demand can be a delicate balance, especially in the drier regions of the world. Recent data show this challenge is not getting any easier.
For instance, the U.S. Geological Survey recently reported that groundwater levels in southern Florida are at record lows. A
report by the California Department of Water Resources found that the current level of water in the state’s snowcap is at its lowest level in more than two decades and 71% below its normal level. And according to a report by the Intergovernmental Panel on Climate Change, global warming will reduce precipitation levels in low-latitude areas such as northern Brazil, the Mediterranean, parts of Africa, South America and South Asia, and also much of the United States west of the Mississippi River.
In the U.S. Southwest, an 8-year drought has significantly drained Colorado River reservoirs, including Lake Mead, the largest reservoir in the nation. In January 2000, Lake Mead had 96% capacity. This year, capacity fell to 51%, and the U.S. Senate Energy and Natural Resources Committee recently warned that the lake could go dry in 10 years.
In South East Queensland, Australia, a severe drought that is the worst on record has plagued the region for the last couple of years, draining the water supply that serves roughly 2.7 million people.
Compounding these problems is the world’s booming population. By 2020, it is expected that there will be an additional 3 billion people living on Earth — and they will require 20% more water than is currently available, according to the June 15, 2006, Goldman Sachs Water Sector Primer Report.
Increased demand for water, coupled with decreased costs in filtration technologies, has driven states and municipalities to pursue long-range, coordinated water reuse and conservation efforts. As a result, there is a wave of groundbreaking water reuse and water treatment projects under way.
Generating Water at Home
Southern California relies on imported water from the Colorado River and the Sacramento and San Joaquin rivers for much of its supply. However, these resources are diminishing and unpredictable. The Colorado River has experienced below-normal runoff in 9 of the last 10 years, and on May 31, state and federal judges ordered a stop to all pumping from the State Water Project Delta facilities — which serve millions of people in Northern and Southern California — because operations were threatening the endangered delta smelt fish. The California Department of Water Resources has since resumed limited pumping because certain areas in Alameda and Santa Clara counties had reached critical shortage levels.
Water professionals in Southern California have said that the region must reduce its dependence on imported water. Two major and highly advanced water projects currently being built in the region are designed to do just that.
In Orange County, Calif., Water Factory 21, one of the first wastewater treatment plants built in the United States to treat secondary effluent with reverse osmosis, has been torn down and is being replaced with the groundwater replenishment system. Once completed, the $481 million project will be the largest indirect potable reuse project of its type in the world, according to Orange County Water District (OCWD; Fountain Valley).
The new facility will treat secondary effluent from the Orange County Sanitation District using a three-step process that includes microfiltration, reverse osmosis, and ultraviolet (UV) light with hydrogen peroxide. The purified water will be used to replenish OCWD’s large groundwater basin in north-central Orange County that currently supplies 70% of the water for 2.3 million people. “The cost of water produced from this facility is comparable to the cost of treated imported water,” said Gina DePinto, spokeswoman for OCWD.
The plant is expected to produce 265,000 m3/d (70 mgd) of water for groundwater recharge. Half the output will be sent to injection wells that act as a natural underground pressure barrier against seawater infiltration. “Many years ago, as the groundwater basin was drawn down, ocean water was pulled into the coastal aquifer,” DePinto said. “For over 30 years, Water Factory 21 was responsible for purifying wastewater to inject into the seawater intrusion barrier. But as the region and the population expanded, Water Factory 21 was no longer capable of producing enough. So it is absolutely critical that we produce enough purified water to protect the groundwater basin from saltwater contamination.”
The remaining 132,500 m3/d (35 mgd) of highly purified water will be conveyed through a 21-km (13-mi) pipeline to OCWD’s recharge facilities in Anaheim, Calif. There, the water will be allowed to percolate into deep aquifers, where it eventually will become part of the natural drinking water supply.
“Because of the sensitivity surrounding this type of project, we have been conducting an extensive and ongoing public outreach effort to educate our residents about the quality of this purified water,” DePinto said.
The new system is scheduled to go on-line this fall.
In Carlsbad, Calif., Poseidon Resources Corp. (Stamford, Conn.) is building a $300 million desalination facility and pipeline system that the company said will be the largest seawater desalination facility in North America. Once on-line, the plant will have the capacity to supply 189,000 m3/d (50 mgd) of treated drinking water, enough to serve 300,000 residents and meet 9% of San Diego County’s total water needs. Locally, the plant will be responsible for supplying 80% of the city of Carlsbad’s total water demand.
Peter MacLaggan, senior vice president of Poseidon Resources, said water produced by the plant will cost the company’s agency partners no more than what they would have paid for imported water. “It will also be a higher quality of water and will be superior in reliability and supply,” he said. In addition, partners receive a $0.20/m3 ($250/ac-ft) financial incentive from the Metropolitan Water District’s Seawater Desalination Program.
San Diego County currently is 85% dependent on imported water. However, the desalination plant and other planned investments in conservation, recycling, brackish water desalination, and water transfers will reduce that demand to 50%.
MacLaggan said that large-scale seawater desalination used to be a highly expensive process, but as reverse osmosis technology improved and membrane filtration efficiency was enhanced, costs came down. “Now, it is actually very affordable,” he said. “That is very important because traditional sources of water in California are no longer cheap and plentiful. Competition for use is much higher. Municipalities, agriculture, and instream uses for environmental purposes are all vying for more allotments.”
Poseidon will act as the owner–operator of the plant and will make supply available to its public agency partners. So far, Poseidon has finalized 30-year contracts with the Valley Center Municipal District (San Diego), Rincon del Diablo Municipal Water District (Escondido), Sweet Water Authority (Chula Vista), and the City of Carlsbad for 65% of the plant’s treated water. Six other agencies are in negotiations for the remaining output.
MacLaggan said the plant also will be an important source of water for Carlsbad’s high-tech and biomedical industries, which require a considerable amount of reliable and high-quality water for their operations. “The output from the new desalination plant will have a higher purity than what they are currently using,” he said. “We are expecting that the operating costs associated with treating their water supply to make it suitable for their processing systems will be significantly reduced.”
Changing a River’s Course
Administered by the Southern Nevada Water Authority and involving Black & Veatch (Kansas City, Mo.) in a joint venture with CH2M Hill (Englewood, Colo.), along with cities and municipalities from seven states, the Long-Term Augmentation Plan for the Colorado River is currently being studied to identify options for enhancing flows on the river.
“The object is to look at everything and anything that is viable,” said J.C. Davis, public information coordinator for the Southern Nevada Water Authority. “We are studying several alternatives from the perspective of technical possibilities, legal and environmental standpoints, and financial feasibility.” Technical options receiving serious evaluation include conjunctive use of surface and groundwater, trans-basin imports, and stormwater management. “There are also pilot projects for enhanced precipitation, such as cloud seeding programs, as well vegetation management including tamarisk [invasive tree species] reduction programs,” Davis said. “Tamarisk plants use more water from the Colorado River than the whole state of Nevada.”
Davis said there is a sense of urgency to take any steps necessary in order to increase flows. “There is no silver bullet solution, but the important thing is to diversify by finding sources that are independent from the Colorado River,” Davis said. “For instance, the Southern Nevada Water Authority is currently seeking permits to draw upon unused, naturally replenished groundwater supplies in the east-central portion of Nevada.”
Battling Drought Down Under
Earlier this year, in response to persistent and severe drought in South East Queensland, Level 5 water restrictions were implemented, the most aggressive ever taken, which put strict limitations on usage. The region’s main urban water supply comes primarily from the Wivenhoe and Somerset Dam system. However, recently the water level in that system reservoir fell below 20% of capacity, leaving less than 16 months of supply remaining, based on current usage.
In response to the impending water crisis, Black & Veatch, CH2M Hill, and MWH (Broomfield, Colo.) are building three advanced water treatment plants that will treat effluent from six different existing wastewater treatment plants in the Queensland region for reuse. The first of those plants to go on-line, Bundamba Advanced Water Treatment Plant, is a multistage water treatment project being fast-tracked by Black & Veatch. Cindy Wallis–Lage, vice president and chief of the company’s Global Water Technology Group and part of the Bundamba project team, said the three projects represent the most advanced water treatment scheme ever undertaken.
“This will be a high-tech water recycling effort and the largest reuse project in the Southern Hemisphere,” Wallis–Lage said. “To effectively achieve nutrient reduction, emerging contaminant control, and World Health Organization standards, it will provide the world’s most advanced wastewater treatment scheme.” The advanced treatment system of Bundamba will make use of microfiltration, reverse osmosis, and advanced oxidation technology using UV light and peroxide.
Treated water will be conveyed to two power stations in Queensland at Swanbank and Tarong. The flow would essentially replace water that those power stations currently access from Wivenhoe Reservoir, which amounts to 14% of the average system demand in South East Queensland.
Wallis–Lage said that after a conveyance has been established to the power plants, testing will commence to demonstrate the quality and consistency of the water in order to benchmark the capabilities of the treatment scheme. For the long term, there is a potential opportunity to use the treated water for irrigation or reservoir recharge via discharge to the Wivenhoe Reservoir. “Public education will be crucial for this to work,” Wallis–Lage said. “By showing a consistent quality, we hope to gain the public’s approval and to establish confidence in its perception of this water. But really, it has come down to accepting this solution or potentially having no water at all.”
According to Wallis–Lage, the new system will implement high environmental standards. “The plant will help mitigate the environmental effects from the current effluent streams by reducing the mass of nitrogen and phosphorus currently discharged via treatment of the reverse osmosis concentrate prior to discharge,” she said.
The speed with which the Bundamba project is being implemented demonstrates the severity of Queensland’s impending water shortage problem. “‘Fast-track’ doesn’t even qualify for what this has been,” Wallis–Lage said. “The project broke ground in December of last year, and after less than a year of construction, testing will begin in late June or July. After a 2-month prove-out system, the first 30-MLD [30-million-L/d] system should be on-line by September.”
The next two advanced water treatment plants, CH2M Hill’s Luggage Point and MWH’s Gibson Island, will be built following Bundamba. Additionally, by mid-2008, Bundamba is anticipated to have another 36,000 m3 go on-line. Bundamba’s total system capacity has been designed for 100,000 m3.
One company is going to the source — literally — to offer seawater desalination. Water Standard Co. (Boca Raton, Fla.), in partnership with various blue-chip companies in the water industry, has designed and patented ships called seawater desalination vessels that will desalinate seawater offshore.
Amanda Brock, CEO of Water Standard Co., said the vessels will use proven components and technologies already in use around the world. However, the vessels will have specific advantages over land-based desalination facilities, including cost-effectiveness, flexibility, significantly reduced environmental effects, and mobility, she said.
“By 2015, nearly 70% of the world will live in urban areas around the world within 50 mi [80 km] of the ocean,” Brock said. “We have to take a hard look at the ocean as being a major source of our future water needs and how desalination can become more of a viable option.”
Brock said the vessels’ advantages are significant. “They have lower operating expenses and eliminate the need for expensive infall and outfall pipelines and related construction,” she said. “Cities and municipalities would only need to build the facilities that may be needed on land to connect the pipeline from the vessel into the customer’s distribution system.” The vessels would be independent from existing power grids. And in case of catastrophic weather, such as a hurricane, a ship could temporarily leave an area and produce water within 48 hours of return, Brock said.
The vessels utilize reverse osmosis. Seawater could be desalinated anywhere from 3.2 to 16 km (2 to 10 mi) offshore in deeper water where the intake water is cleaner, thereby reducing chemical usage and pretreatment costs, Brock said.
Treated water would then be conveyed to shore through permanent seabed pipelines, flexible hoses, or bulk water transport vessels that could hold as much as 75,700 m3 (20 million gal) of water. Each vessel is expected to process from about 18,925 to 283,875 m3/d (5 to 75 mgd) of water, enough water for several communities.
“Brine disposal is basically eliminated, because our patented dilution process requires minimal power, and dilution source water is limitless,” Brock said. “On the feedwater intake side, saltwater would be brought in slowly through a large-diameter depth adjustable intake line protected by a webbinglike structure which significantly minimizes the intake of marine life into the desalination process.”
Brock said the company has received considerable interest from the cities of Monterey and Santa Cruz, Calif., in addition to other municipalities and industrial companies in California, Florida, and Texas. The technology also is being evaluated in a number of countries worldwide, including India, Dubai, Australia, and Saudi Arabia, the largest market in the world for desalination.
— Jeff Gunderson, WE&T
About This Series
This is the first of a two-part series on water reuse. Part 2 of this series (September issue) will explore new and emerging water treatment technologies.
Taking It to the Streets
King County, Wash., biosolids recycling program to fuel mass transit
As fuel prices climb, officials in King County, Wash., are hoping that a new biosolids-to-biofuels program will help to not only stabilize prices but also reduce the region’s carbon footprint. This first-of-its-kind energy and transportation partnership took hold in late April as county officials announced the purchase of 7570 m3 (2 million gal) of homegrown biodiesel to power some 1300 transit buses servicing the region.
Made from canola fertilized with biosolids from Seattle’s two wastewater treatment plants, the new biofuel “made in Washington for Washington” sets the state down a path toward energy independence, said King County Executive Ron Sims in a statement announcing the development.
In linking farms, biosolids, and biofuels, the project offers a “perfect closed loop system,” added Peggy Leonard, biosolids manager for the county’s wastewater treatment division. “You’re fertilizing canola with biosolids, making biodiesel out of it, and then using that biodiesel to power the trucks that are bringing the biosolids out to the farms, which is how this project got started,” she explained.
Even better, the canola-based biofuel burns more cleanly than regular diesel fuel, thereby substantially reducing emissions of air toxics and hydrocarbons, according to Jim Boon, maintenance manager for King County’s transit system. Additionally, the canola-based fuel has a slightly higher energy output than the soy-based biodiesel the county was importing previously from the Midwest.
Blended with 30,280 m3 (8 million gal) of ultralow-sulfur diesel, the canola B20 mix will fuel area buses and other county vehicles for an entire year, according to Boon. Initial shipments will cost roughly $600/m3 ($2.30/gal), almost $66/m3 (0.25/gal) more than regular diesel fuel, with ongoing costs tied to market prices. The B20 mix also powers the county’s biosolids trucks, consuming another 1040 m3 (275,000 gal) per year.
“This is a case of the county turning waste into a resource,” Sims said.
Closing the Loop
Seattle’s two large wastewater treatment plants produce about 100,000 wet tonne (110,000 wet ton) of biosolids annually, according to Leonard. Washington’s Department of Ecology frowns on landfilling or incinerating biosolids, so the county has recycled them as a soil amendment to fertilize forests in western Washington and crops in eastern Washington for more than 15 years.
The push to produce fuel began with an innovative experiment in 2003. What would happen, University of Washington (Seattle) researchers wondered, if some of those biosolids were used to fertilize canola, a fairly drought-resistant crop that also can be used to make biodiesel?
To test the idea, they conducted several demonstration projects at Natural Selection Farms (Sunnyside, Wash.) in Yakima County. During the first phase, they tested different varieties of canola, measured their oil content, and determined what kind of irrigation regime might be best for growing canola with biosolids, according to Sally Brown, a soil scientist at the University of Washington and one of the researchers involved. In Phase 2, they moved into production, planting more acres of canola. Sure enough, biosolids applications helped to grow a quality canola crop, Brown said, adding that it wasn’t long before other farmers joined the effort.
Ted Durfey, the owner of Natural Selection Farms, added a crushing facility next to crush the canola seeds and extract the oil. He uses it to crush not only his seeds but seeds from other farmers in the region. The farmers then sell the oil to Imperium Renewables (Seattle), which processes it into biodiesel fuel.
“Using biosolids in this way not only gives you a really nice, closed-loop system,” noted Brown, “it’s also great from a greenhouse gas perspective, because it’s a cleaner burning fuel.”
Brown cautioned, however, that “it’s not the answer in every situation. Farmers aren’t going to get rich from this.” In Durfey’s case, what’s left over after the oil is extracted is a canola meal, which can be used as an animal feed. He’s able to sell the canola meal to area dairy farmers, which makes the operation more profitable, Brown said. Rising prices for synthetic fertilizers don’t hurt either in making the biosolids applications more cost-effective, she added.
In all, the biosolids-to-biofuels project uses between 20% and 25% of King County’s total biosolids production, according to Leonard. Another 50% goes to dryland wheat production in the eastern part of the state, and 25% is used to fertilize local forests. Roughly 5% goes into making compost for local use.
The county sees this latest project as a win–win situation, creating benefits for both the environment and the economy. As the state’s largest commercial biodiesel customer, “we’re kind of like an anchor tenant, giving the market some stability,” Boon said. “We’re doing millions of miles every month, and it works month in and month out.” In this way, “we’re giving producers the incentive to make more investments and build more refining capacity and encouraging farmers to bring more farm commodities to the market,” he added.
King County’s biodiesel consumption will remove some 22,000 tonne of carbon dioxide from the air over the next year, which is equivalent to removing 2800 vehicles from county roadways, according to county officials.
“We always thought we were bringing biosolids to people who were using biosolids,” Leonard noted. “Now, some of the benefits are coming back to us in terms of cleaner air and a better fuel.”
— Kris Christen, WE&T