INLAND: Water districts betting on bacteria for cleanup
Janet Zimmerman
Press-Enterprise
10/26/2010
Two Inland water agencies are in line for millions of dollars in federal funding to develop the nation's first systems that use naturally occurring bacteria to scrub drinking water of toxic contaminants.
The biological treatment method uses microorganisms that feed on nitrate and perchlorate, which have forced closure of numerous wells and installation of expensive treatment systems.
Using the harmless bacteria is less expensive and more environmentally friendly than other cleansing methods, water experts said. It also avoids adding salt back into the water that would later have to be removed, and it doesn't create waste that has to be disposed.
"It's a simple process, it's natural, it works well, and I think it will benefit a lot of people," said Jack Safely, director of water resources at Western Municipal Water District in Riverside.
Western and West Valley Water District in Rialto are developing the systems, which until now have only been used to clean water that is injected back into the soil to recharge underground basins. This would be the first to be served directly to customers, said Jess Brown, director of research and development at Carolla Engineering, the Walnut Creek company working with the agencies.
ALREADY THERE
The bacteria already exist in soil and water. When the contaminated water is pumped into the treatment plant, it goes into a vessel with sand or granular activated carbon and concentrated vinegar, which makes the bacteria grow. The bugs digest the nitrate, perchlorate and volatile organic chemicals such as trichloroethylene, or TCE, and convert them to nitrogen gas, a harmless byproduct vented to the atmosphere, Brown said.
The bacteria are easily killed by chlorine, the primary disinfectant used in water treatment.
Western and West Valley have conducted pilot studies on the treatment for the state. Once their plants are running, they would have to prove that the process eliminates the contaminants and produces water that meets drinking water standards before the state would issue a permit, said Ken August, spokesman for the Department of Public Health.
The standard method for removing nitrate is reverse osmosis, in which water is forced through a membrane that allows water molecules to pass through but blocks larger compounds. That process requires a lot of energy, Safely said. And ion exchange for perchlorate, which uses resin to change the chemical's properties, is expensive because filters have to be changed frequently with high levels of contamination.
STARTUP EXPENSE
Though biological treatment is more expensive up front, about $4.2 million vs. $3.8 million for ion exchange, it saves money in the long run because it can treat high levels of contaminants and treats multiple chemicals in a single process. Biological treatment is about $238 per acre-foot of water, compared to $254 for ion exchange, according to a 2009 study by the Department of Defense.
On Tuesday, West Valley received a $10 million grant from the state health department to build its treatment plant. Groundwater in the area is contaminated with perchlorate, which can disrupt the thyroid gland's ability to absorb iodide, needed to make the hormones that guide brain and nerve development in fetuses and babies.
Perchlorate is an ingredient in rocket fuel, munitions and fireworks and is believed to have leached into groundwater from decades of industrial use in north Rialto. The U.S. Environmental Protection Agency has declared the 160-acre area a Superfund cleanup site and will build wells to pump the water out and treat it with ion exchange before sending it to taps.
Construction on West Valley's project should start by March. After six months to a year of testing and pending approval by the state, the plant will be providing water for homes in two years, general manager Anthony Araiza said.
