DISCOVERY BAY — While a family of ducks threads its way through the wetlands here and a green heron fishes on the banks, a furious process is churning underneath.
Plants, dirt, birds and fish have all been enlisted to clean Discovery Bay’s wastewater as part of an experimental constructed wetland project.
Facing $100,000 in fines for copper contamination, the town three years ago partnered with UC Berkeley scientists to determine whether the latest advancements in artificial wetlands could help clean the town’s sewage.
The one-of-a-kind project was a success — it reduced copper in the test pond by as much as 90 percent — and the team is now exploring ways to use a modified version of that wetland on the same two-acre plot in the southwest corner of town to remove pharmaceuticals, among other things, from a sample of the wastewater that winds up in Old River.
“No one else has one,” said Alex Horne, professor of ecological engineering at UC Berkeley and an expert in the field. “In Discovery Bay, they’re way ahead of everyone — they’re really trendsetters.”
Over the past decade, wetlands have emerged as a popular option for dealing with polluted water. There are thousands of constructed wetlands around the world, according to Horne, who has worked on treatment projects in large cities from California to China.
But Discovery Bay’s initial trial wetland was the first one to specifically target copper in lightly polluted water, Horne said, and one of the wetlands now set up to target pharmaceuticals represents the debut of a design that uses the sun to break down contaminants. The basic theory of copper treatment wetlands is that plants will eventually die and decompose, robbing the water of oxygen and encouraging certain bacteria to begin breathing sulfate. These bacteria exhale sulfide, which binds with trace amounts of copper in the water to form a heavy solid that falls to the wetland floor and is eventually buried.
The water moves from one end of the wetland to the other over the course of several days, and scientists can manipulate which bacteria grow by using different plants, matching them to a particular pollutant.
“You need to make the environment comfortable for the bacteria that you want to do the work for you,” Horne said. “Bacteria are your friends.”
The bacteria are not so friendly that residents can safely come in direct contact with wetlands water, though.
One of the pharmaceutical wetlands uses ultraviolet rays in addition to bacteria to break down chemicals. This project is shallower than the others, and the water is a rusty copper color instead of a murky green. Preliminary results have been promising.
“It’s a pretty unique concept,” said Robert Knight, president of Wetland Solutions Inc., who is interested in bringing the model to Florida if the team can demonstrate consistency.
Experts are increasingly concerned about the environmental effect of discarded pharmaceuticals. People’s bodies absorb only a fraction of the drugs they take, with the majority of the compounds ending up in the toilet, Horne said.
Drugs such as mood stabilizers and beta-blockers are especially difficult and expensive to remove from wastewater, according to graduate student Justin Jasper, and even small amounts of these compounds can significantly affect the health of animals and ecosystems.
Unabsorbed hormones from birth control pills and other drugs can make their way into rivers, where they can alter the reproductive patterns of fish.
Town officials have so far invested about $200,000 in the project, which is supported in part by the National Science Foundation. They are gambling that the trial will be a money-saver in the long run.
Once built, wetlands are cheap because they use solar energy and require little maintenance. Cleansing wastewater of pharmaceuticals and other contaminants with a high-intensity treatment system, on the other hand, would cost Discovery Bay tens of millions of dollars.
The town is no longer facing fines because the water board has adjusted the way it applies copper standards in the sanitation district, but there is no telling what restrictions the department will impose in the future. Many areas experience copper buildup during construction booms, Horne said, because durable copper pipes initially leach small amounts of copper into the water.
“The state has tightened its standards, and there’s no guarantee that they won’t continue to tighten down,” Community Services District Director David Piepho said.
The town may benefit from having technology custom-made for its particular ecosystem, Jasper said.
Few residents are aware of the project, though scientists hope to get local school children involved with field trips.
And not all board members are convinced of the wisdom of the project. Director Ray Tetreault voted against refunding the project this fall.
“My sense is I’ll do it when I have to,” he said. “I’m more of a pragmatic guy.”
If the trial continues to prove successful, the city may ask Horne and his colleagues to construct a full-scale wetland here to treat all of the town’s wastewater.
“We live on the Delta; it’s the responsible thing to do,” Piepho said. “And in the end, it could really save us a lot of money.”
Contact Hannah Dreier at 925-779-7174.
