Air Date: Week of January 18, 2008
Orange County, CA has opened what is likely the largest sewage purification plant for drinking water in the world. The community is on board, and the idea is already being copied elsewhere in the U.S. and abroad. Living on Earth’s Ingrid Lobet reports. Watch Animations of process at this link.
Orange County, California Groundwater Replenishment System
Q: What is the Groundwater Replenishment System?
A: The Groundwater Replenishment (GWR) System is the largest water purification project of its kind in the world and will help increase Orange County’s water independence by providing a locally controlled, drought-proof supply of safe, very high-quality water. The GWR System takes highly treated sewer water and purifies it to near-distilled quality using state-of-the-art technology. When completed and fully operational in 2007, the GWR System will generate enough pure water to meet the needs of 144,000 families. GWR System water will exceed all state and federal drinking water standards and have water quality similar to, or better than, bottled water.
Q: What happens to the purified water?
A: Most of the purified water eventually ends up in the drinking water aquifer beneath north and central Orange County, but it gets there through two different routes. Roughly half of the purified water from the GWR System will be injected into Orange County’s expanded seawater intrusion barrier. The remaining water will be piped to percolation basins, or large lakes, in Anaheim, California, where the water will take the natural path of rainwater as it filters through clay, sand and rock down to the groundwater aquifer. There the water blends with the existing groundwater before it is used as a source of drinking water for north and central Orange County residents.
Q: How does the GWR System purify water?
A: The GWR System takes highly treated sewer water and purifies it using a state-of-the-art, three-step process – microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide disinfection. The water produced is so pure that it cannot be transported until minerals are added back into the water, similar to what is done by bottled water companies.
The resulting purified water will provide a locally controlled, drought-proof source of water and be of higher quality than water sources currently used to recharge the groundwater basin. Most of the drinking water for north and central Orange County is drawn from the groundwater basin.
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an all together change in our operating certificate,” he said. “Anyone who operates a sewage treatment plant and disposes effluent in any fashion has to have a permit. The existing permit applies to the plant that the city used for the past five decades. The new permit would reflect the cleaner wastewater that comes from the new facility. “The issue before was because we couldn’t (treat sewage) really well (the ministry) was very strict on where we could spray irrigate,” he said. “The water is of such a high quality . . . we meet the (standards) to spray irrigate without notice.” As much as possible the city has tried to reuse wastewater by treating it and then using it as spray irrigation on fields all over the city. Under stricter environmental standards, the city will have to live up to those quality levels in monthly tests. The wastewater is now clean enough that the city could dump all of it into Okanagan Lake, but Gous said Vernon chooses not to except in emergencies. He said “political will” prevents them from pumping waste into the lake.The new wastewater treatment plant uses the most cutting edge technology, Gous said. Large inorganic materials like paper and metal are filtered out at the beginning of the process. After that the wastewater passes through a series of clarifiers where bacteria, organic matter and harmful nutrients such as phosphorous and ammonia are removed. The final product is treated to make it meet Canadian drinking water guidelines, Gous said.
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