Orange County, California, has just proudly inaugurated its brand new $490 million water purification plant. In the face of Southern California's water shortages, this particular plant has the ability to turn 70 million gallons of treated sewage into drinking water, every day.
The "Groundwater Replenishment System", unofficially nicknamed "toilet to tap", is the world's largest, most modern water reclamation facility. Over a series of pipes, filters, holding tanks and pumps extending across 20 acres, treated wastewater suffers a nearly miraculous transformation.
The purification process consists of microfiltration, where the (still brackish) treated sewage from the neighboring sanitation plant is cleared of solids. The water then goes through reverse osmosis, where most mineral and organic contaminants are removed and finally through UV light/hydrogen peroxide sterilization, where the water is sterilized and any remaining pharmaceuticals and carcinogens are broken down.
At this point, the treated water is free of of bacteria, viruses, carcinogens, hormones, chemicals, toxic heavy metals, fertilizers, pesticides and dissolved pharmaceuticals and already exceeds drinking water standards.
In the final treatment step, the treated water is injected underground, where it percolates through the earth replenishing the aquifer, remaining in the ground from 6 months to a year until it is extracted as drinking water.
According to program manager Shivaji Deshmukh in interview:
We view wastewater as a valuable resource, and by us purifying it we are able to create a new drinking water supply that's reliable and drought -proof. -- NPRRecycled water currently runs at $550 per acre-foot, slightly more expensive than supplies brought in from Northern California, despite using less electricity than moving the same amount of water via the state's aqueducts. Water district officials expect it to become more competitive over time, as imported water prices rise.
At the plant's full capacity, up to 130 million gallons a day could be added to the county's freshwater supply, lessening the region's dependence on outside sources and halving the current ocean discharge of treated sewage.
Sources: NPR/ Seattle Times.
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