Monday, October 27, 2008

From wastewater to drinking water

The several million inhabitants of Orange County-a low rainfall area of California, USA- benefit from an innovative solution to the wastewater problem. Instead of millions of gallons of wastewater being dumped directly into the ocean each day, the majority is returned to the water supply. For many years this feat has been achieved by a wastewater treatment plant. After primary treatment, the wastewater undergoes secondary and tertiary treatment. This involves purifying the water so that it is as clean as conventional water. It is then mixed with deep-well water and goes into the groundwater basin. There it replenishes the basin and also prevents salt water from seeping in and ruining the groundwater reservoir. Up to 75 percent of the district's total water needs are drawn from this underground supply.