Envirogen Plans Biological Treatment Facility for Perchlorate Contamination
Company is working with local water district and municipality with high perchlorate levels
Envirogen Technologies Inc. announced that it has begun construction on a first-of-its-kind biological drinking water treatment plant in collaboration with West Valley Water District (WVWD) and the city of Rialto, Calif. The new plant, which will be installed at WVWD headquarters in Rialto, will treat perchlorate and nitrate from groundwater at District Well No. 11 and Rialto Well No. 6, producing up to 3 million gal per day (mgd) of quality drinking water for area residents. The plant represents a significant move toward addressing the cleanup of a major perchlorate plume that has threatened the Rialto-Colton Basin’s water supply since its detection in 1997. It also represents the culmination of more than a decade of technology research and development by Envirogen and a lengthy collaborative process by WVWD and the city of Rialto to secure funding for the project.
The new facility will consist of Envirogen’s fluidized bed bioreactor (FBR) followed by a typical surface water treatment plant to polish the effluent to potable water standards. Using naturally occurring microorganisms on a fluidized media bed, the Envirogen system will simultaneously reduce influent perchlorate concentrations as high as 300 parts per billion (ppb) and nitrate at 20 parts per million to non-detectable levels. The end products of this treatment are innocuous nitrogen gas and sodium chloride. Unlike physical-chemical processes commonly used for the removal of these contaminants, which involve a phase transfer of the perchlorate, the FBR treatment system is “green” in that it is a destruction technology, requires low energy inputs and does not produce hazardous byproducts. According to Envirogen, the technology is suited for handling high levels of perchlorate and nitrate at low cost, and will offer new options for communities and water utilities across the United States faced with treating this contaminant.
Since its detection in 1997, the perchlorate plume affecting the Rialto-Colton Basin has continued to grow and move through the aquifer, resulting in the shutdown of nearly a quarter of the city’s 22 wells. Extensive efforts have been made by the city of Rialto, WVWD and the state of California to arrive at a remediation strategy, first identifying the FBR as a best available technology. This was followed by a cooperative effort by all parties to secure funding for the project that resulted in the obtaining of funds from California’s Proposition 84 legislation and various federal and regional authorities.
Perchlorate is a highly soluble salt anion that is used in the manufacture of solid rocket fuel, fireworks, road flares and several other products. It also occurs naturally in some areas of the southwestern U.S. and in certain fertilizers. Currently, only Massachusetts and California have established maximum contaminant levels for perchlorate. Other states, including New Mexico, New York, Arizona, Nevada and Maryland, have set advisory levels ranging from 1 to 18 ppb. In October 2008, the U.S. Environmental Protection Agency (EPA) made a preliminary determination not to regulate perchlorate on the federal level, but its final decision on the matter is still pending. There are reportedly 33 states that have perchlorate in their groundwater supplies.