Biological Reductive Immobilization of Hexavalent Chromium for Achieving Stringent Regulatory Limits in Drinking Water

Hexavalent chromium (Cr(VI)) is a highly toxic and carcinogenic contaminant found in groundwater throughout the United States. California's maximum contaminant level (MCL) for Cr(VI) is 10 ug/L; a federal MCL is non-existent. Due to its presence and mobility within large aquifers, the potential risk of exposure to Cr(VI) via drinking water is of significant concern for more than 100 million Americans. Robust methods for achieving low treatment levels (e.g., less than 1 ug/L) for Cr(VI) are limited, and face a number of drawbacks such as high cost and secondary waste production. In response to this need, Microvi has developed a biological Cr(VI) removal process based on biological reductive immobilization. Results of a six-month lab study using the new technology to reduce Cr(VI) in synthetic and actual groundwater samples are to be presented, with insights into the transformation of chromium based on analytical and genetic sequencing data. A bench scale technology prototype demonstrated reduction of Cr(VI) from 50 to