AWWA ACE70869

This powerpoint presentation begins by providing a brief overview of perchlorate (ClO₄^-) and nitrate (NO₃^-) as common groundwater contaminants in the western United States. A U.S. Environmental Protection Agency (USEPA) grant to the Metropolitan Water District of Southern California funded this study of biological perchlorate removal from the City of Pasadena groundwater wells. Study objectives were to identify, investigate and resolve some of the primary challenges facing the application of H₂- based biological treatment for the removal of perchlorate and nitrate from groundwater including: start-up; process stability; response to perturbations; use of hydrogen gas; and, regulatory acceptance. The pilot study included: packed column reactor (PCR) (8 ft bed depth, 1 ft diameter, 1 gpm influent flow); non-proprietary, standard design of an upflow reactor; eight month duration. PCR process configuration is presented, along with hydrogen demand calculation, and PCR start-up. Lessons learned are provided for water quality and reactor system. Includes tables, figures.