Biological treatment of perchlorate contaminated waters

The discovery of perchlorate contamination of drinking water sources has created a national crisis due to perchlorate's stability and persistence in conventional drinking water treatment systems. It is demonstrated here that perchlorate can be degraded by microorganisms under anoxic conditions using perchlorate as an electron acceptor, and either acetate or hydrogen gas as electron donors. Perchlorate was removed to below detectable levels (<4 mu g/L) in fixed bed reactors packed with activated carbon as a support medium when acetate was fed in excess to the reactors. When the reactor was temporarily mixed to redistribute the biomass in the column, acetate was completely removed, resulting in perchlorate release likely due to desorption from the carbon. Preliminary suspended growth reactor experiments demonstrated that hydrogen gas could also support perchlorate-degrading cultures.