AWWA WQTC65872

Since the discovery of perchlorate in drinking water sources 10 years ago, substantial work has been done to optimize various abiotic and biological perchlorate treatment processes. Biological processes are now being considered largely because they produce no perchlorate-laden waste stream, and because associated operation and maintenance (O&M) costs are low. However, relatively little is known about how best to treat the effluent from an anaerobic, perchlorate-reducing bioreactor. Post-treatment must have the ability to achieve the following treatment goals: reoxygenation: Since biological perchlorate reduction requires near anaerobic conditions, dissolved oxygen must be supplied during the post-treatment process; residual organic carbon removal: the addition of an easily assimilable organic substrate can lead to the production of biologically unstable product water; sulfide and turbidity removal: under anaerobic conditions, sulfate can be reduced to sulfide, which is odorous, biomass that sloughs from the FXB during production may produce turbidity; and, disinfection: as with any drinking water treatment process, a disinfection step must be included in the FXB biological perchlorate treatment train. This work has demonstrated that these post-biological treatment objectives can effectively be met using a 2nd-stage fixed-bed bioreactor with an inter-stage hydrogen peroxide dosing step and a final chlorine disinfection step. Includes figure.