Biological Drinking Water Treatment? Naturally.

The American Water Works Association (AWWA) hosted its first-ever Biological Drinking Water Treatment Symposium in Denver, in March 2013. The symposium started with a plenary session designed to provide a general overview of biological drinking water treatment and specific discussions on aerobic biofiltration, anoxic biotreatment, natural systems, and regulatory drivers. Biological treatment within a filter at a drinking water treatment facility is an operational practice of managing, maintaining, and promoting biological activity on granular media in the filter to enhance the removal of organic and inorganic constituents before treated water is introduced into the distribution system. A well-designed and operated biofilter can accomplish both objectives. The role of the residence time, or empty bed contact time (EBCT), in biofilter effectiveness is becoming more apparent. Operating non-GAC biofilters without chlorine residual in the influent is critical to successful performance, which is also facilitated by limiting the chlorine or chloramine in the backwash water. Multiple parameters can be monitored in-line to provide real-time feedback on anoxic bioreactor health and performance. Natural biological treatment processes include river-bank filtration (RBF), soil aquifer treatment, and aquifer storage and recharge.