Opportunities and Challenges for Biological Treatment of Drinking Water

Lutgarde Raskin
Department of Civil and Environmental Engineering
University of Michigan

Abstract

The co-existence of multiple contaminants (e.g., nitrate, perchlorate, arsenic, uranium, chromium, and chlorinated organics) in groundwater sources often results in the closure of wells or the need for expensive treatment schemes.  Advanced physico-chemical processes, such as reverse osmosis and ion exchange are capable of removing multiple contaminants simultaneously, but are often cost-prohibitive due to the requirement of treatment of generated concentrated wastes or regeneration of exhausted materials. Microbial processes provide attractive treatment alternatives as several contaminants can be converted to innocuous compounds through microbial conversions. In addition, microbes often can mediate the conversion of contaminants to less toxic and easily separable solid phases in the same treatment system.

I will present how we have developed and optimized fixed-bed anaerobic bioreactor systems over the past 12 years to simultaneously remove several co-existing contaminants, including nitrate, perchlorate, arsenic, and uranium.  Examples from laboratory, pilot, and demonstration scale studies will be shown.  The presentation will also cover how microbial community characterization has been helpful in system optimization.  Finally, the need for appropriate post-treatment when implementing microbial treatment technologies to consistently produce high quality finished drinking water will be illustrated using disinfection studies with culture-independent molecular techniques.