Submitted to: Industrial Wastewater
Publication Type: Popular Publication
Publication Acceptance Date: October 30, 2002
Publication Date: N/A
Technical Abstract: In Japan, municipal wastewater treatment plants use a state-of-the-art technology - large populations of nitrifying microorganisms entrapped in polymer pellets - to nitrify ammonia quickly and effectively. While U.S. municipal wastewater treatment plants regard the nitrification/ denitrification process as the most efficient and economically feasible way to remove nitrogen from municipal wastewater, the Japanese pellet technology exhibits tremendous potential for treating another kind of wastewater that is becoming increasingly problematic in the United States: wastewater from large-scale animal production facilities. As the practice of confined animal production becomes more pervasive, effective and affordable alternatives for managing the nutrient byproducts of these operations are desperately needed. Applying nitrification treatment to animal wastewaters is difficult because high concentrations of ammonia typically present in these effluents inhibit nitrifying bacteria. Furthermore, nitrifying bacteria have a slow growth rate compared to heterotrophic microorganisms. In animal wastewater and other wastewater containing high BOD, nitrifiers tend to become overgrown or washed out of reactors. Thus, retaining the slow-growing autotrophic nitrifiers requires recycling surplus activated sludge in an aerobic reactor or employing a long hydraulic retention time - both of which are prohibitively expensive. Research indicates that using large populations of nitrifying bacteria entrapped in polymer pellets to nitrify ammonia in animal wastewater is much more effective than conventional activated-sludge based treatment systems. Immobilized pellets are quick, efficient, and hold tremendous promise for retrofitting existing lagoons.