Evidence of Anoxic Ammonia Oxidizing and Denitrifying Mixed Cultures as Natural Partners for Nitrogen Removal from Diverse Ecosystem Containing Organic Carbon

摘要

Anaerobically digested cow dung and extended aeration process flocculent sludge employed for treating tannery effluents were identified as potential biomass for simultaneous anoxic ammonia oxidation and denitrification process in presence of organic carbon. Both sludges collected from diverse eco-systems were originally contaminated with ammonia and organic carbon. Sequential batch studies confirmed possibility of anoxic ammonia oxidation in presence of organic carbon (available through endogenous respiration) and ammonia was oxidized anoxically to nitrate at an oxidation reduction potential (ORP) equal to -248 ±25 mV by an unknown mechanism. It is hypothesized that the oxygen required for oxidation of ammonia might be available through catalase enzymatic activity of facultative anaerobes in mixed culture. The presence of catalase enzymatic activity of facultative anaerobes was tested and quantified. The results shows that in presence of organic carbon, anoxic ammonia oxidation to NO_3 is feasible and denitrification via auto and / or heterotrophic route take place in faster way. Such microbial pathway may be useful for treatment of effluents containing reduced forms of carbon, nitrogen and sulphur compounds and may also help in calculating the loss of nitrogen from organically contaminated ecosystem.