Effect of didecyl dimethyl ammonium chloride on nitrate reduction in a mixed methanogenic culture

摘要

The effect of the quaternary ammonium compound, didecyl dimethyl ammonium chloride ( DDAC), on nitrate reduction was investigated at concentrations up to 100 mg/ L in a batch assay using a mixed, mesophilic ( 35 degrees C) methanogenic culture. Glucose was used as the carbon and energy source and the initial nitrate concentration was 70mg N/ L. Dissimilatory nitrate reduction to ammonia ( DNRA) and to dinitrogen ( denitrification) were observed at DDAC concentrations up to 25 mg/ L. At and above 50mg DDAC/ L, DNRA was inhibited and denitrification was incomplete resulting in accumulation of nitrous oxide. At DDAC concentrations above 10 mg/ L, production of nitrous oxide, even transiently, resulted in complete, long- term inhibition of methanogenesis and accumulation of volatile fatty acids. Fermentation was inhibited at and above 75mg DDAC/ L. DDAC suppressed microbial growth and caused cell lysis at a concentration 50 mg/ L or higher. Most of the added DDAC was adsorbed on the biomass. Over 96% of the added DDAC was recovered from all cultures at the end of the 100- days incubation period, indicating that DDAC did not degrade in the mixed methanogenic culture under the conditions of this study.