Factors affecting chemical biodegradation

Microbial degradation is one of the most important processes responsible fo r the removal of chemical contaminants from the environment. Since the aqua tic compartment is frequently the ultimate depository for many man-made sub stances, there is a need to understand factors that control and/or affect t he rate of biodegradation for chemical substances in the aquatic environmen t. In this study, several priority chemicals encompassing various biocides (2,4-dichlorophenoxy acetic acid, carbaryl, fenitrothion, pentachlorophenol ) and a nitroaromatic (2,4-dinitrotoluene were assessed for their biodegrad ability in cyclone fermenters under aerobic and anaerobic conditions, with and without co-metabolites. Among those factors investigated, aerobic and a naerobic conditions, availability of co-metabolites, and pre-exposure of mi croorganisms to the test chemical were found to be the most significant ele ments in controlling the rate of biodegradation. Other factors (e.g., accli mation period) requiring attention in calculating the rate of biodegradatio n were also discussed. (C) 2000 by John Wiley & Sons, Inc.