Factors affecting chemical biodegradation

Microbial degradation is one of the most important processes responsible for the removal of chemical contaminants from the environment. Since the aquatic compartment is frequently the ultimate depository for many man-made substances, there is a need to understand factors that control and/or affect the rate of biodegradation for chemical substances in the aquatic environment. 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 biodegradability in cyclone fermentors under aerobic and anaerobic conditions, with and without co-metabolites. Among those factors investigated, aerobic and anaerobic conditions, availability of co-metabolites, and pre-exposure of microorganisms to the test chemical were found to be the most significant elements in controlling the rate of biodegradation. Other factors (e.g., acclimation period) requiring attention in calculating the rate of biodegradation were also discussed.