Biotransformation of Aromatics in Strip‐Pit Pond

Abstract

A strip‐pit pond formed as a result of past coal mining activities in northeastern Ohio is contaminated with alkylbenzenes and chlorobenzene from tanktruck washing operations. Batch aerobic studies are performed on samples from a strip‐pit pond containing about 100 μg/L each of chlorobenzene, toluene, ethylbenzene, xylenes, styrene, and aniline in order to determine the potential for their biotransformation under field conditions. Microorganisms capable of biotransforming the aromatic compounds are present in the strip‐pit pond water. However, under natural conditions, the biotransformation rate is slow as incomplete removal is observed over a 43‐day incubation period. Volatilization rates exceed the natural rates of biotransformation. Addition of acetate, nitrogen, and phosphorus markedly increase the rate of biotransformation of the aromatic compounds. Enhanced biotransformation rates are more than an order of magnitude faster than volatilization rates. Chlorobenzene is mineralized to carbon dioxide. The presence of 0.61 g/L sediment does not significantly affect biotransformation of the aromatic compounds at a 95% level of confidence. The prospect for successfully stimulating and exploiting biotransformation of the contaminants in a bioreclamation scheme appears very good.