Toxicity reduction associated with bioremediation of gasoline-contaminated groundwaters

In-situ biodegradation has received increasing attention as a method to remediate gasoline-contaminated soils and groundwaters. Typically, oxygen is added to enhance aerobic biodegradation. However, since oxygen is not very soluble in water and is difficult to distribute uniformly throughout an aquifer, nitrate has been investigated as an alternate electron acceptor. Since there are hundreds of organic compounds in gasoline, the possibility exists that there are toxic intermediate metabolites or byproducts formed by biodegradation which may still exert toxicity. This study used the Ceriodaphnia acute toxicity test to determine the degree of toxicity reduction associated with remediation of gasoline-contaminated groundwaters under denitrifying conditions, and compared these results to those for the aerobic process.