Evaluation of sonochemical destruction of PCE in in situ flushing waste fluids

Remediation of source zones at sites contaminated with dense non-aqueous-ph ase liquids using aggressive in situ flushing technologies, such as the add ition of chemical additives known as cosolvents, have been implemented and successfully demonstrated in recent field tests. However, treatment of the waste fluids generated from such cleanup technologies has not received much attention. The purpose of this laboratory research was to evaluate the fea sibility of using sonication as a method for treating waste fluids produced during in situ alcohol flushing at a site contaminated with a dense non-aq ueous-phase liquid. Experimental results showed that sonochemical destructi on of perchloroethylene (PCE) followed pseudo first-order kinetics and that increasing ethanol cosolvent percentages in the aqueous effluent resulted in decreasing degradation rates of PCE in solution. The energy efficiency ( G = degradation/energy input) of the sonication treatment also decreased as the ethanol volume fraction increased. Overall, sonication was seen to deg rade PCE in aqueous solutions, becoming less effective as the cosolvent fra ction increased.