CHEMICAL OXIDATION TO PROMOTE MICROBIAL ACTIVITY AND SURFACTANT PRODUCTION

A comparison was made between biological and modified Fenton (MF) chemistry with respect to the effectiveness of treating hydrocarbon contaminated soil. The MF treatment was performed using both hydrogen peroxide (HP) with Fe³⁺ and a CaO₂ based oxidant to allow for comparisons between different MF oxidants. Slurry filtrate samples were collected throughout the treatment period and tested for hydrocarbon and bulk surfactant concentrations. Viable bacterial numbers were determined at the end of the treatment period as colony-forming units. The MF treated systems had temporarily elevated surfactant concentrations with respect to the control and biologically treated soils, indicating surfactant production during chemical hydrocarbon oxidation. The elevated surfactant concentrations proceeded for approximately two hours in the HP slurry and approximately two days in the CaO₂ slurry. Enhanced total petroleum hydrocarbon (TPH) removal was observed as a result of MF treatment with hydrocarbon removal being greater with the CaO₂ treatment relative to HP treatment. The HP treatment had approximately two times the removal of TPH and CaO₂ treatment had approximately three times the removal of TPH compared to biological treatment alone. At the end of the treatment there was no considerable decrease in viable bacterial numbers between MF and biological treatments. The biological and CaO₂ treatments were significantly indifferent in terms of microbial counts and there was a decrease in viable cells by approximately one order of magnitude during the HP treatment. These data will be presented along with discussion and interpretation of results.