Evaluation of bio-fenton oxidation approach for the remediation of trichloroethylene from aqueous solutions

Abstract

In the present study, a Bio-Fenton oxidation approach for the removal of trichloroethylene (TCE) was developed through the optimization of enzyme-based hydrogen peroxide (H2O2) production from glucose. Glucose oxidase (GOD) was evaluated for the production of H2O2 and the optimized parameters were found to be the oxidation of 60 mM glucose by 1 mg mL−1 of GOD which yielded a conversion of 88.4% of glucose for subsequent utilization in the Bio-Fenton process. The biologically produced H2O2 was further used for the removal of TCE from groundwater samples by addition of ferrous ion to the reaction mixture. To determine the efficiency of hydroxyl radicals generated in Fenton reactions to remove TCE in a cost-efficient way, preliminary experiments such as classical Fenton and pseudo Bio-Fenton were carried out in aqueous solutions containing TCE in order to obtain the optimum conditions and then the efficiency of bio-Fenton was tested in groundwater. Based on these results, almost 97% of TCE was removed from aqueous solution within 30 min of classical Fenton under low pH condition (pH 3.0). While performing pseudo bio-Fenton experiments, the optimum conditions were determined to be pH 7.0 and 30 ppm H2O2 which yielded 61% removal of TCE in 30 min. Although a comparatively lower removal (30.2%) in groundwater containing TCE was achieved using Bio-Fenton process, it was at a neutral pH. The process was further enhanced by the addition of hydrogen peroxide after 3 h of reaction and a maximum of 48.4% removal of TCE was observed. Thus, this process will help to prevent the scavenging of the unstable H2O2 and can be employed in-situ.