Microbial Degradation and Chemical Oxidation of Sandy Sediment Contaminated with Polychlorinated Biphenyl

Abstract

This paper reports the results of various biodegradation experiments on polychlorinated biphenyl (PCB)-contaminated sandy sediment employing a mixed culture of acclimatized bacteria. Following the optimization of different variables, the elimination rate achieved of Aroclor 1242 in slurry phase reactors was 61% after 4 months of treatment. The presence of biphenyl as a cosubstrate was the most important factor affecting PCB biodegradation. The biodegradation occurred as a first-order process, and proved most effective with respect to dichlorinated (100% removal), followed by trichlorinated (92%) and tetrachlorinated biphenyls (24%). The results of the treatment of polychlorinated biphenyl (PCB) contaminated sandy sediment with the Fenton advanced oxidation process (AOP) confirm that the oxidation process occurs on the PCBs adsorbed to particles, producing 98% elimination of the original PCB structure after 72 h. The degree of elimination was found to be dependent on the level of congener chlorination, and the process follows pseudo first-order kinetics. In addition, the Fenton chemical oxidation process may be complemented by subsequent aerobic biologic degradation which, after 15 days, produces 70% mineralization of the products generated during the chemical oxidation process.