ENHANCING BIODEGRADABILITY OF REFRACTORY AROMATICS: PRETREATMENT WITH ELEMENTAL IRON

摘要

Nitro, azo, and chlorinated aromatic compounds are commonly present in industrial wastewaters. Aerobic biological treatment is often inefficient to remove these chemicals from wastewater because of their resistance to aerobic biodegradation. The goal of this study is to investigate the feasibility of using elemental iron to pretreat wastewater through chemical reduction of these aromatics before the activated sludge process. Our hypotheses are that these compounds will become more biodegradable upon reduction with iron and that the combined treatment is more effective and/or less expensive than the activated sludge treatment alone. Preliminary data from batch experiments indicate that nitro and azo compounds are rapidly removed from water through both adsorption and chemical reaction. The reaction rate was found to depend on iron type, pH, and other solutes in the wastewater. These aromatics were reduced to their amino counterparts, such as aniline and sulfanilic acid, which were readily biodegraded. Our results suggest that the sequential abiotic-biological treatment may be a cost-effective approach to degrade refractory aromatics in industrial wastewaters.