Biodegradation potential of MTBE and BTEX under aerobic, nitrate reducing, and methanogenic conditions at a gasoline-contaminated site

[[abstract]]In this study, a gasoline-contaminated site was selected to evaluate the biodegrading potential of methyl tert-butyl ether (MTBE) and benzene (B), toluene (T), ethylbenzene (E) and xylenes (X), collectively known as BTEX under aerobic, nitrate reducing, and methanogenic conditions at the site. Results show that in situ microorganisms had capabilities of degrading MTBE and BTEX using MTBE and BTEX as major carbon sources under aerobic condition. Under conditions of nitrate reduction and methanogenesis, BETX could be decomposed by in situ microorganism; but MTBE was not decomposed. The decomposition of BTEX under anaerobic condition was much slower than aerobic condition. Benzene had the slowest degrading rate. In addition, BTEX was decomposed faster and more completely under methanogenic condition than nitrate reducing condition. The on-site activated sludge system is effective in decomposing BTEX but not effective in decomposing MTBE. Results of this study reveal that the enhanced aerobic bioremediation method is more feasible for renovating this site. Injecting air, pure oxygen or oxygen-releasing chemicals will raise the removal rate of pollutants. Results of this study will be helpful in designing a practical system for bioremediation of this and other similar sites.[[note]]SC