In situ bioremediation of MTBE: Lessons from laboratory experiments
Microcosms and columns experiments were carried out to study the behavior of MTBE degrading consortium in laboratory in soil-groundwater systems and to propose meaningful field bioremediation strategies. MTBE was only seen in those microcosms operated under aerobic condition and inoculated with the MTBE degrading consortium. Complete degradation of 20-25 ppm MTBE was seen in ~ 10 days. A marked decrease in the MTBE biodegradation rate was seen compared to previous experiments without soil, where usual rates of ~ 1 ppm/hr were recorded. A clear decrease in the MTBE degradation rate observed over the successive MTBE spikes was attributed to significant nitrification of ammonia which cause a drop in the pH and resulted in generation of toxic levels of nitrite. MTBE biodegradation maintained over 6 mo showed the stability of the elimination process in soil-water systems and suggested very promising perspectives for field implementation of in-situ bioremediation of groundwater polluted with MTBE.