Feasibility study of aerobic cometabolism biodegradation of MTBE by a microbial consortium: Biomass growth and decay rate

Abstract

In the present study, the feasibility of aerobic cometabolism biodegradation of MTBE was investigated by the microbial consortium obtained municipal wastewater treatment plant in the presence of glucose growth substrate for in situ bioremediation of MTBE as the second most common pollutant in groundwater. For this purpose, various criteria including MTBE removal efficiency, microbial population and activity, biomass growth and decay rate, substrate removal rate, excess sludge generation and sludge settling velocity was investigated due to evaluate its compatibility for in situ bioremediation. At the lowest glucose concentration required for effective growth of microbial consortium (60 mg/L) and initial MTBE concentration of 40 mg/L, MTBE and COD removal efficiencies were 85% and 92%, respectively. Under this operating condition, coefficient of biomass production of 0.51 mg VSS/mg COD and active MLVSS/gross MLVSS of 0.85 were achieved. These high values indicated that MTBE and its intermediate products induced no inhibitory effect on microbial consortium in the presence of glucose, in addition to the survival and growth of microbial consortium, high microbial activity and low cellular debris. Additionally, biomass decay rate was obtained 0.0243 day−1, which indicated its high continuity and resistant to changes in environmental conditions of the aquifer. Furthermore, excess sludge generation and SVI were 44 mg VSS/day and 87 mL/mg, respectively that showed low probability of bio-clogging and high potential for biofilm formation. Therefore, cometabolism in presence of glucose growth substrate by the studied microbial consortium is recommended for in situ bioremediation of MTBE contaminated groundwater.