Comparison of Co-Metabolic and Direct Metabolic Biodegradation of MTBE: Monitoring Main Intermediates and SBR Stable Operation

The present study aimed to compare aerobic biodegradation of MTBE and its intermediate products through a microbial consortium obtained from sludge of municipal wastewater treatment by co-metabolism and direct metabolism via Sequencing Batch Reactor (SBR) method in laboratory scale. For this purpose, the maximum MTBE concentrations, acclimatization speed and duration, shock loading resistance, degradation of intermediate products, bacterial growth, and sludge quality were compared for both metabolisms. MTBE and COD removal efficiencies were 98% and 81%, respectively for co-metabolism and 84% and 93%, respectively for direct metabolism at the highest acceptable MTBE concentration equal to 180 mg/L. This indicates acceptable performance of both processes in MTBE biodegradation. Furthermore, the degradation of intermediate products including tert-Butyl Formate (TBF), tert-Butyl Alcohol (TBA), formaldehyde, and acetone indicated that both metabolites are able to degrade these products. Well-settled sludge was ultimately obtained in both metabolisms. Based on the results, the acclimatization period for co-metabolism was shorter. However, the system was stabilized in a shorter time in direct metabolism and the resulting microbial consortium was more resistance to shock loading. Therefore, the acclimatization of the microbial consortium through direct metabolism has better performance, which is recommended to be used in MTBE biodegradation.