Enhanced simultaneous removal of MTBE and TCE mixture by Paracoccus sp. immobilized on waste silica gel

• MTBE and TCE simultaneous removed by Paracoccus sp. immobilized on waste silica gel.
• Adsorption capacity for MTBE and TCE was 0.42 and 0.65 mg g−1, respectively.
• TCE (20 mg l−1) completely removed through cometabolism with MTBE provided as substrate.
• MTBE removal efficiency reached 70.2 ± 3.1% in immobilized system.

Contamination of groundwater with the gasoline additive methyl tert-butyl ether (MTBE) is often accompanied by the coexistence of chlorinated aliphatic contaminants such as trichloroethylene (TCE). This study reports for the first time an indigenous Paracoccus sp. using MTBE as a sole carbon source while cometabolizing TCE from the mixture. The culture was originally enriched and isolated from the sludge sample at a regional wastewater treatment plant in Macau Special Administrative Region (SAR), China. Waste silica gel was used as a matrix for the microbial immobilization. The effects of different concentrations of MTBE and TCE on the removal efficiencies were investigated, together with their interactions during the bioremoval process, as well as the effects of pH and temperature on MTBE and TCE removal rates. The adsorption kinetics of contaminants on silica gel was also evaluated and the adsorption capacities of MTBE (50 mg l−1) and TCE (50 mg l−1) were 0.42 mg g−1 and 0.65 mg g−1, respectively. In the immobilized system, TCE (20 mg l−1) was removed to non-detectable level while the highest removal efficiency for MTBE (40 mg l−1) was 70.2 ± 3.1%.