Biodegradation of synthetic wastewater containing styrene in microbial fuel cell: Effect of adaptation of microbial community

Abstract

Industrial wastewaters containing styrene produced from industrial units have posed significant environmental and health issues. Microbial Fuel Cell (MFC) could be used as a biotechnological system in volatile organic compound (VOC) degradation, including styrene bioremediation, especially in anaerobic conditions to prevent it from being stripped into the gaseous phase. In the present study, the biodegradation of styrene in the concentration range of 27–105.7 mg L-1 using adapted and unadapted activated sludge as inoculum was investigated in MFCs with respect to degradation rate, degradation efficiency, and power production. Results indicated that the two inoculums tested could lead to efficient degradation of styrene, but the degradation rate and power production of the adapted activated sludge is higher than the unadapted ones. The best performing inoculum, the adapted activated sludge, gave styrene an initial degradation rate of 15.6 mgL-1h-1, the maximum power density of 13.6 mWm-2,and styrene removal of 100%. The Gas Chromatography/Mass Spectrometry (GC/MS) test shows that the phenyl acetate route can be proposed as the dominant mechanism. Methylene blue, methyl orange, and methyl red were used as electron acceptors, and their influence on MFC performance was investigated. The addition of methylene blue achieved a 1.22-fold increase in steady state voltage from 233 mV in the absence of any added mediator to 285 mV in the presence of methylene blue. The present study highlights the possibility of using MFC to achieve efficient treatment of styrene-contaminated wastewater by using activated sludge as an inoculum with concomitant bioelectricity production and showing the influence of the microorganism adaptation to the styrene on power generation.