Simultaneous degradation of anodic sludge and cathodic refractory pollutant in a MFC powered EF system enhanced by co-addition of lysozyme and 2-bromoethane sulfonate

Abstract

To enhance simultaneous bioelectrochemical treatment of excess sludge and refractory wastewater, a microbial fuel cell powered electro-Fenton system (MFCⓅEFs) with the co-addition of lysozyme (LZ) and 2-bromoethane sulfonate (BES) into sludge was set up and an in-depth investigation of pollutants degradation, micro-electricity utilization, microbial communities and functional genes was conducted. Experimental results showed a maximum sludge total chemical oxygen demand (TCOD) removal achieved 80.21 % in 25 d with co-addition of 50 mg/gSS LZ and 25 mmol/L BES in anodic chamber of MFCⓅEFs, while the degradation of syringic acid (SA) as a model refractory pollutant reached 97.42 % in cathodic chamber within 25 h, and obtained a 3.35 W/m3 maximum power density. The quantification of micro-electricity utilization revealed that sludge hydrolysis enhanced by LZ could reduce electricity sink, and methanogenesis inhibited by BES could ensure more electrons to be used for exoelectrogenesis. The co-addition of LZ + BES resulted in an increased abundance of exoelectrogens (Pseudomonas, Bacteriodetes, and Chlorobium) and a decreased major methanogenic group by inhibiting gene-function of coenzyme-M. The columbic efficiency of the MFCⓅEFs with co-addition of LZ + BES was increased to 8.31 % (only 4.22 % for control). The complete mineralization of SA in MFCⓅEFs was ascribed to the high generation rates of hydrogen peroxide and free radicals. The results provided a new insight to use in-situ generated micro-electricity from MFCⓅEFs to realize simultaneous treatment of excess sludge and residual refractory pollutant in the secondary effluent of wastewater treatment plant.