Study On Working Performance And Mechanism Of Microbial Fuel Cells Using Sulfide-containing Wastewater As Substrate

Sulfide is a typical kind of hazardous pollutant to cause water deterioration,pipeline corrosion and anaerobic digestion inhibition due to its toxicity to organisms.Simple or complex organics are always co-existed with sulfide in various wastewaters,such as chemical wastewater, oily wastewater, paper-making wastewater andmunicipal wastewaters. Since conventional sulfide containing wastewater treatmentsare usually with high consumption, lower efficiency and non-thoroughness of sulfideremoval, efficient and cost-effective treatment method is to be urgently developed.Besides, under the press of energy depletion and environment pollution currently,researchers paid more attention to studies on energy-saving or even energy-producingmethods with efficient pollutant removal. Microbial fuel cell (MFC) is a newlydeveloped device to recover electrical energy from pollutants with bacteria ascatalysts, which has arouse concerns on sulfide containing wastewater treatment in theMFCs.In this study, single-chambered MFCs are utilized to simultaneously generatecurrent and remove co-existed sulfide and organics in the simulation sulfidecontaining wastewater (with sulfide and glucose/corn stover). Feasibility of sulfidecontaining wastewater treatment in MFCs is first investigated after long timedomestication. Then the MFCs performance is evaluated by combined pollutant(sulfide and glucose/corn stover) removals and electricity recovery (voltage output,power density and columbic efficiency) since the reactors are operating stably.Microbial working principles of the co-substrate system are further explored on themicrobial diversity analysis. Effects of influent conditions (different sulfideconcentrations, COD concentrations and electrolyte conductivities) on power outputsas well as pollutant removals are also examined to optimize the MFCs operatingperformance eventually.Results showed that in the MFC fed with sulfide (100mg/l) and glucose (800mg-COD/l), both pollutants were efficiently removed by88.7%and81.8%, with themaximum power density of581.4mW/m2. Comparable maximum power density (558.7mW/m2) and sulfide removal efficiency (64.9%) could be realized in the MFCfed with sulfide and corn stover filtrate, while the COD was less removed by only57.3%, due to the macromolecular and refractory components in corn stover filtrateon the gas chromatography/mass spectrometry analysis. Community analysisindicated there was a great diversity of exoeletrogenic and sulfur-related bacteria onthe anode surface, which contributed significantly to the current generation andsulfide oxidation in MFCs. Initial pollutant concentration and electrolyte conductivitycould be adjusted to improve the MFCs working conditions, resulting in higherpollutant removal efficiency and electricity recovery. The MFCs are proposed to be anefficient alternative to sulfide containing wastewater treatment in this study, and thetheoretical and experimental analysis are sure to make for its practical application inthe future.