Chaff And Excess Sludge Treatment Using Microbial Fuel Cell

MFC, is a kind of bio-catalysis technologies, which can oxidize the organic matter thatcan be biodegraded in the medium and transformed it into electrical power throughbiocatalytic functions of the bacteria or enzymatic. It now becomes the favor of manyresearchers. At present, a handful of other studies have used the high concentration organicwastewater as microbial fuel cell system’s substrate, but very few microbial fuel cell systemstudies used solid waste as substrate. If we can release the energy contained in the solidwaste, to carry on the secondary utilization, this would not only solve the problem of thesolid waste disposal, but broaden the way of the development of new energy as well.Firstly, chaff was anaerobic fermented. Using fermentation broth as a substrateand theexternal resistance of100ohms, we built a microbial fuel cell system. The production ofbio-electricity and removal efficiency of substrate in MFC of batch and continuous systemswere investigated.The results show that using fermentation broth as substrate, MFC system successfullyproduces bio-electricity and removes substrate simultaneously. The MFC uses the COD ofchaff fermentation broth at1048mg/L,1935mg/L,3112mg/L, its output power were19.53W/m³,21.51W/m³and24.42W/m³respectively, when the batch systems were used.At the same time, after48h of running, COD removal efficiency of the fermentation brothwere83.45%,86.12%and79.4%. When continuous systems were used at2000mg/L ofCOD concentration and24h of hydraulic retention, the maximum power density35.64W/m³was achieved. Comparing the different modes of operation in the same COD concentration，it has been shown that under the continuous flow operation, the performance of microbialfuel cell system, in terms of power density, apparent resistance and substrate removalefficiency, is superior to that under the batch flow pattern. It is possible that when themicrobial fuel cell system was operated in the modes of continuous flow, the entireenvironment was relatively stable and the activity of anaerobic microorganisms wasimproved, unlike operating under the batch flow pattern where substrate concentrationwould reduce gradually.Secondly, experiments examining the electricity production and digestion of theremaining sludge were conducted using the same microbial fuel cell system. And by introducing a new cathode catalyst, we explored the effect of electricity production capacityand sludge digestion of the microbial fuel cell.The results show that using the different proportion of volume ratio of sludge to water（different MLVSS value） and external resistance of100ohms, this MFC presents differentpower densities. As the volume ratio of sludge to water was1:4（MLVSS=4450mg/L）, themaximum output density was5.1W/m³.When a phosphate buffer solution was added at thesame ratio of sludge to water, the power density of the system increased to29.80W/m³. Thisresult indicates that addition of the buffer system helps reduce the internal resistance of theMFC system, while the system is maintained at a suitable pH range, which greatly improvedthe performance of the battery system. Introduction of a new cathode catalyst MnO₂、Pt/C、MnO₂/GNS in the same experimental conditions, the power density of the system reached3.73W/m³，4.12W/m³，4.27W/m³, and the power density of air cathode with cathode catalystAg was just1.50W/m³. The results show that after adding the new cathode catalyst, theelectron transfer rate accelerated on the cathode surface, which accelerated the total reactionrate and improved the performance of the battery system.