Performance Of Dewatered Sludge Degradation And Electricity Production Accelerated By Bioelectrogenesis In Sludge Anaerobic Composting

Dewatered sludge is a valuable resource. Anaerobic composting technology (AnC)can removal pollutants as well as maximize the retention of sludge nutrients with lowerpower consumption. However the longer cycle of AnC needs to be effectively solved.Microbial fuel cell (MFC) can accelerate the process of anaerobic degradation whilerecycling the electricity from sludge. Basing on the system characteristics of microbialfuel cells (MFC) and anaerobic composting (AnC), an MFC-AnC system wasconstructed by introducing bioelectrogenesis into AnC system to enhance the sludgedegradation and recovery power simultaneously. The performance of sludgedegradation and electricity generation in several aspects, such as the startup, operation,substrate expansion, etc, has been investigated.Results confirmed the feasibility of the MFC-AnC to achieve anaerobiccomposting of sludge and generate electricity. After45days composting, the OMremoval efficiency of dewatered sludge in AnC was17.7%, while in MFC-AnCachieved22.4%and the maximum power density was5.3W/m~3, the OCP was0.84Vand the internal resistance was97ohm with potassium ferricyanide as its electronacceptor. Due to the moisture content decreased during the operation of MFC-AnC,sludge volume can be reduced by7.7%after21days. The compost product had suitableconductivity and pH for plant growth, with nitrogen loss of9.8%and no plant toxicity.MFC-AnC system could extend the limitation on the moisture content ofdewatered sludge. Increasing the moisture content of the raw dewatered sludge canimprove the removal efficiency of organic matter and significantly reduce the internalresistance of MFC-AnC hence enhance increase the power density. After13dayscomposting, the εOMof W84, W86, W88groups were13.5%,14.6%and15.6%, theinternal resistance were84Ω,78Ω,58Ω and the maximum power density were5.4W/m~3,6.0W/m~3,8.1W/m~3. The optimum moisture content was88%in experimentalconditions. The compost product of the MFC-AnC in the optimum moisture conditionswas non-phytotoxic with εOMreached18.7%and nitrogen loss of12.7%.Adding food waste in the raw dewatered sludge can improve the performance ofsludge degradation and reduce system internal resistance. After13days composting, theεOMof F0.3, F0.5, F1groups were6.4%,9.0%,12.8%, the internal resistance were79Ω,49Ω,59Ωand the maximum power density were5.7W/m~3,9.5W/m~3,7.9W/m~3. Thesuitable ratio of food waste and dewatered sludge was0.5:1to1:1, and the optimumratio was0.5:1. The compost product of the MFC-AnC in the optimum ratio had a smalldegree of phytotoxic with εOMreached18.8%and nitrogen loss of13.2%. Thephytotoxic was probably beacause that the fatty in food waste was not entireldegradated. Howere compared with the raw material, the compost product was already improved a lot.