The Research On Municipal Solid Waste Anaerobic Digestion Treatment

With the improvement of peoples' life, the quantities of municipal solid waste (MSW) increasingly build up. Disposal of MSW had become a crucial problem which affected the living environment and hindered development of society. Many cities had been encircled by refuse. MSW contained many reusable materials, so recently the aim of refuse treatment had turn to resource utilization in order to reduce social and environmental burden.Anaerobic digestion processes mainly treat organic components of MSW. Organic materials were converted to CH4 finally in anaerobic process which was regarded as a good choice to the purpose of MSW's resource utilization. According to characteristics of domestic refuse, this paper focused on one stage wet anaerobic digestion, co-digestion of MSW and sewage sludge; two stage anaerobic digestion of MSW and sewage sludge. In the experiments, MSW contained mainly food solid waste, market refuse. The temperature of anaerobic digestion were determined at 35癈 and 55癈. TS (total solid concentration) were 10%, 20% and 30% respective. C: N ratios were 15:1 and 25:1. In one stage wet anaerobic digestion, the pH tendency were nearly the same in 35 C and 55 C. The concentration of VFA(volatile fatty acid) was lower in mesophilic anaerobic digestion than in thermophilic anaerobic digestion. The particle size of MSW was controlled. Results showed that the smaller particle size lead to higher pH value in liquid phase. The optimal particle size was 5mm. In co-digestion of MSW and sewage sludge experiment, when TS increased to 40 percent, the digestion system turned up acidification. The pH value maintained lower than 4.0. Cellulose substrates degradation was little.In two stage anaerobic digestion of MSW and sewage sludge process, UASB (up flow anaerobic sludge bed) and AF(anaerobic filter) were selected to treat acid effluent from acid phase. According to one stage anaerobic digestion system, in two stage process pH in methane phase maintained at above 6.0. CODCr concentration in acid phase was higher than 15000.0mg/L, CODcr concentration in UASB was3000.0mg/L. Effluent from AF reactor contain high CODcr, so the effluent flow back to AF reactor, results showed CODcr concentration in the second effluent was 6000.0mg/L approximately. After anaerobic fermentation, the feedstock were treated in aerobic composting within 10 days, results showed that H2O percent, C:N ratio and cellulose percent dropped notability.