Study on mechanism and application of anaerobic degradation for organic fraction of municipal solid waste (OFMSW)

In this thesis，the characteristics of anaerobic fermentation production of hydrogen and methane were investigated, the anaerobic co-production of hydrogen and methane was introduced to increase energy recovery efficiency, and the anaerobic co-digestion of kitchen waste and waste paper was adopted to avoid the inhibiton of intermediate metabolite on anaerobic degradation. Next, using mechanically sorted and water sorted OFMSW (MS-OFMSW and WS-OFMSW) as substrates, material characteristics were analyzed and the anaerobic methane productions were carried out. Finally, a 500 tons/day treatment process of anaerobic digestion and co-production of heat，power and fertilizer was designed in the light of the bench-scale experimental results. And the economic evaluation was carried out based on the analysis of mass and energy balance. The main conclusions are as follows: (1) The biochemical methane potentials (BMPs) of sugar and starch are 260 mL/gVS, and the BMPs of cellulose, crude fiber, protein and lipid are 244, 145, 258, 757 mL/gVS respectively. For the protein material, anaerobic degaradation would be inhibited by the high concentrations of volatile fatty acids (VFAs) and ammonia and an “inhibited steady state” without methane production may form. In case of lipid, anaerobic digestion would be inhibited by the long chain fatty acids (LCFAs). (2) Compared to the protein, lipid and lignocellulose, the carbohydrates (including sugar, starch and cellulose) are the optimal substrate for anaerobic hydrogen production. The anaerobic co-production of hydrogen and methane could be used to increase energy recovery efficiency. (3) The anaerobic degradation of kitchen waste was inhibited by the high concentration of VFAs. The anaerobic co-digestion of kitchen waste and waste paper can be adopted to avoid the inhibiton of VFAs. (4) Compared to the MS-OFMSW, the WS-OFMSW was a good material for anaerobic methane production with VS/TS of 61.6%. The methane yield of WS-OFMSW was 273~314 L/kgVS. (5) The economic feasibility was dependent on financial subsidy, tax incentive and extra revenue from clean development mechanisim (CDM).