Abstract
High rate thermophilic methane fermentation using a gas circulation-type reactor was explored for its potential to reduce the volume of and make beneficial use of municipal solid waste (MSW) . Treatment without addition of mineral nutrients allowed for a maximum TS volumetric loading rate of only 1 g/l⋅d. However, with addition of mineral nutrients, a high TS volumetric loading rate of 8 g/l⋅d was achieved. At a TS loadingrate of 1 g/l⋅d, the methanogenic activity with addition of mineral nutrients was 4-fold higher than that without mineral nutrients. The concentrations of coenzymes F430 and corrinoids were 0.12 μmol/g-VSS and 0.07 μmol/g-VSS, respectively, at a TS volumetric loading rate of 8 g/l⋅d. Carbon recovery at each TS volumetric loading was nearly 100%, and about 50% of the carbon in raw waste was converted to methane gas. The degradation efficiency of lipid, protein, holocellulose and lignin were 90.7%, 59.4%, 91.9% and 66.0%, respectively. To repress the evolution of hydrogen sulfide, air was supplied to the anaerobic reactor, by which the concentration of hydrogen sulfide in biogas was reduced nearly 100% when air at 7.5% of the amount of evolved biogas was used.
