Two-stage process combines anaerobic and aerobic methods

The organic fraction of the material diverted from landfills has potential to be utilized as a raw material to be recycled, used for the production of compost, converted to energy in waste-to-energy facilities, or used for the production of other end products. Given the uncertainties concerning the future availability, production costs, and market prices for conventional fuels, any potential source of alternate energy and alternative energy technologies deserve serious consideration. Faced with an uncertain energy future, several European countries have already started using biomass and MSW as a source of energy. An innovative high-solids anaerobic digestion/aerobic composting process currently under investigation at the University of California, Davis is as an ideal candidate for processing a large fraction of the organic matter in MSW. The principal advantages of this innovative process which is described and discussed in this paper are: (1) the recovery of biogas that can be used as a fuel for the production of energy, and (2) the production of humus-like material that can be used as a high-quality soil amendment or as boiler fuel. The fact that a liquid waste stream that needs further treatment is not generated in this process is another significant advantage.