Abstract: A method, apparatus and system for processing municipal waste starts with a biomass that has been treated in at least one steam autoclave and dilutes the resulting biomass in a dilution tank while agitating the resulting mixture a sufficient amount and at an effective temperature to cause cellulose fibers within the biomass that became twisted during processing within the autoclave to relax and straighten out. The biomass mixture is fed into a hybrid anaerobic digester having separate zones for digesting the solid portion of the biomass and the fluid portion of the biomass. The hybrid anaerobic digester is a vessel having an inner zone for digestion of the solid portion of the biomass and a concentric outer zone having attached growth media that retains methane producing organisms which produce biogas from the fluid portion of the biomass.