HIGH-RATE BIOMETHANATION USING SPENT BIOMASS AS BACTERIAL SUPPORT

Methanogenic bacteria were found strongly adhered to several green bio mass feedstocks digested in a solid-phase stratified bed (SSB) biogas fermenter, and hence these digested feedstocks were examined for their potential for use as methanogen support for a high-rate biogas fermen ter, A 1.1 l experimental down flow fixed bed (DFFB) fermenter was ope rated at 35 degrees C using synthesized liquid waste, This gave gas pr oduction levels up to 6.5 l/l/d, Methanogenic activities measured on s uch biomass support material exhibited a potential to achieve much hig her biogas production, Short-duration thermal and feed shocks were tol erated without their exhibiting typical methanogen washout characteris tics. The DFFB fermenter functioned well even at 21 +/- 1 degrees C, w ith gas production rates up to 3 l/l/d, and thus appeared to have pote ntial for producing biogas at small scales and at high rates from vari ous combinations of liquid and solid biomass wastes.