Specific energy output from urban residues degraded with leachate and an off-specification industrial carbonated beverage as moisture sources

Landfill leachate was stored at −80 °C or freeze-dried and thereafter evaluated for fermenting cellulose. The −80 °C frozen leachate degraded cellulose under anaerobic conditions, generating 80% CH4 by 127 d. In bench-scale bioreactor studies, the fermentation of synthetic urban residues that received various amounts and types of moisture was compared. Archaea, probed using fluorescent in situ hybridization (FISH), were significantly (p<0.05) higher in leachate-moistened residues. CH4 production was completely inhibited when a non-diluted carbonated off-specification beverage (COSB) was the source of moisture, but this treatment provided maximal H2 production. The soluble COD was determined at two sampling intervals increased significantly (p<0.05) in instances where degradation had been enhanced by the presence of a landfill leachate and a diluted COSB. The specific energy output from the fermenting residues was up to 24-fold in leachate-moistened residues compared with water-moistened residues. Thus, adding moisture to landfilled residues can add to their value but the quality, quantity, and timing of such moisture additions have a direct impact on the specific energy output from the residues.