Microbial Community Dynamics of a Sequentially Fed Anaerobic Digester Treating Solid Organic Waste

A 50 kg-scale high solids anaerobic digestor comprising six sequentially-fed leach beds with a leachate recirculation system and an upflow anaerobic sludge blanket reactor was operated at 37{degrees}C for 88 weeks. The feedstock contained a constant fibre fraction (a mix of cardboard, boxboard, newsprint, and fine paper) and varying proportions of food waste. Significantly enhanced co-digestion and methane production from the fibres was observed as the proportion of FW was increased. The most abundant 16S rRNA amplicon sequence variant (ASV), classified as Clostridium butyricum, was correlated with the amount of FW in the system and total methane yield. However, methane yield specifically from the fibre fraction was significantly correlated with organisms classified as Candidatus Roizmanbacteria and Spirochaetaceae. These ASVs together with ASVs classified as Anaerovorax and Methanoculleus correlated strongly to other ASVs in the microbial community, suggesting these are vitally important for ecosystem function and methane production. In addition, tracing the fate of microbes derived from incoming food waste helped to diagnose a poor batch of bulking agent. Table of Contents (TOC)/ Abstract Art O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/487789v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@2a191forg.highwire.dtl.DTLVardef@1d7497corg.highwire.dtl.DTLVardef@119a43aorg.highwire.dtl.DTLVardef@6d056e_HPS_FORMAT_FIGEXP M_FIG C_FIG