Experimental study on anaerobic co-digestion of the individual component of biomass with sewage sludge: methane production and microbial community

The co-digestion of the individual component of biomass with sewage sludge was investigated, concerning the cumulative methane yield, variation of pH, chemical oxygen demand (COD), volatile fatty acids (VFAs), and total ammonia nitrogen (TAN) during 50-day digestion. The microbial community at the initial stage (stage I) and maximum methane production rate stage (stage II) of the digestion process were identified by Illumina MiSeq sequencing. The cumulative methane yield from co-digestion of cellulose and sludge was increased by 33.33% over the calculated value from that of mono-digestion of cellulose and sludge, while that from co-digestion of hemicellulose and sludge was achieved as 259.32% compared with the calculated value from that of mono-digestion of hemicellulose and sludge. The Firmicutes to Bacteroidetes (F/B) ratio at the stage II of co-digestion of hemicellulose and sludge was notably decreased from 46.53 to that of 1.39 for mono-digestion of hemicellulose. The percentage of Methanosarcina in acetoclastic methanogens at the stage II of mono-digestion of hemicellulose was largely increased from 1.06% to that of 97.03% for co-digestion of hemicellulose and sludge.