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

Abstract

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 codigestion 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 codigestion 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.

Impacts of Anaerobic Co-Digestion on Different Influencing Parameters: A Critical Review

“…For example, a sewage-sludge-fed AD system sustained Microtrichaceae, the mono-digestion of cellulose had a bacterial population dominated by Ruminococcaceae (79.20%), and, for hemicellulose, Clostridiaceae dominated by 84.57%. In the same study, the co-digestion of sewage sludge and lignocellulosic biomass was dominated by Actinobacteria (40%), Proteobacteria (14.38%), and Chloroflexi (23.89%), which showed improved bacterial population diversity over a sole substrate [91].…”

“…Thus, anaerobic co-digestion of compatible substrates improves the stability of the bacteria population. In classical AD, it is mostly groups of phyla, such as Firmicutes, Bacteroidetes, Fibrobacteres, Proteobacteria, and Actinobacteria, that are dominant [91]. However, microorganism structures depend on the types of feed in a digester.…”