Microbiota of anaerobic digesters in a full-scale wastewater treatment plant

Abstract

Abstract:Anaerobic digestion is an important technology for the bio-based economy. The stability of the process is crucial for its successful implementation and depends on the structure and functional stability of the microbial community. In this study, the total microbial community was analyzed during mesophilic fermentation of sewage sludge in full-scale digesters.The digesters operated at 34-35°C, and a mixture of primary and excess sludge at a ratio of 2:1 was added to the digesters at 550 m 3 /d, for a sludge load of 0.054 m 3 /(m 3 ·d). The amount and composition of biogas were determined. The microbial structure of the biomass from the digesters was investigated with use of next-generation sequencing.The percentage of methanogens in the biomass reached 21%, resulting in high quality biogas (over 61% methane content). The abundance of syntrophic bacteria was 4.47%, and stable methane production occurred at a Methanomicrobia to Synergistia ratio of 4.6:1.0. The two most numerous genera of methanogens (about 11% total) were Methanosaeta and Methanolinea, indicating that, at the low substrate loading in the digester, the acetoclastic and hydrogenotrophic paths of methane production were equally important. The high abundance of the order Bacteroidetes, including the class Cytophagia (11.6% of all sequences), indicated the high potential of the biomass for effi cient degradation of lignocellulitic substances, and for degradation of protein and amino acids to acetate and ammonia.This study sheds light on the ecology of microbial groups that are involved in mesophilic fermentation in mature, stably-performing microbiota in full-scale reactors fed with sewage sludge under low substrate loading.

Metagenomics Study of the Microbes in Constructed Wetland System Treating Sewage

“…The abundance of Betaproteobacteria,. Deltaproteobacteria, Cytophagia and Flavobacteria are majorly responsible for organic and nutrient removal in WWTP [15]. Solibacteres (5.71%) is reported to be present in wetlands of Kolkata.…”

“…Dominance of Actinobacteria is reported in wastewater treatment plant, aeration basins and seawater processing wastewater treatment plant. Class Betaproteobacteria is responsible for nutrient and organic removal [15,6]. Ellin6529 is reported to be present in surface sediments of Helgoland mud area, North sea adapted to fresh organic matter.…”

“…Xanthomonadales is active under oxic conditions and survive in nutrient lacking systems. Anaerolineales represented 6.73% in anaerobic digestors of WWTP and capable of conducting chemoorganotrophic decomposition [15]. Anaerolineales, Planctomycetales and Myxococcales are common members of WWTP [6].…”

“…Xanthomonadaceae is reported to exist in WWTP and activated sludge capable of metabolising hydrocarbon and nutrient removal in aerobic granular sludge wastewater treatment systems. They produce extracellular polymeric substances that support biomass production [15]. Hyphomicrobiaceae positively correlates with NH4 N removal [20] and removal of micropollutants in ecological WWTP.…”

Integrative analyses to investigate the link between microbial activity and metabolites degradation during anaerobic digestion

“…Group 2 correlated 14 OTUs from the orders Cloacimonadales, Clostridiales, Anaerolineales, Synergistales, Bacteroidales, Hydrogenedentiales and Coprothermobacterales to 8 molecules including compounds from tryptophan degradation (L-tryptophanol and tryptamine, X217 and X269, respectively), 6-methylquinoline and thioxoacetic acid, among others. In agreement with these metabolites, Anaerolineales and Synergistales are known for their ability to degrade amino acids (Swiatczak et al, 2017). Thus, their correlation with L-tryptophanol and tryptamine is consistent with the literature.…”