Bioelectrochemical system for the enhancement of methane production by anaerobic digestion of alkaline pretreated sludge

Biomethane Yield, Physicochemical Structures, and Microbial Community Characteristics of Corn Stover Pretreated by Urea Combined with Mild Temperature Hydrotherm

“…This further induced reproduction and resulted in a high abundance of hydrogenotrophic Methanobacterium at the later stage. This finding was also similar to the report by Xu et al [ 45 ].…”

“…There was no significant difference in bacterial compositions for each pretreated sample, meaning that all pretreated samples had similar bacterial communities at the phylum level. The high abundance of Firmicutes suggested that the pretreatment was a suitable method for subsequent biomethane production [ 45 ]. However, untreated CS showed an obvious difference in bacterial composition.…”

“…Since CS is a kind of lignocellulosic substrate, hydrolysis is normally a limiting step. Increased Firmicutes abundance should be capable of facilitating cellulose hydrolysis and further acidification processes [ 45 ]. At the beginning of AD, more soluble components and easily-degradable substrates caused a rapid profusion of Firmicutes for all pretreated groups due to their high content of easily-degradable components.…”

How Operational Parameters Affect Electromethanogenesis in a Bioelectrochemical Power-to-Gas Prototype

“…Apart from Methanothrix (32.4 ± 8.4%), the cathode samples revealed the significant presence of OTU 14 and OTU 3, belonging to the genera Atopobium (Actinobacteria) and Methanobacterium (Euryarchaeota) (1.3 ± 0.01% and 0.1 ± 0.01%, respectively, p = 0.011 and p = 0.003 vs. bulk medium; p = 0.002 and p < 0.001 vs. anode). While Methanobacterium is a wellknown H 2 -consuming methanogen and was often reported in the microbial community of EMG biocathodes (Flores-Rodriguez and Min, 2020;Xu et al, 2020; among others), Atopobium was not previously reported and its role is not clear at this stage. In conclusion, the description of the microbial community colonizing the EMG-BES prototype indicated the biological syntrophic relationships between its more relevant members and, as a consequence, the opportunities of such bioelectrochemical system for the simultaneous achievement of electricity storage, CO 2 conversion to CH 4 and wastewater treatment, due to the metabolic potential of the microbial diversity inhabiting this particular ecosystem.…”

“…The single-chamber EMG-BES process requires the presence of both organic matter and CO 2 in wastewater, to sustain the complementary reactions of oxidation at the anode and reduction at the cathode. As organic matter oxidation generates CO 2 , the process can be run efficiently with a regular feeding of wastewater, or sludge (Moreno et al, 2016;Xu et al, 2020). On the other hand, CO 2 injection can contribute to EMG (and generally to bioelectrochemical processes) by increasing the electrical conductivity of the medium, reducing cathode overpotentials and voltage requirements (Rodríguez-Alegre et al, 2019).…”