Computational and experimental analysis of organic degradation positively regulated by bioelectrochemistry in an anaerobic bioreactor system

Abstract

Methane production was tested in membrane-less microbial electrolysis cells (MECs) under closed-circuit (R) and open-circuit (R) conditions, using glucose as a substrate, to understand the regulatory effects of bioelectrochemistry in anaerobic digestion systems. A dynamic model was built to simulate methane productions and microbial dynamics of functional populations, which were colonized in groups R and R during the start-up stage. The experiment results showed significantly greater methane production in R than R, the average methane production of R was 0.131 m/m/d, which was 1.4 times higher than that of R (0.055 m/m/d). The simulation results revealed that bioelectrochemistry had a significant influence on the abundance of microorganisms involved in acidogenesis and methanogenesis. The abundance of glucose-uptaking microorganisms was 87% of the total biomass in R without applied voltage, which was 20% higher than that in R (67%) when external voltages were applied between the anode and cathode. The abundance of hydrogenotrophic methanogens in R was 6% higher than that in R. The simulation results were verified through 16S rDNA high-throughput sequencing analysis. An electron balance analysis revealed that alteration of the acidogenesis type led to more acetate and hydrogen production from glucose fermentation, compared with the situation without bioelectrochemistry. An additional pathway from acetate to hydrogen was introduced by bioelectrolysis. These two factors resulted in significant enhancement of methane production in R. Bioelectrolysis process directly contributed to 26% of the total methane production after the start-up stage. When the applied voltages were cut down or decreased, R could maintain considerable methane productions, because the microbial communities and electron transfer pathways were already formed. Starting-up with high voltage, but operating under low voltage, could be an energy-favorable strategy for accelerating biogas production in bioelectro-anaerobic bioreactors.

Integrating microbial electrochemical technologies with anaerobic digestion to accelerate propionate degradation

“…The net energy that could be recovered from methane in the highest propionate concentration (taking into account the electricity input of the MET when applicable, Table 3) shows an unfavorable balance for hybrid systems (R3, R4 and R5) and places R1 as the most efficient system. It is plausible that the application of METs to AD is more interesting as a means of improving the process in critical aspects than as a vehicle for direct energy recovery, as can be deduced from other works that have reported a limited improvement of these combined systems [44]. This research also suggests that applying a cell potential in early stages of AD could provide a positive energy balance.…”

Microbial community response and SDS-PAGE reveal possible mechanism of waste activated sludge acidification enhanced by microaeration coupled thermophilic pretreatment

“…In this study, to evaluate how the pretreatment operation (MT, M and T) affected the microbial community, three samples were collected from MT, M and T at the end of pretreatment for 24 h and the acidification stage. The genomic DNA of the samples was extracted using an extraction kit (WATSON BIOTECHNOLOGIES Co. Ltd. Shanghai, China) according to the manufacturer's instructions [32]. DNA extracts were used as the template for PCR amplification of the 16S rRNA gene.…”

Electron Fluxes in Biocathode Bioelectrochemical Systems Performing Dechlorination of Chlorinated Aliphatic Hydrocarbons

“…In this study, the pathway with acetate as a direct electron donor for CAHs dechlorination existed in heterotrophic biocathode. In addition, an electron transfer pathway from acetate to hydrogen could be introduced by bioelectrolysis ( Guo et al, 2017 ), competing with dechlorination for electrons provided by acetate. Methane production by acetotrophic and hydrogenotrophic methanogens was considered as an electron sink in heterotrophic biocathode, ultimately reducing the fraction of electrons provided from acetate and electrode that were used for CAHs dechlorination.…”