An electrode-assisted anaerobic digestion process for the production of high-quality biogas

Abstract

Biogas is a sustainable, renewable energy source generated from organic waste degradation during anaerobic digestion (AD). AD is applied for treating different types of wastewater, mostly containing high organic load. However, AD practice is still limited due to the low quality of the produced biogas. Upgrading biogas to natural gas quality (>90% CH4) is essential for broad applications. Here, an innovative bio-electrochemically assisted AD process was developed, combining wastewater treatment and biogas upgrading. This process was based on a microbial electrolysis cell (MEC) that produced hydrogen from wastewater at a relatively high efficiency, followed by high-rate anaerobic systems for completing biodegradation of organic matter and an in situ bio-methanation process. Results showed that CH4 production yield was substantially improved upon coupling of the MEC with the AD system. Interestingly, CH4 production yield increase was most notable once circulation between AD and MEC was applied, while current density was not markedly affected by the circulation rates. The microbial community analysis confirmed that the MEC enhanced hydrogen production, leading to the enrichment of hydrogenotrophic methanogens. Thus, directing soluble hydrogen from the MEC to AD is plausible, and has great potential for biogas upgrading, avoiding the need for direct hydrogen harvesting.

Effect of Electrolysis on Activated Sludge during the Hydrolysis and Acidogenesis Stages in the Anaerobic Digestion of Poultry Manure

“…There was a significant increase in the yield of biogas with treatment, possibly due to the specific effect of the electric current on complexly degradable quail manure. These findings are supported by previous studies conducted on substrates such as agroindustrial wastewater [28], municipal sewage sludge [29,30], and liquid waste from the wine industry [25,31]. On the sixth day of treatment, the CO 2 yield increased (24.0% in the conventional conditions and 27.3% in a two-chamber MEC) and the CH 4 yield increased (4.7% in the conventional conditions and 8.3% in a two-chamber MEC).…”

In situ Biogas Upgrading by CO2-to-CH4 Bioconversion

“…To reach the specification of natural gas, the CH4 content in biogas should be upgraded at least to 95%, at which point it is called biomethane or bionatural gas [11,12]. The biomethane can be used directly as vehicle fuel or injected into the natural gas grid, thereby broadening the range of applications and increasing the value of biogas [13]. For this purpose, biogas upgrading-increasing its CH4 content by removing CO2 or converting CO2 into CH4 is necessary [14].…”

Enhanced degradation and methane production of food waste anaerobic digestate by microbial electrolysis cell for a long-term running

“…In recent years, studies have found that microbial electrolysis cell (MEC) could improve methane yield by modulating microbiota structure and promoting electron transfer (Hui et al,2021;Yanuka-Golub et al,2019;Yu et al,2020). Gao et al used MEC to treat quinoline wastewater, they found that MEC could promote the synergistic effect of quinoline-degrading bacteria and electroactive bacteria, thus achieving simultaneous quinoline wastewater treatment and methane production (Gao et al,2020).…”