Biogas upgrading and energy storage via electromethanogenesis using intact anaerobic granular sludge as biocathode

Beyond the farm: Making edible protein from CO2 via hybrid bioinorganic electrosynthesis

“…AnGS, collected from a wastewater treatment plant operated by Colsen, Netherlands, was used as the biocatalyst for the bioconversion of CO 2 to CH 4 . 34,63 According to our previous study, the dominant Archaea in the raw AnGS were identified as Methanobacterium (14.7% ± 0.7%) and Methanosaeta (14.2% ± 0.5%). 34 The abundance of the hydrogenotrophic methanogen Methanobacterium increased to 28.5%-37.7% after the bio-electrochemical acclimatization.…”

“…The cathode potential was stable at around À1.6$-1.7 V (Ag/AgCl) with slight fluctuations, within the range of the electromethanogenesis process as reported. 32,34,35 Catholyte alkalization is a common problem in the MESs, and therefore, pH control is usually necessary. 3,35,36 Although the acidic anolyte (pH 1-2) could promote protons to move toward the cathode chamber and thereby balance the cathodic pH, the catholyte pH in Control 1 experiment (no CO 2 supply) kept increasing to 9.85 ± 0.42 at the end of the batch (Figure S1).…”

“…The results could be due to the fact that a higher CO 2 flow rate might increase the dissolved CO 2 (aqueous solution [aq]) and HCO 3 À (aq), and thus, diminish gas-liquid-solid mass transfer resistance for the CO 2 -to-CH 4 conversion. 34,44 Besides, the higher concentration of bicarbonate can improve the catholyte conductivity and reduce the system internal resistance. 32 Furthermore, the cathode potential decreased from…”

In situ Biogas Upgrading by CO2-to-CH4 Bioconversion

“…Similarly to the other in-situ methods, renewable electricity can be used to hydrolyze water to form O2 and H + at the anode, and then the H + and eare transferred to the biocathode to reduce CO2 into CH4 [44]. The main difference is that the reducing equivalents are provided as H + and erather than H2 [45][46][47].…”

Gas Biological Conversions: The Potential of Syngas and Carbon Dioxide as Production Platforms

“…A thorough review was published in early 2019 with extensive details on the microbiological aspect of the process and the main factors affecting it [124]. Since then Zhou et al [125] performed the first study using intact anaerobic granular sludge as a biocatalyst in the cathode of the electrolytic cell. The methane content of the produced gas exiting the cell reached a maximum value of 97.9 ±2.3% at an applied voltage of 4 V and the dominant genus in the sludge was the hydrogenotrophic methanogen Methanobacterium.…”