Microbial Electrosynthesis of Bioalcohols through Reduction of High Concentrations of Volatile Fatty Acids

Abstract

The efficiency and characteristics of conversion of volatile fatty acids (VFAs) into alcohols by a microbial electrosynthesis (MES) process were significantly influenced by the initial organic loading concentration and operational period. The acetate and butyrate concentrations ranged from 2 to 8 g-COD/L, and alcohol and other product formations were determined over a 5 day operation. The highest yield of 0.218 g-CODAlcohol/g-CODVFAs was obtained for 4 g-COD/L after a 1 day operation. A gradual decrease over time in alcohol recovery was noticed for all VFA concentrations due to methane generation under elevated pH conditions. At the end of the operation, a higher bioalcohol yield was achieved at a relatively lower VFA concentration of 2 g-COD/L. A large fraction of initial VFAs remained unchanged without bioenergy production from higher substrate concentrations (6 and 8 g-COD/L). The energy recovery of total products (alcohols and methane) based on the input power was less than about 24% at the end of the operation. This study suggests that the optimized loading of VFA and low-pH conditions are essentially required to increase the overall performance of the MES system for alcohol production.

Highly Porous FexMnOy Microsphere as an Efficient Cathode Catalyst for Microbial Electrosynthesis of Volatile Fatty Acids from CO2

“…The MESs were operated under 0.8 V DC power supply source derived from Array 3645 A; 0–36 V/0‐3 A; circuit specialists Ln., USA. The negative lid of the power supply was connected to the cathode; whereas the positive pole was connected with the anode . The MES with catalyzed cathode and without catalyzed cathode (pristine carbon cloth) are named as MES‐1 and MES‐2 throughout the manuscript.…”

Electro-fermentation: Sustainable bioproductions steered by electricity

“…Mainly originating from environmental engineering and target applications such as wastewater treatment, bioelectrochemical-based potential control was quickly also proposed for steering anaerobic fermentations of undefined mixed microbial cultures. Here, the means of process control are in general limited and steering the activity of the community to, as an example, a more reduced product spectrum (as reported in Figure 1D), like fuel gases (hydrogen and methane) or alcohols from volatile fatty acids or sugars has proven very successful (Gavilanes et al, 2019; J o u r n a l P r e -p r o o f Sasaki et al, 2018;Shanthi Sravan et al, 2018;Villano et al, 2017). However, the possibility to enhance the production of oxidized compounds via ORP-driven EF as explained above cannot be ruled out.…”

Microbial electrosynthesis of methane and acetate—comparison of pure and mixed cultures

“…A mix of products was observed in other studies as besides methanogens (Song et al 2019a). A diverse group of microorganisms were present in native mixed cultures that were capable of reducing CO 2 to acetate or higher volatile acids in MES reactors (Arends et al 2017;Batlle-Vilanova et al 2017;Gavilanes et al 2019;Vassilev et al 2019;Mateos et al 2019). To avoid more than one product, the consortium of microorganisms must be selected beforehand.…”