Acetate-to-bioproducts by chain elongation microbiome catalysis under applied voltage regulation

Abstract

Acetate is the main component in the anaerobic digestion broth of organic waste, which is difficult to be extracted and further recovered because of its completely miscibility. A novel technology convert acetate to bioproducts (like ethanol, butyrate, and caproate) in electro-fermentation system by chain elongation microbiome has recently attracted attention. This work focused on the fate of acetate as substrate and sole electron acceptor under different applied voltage regulation. Products spectrum analysis showed that acetate was effectively converted and accumulated to a maximum concentration of 4.26 g L−1 ethanol firstly at 0.6 V, then butyrate (2.40 g L−1) and caproate (0.12 g L−1) were synthesized respectively. With the increase in voltage intensity, the bioconversion performance of acetate gradually deteriorated. The monitoring results of cathode chamber indicated an appropriate applied voltage creating a more favorable conversion environment for chain elongation microbiome, and a biocathode with better redox capability could act as an effective catalyst, contributing to the hydrogen-mediated electron transfer for chain elongation process. The correlation analysis between cathode multi-parameters and bioproduct performance at 0.6 V showed that the chain elongation process may be more dependent on the fermentation environment than the reduction of acetate to ethanol, especially for pH and redox potential. This study provides a sustainable and energy-saving platform for producing bioproducts from readily available acetate under the regulation of applied voltage.