Reinforcement of methanogenesis in anaerobic digesters through the application of a purple non-sulfur bacteria bio-augmentation scheme

Abstract

Purple non-sulfur bacteria generally possess a distinguishingly diverse metabolism, rendering them being classified among the most adaptable bacteria. Rhodobacter capsulatus, ATCC® 11166™ strain, was utilized for inoculating two bench-scale anaerobic digestion reactors, within an experimental configuration comprising five bench-scale anaerobic digestion reactors. The investigation assessed the effect of applying a bio-augmentation scheme onto anaerobic digestion processes, with respect to biodegradation, resilience, and energy capture efficiency. The results implied significant evidence of the positive impact of the applied scheme onto the methanogenesis process within the bio-augmented reactors, comparing the outputs attained within the bio-augmented reactors to the non-bio-augmented reactors. An increase within the specific methane production per added and destroyed chemical oxygen demand was observed, associated with a consequent increase in chemical oxygen demand destruction. This indicated an overall enhancement of the anaerobic digestion processes, specifically those typically attributed to the methane-forming Archaea. The bio-augmented reactors were also subjected to a set of perturbation-causing conditions, aiming to assess the performance of the methanogenic culture under such conditions, as compared to non-bio-augmented reactors that are subjected to the same conditions. A relatively higher and more stable methane production rate was observed within the bio-augmented reactors, during the application of the referred-to conditions.