Bioelectrochemical treatment of acid mine drainage: Microbiome synergy influences sulfidogenesis and acetogenesis

• Published in: Sustainable Chemistry for the Environment Vol. 6; p. 100106
• Main Authors: J., Annie Modestra, Bajracharya, Suman, Matsakas, Leonidas, Rova, Ulrika, Christakopoulos, Paul
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2024; Elsevier
• Subjects: Acid mine drainage; Autotrophic sulfate reduction; Biochemical Process Engineering; Biokemisk processteknik; Bioremediation; Metal sulfides; Microbial synergy; Microbial synergy; Bioremediation; Autotrophic sulfate reduction; Acid mine drainage; Metal sulfides
• ISSN: 2949-8392; 2949-8392
• DOI: 10.1016/j.scenv.2024.100106

Bioelectrochemical systems (BES) are emerging as potential technologies that can remediate acid mine drainage (AMD) by cathodic reduction of sulfates to metal sulfides. This study evaluated bioelectrochemical remediation of sulfate rich AMD at two applied cathode potentials; BES-1: −1.0 V and BES-2: −0.8 V. Sulfate reducing bacteria were selectively enriched to be used as biocatalyst in BES. Initially, lactate was fed as carbon source and switched to chemolithoautotrophy with only CO2-fed conditions. Both BESs were operated at 3±0.2 g/l of sulfate with synthetic AMD (SAMD) fed first, and gradually changed to 50% AMD from mining site with 50% SAMD. Sulfate reduction was relatively higher with BES-1: 82% than BES-2: 76% coupled with sulfidogenesis. Interestingly, acetogenesis (BES-1: 2.12±0.2 g/l, BES-2: 1.9±0.2 g/l) was also noticed with high reduction currents (BES-1&2: >-70 mA). Microbiome community analysis revealed the dominant presence of sulfate reducers, acetogens, syntrophic bacteria and Methanobacterium, probing microbial synergy aiding sulfate reduction. An added advantage was the iron-sulfide (FeS) particles formation on cathode, which might have contributed to increased reduction currents. This study reveals insights into microbial synergy for autotrophic sulfate reduction within mixed microbiome communities along with the impact of FeS particles as conducive facilitator for electron transfer in BES, thereby enhancing electrosynthetic acetate production. [Display omitted] •Bioelectrochemical autotrophic sulfate reduction is attained in AMD.•Electrosynthetic acetate production is observed along with sulfate reduction.•Fe-S particles could act as conducive aids for electron transfer in BES.•Microbial synergy among diverse bacteria enhanced autotrophic sulfate reduction.•Microbiome analysis revealed dominant presence of Methanobacterium on cathode.