Removal of Ni (II) and microbial dynamics in single-chamber microbial electrolysis cell

Abstract:

[Objective] Single-chamber microbial electrolysis cell (SMEC), inoculated by granular sludge from upflow anaerobic sludge bed, can remove Ni(Ⅱ). Therefore, it is of great significance to explore the role microbial community to remove Ni(Ⅱ) in SMEC.[Methods] With sodium acetate as substrate, single-factor control method and Illumina high-throughput sequencing were applied to analyze Ni(Ⅱ) removal, as well as microbial community structure and dynamic characteristics in SMEC.[Results] Adsorption and microbial functions were the major mechanisms for removing Ni(Ⅱ). In mature single-chamber microbial fuel cell (SMFC), Geobacter sp. of Proteobacteria (91.42%) was dominant on the anode with an abundance of 76.25% whereas Niabella sp. of Bacteroidetes (47.99%) was dominant on the cathode with an abundance of 33.01%, followed by Ochrobactrum sp. of Poribacteria (45.74%) accounting for 10.08%. In SMEC modified from mature SMFC with 12.5 mg-Ni(Ⅱ)/L, the dominant bacteria turned from single Geobacter sp. to Geobacter sp. (41.56%) and Azospirillum sp. (5.97%) on the anode; the dominant bacteria on the cathode turned from Niabella sp. and Ochrobactrum sp. to Acetoanaerobium sp. (19.28%), Dokdonella sp. (16.48%) and Azospirillum sp. (9.49%).[Conclusion] Microbial populations in raw sludge were selectively acclimated in the Ni(Ⅱ) removal process of SMEC, and effective microbial communities of electrogenesis and nickel removal were built on the electrode to promote the removal of Ni(Ⅱ) in SMEC.