Effects of electrochemical intervention on the remediation of black-odorous water: insights into microbial community dynamics and functional shifts in sediments

Abstract

Black-odorous water is a severe environmental issue that has received continuous attention. The major purpose of the present study was to propose an economical, practical, and pollution-free treatment technology. In this study, the in situ remediation of black-odorous water was conducted by applying different voltages (2.5, 5, and 10 V) to improve oxidation conditions of the surface sediments. The study investigated the effects of voltage intervention on water quality, gas emissions, and microbial community dynamics in surface sediments during the remediation process. The results indicated that the voltage intervention can effectively increase the oxidation–reduction potential (ORP) of the surface sediments and inhibit the emissions of H2S, NH3, and CH4. Moreover, the relative abundances of typical methanogens (Methanosarcina and Methanolobus) and sulfate-reducing bacteria (Desulfovirga) decreased because of the increase in ORP after the voltage treatment. The microbial functions predicted by FAPROTAX also demonstrated the inhibition of methanogenesis and sulfate reduction functions. On the contrary, the total relative abundances of chemoheterotrophic microorganisms (e.g., Dechloromonas, Azospira, Azospirillum, and Pannonibacter) in the surface sediments increased significantly, which led to enhanced biochemical degradability of the black-odorous sediments as well as CO2 emissions. HIGHLIGHTS Voltage intervention contributes to the remediation of black-odorous water.; Applied voltages can effectively improve the oxidation conditions in the sediments.; Voltages significantly inhibited the emissions of H2S, NH3, and CH4 from sediments.; Relative abundances of methanogens and sulfate-reducing bacteria decreased at 10 V.; Abundances of chemoheterotrophic microorganisms increased with increasing voltage.;

Keywords

• black-odorous water
• methanogenesis
• microbial community dynamics
• oxidation–reduction potential
• sulfate reduction
• voltage intervention