Hydraulic flow direction alters nutrients removal performance and microbial mechanisms in electrolysis-assisted constructed wetlands. (April 2021)

• Record Type: Journal Article
• Authors: Wang, Yingmu; Zhou, Jian; Shi, Shuohui; Zhou, Jiong; He, Xuejie; He, Lei
• Is Part Of: Bioresource technology. Volume 325(2021)
• Publication Date: 2021-04
• Subjects: Electrolysis-assisted constructed wetland -- Tertiary treatment -- Hydraulic flow direction -- Multi-path denitrification -- Microbial community structure; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2021.124692
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: Hydraulic flow direction altered nutrients removal and microbial ecology in E-VFCWs. Down-flow mode of E-VFCWs favored higher NO3 − -N reduction efficiency. Multi-path denitrification occurred in the E-DFCW, whereas AHD dominated in the E-UFCW. S cycle (sulfate reduction/pyrite deposition/PDAD) enhanced N removal in the E-DFCW. More abundant and diverse denitrifiers enhanced N removal efficiency in the E-DFCW. Abstract: In this study, an electrolysis-assisted down-flow constructed wetland (E-DFCW) was successfully established, and achieved simultaneously efficient removal of PO4 3− -P (93.6% ± 3.2%), NO3 − -N (97.1% ± 2.0%) and TN (80.6% ± 5.4%). When compared with electrolysis-assisted up-flow constructed wetland (E-UFCW), E-DFCW allowed significantly lower concentrations of PO4 3− -P, NO3 − -N, total Fe and SO4 2− -S in effluents. In addition, microbial community and functional genes prediction results indicated that hydraulic flow direction significantly altered microbial nitrogen, sulfur and carbon metabolisms in electrolysis-assisted constructed wetlands (E-CWs). Specifically, multi-path denitrification facilitated NO3 − -N reduction in cathodic chamber of E-DFCW, whereas autohydrogenotrophic denitrification might dominate NO3 − -N reduction in cathodic chamber of E-UFCW. More abundant and diverse denitrifiers in cathodic chamber of E-DFCW contributed to enhanced denitrification performance. Overall, this work provides microbial insights into multi-path nitrogen metabolisms in electrolysis-assisted denitrification systems in response to hydraulic flow direction.