Characteristics of N2O generation within the internal micro-environment of activated sludge flocs under different dissolved oxygen concentrations. (November 2019)

• Record Type: Journal Article
• Authors: Yan, Xu; Zheng, Shikan; Qiu, Dezhi; Yang, Jie; Han, Yunping; Huo, Zhaoman; Su, Xianfa; Sun, Jianhui
• Is Part Of: Bioresource technology. Volume 291(2019)
• Publication Date: 2019-11
• Subjects: Nitrous oxide -- Activated sludge flocs -- Micro-environment -- Microelectrode -- Microbial community; 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.2019.121867
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: The DO, NH4 + –N, and NO3 − –N concentrations in flocs under 1 mg DO/L and 2 mg DO/L were compared for different particle sizes. The N2 O concentrations and generation rates were distinct with different micro-environment of flocs. The microbial community and distribution characteristics correlated with the micro-environment of flocs. Abstract: Nitrous oxide (N2 O) is a strong greenhouse gas that is produced in significant quantities through biological nitrogen removal processes in wastewater treatment plants; however, N2 O generation within the internal micro-environment of activated sludge flocs (ASFs) is poorly understood. In this study, microelectrodes and molecular techniques were employed to investigate the concentrations of N2 O and other chemicals and the composition and distribution of microbes within ASFs, respectively. The results showed that N2 O generation was correlated with the ASF micro-environment, and was significantly influenced by the dissolved oxygen (DO) concentration of the bulk wastewater. Equal N2 O, DO, NH4 + –N, and NO3 − –N concentrations were found in small flocs (<100 μm). By contrast, higher N2 O generation rates and lower DO, NH4 + –N, and NO3 − –N concentrations were detected in the center of large flocs (>200 μm) compared with those at their surfaces. Microbial structures of varying particle sizes were distinct and depended on the micro-environmental characteristics.