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Lei Z, Xue J, Feng Y, Li YY, Kong Z, Chen R. Sludge granulation in PN/A enhances nitrogen removal from mainstream anaerobically pretreated wastewater. Sci Total Environ 2023; 895:165048. [PMID: 37355132 DOI: 10.1016/j.scitotenv.2023.165048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/23/2023] [Accepted: 06/19/2023] [Indexed: 06/26/2023]
Abstract
Treating anaerobically pretreated wastewater using partial nitritation/anammox (PN/A) process faces severe challenges because of the complex syntrophic and competitive relationship among various bacteria. Results of this study suggested a continuous low dissolved oxygen (DO) concentration failed to sustain NH4+ removal (<80 %), whereas moderate DO concentrations with high aerobic periods suppressed anammox reaction. Through implementing a moderate DO concentration with low aerobic periods (MDO-LA), NH4+ and total nitrogen removal efficiency reached 91.5 ± 5.5 % and 71.3 ± 2.8 % respectively. The specific activities of ammonium-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing bacteria (AnAOB) reached 0.942 ± 0.030 and 0.277 ± 0.010 g nitrogen per gram mixed liquor volatile suspended solids, respectively, mainly because MDO-LA favored Thiothrix (filamentous bacteria) wash-out and promoted Nitrosomonas growth. Moreover, sludge granules covered by a thin exterior rim with abundant AOB were formed, favoring Ca. Brocadia growth (5.4 % to 13.2 %) and mass transfer between AOB and AnAOB, which consequently increased the expression of genes coding hydroxylamine oxidase and hydrazine synthase. Overall, achievements in this study provide a promising operating strategy for PN/A treating anaerobically pretreated wastewater.
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Affiliation(s)
- Zhen Lei
- Key Lab of Environmental Engineering, Shaanxi Province, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an 710055, PR China
| | - Jingjing Xue
- Key Lab of Environmental Engineering, Shaanxi Province, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an 710055, PR China
| | - Yongning Feng
- Key Lab of Environmental Engineering, Shaanxi Province, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an 710055, PR China
| | - Yu-You Li
- Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan
| | - Zhe Kong
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
| | - Rong Chen
- Key Lab of Environmental Engineering, Shaanxi Province, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an 710055, PR China; International S&T Cooperation Center for Urban Alternative Water Resources Development, Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an 710055, PR China.
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