The benefits of autotrophic nitrogen removal from high concentration of urea wastewater through a process of urea hydrolysis and partial nitritation in sequencing batch reactor. (15th August 2021)

• Record Type: Journal Article
• Authors: Chen, Yongxing; Chen, Haochuan; Chen, Zhenguo; Hu, Haolin; Deng, Cuilan; Wang, Xiaojun
• Is Part Of: Journal of environmental management. Volume 292(2021)
• Publication Date: 2021-08-15
• Subjects: Urea wastewater -- Intracellular hydrolysis -- Free ammonia -- Partial nitritation -- Anammox; AOB Ammonium-oxidizing Bacteria -- CANON Completely autotrophic nitrogen removal over nitrite -- DO Dissolved oxygen -- FA Free ammonia -- MLSS Mixed liquor suspended solids -- NAR Nitrite accumulation rate -- NOB Nitrite-oxidizing Bacteria -- NRE Nitrogen removal efficiency -- NRR Nitrogen removal rate -- TN Total nitrogen -- SBR Sequencing batch reactor -- URE Urea removal efficiency; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2021.112762
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: For the sake of high efficiency and saving operational cost for high-concentration urea wastewater treatment, a novel two-stage partial nitritation (PN)-anammox process containing simultaneous urea hydrolysis and PN in sequencing batch reactor (SBR) was investigated. Although the influent urea concentration increased from 500 to 1200 mg/L, the SBR simultaneously achieved urea removal efficiency higher than 98% and stable PN with effluent NO2 − -N/NH4 + -N ratio of 1.0–1.3 without any extra alkalinity addition. The intracellular hydrolysis was the dominant mechanism for urea removal and persistent free ammonia inhibition on nitrite-oxidizing bacteria was the main reason for nitrite accumulation of 97.92% in SBR. The subsequent anammox reactor showed efficient nitrogen removal performance with average ammonium removal efficiency, nitrogen removal efficiency and maximum nitrogen removal loading rate of 98.08%, 81.45% and 1.05 kg N·m −3 ·d −1 respectively. High-throughput sequencing results indicated Gemmatimonadetes became the most abundant bacterial phylum related to potential intracellular urea hydrolysis and displayed obvious ammonium-oxidizing bacteria enrichment and nitrite-oxidizing bacteria inhibition in SBR, and the dominant anammox bacteria ( Candidatus_Kuenenia ) in anammox reactor. The proposed process was proven to be promising for high-concentration urea wastewater treatment, facilitating the sustainable development of the urea industry in the future. Graphical abstract: Image 1 Highlights: A novel biological nitrogen removal process for urea wastewater was investigated. Autotrophic N removal with no alkalinity added was achieved for urea wastewater. Intracellular urea hydrolysis and stable partial nitritation was integrated in SBR. 81.45% of total N was removed by anammox with N removal rate of 1.05 kg N·m −3 ·d −1 .