Increasing specific biomass nitrogen load facilitated nitrite accumulation in mainstream wastewater treatment

• Published in: Bioresource technology 2023-10, Vol.385, p.129337-129337, Article 129337
• Main Authors: Zhang, Jianhua, Zhang, Wenke, Bi, Xuejun, Gao, Zhongxiu, Li, Yitong, Miao, Yuanyuan
• Format: Article
• Language: English
• Subjects: Bacterial activity analysis; Mainstream partial nitrification; Nitrification sludge; Nitrogen loading rate; Solids retention time
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2023.129337

[Display omitted] •Increasing BNL could promote nitrite accumulation in mainstream wastewater treatment.•Initial high AOB activity in sludge can further accelerate the nitrite accumulation.•Controlling biomass growth was important to start up mainstream PN via increasing BNL.•Desirable PN with an average NAR of 81.7% was obtained via controlling SRT at 30 days.•Increasing BNL by regulating SRT could be a potential way for start-up of PN process. By regulating influent nitrogen loading rate (NLR) and solids retention time (SRT), the effect of specific biomass nitrogen load (BNL) on the start-up of mainstream partial nitrification (PN) was investigated in five parallel sequencing batch reactors inoculated with ordinary nitrification sludge. The results showed that increasing BNL by both methods could achieve nitrite accumulation. Moreover, a high initial activity of ammonium oxidizing bacteria (AOB) accelerated nitrite accumulation. Increasing influent NLR (ammonium: 55–70 mg N/L) achieved only 30%–40% of nitrite accumulation ratio (NAR) and gradually decreased with reactor operation. By increasing BNL via controlling SRT (30 days), desirable PN with an average NAR of 81.7 ± 4.4% (effluent nitrite: ∼10 mg N/L) was obtained. Nitrite oxidizing bacteria (NOB) were effectively inhibited, and the AOB to NOB activity ratio increased from 1.5 to 7.8, promoting efficient nitrite accumulation. Overall, increasing BNL by regulating SRT was a potential method for start-up of mainstream PN.