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Nitritation, nitrous oxide emission pathways and in situ microbial community in a modified University of Cape Town process

Li, Ning, Zeng, Wei, Wang, Baogui, Li, Shuaishuai, Guo, Yu, Peng, Yongzhen
Bioresource technology 2019 v.271 pp. 289-297
Nitrosomonas, Planctomycetes, anaerobic ammonium oxidation, greenhouse gases, microbial communities, nitrites, nitrogen content, nitrous oxide, nutrients
Achieving nitritation is a prerequisite to promote nutrients removal and save energy, but emission of nitrous oxide as a greenhouse gas cannot be ignored. This study established the nitritation in a continuous-flow MUCT process and investigated the mechanism of N2O generation. The nitrite accumulation ratio (NAR) reached 95% by controlling the low DO of 0.3–0.5 mg/L and short HRT of 8 h. The 15N-isotope tracer experiment indicated that the percentage of nitrifier-denitrification (ND) pathway increased by 12.7% under the limited-aeration mode, improving the stable operating of nitritation. Meanwhile, the autotrophic anammox pathway increased with the contribution ratio of 14.7% to N2 emission under the nitritation mode. The 15N-DNA-SIP revealed that the Nitrosomonas executed the ND pathway and the Planctomycetes conducted the anammox process, respectively. The integration of autotrophic and heterotrophic process based on nitritation technique has potential to solve the carbon-limited issue for total nitrogen removal in mainstream WWTPs.