Start-up of single-stage partial nitrification-anammox process treating low-strength swage and its restoration from nitrate accumulation

• Published in: Bioresource technology 2016-10, Vol.218, p.771-779
• Main Authors: Miao, Yuanyuan, Zhang, Liang, Yang, Yandong, Peng, Yongzhen, Li, Baikun, Wang, Shuying, Zhang, Qian
• Format: Article
• Language: English
• Subjects: aeration; Ammonium Compounds - chemistry; anaerobic ammonium oxidation; Bacteria - metabolism; Bioreactors - microbiology; Denitrification; Intermittent aeration; Low-strength swage; microbial activity; Nitrate accumulation; nitrates; Nitrates - chemistry; Nitrates - metabolism; Nitrification - physiology; Nitrite oxidization bacteria; nitrites; nitrogen; Nitrogen - metabolism; Nitrogen Oxides - metabolism; oxygen; Sewage - chemistry; Sewage - microbiology; Single-stage partial nitrification-anammox; sludge; technology; Waste Disposal, Fluid - methods
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2016.06.125

The conversion pathway of NH4+ in deterioration and restoration periods. [Display omitted] •Intermittent aeration restored single-stage PN/A process from nitrate build-up.•NOB accumulated under continuous aeration mode, Nitrospira was the dominant NOB.•Reducing DO to 0.17±0.08mg/L was failed to inhibited the NOB activity.•Sewage PN/A reactor was quickly started up by inoculating anammox sludge. A single-stage partial nitrification-anammox (PN/A) reactor treating low-strength swage was operated for 288days to investigate the recovery of nitrogen removal from nitrate accumulation. The reactor was quickly started up by inoculating anammox sludge. However, nitrite oxidizing bacteria (NOB) abundance gradually increased on day 25, leading to high effluent nitrate concentration. Two strategies were executed to control the effluent nitrate. In strategy I, dissolved oxygen (DO) concentration was kept low (0.17±0.08mg/L), but nitrate production increased from 4.71 to 38.18mg-N/L. In strategy II, intermittent aeration operation mode (aeration 7min/anoxic 21min) was adopted, which significantly lowered the nitrate concentration to 1.3mg-N/L, indicating the NOB was inhibited. The high nitrogen removal rate of 73mg-N/(L·d) was achieved. The evolution of bacterial activity and abundance verified the changes of the nitrogen removal performance and proved the intermittent aeration strategy could successfully solve the problem of nitrate build-up in the PN/A process.