Influence of reflux ratio on treatment of landfill leachate in middle and late stage by DN-PN-ANAMMOX process

Effect of Reflux Ratio on Treatment of Landfill Leachate in Middle and Late Stage by DN-PN-ANAMMOX Process

Lu Mingyu 1, 2, Yin Jiqiang 1, 2, Yao Fenggen 3, Li Xiang 1, 2, Huang Yong 1, 2, Qiu Qingchun 3, Xia Yu 3

1. School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, Jiangsu 215009;

2. Institute of Environmental Biotechnology, Suzhou University of Science and Technology, Suzhou, Jiangsu 215009;

3. Qizishan Domestic Waste Landfill Site of Suzhou Environmental Sanitation Management Office, Suzhou 215009  , Jiangsu Province  


In order to further improve the denitrification-partial nitrification and anaerobic ammonia oxidation (DN-PN-ANAMMOX) process for the treatment of mid-and late-stage leachate containing high concentration of NH4 +-N, the mid-and late-stage leachate from a local landfill was used as experimental water. The removal of organic matter and nitrogen by the process under different reflux ratios and the changes of microbial communities in each functional area were investigated.


The results show that: When the reflux ratio is adjusted from 5 to 9, The removal rate of CODCr (chemical oxygen demand) gradually increased from 47% to 53%, Among them, the proportion of CODCr removed by UASB (Up-flow Anaerobic Sludge Bed/Blanket, Upflow Anaerobic Sludge Bed/Blanket) is 41%, It provides a low carbon environment for the subsequent PN-ANAMMOX process. However, when the reflux ratio is adjusted to 9, Due to the dilution effect of high reflux ratio, the mass concentration of free ammonia (FA) decreases ((FA) < 2 mg/L), As a result, it cannot inhibit the activity of nitrite oxidizing bacteria (NOB) in the PN region, The stability of some nitrosation processes decreased and the accumulation rate of NO2-N decreased to less than 50%, which adversely affected the nitrogen removal performance of the subsequent ANAMMOX zone, and the nitrogen removal rate in the ANAMMOX zone decreased to 4.29 kg/(m 3 · d). The research shows that the best reflux ratio of the DN-PN-ANAMMOX process with reflux is 8 to treat the middle and late landfill leachate with a (NH4 +-N) as high as 1 900 mg/L, and the nitrogen removal rate in the ANAMMOX zone reaches 7.41 kg/(m 3 · d), and the effluent (TN) (8.83 mg/L) is even lower; At the same time, when the reflux ratio is 8, Pseudomonas, Nitrosomonas and Candidatus_Kuenenia get the best enrichment in the pre-UASB, PN zone and ANAMMOX zone of the DN-PN-ANAMMOX process, respectively.

Source: Environmental Science Research

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