Lü Li-ping,LI Hang,ZHANG Xin,et al.Effect of Step-feed on Nitrogen and Phosphorus Removal of Pre-anoxic A2/O Process[J].China Water & Wastewater,2021,37(15 15):8-13.
Effect of Step-feed on Nitrogen and Phosphorus Removal of Pre-anoxic A2/O Process
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第37卷
Number:
15 15
Page:
8-13
Column:
Date of publication:
2021-08-01
- Keywords:
- A2/O process; pre-anoxic process; step-feed; flow distribution ratio; nitrogen and phosphorus removal; carbon source
- Abstract:
- Effect of step-feed on nitrogen and phosphorus removal in the pre-anoxic A2/O process of an urban wastewater treatment plant was investigated. Influent flow distribution ratio of pre-anoxic tank, anaerobic tank and anoxic tank was set to be 8∶1∶1, 7∶1 ∶2, 6∶1∶3, 5∶1∶4, 6∶2∶2 and 6∶3∶1, respectively. The influent flow distribution ratio had significant effects on nitrate nitrogen in the treatment process and total nitrogen and total phosphorus in the effluent. However, it had little effect on ammonia nitrogen in the effluent. Optimization of the influent flow distribution ratio could achieve a rational allocation of carbon sources in the two denitrification units of pre-anoxic and anoxic tanks, and achieve efficient removal of total nitrogen. Meanwhile, it could also weaken the inhibition of high nitrate nitrogen on anaerobic phosphorus release, and significantly promote the subsequent excessive phosphorus absorption in the aerobic stage. Among the six different conditions, the optimal influent flow distribution ratio of pre-anoxic tank, anaerobic tank and anoxic tank was 6∶2∶2. Under this operating condition, the average ammonia nitrogen in the effluent was 0.26 mg/L, the total nitrogen was between 4.88 mg/L and 6.69 mg/L, and the total phosphorus was lower than 0.15 mg/L. The effluent quality was significantly better than the national first level A standard. Compared with the original operating condition, after optimizing the influent flow distribution ratio, the annual carbon source cost of more than 2 million yuan could be saved, and the effluent quality was more stable, which effectively promoted the win-win situation in water quality and operating cost.
Last Update:
2021-08-01