AI Article Synopsis
- The study investigated how hydraulic retention time (HRT) affects the removal of phosphorus and nitrogen in a modified two sludge A/O-BAF system.
- The results showed that with varying HRTs of 9, 8, 7, and 6 hours, the effluent's chemical oxygen demand (COD), nitrogen (NH-N), and total phosphorus (TP) levels were consistently low, with the best denitrifying performance observed at 8 hours HRT.
- It was noted that as HRT decreased, the proportion of denitrifying phosphorus accumulation organisms (DPAOs) dropped significantly, and overall sludge activity reduced, indicated by lower MLVSS/MLSS ratios.
Article Abstract
The effect of hydraulic retention time (HRT) on denitrifying phosphorus and nitrogen removal in a modified two sludge A/O-BAF system was studied. The influent COD, NH-N, and TP were 189.6, 60.4, and 5.1 mg·L, respectively. When HRT was 9, 8, 7, and 6 h, the average effluent COD was less than 42 mg·L. The average effluent NH-N levels were 2.4, 2.8, 3.3, and 6.5 mg·L, respectively. The average effluent TP values were 0.3, 0.4, 0.7, and 0.8 mg·L, respectively. The ratio of the denitrifying phosphorus accumulation organisms (DPAOs/PAOs) in the system of anoxic zone was reduced from 76.8% to 48.8%. When HRT was 8 h, the ratio of denitrifying phosphorus to nitrogen (ΔPO/ΔNO-N) was increased by 37.5% by a mathematical statistics method. The ΔPO/ΔNO-N in the anoxic zone was 1.24 (the theoretical value is 1.41). At this time, the effect of denitrifying phosphorus to nitrogen was the best. The SVI value was lower than 100 mL·g throughout the experiment, and the MLVSS/MLSS gradually decreased from 0.74 to 0.63, indicating that the sludge activity was reduced.
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| http://dx.doi.org/10.13227/j.hjkx.201907167 | DOI Listing |
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