Bench scale experiments were carried out with four biological nutrient removal(BNR) units, A/O, A2/O, Phostrip and P/L units, to investigate the behavior of phosphorus in the system and to compare the characteristics of phosphorus removal in four experimental BNR units. The influent COD/T-P ratio was varied from 22 to 64 by changing COD concentration while maintaining phosphorus concentration constant. In general sidestream BNR units such as Phostrip and P/L units outperformed mainstream BNR units such as A/O and A2/O units in terms of phosphorus removal. While phosphorus release and uptake in A/O and A2/O units became less significant at low influent COD/T-P, the phosphorus release in A2/O unit was further influenced by nitrate in return sludge and thus A2/O unit required even higher influent COD/T-P ratio for luxury uptake of phosphorus. The luxury uptake of phosphorus in Phostrip and P/L units were not affected by influent COD/T-P ratio and the adverse effect of nitrate in return sludge on anaerobic phosphorus release in P/L process was not significant due to the sludge blanket in P-stripper.
Comparison of phosphorus removal characteristics between various biological nutrient removal processes
Eun Lee Sang, Soo Kim Kwang, Hwan Ahn Jae, Whoe Kim Chang; Comparison of phosphorus removal characteristics between various biological nutrient removal processes. Water Sci Technol 1 December 1997; 36 (12): 61–68. doi: https://doi.org/10.2166/wst.1997.0431
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