Green Energy & Environment (Oct 2021)

Salt effect on MUCT system performance of nitrogen and phosphorus removal

  • Huining Zhang,
  • Zhuowei Zhang,
  • Kewei Jiang,
  • Zhili Li,
  • Kefeng Zhang,
  • Jianqing Ma,
  • Yongxing Qian

Journal volume & issue
Vol. 6, no. 5
pp. 670 – 677

Abstract

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The effect of salinity on biological nitrogen and denitrifying phosphorus removal was investigated in a Modified University of Cape Town (MUCT) system. Removal rates of COD, NH4+-N, NO3−-N, NO2−-N, phosphorus and the sludge characteristics at salt concentrations (0.0, 3.2, 6.4, 11.2 and 16.0 g L−1) were analyzed. With the salt concentration increasing, all the COD, NH4+-N, TN and TP removal rates exhibited a trend of decline, and exhibited an initial reduction and subsequent increase at every stage of salt concentration. NH4+-N, TN and TP removal rates were 92.7%, 51.5% and 67.2% in 16 g L−1 salt concentration, respectively. And they were outperformed the literature reported and acceptable in practical applications. When the salinity of wastewater changed from 0.0 to 16.0 g L−1, the biomass yield coefficients increased from 0.0794 to 0.126 g VSS/g COD. Increased salinity had a detrimental effect on phosphorus-accumulating organisms (PAOs) and denitrifying PAOs (DPAOs) (especially DPAOs). Therefore, phosphorus removal gradually depended on PAO. The simultaneous nitrification and denitrification (SND) rate and nitrogen removal rate (including nitrification rate, denitrification rate, and total nitrogen removal rate) gradually decreased with the increased salinity.

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