Abstract: | The characteristic of phosphorus removal and appropriate change of the traditional operation modes were investigated in UniFed
sequencing batch reactor (SBR) laboratory-scale apparatus (40 L), treating actual domestic wastewater with low ratios of C/N
(2.57) and C/P (30.18), providing theoretical basis for actual application of wastewater treatment plant. UniFed SBR system
with its unique operation mode had the distinct superiority of phosphorus removal. On this occasion, the effect of volumetric
exchange ratio (VER) and the method of influent introduction for phosphorus removal were studied. When the carbon source became
the limiting factor to phosphorus release, the higher the VER, the lower the phosphorus concentration in the effluent. Three
different influent patterns, including one-time filling, four-time filling, and continuous filling with the same quantity
of wastewater could increase the release rate of anaerobic phosphorus from 0.082 to 0.143 mg·P·(L·min)−1. Appropriate change of the traditional operation modes could optimize the efficiency of phosphorus removal. When the feed/
decant time was extended from 2 h to 4 h, the phosphorous removal efficiency increased from 59.93% to 88.45% without any external
carbon source. In the mode of alternation of anoxic-aerobic (A/O) condition, phosphorous removal efficiency increased from
55.07% to 72.27% clearly. The carbon source in the influent can be used adequately, and denitrifying phosphorus removal was
carried out in anoxic stage 2 (A2). This mode was optimal for the treatment of actual domestic wastewater with low C/N and
C/P ratios. |