The Effect of Extracellular Polyphosphate in the Process of Enhanced Biological Phosphorus Removal (EBPR): from the Perspective of Transformations of Extracellular Polyphosphate and Intracellular Energy-storing Substances

Abstract

Abstract The distributions and cycle changes of orthophosphate (ortho-P), polyphosphate (poly-P), glycogen and polyhydroxyalkanoates (PHAs) in the 2 reactors fed with acetate at 20°C or 35°C were investigated to understand the effect of extracellular polyphosphate (poly-P) in enhanced biological phosphorus removal (EBPR) process. The specific anaerobic-uptake acetate rate in the 20°C EBPR reactor was about 2.24 times that in the 35°C non-EBPR reactor. The anaerobic-hydrolysis and the aerobic-synthesis amounts of intracellular glycogen in the former were only half those in the latter, with the comparable corresponding-transformation amounts of intracellular PHAs between the 2 reactors. The anaerobic-hydrolysis / aerobic-synthesis of extracellular poly-P and the anaerobic-release / aerobic-uptake of intracellular ortho-P occurred in the 20°C EBPR sludge, corresponding to the lower transformation level of intracellular glycogen and the higher anaerobic-uptake rate of acetate. A hypothesis that the anaerobic-hydrolysis of extracellular poly-P could accelerate the acetate migration though anion-exchange was proposed. In addition, phosphorus accumulating organisms (PAOs) was the microbial population basis for the existence and transformation of extracellular poly-P.