Three carbon sources, namely sodium acetate, sewage and effluent, were used to simulate the process of phosphorus release in an actual sewage treatment plant, in order to explore the phosphorus release performance of the sludge, the relationship between phosphorus release and chemical oxygen demand (COD) in sewage, and the stability of phosphorus-rich sludge. The results showed that the type and concentration of carbon sources had significant effects on the rate of phosphorus release, reaction equilibrium time and phosphorus release amount. When sodium acetate was used as the carbon source, the phosphorus release rate reached 12.54 mg P (g VSS center dot h)(-1), and tended to be stable at 4.0 hours. The phosphorus release amount in the first 2.5 hours accounted for 36.88 of the total phosphorus in the sludge. When sewage was used as the carbon source, the phosphorus release rate did not reach equilibrium even at 5.0 hours, and the phosphorus release amount increased by 1.0 mg L-1 for every 10.5 mg L-1 increase sewage COD within a certain range. When effluent was used as the carbon source, the visual phosphorus release amount was only 0.83 mg L-1 after standing for 24 hours and the actual phosphorus release amount was 17.98 mg L-1. These conclusions can provide technical support for the optimization of phosphorus removal in sewage treatment plants.
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