Effect Of Different Ratios Of Glucose To Acetate On Phosphorus Removal In The Aerobic/Extended-Idle Regime

Excessive nitrogen and phosphorus nutrients due to human reason discharged into receiving waters, may cause more and more serious problem of eutrophication for the environment, which will be a huge threaten to the security of drinking water. Therefore, the development of reliable and cost-effective methods for removal of phosphorus from waste effluents is of considerable environmental importance.In recent years, the aerobic/extend-idle regime, namely, AEI regime, has attracted widespread attention. Previous studies proved that biological phosphorus removal could be achieved in the aerobic/extended-idle regime with typical substrates of glucose, acetate or propionate as the sole carbon source. The previous results suggested that the AEI regime was simpler and cost-saving, which might serve as an alternatively effective supplement to the existing method of phosphorus removal.Taking the artifical wastewater as target, the effects of different ratios of glucose to acetate serving as carbon source on the activated sludge in the AEI process were further evaluated in this paper. A glucose/acetate mixture was separately added to the reactors in ratios of0:100%,25:75%,50:50%,75:25%and100:0%, then biological phosphorus removal performance was compared. The changes of polyhydroxyalkanoates (PHAs), glycogen and the removal of phosphorus and COD in typical circle were investigated during steady-state operation. In this study, PCR-DGGE technique was also employed to investigate the microbial community in different reactors.The experimental results showed that the glucose/acetate mixture could induce better performance of biological phosphorus removal in AEI regime than that of the glucose or acetate as sole carbon source. For example, the glucose/acetate mixture in the ratios of25:75%and50:50%obtained the higher phosphorus removal efficiency. Under the same operation conditions, the accumulations/transformations of PHAs and glycogen in the AEI SBRs fed with different ratios of glucose and aceteta were different. The AEI SBR with glucose/acetate mixture in the ratio of50:50%showed a much higher transformation of glycogen and PHAs. When the activated sludge acclimated from long-term A/O process was operated with AEI process, the reactors fed with glucose in higher levels obtained better results in phosphorus removal. Finally, the analysis of DGGE mothod futher demonstrated that there were significant difference in the major bands of different lanes of sludge samples, and the microbial community structure in different reactors had very low similarity, which manifested that different ratios of glucose to acetate probably had a great influence on the microbial community structure in biological phosphorus removal sludge.