间歇梯度曝气下首段延时厌氧强化好氧颗粒污泥脱氮除磷

本研究采用SBR反应器，以实际低C/N比生活污水为进水基质，采用间歇梯度曝气（各曝气段溶解氧浓度递减）充分利用内碳源，探讨不同首段厌氧时间下好氧颗粒污泥脱氮除磷效果.结果表明，间歇梯度曝气的初始厌氧段从50 min增加至90 min，使颗粒污泥内碳源的储量增加，这一延时厌氧的改进条件导致颗粒污泥脱氮除磷效果提升，当延时至70和90 min时，COD、TN和TP的去除效率分别可达84.74%、70.05%和89.7%以及86.65%、78.81%和85.5%.但随后首段厌氧时间增至110 min后，由于部分细胞解体，污泥流失较严重，使内碳源储量约降低13.6%，进而污染物去除效率下降.在首段厌氧时间从50 min延长至90 min的过程中，LB-EPS中PS含量变化较小，随后延时至110 min后PS含量增加至约7.18 mg·g^-1，PN含量增加至约5.56mg·g^-1.TB-EPS中PN和PS含量均较稳定，进而表明内碳源储量对LB-EPS的影响较TB-EPS大，同时污泥沉降性能下降与LB-EPS中PS含量增加密切相关.颗粒污泥中DPAOs占比随首段厌氧时间的适当增加而升高，其中首段厌氧时间为70 min时DPAOs占比达到51.5%.

First Extended Anaerobic Phase Enhanced Nitrogen and Phosphorus Removal by Aerobic Granular Sludge Under Intermittent Gradient Aeration

In this study, a SBR reactor was selected to explore the effect of nitrogen and phosphorus removal by aerobic granular sludge under different initial anaerobic time using intermittent gradient aeration (decreasing dissolved oxygen concentration in each aeration section) and actual domestic wastewater with low C/N ratio as the influent matrix. The results showed that the initial anaerobic stage of intermittent gradient aeration increased from 50 min to 90 min, which increased the carbon source reserves in granular sludge. This improved delayed anaerobic condition led to the improvement of nitrogen and phosphorus removal efficiency of granular sludge. When delayed to 70 and 90 min, the removal efficiency of COD, TN, and TP reached 84.74%, 70.05%, and 89.7% and 86.65%, 78.81%, and 85.5%, respectively. However, after the first anaerobic phase time was increased to 110 min, the sludge loss was more severe owing to the disintegration of some cells, leading to a decrease in internal carbon source reserves by about 13.6%. Owing to this, the pollutant removal efficiency decreased. In the process of prolonging the first anaerobic phase time from 50 min to 90 min, the content of PS in LB-EPS changed minimally; when it was delayed to 110 min, the content of PS increased to about 7.18 mg·g^-1, and the PN content increased to about 5.56 mg·g^-1. The contents of PN and PS in TB-EPS were stable, which indicated that the effect of internal carbon storage on LB-EPS was greater than that of TB-EPS, and the decrease in sludge settling performance was closely related to the increase in PS content in LB-EPS. The proportion of DPAOs in granular sludge increased as the first anaerobic phase time increased, and the proportion of DPAOs reached 51.5% when the first anaerobic phase time was 70 min.