厌/缺氧时间对好氧颗粒污泥同步硝化内源反硝化和除磷的影响

选用4组同规格SBR反应器,在A/O/A模式下以水解酸化液为进水,调整厌/缺氧时间分别为50min/170min、90min/130min、130min/90min、180min/40min,探讨颗粒污泥在不同厌/缺氧时间下脱氮除磷特性.结果表明,厌氧时间从50min延长至90min时,污泥内碳源储存量和释磷量增加,同步硝化反硝化(SND)效率提高至62.65%,TN、TP去除率分别从81.1%、 82.2%上升92.9%、98.5%.当厌氧时间从90min升至180min时,释磷量反而下降,厌氧内源性条件刺激胞外聚合物(EPS)增加造成聚羟基烷酸(PHA)合成下降,TP去除率降至88.1%;同时缺氧时间从130min降至40min,系统残留的NO_X^-较多,造成TN去除率降低至84%.机理分析表明系统中TN在好氧段由反硝化聚磷菌(DPAOs)和反硝化聚糖菌(DGAOs)利用PHA以SND方式消耗,并在缺氧段由DGAOs内源反硝化进一步去除,TP由PAOs和DPAOs去除,由批次实验估算得DPAOs占比在R2中最高,达41%,4组反应器运行期间颗粒均未发生解体,以水解酸化液为基质培养的颗粒结构完整、稳定性强.结果表明,厌/缺氧时间的适当延长有利于加强内碳源的贮存与转化,强化厌氧释磷、SND和后置内源反硝化效果,实现同步硝化内源反硝化和除磷高效稳定运行.

Effects of anaerobic/anoxic time on simultaneous nitrification - endogenous denitrification and phosphorous removal from aerobic granular sludge

In this study, four groups of SBR reactors with the same specification was selected to explore effects of total nitrogen (TN) and total phosphorus (TP) removal from aerobic granular sludge under different anaerobic/anoxic time as 50/170, 90/130, 130/90, 180/40min and the hydrolytic acidification liquid as the influent matrix in A/O/A mode. The results show that the carbon (C) source reserves and P release from granular sludge increased with an increment in the anaerobic time from 50 to 90min. The efficiency of simultaneous nitrification and denitrification (SND) increased to 62.65%, and the removal rates of TN and TP increased from 81.1% to 92.9% and 82.2% to 98.5%, respectively. When the anaerobic time increased from 90 to 180min, the P release decreased and the anaerobic endogenous conditions stimulated the increase in EPS and the decrease in PHA synthesis, which led to a decrease in the TP removal rate to 88.1%. At the same time, when the anoxic time was shortened from 130 to 40min, more NO_x^- remained in the system, resulting in a reduction in TN removal rate to 84%. Mechanism analysis suggests that TN was consumed by denitrifying polyphosphate accumulating organisms and denitrifying glycogen accumulating organisms in the aerobic section by means of PHA in the form of SND; then further removed by endogenous denitrification of DGAOs in the anoxic section; and finally, TP was removed by PAOs and DPAOs. Our batch experiments demonstrated the highest proportion of DPAOs in R2, up to 41%. During the operation of the four groups of reactors, the particles did not disintegrate, implying that the particles cultured with hydrolytic acidification solution had complete structure and strong stability. We conclude that appropriate extension of anerobic/anoxic is conducive to strengthening the storage and transformation of internal C source, enhancing the effects of anaerobic P release, SND, and post endogenous denitrification, and realizing the efficient and stable operation of simultaneous nitrification-endogenous denitrification and P removal.