内源短程反硝化颗粒污泥培养及关键影响因素研究

RESEARCH ON ENDOGENOUS PARTIAL DENITRIFICATION GRANULAR SLUDGE CULTIVATION AND KEY INFLUENCING FACTORS

为推动污水生物脱氮技术绿色转型,针对厌氧氨氧化中底物亚硝氮(NO_(2)^(-)-N)难以稳定获得的问题,利用好氧颗粒污泥(AGS)诱导其进行内源短程反硝化(EPD),实现低碳源条件下NO_(2)^(-)-N的积累,可为主流厌氧氨氧化的应用推广提供理论支撑。当进水ρ(COD)/ρ(NO_(3)^(-)-N)为3时,采用厌氧/缺氧/微氧条件,可实现EPD颗粒污泥的富集与稳定,NO_(3)^(-)-N→NO_(2)^(-)-N转化率(NTR)达到72.73%。在厌氧段,消耗有机物和糖原(Gly),合成聚羟基烷酸(PHA),ΔPHA/ΔGly(1.30 mol C/mol C)接近聚糖菌(GAOs)模型值,说明内碳源储存主要由GAOs完成。在缺氧段,NO_(2)^(-)-N积累,并伴随PHA降低和Gly合成,硝酸盐还原酶活性显著高于亚硝酸盐还原酶活性,证明系统实现了EPD过程。通过优化运行参数发现,当ρ(COD)/ρ(NO_(3)^(-)-N)为4.2时,系统的NTR提高至80.01%。批次试验结果表明,pH由6.0上升至9.0时,NTR升高至89.15%;温度从40℃降低至5℃时,NTR达到峰值91.16%,说明碱性和低温条件下更有利于NO_(2)^(-)-N累积。因此,选择合适的COD/NO_(3)^(-)-N、pH和温度,能够有效提升EPD过程的NO_(2)^(-)-N积累效果。

To facilitate the green transition of biological nitrogen removal,it is imperative to address the challenge of stable nitrite nitrogen(NO_(2)^(-)-N)acquisition for mainstream anammox application.In this study,aerobic granular sludge(AGS)was acclimatized for endogenous partial denitrification(EPD)to accomplish stable NO_(2)^(-)-N accumulation with limited carbon sources.This research provides theoretical support for the application of mainstream anammox.When the influent chemical oxygen demand/nitrate nitrogen(COD/NO_(3)^(-)-N)was 3,the enrichment and stability of EPD granular sludge could be achieved under anaerobic/anoxic/micro-oxygen condition,and nitrate-to-nitrite transformation ratio(NTR)reached 72.73%.During the anaerobic stage,carbon source and glycogen(Gly)were consumed to synthesize polyhydroxyalkanoic acid(PHA),and theΔPHA/ΔGly of the anaerobic stage(1.30 mol C/mol C)was close to the glycogen accumulating organisms(GAOs)model value,indicating that the intracellular carbon source storage was mainly completed by GAOs.NO_(2)-N was accumulated with the reduction of PHA and the synthesis of Gly during the anoxic phase.The activity of nitrate reductase remarkably exceeded nitrite reductase,confirming the successful implementation of EPD.The NTR was improved to 80.01%under a COD/NO_(3)^(-)-N of 4.2 by optimizing the operating parameters.The results of batch tests found that NTR rose to 89.15%as the pH varied from 6.0 to 9.0,and the NTR reached a peak of 91.16%with the temperature reduced from 40℃to 5℃.The results suggested that the alkaline condition and lower temperature were more conducive to NO_(2)^(-)-N accumulation.Therefore,appropriate COD/NO_(3)^(-)-N,pH and temperature can effectively reinforce the NO_(2)^(-)-N accumulation of EPD.