钙离子胁迫下反硝化除磷污泥系统氮磷去除及其响应调控的机理研究

Wastewater treatment process based on denitrifying phosphorus removal pathway has received extensive attentions due to its characteristics of saving carbon source and aeration energy, and low surplus sludge production. Previous studies found that the high concentration of calcium ion (Ca2+) in municipal sewage exerted a negative influence on the structure and metabolism of microbial community in denitrifying phosphorus removal system, resulting in the performance deterioration of simultaneous nitrogen and phosphorus removal, but the related mechanism is not yet clear. This work intends to study the mechanism of nitrogen and phosphorus removal and response regulation of denitrifying phosphorus removal system under different influent Ca2+ concentration, focusing on (1) exploring the dynamic variations of the simultaneous removal of nitrogen and phosphorus and the release level of gaseous nitrogen oxides under Ca2+ stress, (2) understanding the distribution and existing form of Ca2+ in the system, (3) clarifying the response mechanism of microbial community structure, extracellular polymeric substances, functional genes, key enzymes and metabolites of denitrifying phosphorus removal system to Ca2+ stress, (4) revealing the mechanism of response feedback and regulation of performance recovery by the information flow of bacterial quorum sensing. The obtained results can provide an important theoretical and practical basis for predicting and evaluating the potential threat of high Ca2+ loading to the biological nitrogen and phosphorus removal system, and maintaining and improving the operation stability of activated sludge system under Ca2+ stress.

基于反硝化同步脱氮除磷代谢途径的活性污泥污水处理工艺，具有节约碳源和曝气能耗、剩余污泥产量少等优点，一直倍受关注。前期研究发现，市政污水中高浓度的钙离子（Ca2+）会对反硝化除磷污泥系统内菌群结构及其代谢产生胁迫影响，造成系统脱氮除磷性能下降，但相关影响机理尚不明确。本项目拟开展不同进水Ca2+负荷条件下反硝化除磷污泥系统氮磷去除及其响应调控的机理研究：重点探索Ca2+胁迫下系统氮磷同步去除性能与气态氮氧化物释放通量之间的动态变化规律；掌握Ca2+在系统内的分布和存在形态；阐明系统功能菌群结构、胞外聚合物、功能基因、关键酶和代谢产物在Ca2+胁迫下的响应机制；揭示基于微生物群体感应信息流的系统抗Ca2+胁迫响应及其性能恢复调控机理。研究结果可为正确预测与全面评价高浓度Ca2+负荷对污水生物脱氮除磷系统的潜在威胁、维护与提高Ca2+胁迫下活性污泥系统的运行稳定性，奠定坚实的理论和实践基础。

污水水质是影响反硝化聚磷系统脱氮除磷性能及其稳定运行的关键因素。市政污水中Ca2+ 的含量约为30～100 mg/L，主要来源于天然水体本底值以及含钙废水的排放。因此，研究污水中Ca2+ 对活性污泥系统的胁迫效应与作用机制，对维持和提高污水生物处理系统的稳定运行具有重要的理论和实际意义。本项目通过研究市政污水中Ca2+ 对反硝化除磷污泥系统氮磷去除特性及氮氧化物释放规律的影响，揭示不同浓度Ca2+对系统的影响机理。研究结果如下：（1）随着反硝化聚磷污泥系统进水Ca2+浓度的提高（0~150 mg/L），各反应器中游离亚硝酸（FNA）呈现上升的趋势。当Ca2+ 浓度为150 mg/L时，N2O的总释放量为2.11 mg/L，较Ca2+ 浓度为0 mg/L时增加了214.93%，这表明Ca2+高浓度积累对FNA的生成和N2O的释放具有显著的促进作用；（2）Ca2+ 胁迫下并没有改变反硝化聚磷菌的代谢途径，仅对其聚磷酸盐和糖原的分解和生成存在轻微抑制作用。随着进水Ca2+浓度的升高，污泥EPS中GG嵌段含量出现轻微下降，分析认为这可能是由于Ca2+可以与GG嵌段结合有关；（3）在不同进水Ca2+浓度分别为0、50、100和150 mg/L）条件下，各反应器中MLVSS/MLSS的值分别为0.76、0.64、0.58和0.42，SVI30分别为103.11 、85.21、73.12和63.32 mL/g MLSS，表明较高浓度的Ca2+ 胁迫下污泥絮体整体更加密实，无机质含量更高，有利于提高反硝化除磷污泥的沉降性能；（4）定量分析反硝化聚磷污泥中群体感应信号分子发现C4-HSL、C8-HSL、3OC8-HSL和3OHC12-HSL是反硝化除磷污泥的主要AHLs。随着Ca2+ 浓度从0 mg/L上升到150 mg/L，C4-HSL、C8-HSL和3OHC12-HSL的含量分别增加了98.31%、202.33%和535.54%，3OC8-HSL的含量降低了69.08%。这说明Ca2+ 胁迫下可调控C4-HSL、C8-HSL、3OHC12-HSL的大量生成，同时抑制了3OC8-HSL的生成。以上研究结果为正确预测与全面评价市政污水中高浓度Ca2+ 对生物脱氮除磷系统的潜在威胁、推动受Ca2+ 胁迫影响的活性污泥污水处理工艺应急调控策略与措施的建立，提供必要的理论指导与技术支撑。