腐殖酸介导促进剩余污泥厌氧发酵产酸耦合污水强化生物除磷的机理研究

For the objective to meet the urgent need of sound carbon source for the efficient and stable operation of enforced biological phosphorous removal process (EBPR)in municipal wastewater treatment plant, this project is to investigate the effect and influential factors of enhanced anaerobic fermentative acidogenation of excessive activated sludge under the mediation of humic acids according to their electron transfer properties, to clarify the evolution of microbial community and the express of the activation of key enzymes in the fermentative acidogenic process mediated by the humic acids, to analyze the effect of humic acids on the balance of intra cellular NADH/NAD+ and the concentration of the intermediate products in the metabolism of acidogenic bacteria, and to study the influence of fermentation liquid of the excessive activated sludge on the phosphorous removal in the EBPR and competition of phosphorous accumulative organisms (PAOs) and glycogen accumulative organisms (GAOs). Moreover, the project will elucidate the mechanism of the enforced phosphorous removal from wastewater in couple with fermentative acidogenation of excessive activated sludge under the mediation of humic acids, to provide the theoretical fundamental for the realization of high efficient and stable operation of EBRP by using the acidogenic fermentative liquid of the excessive sludge.

本项目针对城市污水处理厂强化生物除磷工艺（EBPR）高效稳定运行对优质碳源的迫切需求，依据腐殖酸介体具有的电子传递特性，考察腐殖酸介导强化剩余污泥厌氧发酵产酸效果及影响因素；明确腐殖酸介导剩余污泥发酵产酸过程中功能微生物的种群变化和关键酶的活性表达；分析腐殖酸对发酵产酸菌胞内NADH/NAD+平衡和发酵产酸菌代谢中间产物浓度变化的影响，研究剩余污泥厌氧发酵液对EBPR除磷效果及聚磷菌（PAOs）和聚糖菌（GAOs）竞争的影响。揭示腐殖酸介导促进剩余污泥厌氧发酵产酸耦合污水强化生物除磷的机理，为利用剩余污泥厌氧发酵液，实现EBPR高效稳定运行提供理论依据。

本课题运用先进的分析手段，研究了腐殖酸介导促进剩余污泥厌氧发酵产酸的效果及作用机制。结果表明，所用腐殖酸结构中-OH、C-H、C=O、C=C、COO-、-CH3等活性官能团较多，存在缔合的芳环结构，分子量、芳香性结构的缩合度及腐殖化程度较高。添加腐殖酸可以有效提高剩余污泥厌氧发酵产VFAs总量及乙酸占比，当腐殖酸浓度为0.15、0.30、0.60和1.20 g/g-TCOD时，VFAs总量较空白样品提高率依次为5.65 %、18.69 %、57.46 %，115.01 %，同时VFAs中乙酸占比也逐渐增高，丙酸和异戊酸占比逐渐下降；在初始pH为10.0、反应时间为4 d，腐殖酸投加量1.20 g/g-TCOD时，剩余污泥厌氧发酵产VFAs和乙酸量最高。添加腐殖酸使发酵产酸微生物Acetoanaerobium、Proteiniclasticum，Fusibacter菌属的相对丰度分别提高了 3倍、20倍、1倍。添加腐殖酸降低了NADH的浓度，维持了NADH/NAD+平衡，抑制了产丙酸代谢途径；腐殖酸对与发酵产酸过程密切相关的代谢通路metabolic pathway影响较为显著，淀粉和蔗糖的代谢过程、鞘脂类代谢过程及嘧啶代谢过程均有差异代谢物存在。采用三个SBR反应器（S1、S2、S3），分别以乙酸、乙酸和丙酸、乙酸和丙酸以及腐殖酸（模拟富含腐殖酸的剩余污泥厌氧发酵液）为碳源，研究了富含腐殖酸的厌氧污泥发酵液对EBPR系统除磷的影响。结果表明，S3的磷酸盐去除率最高，达到了95%；典型周期中S3的释磷量与吸磷量、PHA合成量与分解量、VFAs的利用速度均显著大于S1和S2；S3中Accumulibacter的相对丰度最高，分别为S1、S2的1.47倍和1.13倍，S3中 Defluviicoccus和Competibacter菌属相对丰度最低，分别为S1、S2的 38%、61%；S3中PAOs的聚磷水解酶（PPX）、聚磷酸盐激酶（PPK）活性均高于S2和S1，富含腐殖酸的厌氧污泥发酵液为碳源，可以有效抑制GAOs的生长代谢，显著提高了PAOs的相对丰度和关键酶活性，强化了PAOs的优势地位，提高了EBPR除磷效果，为利用剩余污泥厌氧发酵液，实现EBPR高效稳定运行提供了理论依据。