胞外聚合物中磷酸盐的吸附/结合与转化机制研究

The technology of enhanced biological phosphorus removal (EBPR) has been widely applied. However, there are unpredictable deteriorations frequently occurred in the full-scale EBPR systems. Therefore, it is necessary that the mechanisms of EBPR should be improved, for enhancing the effect and stability of biological phosphorus removal. Actually, there are many three-species phosphates of located in extracellular polymer substances (EPS), which participate in biological phosphorus-accumulation, and play important roles in biological phosphorus removal. Unfortunately, the exact roles of EPS in the mechanisms of EBPR are still unknown, which are required to clarify three problems, including patterns of phosphate adsorption/combination in EPS, and the microorganism-metabolism mechanism of EPS participating biological phosphorus-accumulation as well as the dephosphorization relationships between PAOs and EPS. In this program, adopting the activated sludge systems of biological phosphorus removal as objects, the mechanisms of phosphates adsorption/combination and transformation in EPS will be researched, which include the mechanism of physical chemistry of phosphate adsorption/combination in EPS, and the mechanism of biochemical reaction of polyphosphate decomposition/synthesis in EPS as well as the mechanism of microorganism bioecology of polyphosphate decomposition/ synthesis in EPS. Furthermore, the complicated interaction relationships among microorganism communities, metabolism patterns, forms and properties of extracellular substances, and patterns of phosphate adsorption/combination in EPS will be investigated, to discover mechanisms of phosphates adsorption/combination and transformation in EPS, and to improve the whole mechanisms of EBPR, for providing the theoretical bases to further optimize design and operation of EBPR systems.

生物强化除磷（EBPR）已广泛应用，但常发生不可预知的恶化，因此需完善EBPR机制，提高处理效果和运行稳定性。胞外聚合物（EPS）含有大量不同形态的磷酸盐，参与生物聚磷过程，在生物除磷中起重要作用。然而，EPS在EBPR机制中的确切作用还不清晰，主要表现为EPS吸附/结合磷酸盐方式、EPS参与生物聚磷的微生物代谢机制、PAOs除磷与EPS除磷的联系均未明确。为此，本项目从物化作用、生化反应和微生物生态学角度分别研究EPS大分子影响下EPS吸附/结合磷酸盐的物化作用机制、微生物代谢方式影响下EPS聚磷酸盐分解/合成的生化反应机制、微生物种群影响下EPS聚磷酸盐分解/合成的微生物生态学机制，深入探讨“微生物种群结构―代谢方式―胞外物质形态与性质―EPS吸附/结合磷酸盐方式”的复杂作用，全面揭示EPS中磷酸盐的吸附/结合与转化机制，完善EBPR机制，为优化EBPR系统的设计与运行提供理论依据。

生物强化除磷（EBPR）系统常发生不可预知的恶化，有待完善EBPR机制，提高处理效果和运行稳定性。胞外聚合物（EPS）含有大量不同形态的磷酸盐，参与生物聚磷过程。因此，需从EPS的角度审视EBPR机制。本项目实施过程中逐步完善与建立了采用低频（约21 kHz）低功率密度超声波（1 W/mL下作用3 min）、阳离子交换树脂法（400 rmp下搅拌30 min）和低频高功率密度超声波（10 W/mL下作用10 min）分级提取疏松结合EPS（LB-EPS）、紧密结合（TB-EPS）和细菌细胞中P的方法。以不同温度（20 ℃和35℃）和不同碳源（乙酸钠和丙酸钠）的A/O-SBR反应器为研究对象，采用准稳态反应器试验、批次试验和降低温度反应器试验，结合31 P核磁共振、TOC、红外光谱、气相色谱和16S rRNA等实验手段和方法，研究EPS中磷酸盐的吸附/结合与转化机制。结果表明，EPS中的聚磷酸盐（polyP）主要赋存于TB-EPS。EBPR过程中TB-EPS不仅中转/滞留正磷酸盐（orthoP），而且参与生物聚P；LB-EPS发挥中转/滞留orthoP的作用。K+和Mg2+是EBPR污泥TB-EPS中polyP重要的反离子，但少量Al3+和适量Ca2+在促进TB-EPS絮凝与吸附/结合磷酸盐中发挥重要作用。采用污泥P分级提取方法证实了EBPR污泥polyP包括细菌细胞内polyP和TB-EPS中polyP，明确了EBPR过程涉及细菌细胞内polyP和TB-EPS中polyP的联合作用。并且，提出了胞外polyP厌氧水解产生orthoP促进PAOs摄取挥发性脂肪酸（VFAs）的阴离子交换假说。EBPR过程存在（i）orthoP厌氧直接释放/好氧直接吸收和（ii）polyP厌氧水解/好氧合成2种途径，其中胞内聚羟基烷酸酯（PHAs）是细菌细胞内和TB-EPS中polyP合成的能量来源，其厌氧有效贮存是（ii）途径为主导EBPR过程的物质条件。此外，PAOs是TB-EPS中polyP贮存和转化的微生物种群基础。上述结果进一步完善了EBPR机制，为优化EBPR系统建设和运行提供了部分理论依据。