碳源胁迫对颗粒污泥稳定性及除磷特性的影响及机制

Granular sludge represents a promising potential for application in the removal of nitrogen and phosphorus, with high settling velocity, activity and sludge concentration. But its application is limited due to the lack of sludge stability. The extracellular polymeric substances (EPS) is a key material to determine the stability of granular sludge, which may also play an important role in the phosphorus removal process. Carbon sources can affect the composition of EPS in the granular sludge by changing the microbial community structure, and thus affecting the stability of sludge and phosphorus removal efficiency, up to know, however, there is little information on this process. In the present project, the simultaneous nitrogen and phosphorus removal granular sludge will be firstly cultivated with different carbon sources and then be studied. By adopting the SEM, PCR-DGGE, etc, the microbial morphological and microbial community structure of the granular sludge will be studied. The morphology, composition, distribution and content of EPS will also be studied adopting TEM, TOC, and other technological means. Basing on the correlation between carbon resources and EPS along with microbial community structure, the effect and mechanism of carbon resources on the granular sludge stability will be revealed. And by adopting the XRD and other technological means, the morphology and content of phosphorus in granular sludge with different carbon sources will be studied. The form, distribution and content of phosphorus in the granular sludge will be discussed. Then the mechanism of phosphorus removal will be analyzed. Thus the effect and mechanism of carbon resources on the phosphorus removal will be revealed. Research results can give theoretical and technical supports to stable operation and efficient phosphorus removal of granular sludge system.

颗粒污泥具有沉速快、活性高、污泥浓度高等特点，在脱氮除磷方面具有较好的应用前景，但污泥稳定性不足制约了其应用。EPS是决定颗粒污泥稳定性的关键物质，并在颗粒污泥除磷过程中可能扮演重要角色。不同碳源可通过改变细菌群落结构从而影响颗粒污泥中EPS组成，进而影响污泥稳定性及除磷效果，但目前对该过程尚缺乏认识。本研究拟以不同碳源下培养的同步脱氮除磷颗粒污泥为研究对象，利用SEM和PCR-DGGE等手段研究颗粒污泥中微生物形态和菌群结构，利用TEM和TOC等手段研究颗粒污泥EPS的形态、组成等，根据碳源、菌群结构和EPS组成间的关系，揭示碳源对颗粒污泥稳定性的影响及机制；利用XRD等手段研究不同碳源下颗粒污泥中磷的形态及含量，探讨磷在颗粒污泥中赋存形式、分布及其含量，分析EPS对除磷的作用机制，进而揭示碳源对颗粒污泥除磷的影响及机制。研究结果可为颗粒污泥系统稳定高效除磷提供理论和技术支持。

分别以葡萄糖和醋酸钠为碳源培养成熟的脱氮除磷颗粒污泥，研究了环境条件（温度变化及低DO）和营养不足（氮缺乏）条件会使系统由于丝状菌过度繁殖而发生膨胀，两种膨胀条件下，EPS变化不同，前者EPS升高而后者EPS降低，前者污泥反硝化加强，而后者反硝化减弱。究其主要原因为膨胀中优势微生物的差异引起。另外，两种碳源条件下形成的颗粒污泥微生物优势种群结构不同（以葡萄糖为碳源的颗粒污泥中，Candidatus Saccharimonas含量最高，其次是Thauera，Candidatus Accumulibacter和Lebinella。而以醋酸钠为碳源的颗粒污泥中Chitinophagaceae unclassified含量最高，其次是Rhodocyclaceae unclassified，Deltaproteobacteria unclassified，Thiothrix丝硫细菌属），EPS含量不同，但EPS中蛋白质均为其主要组成部分，其次是多糖。两种碳源条件下的生物除磷中，糖原是重要的能量物质，其中以葡萄糖为碳源的颗粒污泥中糖原的含量达15%以上系统均能保持稳定，SEM结果显示其微生物以球菌为主，污泥中磷含量在5%左右；而醋酸钠为碳源的颗粒污泥中糖原在10%以下，系统维持稳定，其微生物以球菌和短杆菌为主，污泥中的磷的含量在6%左右。同时，前者中EPS中磷含量高达30%，后者EPS中磷含量基本维持在10%，前者EPS含量在 285mg/g VSS左右，后者EPS总量在200mg/g VSS左右。由此看出，两种碳源条件下，前者除磷的主要机理为生物除磷作用和胞外EPS的化学除磷作用，而后者主要以胞内生物除磷为主，而生物除磷中糖原是其代谢途径中不可缺少的重要部分。利用XRD和SMT手段对污泥中磷的成份分析发现，污泥中磷主要以无机磷为主，其中Ca-P是无机磷的主要组成形式，其中以葡萄糖为碳源的颗粒污泥中基于EPS的化学除磷作用，无机磷种类较多，利用SMT法不能检测出其他形态磷。利用31P-NMR法对EPS 中磷进行分析发现，EPS中未发现有Mono-P，Diester-P和膦酸酯有机磷，而主要以Ortho-P和Poly-P无机磷形式存在。说明在EPS中不存在生物作用，EPS中磷主要源于磷的化学作用及传输过程中截留的部分磷。同时研究发现，0.06g/L GO虽然对除磷和反硝化作用不具