藻-菌颗粒污泥胞外聚合物及其表面特性研究

藻-菌颗粒污泥具有能耗低、温室气体排放量少等优点,近年来在污水处理领域受到关注.胞外聚合物(EPS)在保护微生物免受恶劣环境影响及促进细胞聚集方面发挥重要作用,而关于藻-菌颗粒EPS及其表面特性鲜有报道.选取了粒径范围在0.36~0.71、1~1.25、1.6~2.0 mm的3组藻-菌颗粒,分析了其EPS中多糖和蛋白质的含量,并进一步地对其组成差别以及官能团特征进行探究,探讨了EPS提取前后藻-菌聚集体表面电荷的变化.结果表明,随着粒径的增大,藻-菌颗粒污泥EPS中多糖和蛋白质的含量均有增加,而蛋白质与多糖的比值减小.不同粒径的藻-菌颗粒污泥EPS中芳香蛋白与酪氨酸类物质的含量明显增加,腐殖酸类物质含量亦呈总体增加趋势,与胞外蛋白相比,胞外多糖特征峰的波峰强度增加较明显.进一步分析表明,粒径较大的颗粒可能更能抵御外界环境因素的变化,以维持颗粒性能.以上结果表明,粘性和亲水性的多糖、芳香蛋白和酪氨酸类物质可能更有利于藻-菌颗粒的微生物细胞聚集.本文的研究结果进一步地拓展了对藻-菌颗粒污泥的认识,并为其进一步的工程应用提供基础.

Study on the extracellular polymeric substances of the microalgal-bacterial granular sludge and its surface characteristics

Microalgal-bacterial granular sludge has the advantages of low energy consumption and low greenhouse gas emissions, etc. Therefore, it has attracted attention in the field of wastewater treatment in recent years. Extracellular polymeric substances (EPS) play an important role in protecting microorganisms from harsh environments and promoting cell aggregation. However, there are few reports on the EPS and its surface characteristics of microalgal-bacterial granular sludge. In this study, three groups of microalgal-bacterial granular sludge with particle sizes of 0.36~0.71 mm, 1~1.25 mm and 1.6~2.0 mm were applied for study. The contents of polysaccharide and protein in EPS were analyzed, and the composition differences and functional group characteristics were further explored. The changes in the surface charge of microalgal-bacterial aggregates before and after EPS extraction were analyzed. The results showed that with the increase of the particle size, the content of polysaccharide and protein from the EPS of microalgal-bacterial aggregates sludge increased, while the ratio of protein to polysaccharide decreased. The content of aromatic protein and tyrosine substances increased significantly, while the content of humic acid substances also showed an overall increase trend. Compared with extracellular proteins, the peak strength of extracellular polysaccharide characteristic peaks increased more significantly. Further analyses showed that microalgal-bacterial granules with a larger particle size might be more resistant to changes in external environmental factors with a stronger granular stability. The above results showed that sticky and hydrophilic polysaccharides, aromatic proteins and tyrosine-like substances might be more conducive to the accumulation of microbial cells in microalgal-bacterial granular sludge. Results of this study could advance the basic knowledge on microalgal-bacterial granular sludge for its further possible engineering application.