用三维荧光和红外技术分析好氧颗粒污泥形成初期胞外聚合物的变化

Analysis of extracellular polymeric substances changes during the initial stage of aerobic granulation by 3D-EEM and FTIR

为了研究聚合氯化铝(PAC)的投加在好氧颗粒污泥培养初期的作用,本研究分别在污泥培养的第1—7天(R1)和第8—14天(R2)投加PAC,并采用三维荧光光谱(3D-EEM)和傅立叶红外光谱(FTIR)技术分析好氧颗粒污泥形成初期胞外聚合物(EPS)各组分的含量及变化规律.结果表明,PAC投加时间推迟后,污泥沉降性能良好,且反应器中胞外聚合物和蛋白质含量明显增多,松散附着的EPS(LB-EPS)中蛋白含量变化趋势明显,多糖含量保持在较小范围内波动,与溶解性胞外聚合物(S-EPS)和紧密黏附的胞外聚合物(TB-EPS)相比较,LB-EPS和污泥颗粒化有密切关系;三维荧光光谱分析结果显示,R2中荧光类蛋白物质(峰A和峰B)强度均大于R1,而腐殖酸类物质(峰C)强度小于R1,说明A和B这两种荧光类蛋白物质在微生物聚集体形成过程中的作用更加重要;红外光谱表明,1636 cm-1、1654 cm-1分别属于蛋白质二级结构中C=O伸长振动引起的,分别存在于S-EPS和LB-EPS、TB-EPS中,且在投加PAC的时间推迟后1654 cm-1处的吸收峰吸收较弱,和三维荧光分析共同表明LB-EPS中的蛋白类物质是好氧颗粒污泥形成初期加入PAC进行强化造粒的核心原因之一.

In order to investigate the effect of PAC during the initial stage of aerobic granulation,two dosing periods of PAC were chosen in this study（ day 1—7,R1; day 8—14,R2）. In addition,the content of EPS components was quantified and their variation was analyzed by using threedimensional fluorescence spectrum（ 3D-EEM） and Fourier transform infrared spectroscopy（ FTIR）.The results showed that the granules formed in R2 performed better in settling properties and EPS production than that in R1. Moreover,more proteis were also observed. The contents of proteins in Loosely Bound EPS（ LB-EPS） changed significantly,while the contents of polysaccharide fluctuated a narrow range. Compared with the Soluble EPS（ S-EPS） and Tightly Bound EPS（ TB-EPS）,the LB-EPS was closely related to the sludge granulation. According to the 3D-EEM,compared with R1,the fluorescence intensity of peak A and B was stronger in R2,while the intensity of peak C was weaker. This result indicated that protein-like substances played a more important role on the formation of aggregations. The result of FTIR reveal C=O stretching vibration peak,which is associated with protein secondary structure, was observed in S-EPS, LB-EPS and TB-EPS.Furthermore,its intensity was higher in R1 than in R2,suggesting that the proteins in LB-EPS played a significant role during the initial period of aerobic granulation. This result was in accordance with the analysis of 3D-EEM.