好氧污泥强化造粒过程中EPS的分布及变化规律

Distribution and changes of EPS in strengthening granulation process of aerobic sludge

通过在好氧颗粒污泥生长前期投加混凝剂的方式,考察混凝剂的投加对颗粒生长的影响,用三维荧光光谱法分析胞外多聚物(EPS)在颗粒生长过程中的变化规律及其与污泥特性的相关性。结果表明,强化造粒条件下的污泥完全颗粒化的时间比对照组提前12 d,其强度和比重也分别比对照组高出2.05%和0.032。对各形态EPS三维荧光光谱分析,发现生长期松散型胞外多聚物(LB-EPS)的峰点为溶解性微生物代谢产物,及少量的芳香蛋白类物质和腐殖酸类物质,颗粒成熟后溶解性微生物代谢产物和蛋白类物质的荧光强度均减小,腐殖酸类物质消失,而溶解型胞外多聚物(S-EPS)和紧密型胞外多聚物(TB-EPS)的峰点及强度在两阶段无明显变化。在颗粒生长过程中,LB-EPS中的蛋白质含量随颗粒生长逐渐升高,颗粒成熟后逐渐降低至稳定,而多糖含量基本保持在1~5 mg/g MLSS。与S-EPS、TB-EPS相比较,LB-EPS和污泥颗粒化有密切关系,且与SVI呈正相关性(相关系数r=0.812),与相对疏水性呈负相关性(相关系数r=-0.973)。

In this study,the influence of coagulants on the aerobic granular sludge during the early growth stage of granular sludge was investigated,and the changes of extracellular polymeric substances( EPS) and its correlation with sludge during aerobic granular growth period were also analyzed by using three-dimensional fluorescence spectrum(3D-EEM) method. Results showed that the time of complete granulation under the strengthening granulation was 12 days earlier than the control group; the strength and specific gravity of aerobic granular sludge were 2. 05% and 0. 032 higher than the control group,respectively. The 3D-EEM analysis for all forms of EPS showed that peak point of loosely bound EPS( LB-EPS) were mainly soluble microbial metabolites,a small amount of aromatic protein-like and humic acid-like during the aerobic granular sludge growth stage. After the granule matured,the fluorescence strength of soluble microbial metabolites and protein-like decreased,and humic acid-like disappeared. However,the peak point and strength of soluble EPS( S-EPS) and tightly bound EPS(TB-EPS) changed little during these two stages. Protein content of LB-EPS increased with the granule growth and decreased gradually to a certain range after granular sludge matured,while polysaccharide content was basically remained 1 ~ 5 mg / g MLSS. LB-EPS was closely related with sludge granulation compared with the S-EPS and TB-EPS,and it has a positive correlation with SVI( correlative coefficient = 0. 812),and a negative correlation with relative hydrophobicity( correlative coefficient =- 0. 973).