钛盐混凝剂调理对活性污泥絮体理化性质的影响作用机制

研究了预制的不同形态钛盐混凝剂对污泥的调理效果,结果表明不同碱化度B值,即n(OH)/n(Ti)]聚合氯化钛(PTC)单一调理污泥时,在相同投加量时,PTC_(0.5)调理后污泥比阻、可压缩性以及EPS中有机物含量均低于其他形态钛盐,其最佳投加量以TSS计,为0.005 g·g~(-1),该投加量远低于传统的铁盐和铝盐混凝剂.不同B值PTC调理污泥脱水能力的强弱顺序为:PTC_(0.5)PTC_(1.5)Ti Cl_4PTC_(2.5).同时分析了调理过程中污泥絮体粒径(d_(0.5))和分形维数(D_F)的变化特征.采用三维荧光光谱和高效体积排阻色谱,解析了钛盐混凝剂对污泥胞外聚合物(EPS)分布和组成的影响,EPS蛋白峰的荧光强度和有机物相对分子质量峰分布变化规律与污泥比阻、可压缩性和脱水能力变化规律有一定相关性.

Influencing Mechanism of Titanium Salt Coagulant Chemical Conditioning on the Physical and Chemical Properties of Activated Sludge Flocs

The effect of the different forms of titanium salt coagulant conditioning on sludge dewatering performance was studied. The result showed that the sludge dewaterability was the best and the specific resistance to filtration (SRF), the compressibility and the content of organic content in EPS were the lowest when B=0.5 compared with others. The optimal dosage of polymeric titanium chloride (PTC) was 0.005 g·g^-1, which was far less than those of the traditional iron salts and aluminum coagulants. When the dosage of PTC with different B values was 0.005 g·g^-1, the order of dewaterability was:PTC _0.5> PTC_1.5> TiCl₄> PTC_2.5. In addition, the variations of characteristics such as particle size (d_0.5) and fractal dimension(D_F) of sludge during conditioning were analyzed. The effect of titanium salt coagulant conditioning on the distribution and composition of the sludge extracellular polymeric substance(EPS) was characterized by Three-dimensional Excitation Emission Matrix Fluorescence (3DEEM) and High Performance Size Exclusion Chromatography(HPSEC).The decrease of fluorescent intensity and molecular weight of peak distribution and intensity of organics in EPS was highly correlated to the improvement of the dewatering performance and change of sludge properties.