活性污泥的理化性质与絮凝调理投药量的关系

采用烧杯试验研究了活性污泥理化性质与絮凝调理投药量的关系,分析了活性污泥离心上清液黏度及其中胶体的Zeta电位和表面电荷密度、污泥絮体的粒度、分形维数和强度等理化性质指标随调理絮凝剂(CPAM,CZ-8698)投药量的变化规律,探讨了这些指标在确定絮凝调理最佳投药量方面的差异.结果表明,CZ-8698的投药量对污泥的脱水性能和理化性质均可产生明显的影响,基于毛细吸水时间(CST)、污泥比阻(SRF)确定的活性污泥絮凝调理的最佳投药量范围为4.28～7.13g.kg-1,对应的CST与SRF值分别为(12.62±1.39)s、0.56×1012m.kg-1.在此最佳投药量区间,污泥离心上清液中胶体的Zeta电位与表面电荷密度均由负值变为正值,污泥絮体的分形维数分别为1.09(一维)和1.51(二维),其表面不规则程度最低、结构较为密实;污泥絮体的粒径随着絮凝剂投药量的增加持续增大到mm尺度,但其强度在投药量高于4.60 g.kg-1以后逐渐趋于稳定.此外,当絮凝剂投药量低于上述最佳范围时,污泥离心上清液的黏度已经达到了最小值(1.24±0.04)mPa.s.

Relationship Between Physicochemical Characteristics of Activated Sludge and Polymer Conditioning Dosage

Jar test was employed to determine the relationship between physicochemical characteristics of activated sludge(AS) and polymer conditioning dose. The evolutions of indexes representing the AS physicochemical characteristics, such as the viscosity of AS centrifugal supernatant, zeta potential and surface charge density of colloids in it, size, fractal dimensions and strength of AS flocs, with polymer doses of CZ-8698 in flocculation conditioning process were recorded and analyzed. In addition, the difference in determining the optimum dosage of AS conditioner was identified among the aforementioned indexes. The results showed that CZ-8698 doses had a great impact on the dewaterability and physicochemical characteristics of AS. The range for optimum CZ-8698 dose was 4.28-7.13 g·kg^-1 on the basis of capillary suction Time (CST) and specific resistance to filtration (SRF) test, and the corresponding values for CST and SRF were (12.62±1.39)s and 0.56×10¹² m·kg^-1, respectively. In this optimum range, both the zeta potential and surface charge density of colloids in AS centrifugal supernatant changed into positive values from negative ones, and AS flocs showed the most irregular boundary or surface and much compact structure, which was demonstrated by their fractal dimensions of 1.09(one-dimensional fractal dimension, D₁) and 1.51(two-dimensional fractal dimension, D₂). Although AS flocs grow up to millimeters scale with the increase of CZ-8698 doses, the strength of these flocs gradually tended to keep constant at the conditioner doses higher than 4.60 g·kg^-1. Furthermore, when conditioner dosage was much less than above optimum dosage range, the viscosity of AS centrifugal supernatant reach the minimum value(1.24±0.04) mPa·s.