铝盐在污泥颗粒化进程中的强化作用及其空间分布

为考察铝盐在好氧颗粒污泥形成过程中的强化作用,通过在不同SBR反应器运行的第10~16天分别投加聚合氯化铝(PAC)和硫酸铝的方式来促进颗粒污泥的形成.探讨不同铝盐混凝剂的投加对颗粒污泥特性的影响,解析铝元素在污泥成长过程中的质量分数变化和空间分布规律.结果表明:铝盐的投加加速了污泥的颗粒化过程,对成熟颗粒污泥中EPS的化学结构有影响;停止加药后,投加PAC的污泥中铝质量分数在16~29 d期间由30.46%降至0.43%,投加硫酸铝的污泥中铝质量分数由45.69%降至13.29%.且在投加PAC之后,其水解产物主要分布在污泥絮体的外围,随着颗粒的成熟,污泥中铝元素的分布低于检测限;而硫酸铝经水解聚合后与污泥充分接触,在整个颗粒均有铝元素分布,颗粒成熟后主要集中在颗粒的中心位置.这说明两种铝盐在颗粒污泥形成过程中的作用可能有所差别,PAC的投加主要是促进污泥EPS的分泌,使微生物聚集;硫酸铝的投加主要是形成晶核并强化EPS的产生,从而加速颗粒污泥的形成.

Enhancing effects and the space distribution of aluminum coagulants in the process of sludge granulation

To investigate the effect of aluminum additive on the formation of granular aerobic sludge, PAC and aluminum sulfate were added into different SBR reactors to strengthen the granular sludge during the period of 10^th to 16^th day, and the chemical characteristics of granules cultivated with different coagulants were analyzed. Meanwhile the content and distribution changes of aluminum in the sludge were evaluated. Experimental results showed that aluminum coagulants additive could significantly accelerate the formation of granules and influence the chemical structure of sludge EPS. Once dosing terminated, the quality of Al in the granules cultivated with PAC decreased from 30.46% to 0.43% during the 16^th to 29^th day operation. Meanwhile, for the aluminum sulfate enhanced granules, the Al content decreased from 45.69% to 13.29%. Hydrolysis products of PAC mainly distributed in the periphery of flocs and the aluminum content of sludge was eventually below the limit of detection after granulation. However, aluminum sulfate fully contacted with flocs after polymerization and hydrolysis, and then concentrated in the center of granular after maturation. Above results demonstrated that aluminum coagulants played different roles in the granulation process. For PAC, the promotion of EPS secretion enhanced the aerobic granulation and then the microorganism aggregated; while a nucleation is formed after aluminum sulfate additive, leading to an increasing of EPS content