给水厂排泥水破碎-再絮凝过程中镉迁移转化研究

Cadmium Migration and Transformation in Sludge Water Treatment during“Broken-Recoagulation”in Waterworks

针对目前国内部分给水厂排泥水受到镉污染,致使排泥水回用具有镉超标的风险,基于排泥水"破碎-再絮凝"过程,分析上清液与污泥中镉的变化,研究排泥水中镉的迁移转化规律。结果表明,排泥水污泥对镉的吸附量与排泥水中镉的总量线性相关;破碎、高p H值、低温和投加适量阳离子絮凝剂都有助于污泥吸附镉;但对处理后的污泥进行长时间搅动会导致其中的镉释放。污泥中的镉以铁锰氧化物结合态为主,使用PAM对污泥进行调质,离子交换态镉和部分铁锰氧化物结合态镉转变为有机结合态镉。"破碎-再絮凝"过程有利于排泥水中溶解态镉迁移至污泥中,但再絮凝的污泥不宜过多扰动和停留。

In view of sludge water being polluted by cadmium and reuse with risk of cadmium ex- ceeding standard in some waterworks in China, the migration and transformation of cadmium in sludge water were studied by analyzing the change of cadmium in the supernatant and sludge during broken - re- coagulation process. The results showed that the amount of cadmium adsorbed by sludge was linearly to the total cadmium in sludge water and crushing, high pH, low temperature and adding appropriate a- mount of cationic flocculant were beneficial to the adsorption of cadmium by sludge, but a long period of stirring of the treated sludge could lead to the release of cadmium from the sludge. The cadmium in the sludge existed mainly in Fe - Mn oxide combined state. After using PAM to adjust sludge, some ex- change state Cd and Fe - Mn oxide combined state Cd in sludge changed into organic combined state Cd The broken - recoagulation process was beneficial to the migration of dissolved cadmium from supernatant into sludge, but the treated sludge should not be disturbed or stayed too long