电渗透耦合Fe^(2+)-过硫酸钠污泥脱水过程中EPS的变化特性

Variation characteristics of extracellular polymeric substances in sewage sludge dewatering by coordination of electro-osmotic and Fe2+-sodium persulfate oxidation process

为了考察电渗透耦合Fe^(2+)-过硫酸钠污泥深度脱水的机制,采用自制装置对市政污水处理厂的污泥进行了脱水研究。系统研究了在不同电压梯度、机械压力、过硫酸钠投加量、Fe^(2+)与过硫酸钠比例、阴阳极间距等操作条件下,污泥中胞外聚合物(EPS)的组成及分布对污泥脱水效果的影响。结果表明,电渗透耦合Fe^(2+)-过硫酸钠可以改善污泥的脱水效果,过硫酸钠经过Fe^(2+)和热活化作用产生的硫酸根自由基对污泥中EPS的破坏作用明显,从而造成EPS特性改变。其中,紧密型胞外聚合物(TB-EPS)中的蛋白质和多糖、松散型胞外聚合物(LB-EPS)中的蛋白质及各层EPS中的蛋白质/多糖与污泥脱水效果存在显著相关性;黏性胞外聚合物(S-EPS)和LB-EPS中的多糖与污泥脱水效果存在显著相关性。TB-EPS、LB-EPS及其中含有的蛋白质和多糖含量是影响污泥电渗透耦合Fe^(2+)-过硫酸钠脱水效果的主要因素。

In order to investigate the mechanisms of sewage sludge dewatering by coordination of electroosmotic and Fe2+-sodium persulfate oxidation process, the dewatered sludge from a sewage treatment plant was treated by a self-made experimental device. The effects of EPS constituent and distribution on sludge dewatering behavior were investigated under the different voltage gradients, mechanical pressures, persulfate dosages, the ratios of Fe2+and sodium persulfate, and anode-cathode distances. The results showed that sludge dewatering effect can be improved by the coordination process of electro-osmosis and Fe2+-sodium persulfate oxidation. The sulfate radical anions produced from sodium persulfate activated by Fe2+and thermal activation presented an obvious damage to EPS in the sludge, thus the EPS characteristics changed. The protein in tightly bound extracellular polymeric substances(TB-EPS) and loosely bound extracellular polymeric substances(LB-EPS)and the ratio of protein to polysaccharide in three layer EPS significantly correlated with the sludge dewatering effect, so did the polysaccharide in TB-EPS, in slime extracellular polymeric substances(S-EPS) and LB-EPS.The TB-EPS, LB-EPS, and their protein, polysaccharide contents are the primary factors affecting sludge dewatering by the coordination process of electro-osmosis and Fe2+-sodium persulfate oxidation.