Correlation and mechanism of extracellular polymeric substances (EPS) on the effect of sewage sludge electro-dewatering.

Electro-dewatering (ED) is an attractive technology for enhancing dewaterability of waste activated sludge (WAS), and the distribution and composition of EPS and secondary structure of extracellular protein in sludge has a great influence on the sludge dewaterability. Therefore, in order to optimize and regulate sludge ED process, it is necessary to study the influence of EPS components and composition on the efficiency of sludge ED. In this study, the effects of distribution and composition of EPS and the structure of extracellular proteins on the ED rates and performance were analyzed using eight sludges from different sewage treatment process. The results showed that ED rates at both electrodes were significantly negatively correlated with the concentration of soluble EPS (S-EPS) and loosely bound EPS (LB-EPS), and this correlation was gradually weakened with the in-depth structure of layered EPS structure. High concentration of S-EPS and LB-EPS decreased the initial current and the pH gradient, deteriorating the anodic oxidation and acidification, which affect the release and degradation of EPS. Additionally, the proteins secondary structure can be destroyed and transformed by anodic oxidation and acidification, which can impact the protein water-holding capacity and ED performance.