Employing Electrochemical-Fenton process for conditioning and dewatering of anaerobically digested sludge: A novel...

In this study, for the first time, the occurrence mechanism of anaerobically digested sludge conditioning for dewatering process based on Electrochemical-Fenton technology was investigated and the optimum condition has been determined to employ a lab-scale reactor. Due to the results of current studies using electrochemical and Fenton methods, a comparative economic-technical investigation has been provided accordingly. The results showed that under optimum operational condition by utilizing Electrochemical-Fenton process e.g. H₂O₂ = 25 mg/g DS (dry solid), Fe²⁺ = 15 mg/g DS, retention time = 20 min, electrolysis voltage = 11 V, the specific resistance to filterability (SRF) and time to filter (TTF) parameters reduction equal to 93.8% and 75.9% respectively. The occurrence mechanism of the sludge conditioning was determined by evaluation of extracellular polymeric substances (EPS), particle size distribution, zeta potential and bound water tests. The dry solids concentration of the conditioned sludge by Electrochemical-Fenton process was increased from 2.3% to 41% by dewatering employing filter press system. Furthermore, the estimated cost of conditioning using this method is 41.82 USD$/t DS, which is less than other investigated methods e.g. traditional Fenton process. It can be concluded that the results reached in this comprehensive and comparative study could be a suitable basis for further investigations regarding utilization of novel electrochemical advanced oxidation technologies for efficient sludge conditioning and dewatering purposes.