Highlighting the cathodic contribution of an electrooxidation pretreatment study on waste activated sludge disintegration

Abstract

In this study, the effect of the cathodic contribution in the performance of electrooxidation (EO) pretreatment of waste activated sludge (WAS) was investigated using different electrode pairs, namely titanium dioxide (TiO 2 )/TiO 2 , TiO 2 /TiO 2 coated Platine (Pt) and TiO 2 /TiO 2 coated ruthenium dioxide (RuO 2 ) and main operational parameters such as dosage of electrolyte solution (Na 2 SO 4 ), initial pH, applied current, and electrolysis time were optimized. Disintegration degree (DD) in terms of soluble chemical oxygen demand (CODs) increased with an increase in initial pH of WAS, applied current, and electrolysis time for all pairs of electrodes. Under the optimized conditions (5 g/L Na 2 SO 4 , pH 10, 3 A of current, and 100 min of e time), a maximum DD value of 23.93 and 14.26% was obtained using TiO 2 /RuO 2 and Pt/TiO 2 electrodes, respectively. However, lower DD COD value of 12.85% was obtained for TiO 2 /TiO 2 electrodes at similar conditions except for 4 A current. Soluble extracellular polymeric substances analysis and their protein and polysaccharide concentrations confirmed the disintegration of WAS flocs by the EO process. The operational cost (OC) of applied processes was also calculated and OC values were found in the following order: TiO 2 /RuO 2 (46.54 €/m 3 ) > TiO 2 /TiO 2 (41.77 €/m 3 ) > TiO 2 /Pt (32.99.54 €/m 3 ) from the point of energy consumption.

Enhancement of Electrochemical–Anaerobic Digested Palm Oil Mill Effluent Waste Activated Sludge in Solids Minimization and Biogas Production: Bench–Scale Verification

“…Furthermore, a study by Heng et al [19] showed a solid removal rate of 38% with Ti/RuO 2 electrodes considering the current density (6 mA/cm 2 ), electrolysis time (35 min) and sodium chloride (NaCl) electrolyte (1000 mg/L). Erkan et al [20] also reported a disintegration degree of 23.93% on pre-treated WAS, conducted at pH 10 with 3 A for 100 min using Ti/RuO 2 electrodes. Another research on EO pre-treatment of food waste using Ti/RuO 2 electrodes conducted by Liyanage and Babel [2] with operating conditions of 20 V for 40 min improved the sCOD solubilization by 40%.…”

“…An innovative pre-treatment-electrochemical oxidation (EO), a form of advanced oxidation process, has been showing its positive traits as a pre-treatment, to improve the biodegradability of waste activated sludge (WAS) [18][19][20][21]. EO is a clean technology that involves electrons by generating strong oxidizing agents in breaking down the EPS protecting layer of organic matter, which subsequently helps in dewatering and degrading the organic matters into simpler forms to help with the subsequent AD process [3,10,22].…”