Yucel, EsraOzen, IremCene, Gulay ArslanIlhan, HilalGuvenc, Senem YaziciCan-Guven, EmineDemir, Ahmet2026-02-082026-02-0820252214-7144https://doi.org/10.1016/j.jwpe.2025.109221https://hdl.handle.net/20.500.12885/5740In this study, the treatment of landfill leachate nanofiltration concentrate (LNFC) was investigated using sequential (two distinct stages, one following the other) and combined (two mechanisms operating simultaneously in a single reactor) electrochemical processes. In the first stage, initial pH, applied current, and reaction time were optimized for individual processes: electro-oxidation (EO), peroxi-coagulation (PC), and electrochemical-peroxidation (EP). In the second stage, sequential (EO-PC, PC-EO, EO-EP, EP-EO) and combined (EO/PC, EO/EP) processes were applied with the optimal conditions determined in the first stage. Under optimum conditions (pH 5; applied current 1 A; reaction time 60 min), chemical oxygen demand (COD) removal efficiencies of 38.9 %, 42.1 %, and 53.1 % were obtained for the EO, PC, and EP processes, respectively. Enhanced COD removal was obtained by sequential processes, yielding removal rates of 65.6 % for EO-PC, 71.1 % for PC-EO, 78.3 % for EO-EP, and 83.6 % for EP-EO. The highest efficiencies were observed in the combined systems, with COD removals of 76.4 % for EO/PC and 89.1 % for EO/EP. The lowest specific energy consumption (SEC) was calculated as 31.2 kWh/kg COD for EP among the single processes, 41.0 kWh/kg COD for EP-EO among the sequential processes, and 47.5 kWh/kg COD for EO/EP among the combined processes. These findings suggest that EP-based systems require less energy than EO-based systems. The EO/EP process can be proposed as an alternative treatment for LNFC due to its compliance with the discharge standards (500 mg/L for COD for leachate) specified in the Water Pollution Control Regulation of T & uuml;rkiye and its relatively low SEC.eninfo:eu-repo/semantics/closedAccessAdvanced oxidationElectrochemical treatmentLandfill leachateSpecific energy consumptionWastewater treatmentArticle10.1016/j.jwpe.2025.10922180WOS:0016331467000012-s2.0-105024189170Q1Q1