Combined treatment of paper industry wastewater by Fenton and ultra/nanofiltration membrane processes: comparison of membrane types

BACKGROUND The paper industry wastewater treatment using Fenton oxidation, ultrafiltration, and nanofiltration membrane processes was researched in this study. The different Fe 2+ and H 2 O 2 concentrations, pH values, and oxidation times were evaluated on wastewater treatment, and the oxidation kinetics were determined in the Fenton process. The different membranes (UC30 and UC100) during the ultrafiltration process, and the different membranes (NP30 and NP10) during the nanofiltration process were used at various pH values (3, 5, and 7). RESULTS pH 3, 3000 mg L −1 Fe 2+ , 8000 mg L −1 H 2 O 2 and 1 h were determined as the optimum operating conditions for the Fenton oxidation process. UC100 membrane for ultrafiltration and UC30 membrane for nanofiltration provided the highest treatment efficiencies, while treatment performance in both membrane systems improved under alkaline conditions (pH 11). As a result, overall removal of COD, TOC, and color was achieved as 97.9%, 96.1%, and 99.9% by the combination of the Fenton–ultrafiltration–nanofiltration system. CONCLUSIONS These findings demonstrate that the proposed sequential treatment system enables advanced treatment of paper industry wastewater and provides a strong potential for wastewater reuse applications.