Eletrocoagulação com eletrodos de alumínio e ferro e processo Fenton eletroassistido para o tratamento de concentrado de osmose inversa após ultrafiltração: um estudo comparativo

This study investigates the application of electrocoagulation (EC), using aluminum (Al) and iron (Fe) electrodes and the electro-assisted Fenton (EAF) process to treat ultrafiltration-treated concentrate leachate from the reverse osmosis (RO) process. Treatability tests were conducted using a laboratory-scale apparatus. Electrolysis time was monitored to determine the ideal residence time. Treatment performance was assessed based on true color, absorbance at 254 nm (Abs254), and dissolved organic carbon (DOC). The Abs254/DOC ratio, termed specific ultraviolet absorbance (SUVA), was monitored to assess changes in the aromaticity of wastewater organic matter. A preliminary cost estimate was prepared to compare the operating costs of Al/Fe-EC and EAF. Iron electrodes showed better performance than aluminium electrodes in terms of pollutant removal efficiency and treatment time. Treatability performance of electrochemical methods, based on color, Abs254, and DOC removal, was determined as follows: EAF > Fe-EC > Al-EC. Considering benchmarking of performance indicators for treatment costs, i.e., USD g-1 DOC removed, the results were reported as follows: 32.28 USD g-1 DOC (Al-EC), 14.74 USD g-1 DOC (Fe-EC), and 29.27 USD g-1 DOC (EAF). Although Fe-EC was more cost-effective than EAF, the electro-assisted Fenton process achieved higher removal efficiencies across true color, Abs254, and DOC parameters. In addition, EAF was the only process capable of reducing SUVA, indicating a decrease in the recalcitrance of the treated effluent (from 6.5±0.3 to 3.4±0.2 L mg-1 m-1).