Simultaneous degradation and rejection of PPCPs from wastewater in a 3DEO-FO-RO process

This study established a novel three-dimensional electrochemical oxidation coupled with forward osmosis and reverse osmosis (3DEO-FO-RO) system with the purpose to achieve simultaneous degradation and rejection of pharmaceuticals and personal care products (PPCPs) in wastewater. 18 frequently detected PPCPs were selected as the target pollutants to prepare the synthetic wastewater with a concentration of 200 μg/L for each pollutant. Ti/IrO2–Ta2O5–SnO2 mesh anode, titanium mesh cathode and Sn–Sb–Bi/γ-Al2O3 particles electrodes were integrated in the 3DEO-FO reactor. Experimental results demonstrated that degradation efficiency exceeding 98.5 % and rejection exceeding 99.4 % for each PPCP were achieved simultaneously in the 3DEO-FO-RO processes at a current density of 1 mA/cm2 after 8 h treatment. Despite variations in applied current density, the 3DEO-FO-RO processes exhibited superior PPCPs removal efficiencies, particularly for refractory compounds, compared to the 2DEO-FO-RO processes. Increased hydroxyl radical (·OH) generation in the 3D reactor was considered to be responsible for the excellent performance. Furthermore, results derived from ultraviolet (UV) absorption spectra and fluorescence excitation-emission matrix (EEM) spectra provided additional validation for the effective removal of PPCPs in the 3DEO-FO-RO processes, along with evidence indicating the decomposition of PPCPs into smaller constituents. Ultimately, the 3DEO-FO-RO process demonstrated its capacity in removing PPCPs from actual secondary effluent from a wastewater treatment plant. This integrated system coupling 3D EO with FO-RO membranes can provide an efficient approach for simultaneous degradation and rejection of trace contaminants for wastewater reuse.