Photocatalytic mineralization of secondary effluent organic matter with mitigating fouling propensity in a submerged membrane photoreactor

Secondary effluent organic matter (SEOM) is an unwanted constituent that impairs the reuse of wastewater effluent. The potential of a membrane photoreactor (MPR) involving TiO2 photocatalysts and submerged microfiltration (MF) membranes was investigated with regard to SEOM degradation and fouling control. Colloidal particles interfered with the photocatalysis of the SEOM when accumulated inside the reactor. Air bubbles, which were continuously supplied to disturb the cake formation at the membrane surface, also hindered the photocatalytic performance due to light scattering. Intermittent bubble-free backpulsing was attempted and found to help improve membrane permeability, with considerably reduced energy requirements, while detaching photocatalysts from the membrane. Bubbleless backpulsing for short periods (30 s every 1 h) at low pressures (0.5 bar) was effective in reversing the fouling layers. MPR treatments removed >60% of the SEOM at a hydraulic residence time of 140 min, degrading a wide range of SEOM molecules. The synergistic reactions of adsorption and photocatalysis of the SEOM at the TiO2 surfaces induced their self-sustaining capability after rapid organics sequestration. (C) 2015 Elsevier B.V. All rights reserved.