Coupling of membrane separation with photocatalytic slurry reactor for advanced dye wastewater treatment

In this study, a flat polytetrafluoroethylene (PTFE) membrane module was submerged into a TiO2 based slurry photocatalytic reactor to form the hybrid membrane photocatalytic reactor (MPR), for advanced wastewater treatment. The long term MPR performance was evaluated for the degradation of reactive black 5 (RB5) dye and by studying the effect of initial dye concentration on energy consumption per amount of dye removed. The different operational parameters that affect the performance of the reactor were also studied. Nearly 82-100% color, 45-93% TOC and 50-85% COD removal were achieved at hydraulic retention time (HRT) of 4 h, depending on the initial RB5 concentration. The energy consumption per mg of dye removed decreased as the dye concentration increased, up to certain limit, and remained almost constant afterwards. The results revealed that the TiO2 particles size varies within the micron range (0.1-40 mu m) during the continuous MPR operation and their size distribution was greatly influenced by the surrounding conditions. In this reactor type, the catalyst can also be reused effectively without much loss in dye degradation efficiency. The reactor operating conditions played a major role in keeping TiO2 catalyst in suspension, which in turn reduces the quick deposition of catalyst onto the membrane surface. (C) 2010 Elsevier B.V. All rights reserved.