Development of Membrane Bioreactor Using Polyvinylidene Difluoride Composites for Textile Dyeing Wastewater Treatment

A laboratory-scale membrane bioreactor (MBR) has been developed for textile dyeing wastewater treatment using fine-tuned polyvinilidinedifluoride (PVDF) composite microfiltration membrane combined with ozonation. These composite membranes were prepared by blending PVDF with Polyetherimide (PEI) and tungsten oxide via phase inversion method. The membrane performance was evaluated by filtering pure water and real textile dyeing wastewater. The composite membrane characterisations such as morphology, water uptake, surface roughness, hydrophilicity and porosity were investigated. Contact angle measurements indicated that the hydrophilic property of the PVDF/PEI composite membranes have been increased by increasing the PEI concentration in the casting solution. The real wastewater used for the experiments were combined effluent which is dark in colour. Optimised ozonation of 5 hours was used in the pre-treatment prior to MBR. The membrane modules were fabricated as modules and submerged into the reactor, having working volume of 20L. The filtration experiments have been carried out for 15 days continuously to obtain the membrane flux. Pure water flux values have been found to increase with the modified membranes from 19LMH to 21 LMH. The hydraulic retention time of 10 hours was given. Total suspended solids were removed completely after this filtration. The overall COD and colour removal efficiency achieved were 92% and 88%.