Membrane-based microfiltration/electrodialysis hybrid process for the treatment of paper industry wastewater

In this research, the pilot plant of a hybrid microfiltration (MF) and electrodialysis (ED) system was designed, constructed and employed successfully to remove the color and contaminants of paper industry wastewater. Microfiltration module comprising of ceramic membrane was used at constant pressure as a pretreatment step for the ED pilot scale unit operation. The ED stack consisted of 11 cation-exchange and 10 anion-exchange membrane pairs. Tubular ceramic module was employed to pre-filter the wastewater at 60 °C and ambient temperature. Electrodialysis was successfully applied for the treatment of paper industry effluent for the first time with MF as a pretreatment step. The combined hybrid process at the applied potential of 50 V showed a low content of total dissolved solids (TDS) of 546 mg/L, conductivity of 0.61 mS/cm, and chemical oxygen demand (COD) of less than 20 mg/L. The hybrid MF/ED module used in this research gave a recovery and reuse of more than 90% of original wastewater. The proposed pilot plant was found to be more advantageous, since the ceramic membrane module used could withstand higher temperature of the discharged effluent and given the permeate that is free from the suspended particles of colloidal nature. It is also evident from the results that the hybrid process is more efficient than the single unit process.