Integrated Membrane Processes (EDR-RO) for Water Reuse in the Petrochemical Industry

The objective of this work was to apply a hybrid process, including electrodialysis reversal (EDR) and reverse osmosis (RO) to the treatment of petrochemical wastewater in order to obtain process water for reuse. A water balance was carried out to defne the main water consumers and the process step that could receive the produced water. Additionally, toxicity assays were performed to evaluate the removal of toxic compounds after EDR and RO processes. Different operation parameters in the EDR and RO processes were investigated to enhance the membrane performance. The EDR assays were performed in a pilot plant, with 300 ion-selective membranes and an area of 0.096 m2 for each membrane. The process conditions were: electrical potential of 150 V and 250 V, dilute flow rate at 600 L.h-1 and 1,000 L.h-1, concentrate flow rate maintained at 200 L.h-1, with 25% recirculation and operation in series and parallel modes. The RO assays were conducted in pilot equipment, with a polyamide spiral membrane module with a membrane area of 7.2 m2. Assays were performed at 8 bar, varying the reject flow in each experiment as follows: 150, 300, 450 and 600 L.h-1. The EDR-RO hybrid system presented a removal rate above 90% for most physicochemical parameters from the wastewater, generating a process water without toxicity.