Nano-porous membrane process for oily wastewater treatment: Optimization using response surface methodology

A sheet nano-porous membrane (PAN), nominal pore size 10 nm is experimentally employed in order to treat the oily wastewater in a desalter plant. Response surface methodology (RSM) based on Box–Behnken method is used to design the experiment and analyze five operating parameters including; trans-membrane pressure (TMP), salt concentration, cross flow velocity (CFV), pH and feed temperature. The maximum permeation flux of 180.1 L/m2 h is identified by RSM at feed temperature of 45 °C, TMP of 4 bar, CFV of 1.3 m/s, pH of 10 and salt concentration of 11.2 g/L. The results show that nano-porous membrane is efficient for treatment of petroleum refinery waste water, so that total suspended solids, total dissolved solids, oil and grease content and chemical and biochemical oxygen demand are increased to 100%, 44.4%, 99.9%, 80.3% and 76.9%, respectively. The treated water by the proposed method meets the process and industrial water quality requirements for the discharge to the environment or reuse as agricultural water.