Membrane Distillation Treating a Petrochemical Reverse Osmosis Concentrate

This study investigated the applicability of Direct Contact Membrane Distillation (DCMD) process for the treatment of a petrochemical industry effluent, intending to recover water from the concentrate produced by reverse osmosis (RO). In DCMD, the experiments were accomplished with a feed and permeate-inlet temperature of 60 °C and 20 °C, respectively. Four commercial microporous hydrophobic flat-sheet membranes made of polytetrafluoroethylene (PTFE), with or without a support layer, laminated or not with butylated hydroxyanisole (BHA), having different thickness, pore size, effective porosity and contact angle, were evaluated. All evaluated membranes presented a very satisfactory water recovery ratio (~90%), getting high rejection factors (above 99.5%) for all analysed parameters and producing a high-quality water having a very low electrical conductivity (around 2 μS cm–¹). The membrane with BHA in its composition presented the lowest permeate flux decay that occurred gradually along the experimental runs, representing a productivity loss of only 14% for a water recovery ratio near 90%. These results indicate that this membrane has a low propensity to fouling and scaling when treating a wastewater with characteristics like the ones evaluated in this work.