Integrating a novel TS-af-HFM NF process for portable treatment of oilfield produced water

A novel two-stage anti-fouling hollow fiber membrane (TS-af-HFM) nanofiltration (NF) process was integrated with a super hydrophobic organic silica modified polyvinylidene fluoride (PVDF/Si-R) hollow fiber membrane and a super hydrophilic silica modified polyethersulfone (PES/SiO2) based TFC hollow fiber membrane for portable treatment of oilfield produced water. The performance of the TS-af-HFM NF system was investigated in terms of organics removal efficiency, permeate water flux and salt rejection. The result showed that the PVDF/Si-R membrane can dramatically remove dissolved organics from the produced water in the first stage, with the organics rejection efficiency up to 98.7%. Meanwhile, the PES/SiO2 TFC membrane showed encouraging desalination ability with a relatively low operating pressure in the second stage. The high-efficient removal of dissolved organics in the first stage effectively eliminated the organics fouling occurred during the desalination process in the second stage. The variation of feed rate (0.05-0.2 ml/min) and operating pressure (0-30 psi) in the first stage has no significant effect on the performances of the TS-af-HFM NF system. However, with the increase of operating pressure from 50 psi to 80 psi in the second stage, the permeate water flux and salt rejection efficiency linearly increased. The system showed attractive regeneration ability for oilfield produced water treatment application. (C) 2016 Elsevier B.V. All rights reserved.