Electric field assisted membrane separation for oily wastewater with a novel and cost-effective electrocoagulation and electroflotation enhanced membrane module (ECEFMM)

摘要

The present study discusses the simultaneous application of electric field during membrane separation of oil from oily wastewater on eliminating the fouling propensity over the membrane. A novel hybrid electrocoagulation and electroflotation enhanced membrane module (ECEFMM) was proposed here to expect the benefits of electrocoagulation and electroflotation with the membrane separation. The synergistic effect of applied voltage and membrane operation facilitates demulsification for emulsified oily wastewater along with substantial turbulence creation over the membrane surface through hydrogen bubbling. Such turbulence reduces the deposition over the membrane surface that eventually restricts the permeate flux decrease by 43-72 %. Voltage was applied both continuously and periodically, along with a gradual voltage increment in each mode. Further with both the mode of applied voltage, polyethersulfone (PES) and polysulfone (PSf) membrane were employed with each of the modes. It was observed that the permeation of the PES membrane is not substantially affected by the mode of the applied voltage. On the contrary, with relatively low hydrophilic PSf membrane, the permeation is highly dependent on the applied voltage and its mode of application. The minimum flux decline for PSf membrane can be achieved with periodical voltage application at 10 V with substantial oil rejection of 94-96 %.