Study on a novel composite membrane for treatment of sewage containing oil

When treated with sewage, polysulfone (PSF) membranes have a tendency to be contaminated due to their hydrophobicity, which limits large scale applications. To enhance the hydrophilic and anti-fouling property of PSF membrane, a novel organic–inorganic composite membrane was prepared by adding sulfated Y-doped nonstoichiometric zirconia (zirconia with defects, ZD) to PSF through a sol–gel process. The composite membranes were exposed to sewage containing oil, and the effects of the added amount of ZD, oil concentration, operating pressure, temperature and time on properties of composite membrane were researched. The optimum parameters are: 15 wt.% added ZD; 80 mg/L oil concentration; 0.15 MPa operating pressure; operating temperature between 22 and 30 °C and up to 5 h of operating time. At 80 mg/L sewage containing oil, the oil retention is 99.16% and the oil concentration in the permeate is 0.67 mg/L, which meets the requirement for discharge (less than 10 mg/L). After backflushing and chemical cleaning, the composite membranes could still keep a high permeation flux. It can be concluded that the hydrophilic and anti-fouling property of composite membrane can be significantly enhanced and hence the novel composite membrane is desirable in the treatment of sewage containing oil.

► Sulfated Y-doped nonstoichiometric zirconia particles (ZD) are prepared.
► ZD particles are doped into polysulfone to prepare a composite membrane.
► This composite membrane can be applied to the process of oil–water separation.
► This composite membrane has stronger hydrophilic property and anti-fouling ability.