Chemical cleaning of PVDF microfiltration membrane fouled by emulsified oil wastewater

Hydrophilic polyvinylidenefluoride (PVDF) membranes were successfully employed for treatment of emulsified oil wastewater. The dominant mechanism for fouling is the formation of an oil layer on the membrane surface. Cleaning removes the deposited layer at least partly. In this study, fouled membranes were cleaned with (NaOH, alkalis KOH and NH(3)), acids (HNO(3), H(3)PO(4) and H(2)SO(4)), solvent (2-propanol), complexing agents (EDTA and Citric acid) and surfactants (Triton X-100 and SDS). NaOH, EDTA and SDS resulted in a maximum flux recovery and resistance removal. Other cleaning agents showed moderate or weak effects. In general, alkaline solutions are more efficient compared to acids for removal of organic compounds such as oils. Cleaning efficiency depends on the concentration of the cleaning agent. For NaOH, EDTA and SDS, efficiency rose with increasing the concentration. The increment in low concentration was more pronounced. Operating conditions affect the cleaning efficiency. For longer cleaning times and higher cross-flow velocity, better removal of deposits and higher cleaning efficiency were observed.