Purification of oily wastewater by hybrid UF/MD

Investigations on the treatment of oily wastewater by a combination of ultrafiltration (UF) and membrane distillation (MD) as a final purification method have been performed. A tubular UF module equipped with polyvinylidene fluoride (PVDF) membranes and a capillary MD module with polypropylene membranes were tested using a typical bilge water collected from a harbour without pretreatment. The permeate obtained from the UF process generally contains less than 5 ppm of oil. A further purification of the UF permeate by membrane distillation results in a complete removal of oil from wastewater and a very high reduction of the total organic carbon (99.5%) and total dissolved solids (99.9%).