Ultrafiltration membranes are used for separating oil from water and treating metalworking effluent using two PVDF ultrafiltration membranes of 200 kD and 100 kD molecular weigh cut-off. The influence of feed stream temperature on the permeate quality has been investigated. Fouling of membranes is a limiting factor of the technique. Fouling has occurred in all cases at different degrees and therefore washing cycles were introduced using Micellar solutions, which might affect the membrane surface and change its properties. The work presented here is a study of washing cycle optimisation of an ultrafiltration plant used to treat waste metalworking fluids. For the washing cycle, six factors were investigated. Interactions between oily material fouling the membrane surface, the surfactant and oil emulsion are discussed.