DESALINATION zyxwv ELSEVIER Desalination I56 (2003) 199-207 www.elsevier.com/locate/desal Optimisation of washing cycle on ultrafiltration membranes used in treatment of metalworking fluids Gerald Busca, Nidal Hilal*, Brian P. Atkin .-ldvanced Water Treatment Group. School of Chemical, Environmental and Mining Engineering. The University of Nottingham, Nottingham NC7 2RD, UK Tel. +J-/ (115) 95ld168. Fax 4-44 (11.5) 95iJll5. entail: nidal.hilal@nottingham.ac.uk Received 29 January 2003; accepted 4 February 2003 Abstract 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 ofmembranes is a limiting factor ofthe 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. Keywords: Ultrafiltration; Metalworking fluid; Membrane fouling; Surfactant; Emulsion zyxwvutsrqponmlkjihgfedcbaZYXWVU 1. Introduction Metalworking fluids (MWF) are extensively used in the metal working industry to cool and lubricate the tool-workpiece interface. They increase tool life, wash away removed metal, protect the tool from corrosion, reduce friction and improve --~_ *Cot-responding author. the overall finish of the workpiece [l]. They are largely based on water-soluble oils: synthetic, semi-synthetic and biodegradable. Synthetic MWF consist ofwater-soluble components while the semi synthetics are stabilised oil in water emulsions or micro-emulsions. The resultant emulsions contain a mixture of free and emulsified oils, surfactants, co-surfactants and various l’rewnted trt /he C‘uropean Conference on L)esn/irmtion and the Environtnent: Fresh Water-for All, Malta, 4-Y May 200.3. lkropcctn Ile~sctlincttio~a Society lnternntional Water- Associntior~. 00 I l-9 I64/03/$- See front matter 0 2003 Elsevier Science B.V. All rights reserved PII: SO01 l-9164(03)00342-4