Desalination 204 (2007) 204–212 Presented at EuroMed 2006 conference on Desalination Strategies in South Mediterranean Countries: Cooperation between Mediterranean Countries of Europe and the Southern Rim of the Mediterranean. Sponsored by the European Desalination Society and the University of Montpellier II, Montpellier, France, 21–25 May 2006. *Corresponding author. Effect of natural coagulant application on microfiltration performance in treatment of secondary oxidation pond effluent S. Katayon*, M.J. Megat Mohd Noor, W. Kien Tat, G. Abdul Halim, A.M. Thamer, Y. Badronisa Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia Tel. +60 389466362; Fax +60 386567129; email: katayon@eng.upm.edu.my Received 17 January 2006; accepted 27 March 2006 Abstract A secondary oxidation pond effluent was treated using hollow-fibre crossflow microfiltration and coagulation process. Preliminary tests were carried out to find the optimum dosage of Moringa oleifera (a natural coagulant) for the coagulation process. Optimum dosage of Moringa oleifera was recorded as 100 mg/L for turbidity of secondary oxidation pond effluents ranging between 30 and 100 NTU. Turbidity removal achieved ranged between 50 and 57%. The performance of microfiltration coupled with coagulation using optimum dosage of Moringa oleifera was investigated. Better flux performance and lower rate of fouling were achieved when combining microfiltration with coagulation. Pseudo-steady state flux of 3 L/m 2 .h at a relatively constant suction pressure of less than 0.6 bar was obtained after 300 h of filtration time. Results showed that the values of COD, BOD 5 , alkalinity, VSS, TS, turbidity and pH in the filtrate were not influenced significantly by incorporation of coagulation using Moringa oleifera. The filtrate quality of about 50 mg/L COD, 25 mg/L BOD 5 , 2 mg CaCO 3 /L alkalinity, 1 NTU turbidity, 1 mg/L TSS and VSS respectively was produced when using microfiltration with and without coagulation. Keywords: Moringa oleifera; Oxidation pond effluent; Natural coagulant; Microfiltration; Coagulation 0011-9164/07/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2006.03.541