Ong Say Leong

Department of Civil and Environmental Engineering

Postal Address:
  National University of Singapore
  1 Engineering Drive 2, E1A 07-03
  Singapore 117576
Tel: (65) 6516 2890
Office: E1A-02-14


Professor ONG SAY LEONG graduated from the then University of Singapore with a BEng (Civil Engrg) in 1979. He obtained his MESc (Biochemical Engrg) from the University of Western Ontario in 1980 and PhD (Civil Engrg) from the University of Toronto in 1983. His MESc research topic was on fuel alcohol production by Zymomonas Anaerobia whereas his PhD research topic was on regional wastewater treatment system planning and optimization.

Professor Ong has taught courses in water and wastewater engineering, advanced wastewater treatment, environmental modelling, water quality management, design of wastewater treatment system, industrial wastewater control, physical principles of environmental engineering, biological treatment processes and computing. He has published over 200 technical papers covering topics such as biofilm systems, water/wastewater reclamation and reuse applications, biological wastewater treatment and modelling, membrane technology, emerging contaminants detection and removal as well as computer applications in water and wastewater engineering.

Professor Ong is a registered professional engineer and has been involved in consulting jobs on water and wastewater treatment system and water quality management. He is active in the professional circle and is serving in several environmental engineering committees. These includes Governing Board Member of the International Water Association (UK), Member of the Board of Director of the Water Environment Federation (USA), Head of PUB Internal Audit Panel for NEWater and Water Supplies, and Chairman of Singapore Technical Committee on Drinking Water Quality Standards. Professor Ong also serves as Editor/Associate Editor/Editorial Board Member of 10 international journals in the area of water environment. These include an Editor of Water Environment Research (USA); Associate Editor of Water Research (UK); Associate Editor of ASCE Hazardous, Toxic, and Radioactive Waste Management Journal (USA); and Editorial Board Member of the Journal of Water Supply: Research & Technology - AQUA.


  • Registered Professional Engineering (PEng), Singapore
  • Board Certified Environmental Engineering Member (BCEEM) in Water Supply and Wastewater: American Academy of Environmental Engineers, USA
  • Diplomate (D.WRE), American Academy of Water Resources Engineers, USA
  • Fellow, The Institution of Engineers, Singapore, 2005
  • PhD (Civil Engrg), University of Toronto, Canada, 1983
  • MESc (Biochemical Engrg), University of Western Ontario, Canada, 1980
  • BEng (Civil Engrg), University of Singapore, Singapore, 1979

Career History

  • Professor, National University of Singapore (January 2003 - present).
  • Associate Professor, National University of Singapore (July 1997 - Dec 2002).
  • Senior Lecturer, National University of Singapore (July 1988 - June 1997).
  • Lecturer, National University of Singapore (September 1983 - June 1988).

Honours & Awards

  • Public Service Star (BBM), National Day Awards 2016
  • IWA Fellow, International Water Association
  • Diplomate (by Eminence) of Water Resources Engineer, American Academy of Water Resources Engineers
  • Board Certified Environmental Engineering Member (by Eminence), American Academy of Environmental Engineers

Professional Activities

  • The Institution of Engineers Singapore
  • Environmental Engineering Society of Singapore
  • Water Environment Federation
  • International Water Association

Teaching Areas

  • Water and Wastewater Engineering
  • Municipal Wastewater Engineering
  • Environmental Modelling
  • Advanced Wastewater Treatment
  • Industrial Wastewater Control
  • Water Quality Management
  • Biological Treatment Processes
  • Final Year Integrated Design Project

Research Interests

  • Water Quality Enhancement
  • Water Reclamation and Reuse
  • Membrane Technology for Water and Wastewater Treatment
  • Biotreatment Processes
  • Sustainable Urban Water Resources Management
  • Modelling of Water Quality Enhancement Systems

Selected Publications

  1. Maung, H O and S L Ong, "Boron Removal and Zeta Potential of RO Membranes: Impact of pH and Salinity". Desalination and Water Treatment, 39, no. 1-3 (2012): 83-87.
  2. Koh, L C, H Zhang, H Nguyen and S L Ong, "Performance of an Ultra-Compact Biofilm Reactor Treating Domestic and Synthetic Wastewaters". Water Science and Technology, 65, no. 3 (2012): 484-489.
  3. Tao, G. H., B Viswanath, K Kekre, L Y Lee, H Y Ng, S L Ong and H Seah, "RO Brine Treatment and Recovery by Biological Activated Carbon and Capacitive Deionization Process". Water Science and Technology, 64, no. 1 (2011): 77-82.
  4. Sandhi, E B, Y S Lam, S L Ong and J HE, "A Mesophilic Clostridium Species that Produces Butanol from Monosaccharides and Hydrogen from Polysaccharides". Bioresource Technology, 102 (2011): 9558-9563.
  5. Muthuswamy, S, S Pavagadhi, V Kuppusamy, R Balasubramanian and S L Ong, "Concomitant Uptake of Microcystin-LR and -RR by Peat under Various Environmental Conditions". Chemical Engineering Journal, 172, no. 2-3 (2011): 754-762.
  6. Huang, Z, S L Ong and H Y Ng, "Submerged Anaerobic Membrane Bioreactor for Low-Strength Wastewater Treatment: Effect of HRT and SRT on Treatment Performance and Membrane Fouling". Water Research, 45 (2011): 705-713.
  7. Muthuswamy, S, S PavagadhI, V Kuppusamy, R Balasubramanian* and S L Ong, "Experimental Studies on Microcystin-LR Removal by Peat". Journal of Hazardous Materials, 184, no. 1-3 (2010): 417-424.
  8. Jin, L, S L Ong and H Y Ng, "Comparison of Treatment and Membrane Performances of Different Pore-Sized Submerged Ceramic Membrane Bioreactors". Water Research, 44 (2010): 5907-5918.
  9. Maung, H O and S L Ong, "Implication of zeta potential at different salinities on boron removal by RO membranes". Journal of Membrane Science, 352, no. 1-2 (2010): 1-6.
  10. Zhao, Y, L F Song and S L Ong, "Fouling of RO membranes by effluent organic matter (EfOM): Relating major components of EfOM to their characteristic fouling behaviors ". Journal of Membrane Science, 349, no. 1-2 (2010): 75-82.
  11. Zhao, Y, L F Song and S L Ong, "Fouling behavior and foulant characteristics of reverse osmosis membranes for treated secondary effluent reclamation". Journal of Membrane Science, 349, no. 1-2 (2010): 65-74.
  12. Fang, W, J Y Hu and S L Ong, "Effects of phosphorus on biofilm disinfections in model drinking water distribution systems". Journal of Water and Health, 8, no. 3 (2010): 446-454. (United Kingdom).
  13. Jin, X, J Y Hu and S L Ong, "Removal of Natural Hormone Estrone From Secondary Effluents Using Nanofiltration And Reverse Osmosis". Water Research, 44, no. 2 (2010): 638-648.
  14. Lee, L Y, H Y Ng, S L Ong, J Y Hu, G. Tao, K. Kekre, W. Lay and H. Seah, "Integrated Pretreatment with Capacitive Deionization for Reverse Osmosis Reject Recovery from Water Reclamation Plant". Water Research, 43, no. 18 (2009): 4769-4777.
  15. Fang, W, J Y Hu and S L Ong, "Influence of Phosphorus on Biofilm Formation in Model Drinking Water Distribution Systems". Journal of Applied Microbiology, 106, no. 4 (2009): 1328-1335.
  16. Lee, L Y, H Y Ng, S L Ong, J Y Hu, G Tao, K Kekreb, B Viswanathb, W Lay and H Seah, "Ozone-Biological Activated Carbon as a Pretreatment Process for Reverse Osmosis Brine Treatment and Recovery". Water Research, 43, no. 16 (2009): 3948-3955.
  17. Shan, J H, J Y Hu and S L Ong, "Adsorption of Neutral Organic Fractions in Reclaimed Water on RO/NF Membrane". Separation and Purification Technology, 67, no. 1 (2009): 1-7, 7.
  18. Ong, S L and J Y Hu, "Emerging contaminants in water-do we have solutions". Water Environment Research, 80, no. 9 (2008): 771-773.
  19. Lee, L Y, S L Ong, H Y Ng, J Y Hu and Y N Koh, "Simultaneous Ammonium-Nitrogen and Copper Removal and Copper Recovery Using Nitrifying Biofilm from the Ultra-Compact Biofilm Reactor". Bioresource Technology, 99, no. 14 (2008): 6614-6620.

Last Updated on 22 August, 2012 by Department of Civil and Environmental Enginering