13 th International Conference on Urban Drainage, Sarawak, Malaysia, 7-12 September 2014 1 A Field Evaluation of Bioretention System Flow and Pollutant Treatment in Tropical Climate Norshafa Elyza Muha 1,2 , Lariyah Mohd Sidek 2 , Hidayah Basri 2 , Simon Beecham 3 and Mohamed Roseli Zainal Abdin 4 1 Faculty of Civil Engineering, Universiti Teknologi MARA, UiTM Pulau Pinang, Jalan Permatang Pauh,13500 Permatang Pauh, Pulau Pinang 2 Centre for Sustainable Technology and Environment, College of Engineering, Unversiti Tenaga Nasional Jalan UNITEN-IKRAM 43000 Kajang, Selangor 3 School of Natural and Built Environments, University of South Australia, Mawson Lake South Australia 5095 Adelaide, Australia 4 Humid Tropic Centre, No 2 Jalan Ledang off Jalan Duta 50490 Kuala Lumpur *Corresponding author’s e-mail: adeq_sha@yahoo.com ABSTRACT Bioretention is a new technology for urban storm water management in Malaysia. Universiti Tenaga Nasional (UNITEN) in collaboration with Universiti Sains Malaysia (USM) began construction of a bioretention system with the expectation that it would become a model of lot-scale application in Malaysia, as well a pilot learning showcase. The project anticipated to observe and discover how bioretention systems remove storm water pollutants as no prior studies on the performance of bioretention systems of this scale have been done in Malaysia. Guidelines in the Urban Storm Water Management (MSMA), 2 nd Edition, are yet to be proven effective in Malaysia. Therefore, there is an urgent need to learn how bioretention systems perform so that local design guidelines can be established. A preliminary study was conducted to determine the types of pollutants in the storm water runoff from a parking lot at the College of Engineering, UNITEN. After construction of the system was completed in July 2013, water quality measurements were taken. The water quality and flow at the inlet and outlet were measured and recorded manually as the automatic monitoring system has not been completed yet. All samples were collected within 24 hours of a monitored storm event. Preliminary results showed that Total Suspended Solids, Total Volatile Solids, Biochemical Oxygen Demand, and Chemical Oxygen Demand were effectively removed by more than 80%. Initially, the pollutant load also appeared to have reduced, showing effective bioretention performance. Further monitoring and analysis will be made to observe continuing performance and behavior of the system in the conditions typically found in Malaysia. KEYWORDS Bioretention; urban runoff; storm water management treatment; green technology INTRODUCTION Urbanization growth in Malaysia, has been exceedingly rapid in these recent years. Expansion of the city will change the local environment and indirectly the water environment