The production of highly polluted waste cooking oil (WCO) that contains both inorganic and organic compounds has been increased in Malaysia particularly in food industries. This study was aimed to utilize a sequencing batch reactor (SBR) in order to investigate the aerobic treatment of WCO. The system was operated at pH ranging from 4 to 5 and temperature ranged from 25°C to 31°C. The SBR reactor was fabricated using Perspex with a working volume of 2 L. Experiments were con-ducted daily at fill, react, settle, draw, and idle phase at 1, 1, 2, 1, and 1 h, respectively. The chemical oxygen demand (COD) and turbidity were assessed in determining SBR performance. Highest COD removal and turbidity values were at 67% and 0.94 NTU, respectively. A stable effluent quality was achieved after 13 d of operational investigation. In general, the SBR treatment was able to achieve acceptable discharge limit for the final treated effluent.
