Filtration is a common unit operation in a water treatment plant. The effectiveness of granular filter media in treating surface water and removing suspended solids is already well established. However, less effort in the mathematical modeling towards the design of the filtration unit is observed. The current study involved head loss performance evaluation and development of a mathematical model to correlate maximum service time of filter at a maximum allowable head loss with various effective sizes and flow rates. Sand and burnt oil palm shell (BOPS) used as filter media in single and dual media filters were subjected to different effective sizes and flow rates. The average influent water turbidity for each filter (at specific effective size and flow rate) before entering the filtration unit was from 1 to 5 NTU. This was a pilot a study on settled water that was conducted in a Malaysian water treatment plant. Results suggest that all filters are capable of producing water with acceptable turbidity unit (<1 NTU). The total running time and filtrate water quality produced by BOPS/sand dual media filter was much better (i.e. the running time of BOPS/sand was four to nine times greater than sand single media filter) than BOPS and sand single media filters. The experimental data were well represented by a newly developed model and results of fitting show a high correlation coefficient (R2) of 0.991. The maximum allowable head loss was selected as 240 cm with an acceptable filtrate water quality (less than 1 NTU). In addition, the current results will be a supplementary tool for engineers in designing a proper filtration unit.

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