Application of Computational Fluid Dynamics to the Design of Kitchen Grease Trap in the Building Drainage System

Hong Kong is a gourmet paradise, famous in Asia especially for its Chinese restaurants.. Before the full implementation of the Harbour Area Treatment Scheme, the wastewater that was disposed from the kitchens of these restaurants contained grease and oil that caused sewer blockages, pollution at ultimate disposal destinations and harmful effects on marine life. Currently, statutory regulations require each kitchen to have a grease trap that is designed in accordance with the guidelines developed by the Environmental Protection Department (EPD) of the Government of Hong Kong Special Administrative Region (HKSAR). However, the simple guidelines are considered insufficient to design grease traps with maximum effectiveness. Hence, this project will design a grease trap in a more scientific manner by applying computational fluid dynamics (CFD) techniques to achieve the most effective oil-water separation. The volume fractions of the grease inside the grease-water mixtures at the inlet and outlet of the grease trap will be sampled to measure the effectiveness of grease removal. Parametric study will be carried out on the locations of baffles, size and water depth of the grease trap, etc., to arrive a design with maximum effectiveness.