An experimental investigation of wastewater treatment in a grease interceptor trap

Grease interceptor traps (GITs) are widely used by food service facilities to reduce oil and grease (OG) to an acceptable level before waste water discharge to public sewerage and to recover oil and grease as a feedstock for new products. However, wastewater discharge to a simple GIT at high flowrate can result in a short circuit to the outlet. Consequently, there remains a high concentration of OG potentially leading to blockage of the sewerage system and a waste of valuable resources. It is therefore important to understand the characteristics and fluid flow behaviour of a GIT. The research presented in this paper relates to an intensive experimental investigation of a single GIT serving a large commercial kitchen and multiple restaurants. Composition and physical characteristics of the wastewater was quantified and analysed. Short circuiting flows were also observed. The removal efficiency of this GIT was found to be very low; indicating inefficiency of this GIT due to an inappropriate design that fully complied with local regulations. This indicates that there is ineffective design of baffles and/or inlet-outlet positions of the GIT and a need for review of regulations governing these devices.