Innovative grease interceptor to enhance fat, oil and grease removal from the wastewater generated from food service establishments.

Abstract

Commercial grease interceptors (GIs), commonly used in food service establishments, are primarily designed to treat fat, oil and grease (FOG) from handwash sink (HS) wastewater. They are generally less effective for removing highly concentrated FOG from dishwasher (DW) effluents which contain highly emulsified FOG with complex long-chain fatty acids (LCFAs). Furthermore, standard testing of GIs uses diesel fuel to simulate FOG separation; however, the flow properties of typical cooking oils and animal fats differ significantly from diesel. We developed a novel GI (bench-scale with 72 L capacity) and examined the impact of various baffle configurations on FOG removal efficiency using samples containing representative FOG components of cooked oil, fat and food solids. The results demonstrated that the installation of two short baffles projecting from the top along with one short baffle projecting from the bottom in the first chamber, and another short baffle projecting from the top in the second chamber, led to FOG removal efficiencies of up to 88% and 40% for HS and DW effluents, respectively, at a hydraulic retention time (HRT) of 44 min. The short baffles acted as barriers, thus enhancing the loss of kinetic energy, subsequently ensuring a quiescent flow condition, resulting in an increased HRT for effective FOG separation. The addition of alum as coagulant at 200 mg/L (18.2 mg of Al³⁺/L) significantly enhanced the removal of FOG from treated DW effluents (up to 87%), effectively reducing the concentrations of various extra-LCFAs, such as paullinic (C20:1), arachidic (C20:0), eicosadienoic acid (C20:2), mead (C20:3), eicosapentaenoic (C20:5), erucic (C22:1), cervonic (C22:6), tricosanoic acid (C23:0), lignoceric (C24:0) and nervonic (C24:1) acid by up to 99%. These findings provide significant insights into the advanced GI design, offering a proactive solution to prevent fatberg formation while promoting a more sustainable and economically viable approach to sewer management.