The Production and Fate of Fats, Oils, and Grease (FOG) from Small Dairy-Based Food Service Establishments

Abstract

Grease accumulation in sewers is the leading cause of sewer blockages resulting in Sanitary Sewer Overflows. Nationwide Fats, Oils, and Grease (FOG) control programs exist to address this problem, but the guidelines with respect to wastewater from dairy-based food service establishments (FSEs) are unclear, with no existing scientific investigation on potential separation of dairy products. The separation tendencies of wastewater originating from dairy-based FSEs were investigated, and significant separation of dairy constituents (Kjeldahl Nitrogen and fats) was observed under acidic conditions (pH 4-5.4), with maximum separation at the isoelectric point of casein proteins (pH = 4.6). Physical treatment at field-scale grease interceptors for dairy-based FSEs showed accumulation of dairy constituents, particularly fats, at pH 4.4-5 caused by dairy products souring. Separation induced by souring in neutralized pH persisted but to a lesser extent (10% vs. 2%). Based on research conducted, physical treatment of wastewaters originating from dairy-based FSEs is recommended.