Fat, Oil, and Grease Accumulation in Sewer Systems: Comprehensive Survey of Experiences of Scandinavian Municipalities

Problems with fat, oil, and grease (FOG) in sewer systems have received relatively little attention, although in the longer term this might imply (inter alia) blockages and sanitary overflows. Therefore, the experiences of Swedish and Norwegian executive water engineers concerning FOG-related issues were assessed using a comprehensive questionnaire that was distributed to all Swedish and Norwegian municipalities (with a response rate of 35% and 25% in Sweden and Norway, respectively). Blockages caused by FOG in sewers and pumping stations were the most prevalent reported problem, followed by increased demand for line flushing. The water engineers singled out city centers as the areas whose sewers had the most severe problems with FOG buildups. Most municipalities mandated the use of grease interceptors (GIs) by businesses, but the maintenance and functional status of these devices were reported to be inadequate. Commonly, water engineers had faith in the functioning of the GI despite the lack of stringent inspections. Where FOG collection systems had been implemented, they generally targeted businesses and other enterprises rather than private households. Because problems caused by FOG buildups are likely to become more common in the future, it is important that prevention strategies characterize management to a higher degree than ones based on removal.