Assessment of grease traps used in the small-scale food Industry: a pilot study

Fat, oil and grease (FOG) deposits in sewer systems are becoming a serious environmental concern for infrastructure engineers and council managers. These deposits can come from both domestic and commercial wastewater. Water and wastewater company Watercare has reported that 70% of sewer blockages in Auckland, New Zealand, are due to material such as rags, wet wipes, wood, tissues, hygiene products, etc., that shouldn’t go down the sewer drain. These materials can lead to the blockage of pipes when combined with FOG. This preliminary study was about assessing the grease traps (GTs) that are being used in the small-scale food industry in Auckland. The purpose of this study was to address four key questions: How are FOG deposits actually formed? What types and sizes of GTs are being used? Do the sizes that are used comply with the recommended sizes? What are the issues and/or what is missing in terms of the operation and maintenance of GTs? A questionnaire was prepared to collect data such as type of food service, type of GTs used and their sizes, type of fixtures that are used in the small-scale commercial kitchen area, etc. This study shows that there are some issues with the way the GTs are being operated, maintained and monitored (i.e., some regulatory gaps). The paper also gives a brief overview of different types of GTs, reviews the current compliance practice, and then provides some recommendations and solutions that could lead to improved practice to mitigate wastewater pipe blockage