Fats, oils, and greases present a significant challenge to municipal solid waste and waste water treatment operations. Most waste water blockages can be traced to an accumulation of fats, oils, and greases, resulting in sewage spills, manhole overflows, and sewage backups in homes and businesses. As a result, many municipalities already confronted with tight operating budgets, are passing the cost and responsibility of storing and disposing of fats, oils, and greases along to businesses.
For small volume restaurants, fast food restaurants with limited hours and dishwashing, a grease trap is typically adequate to handle fats, oil, and grease waste. A grease trap is a small reservoir built into the waste water system a short distance from the waste producing area. Baffles located within the reservoir allow the waste water to cool long enough for fats, oils, and greases congeal and to rise to the surface, permitting removal and proper disposal.
Large volume restaurants, hotels, hospitals, school kitchens, and cafeterias require a larger volume grease interceptor. The grease interceptor is a vault or tank, with a minimum capacity of 500-750 gallons, located on the exterior of the building. The grease interceptor operates in the same manner as the grease trap, but handles a much larger volume of waste water and fats, oils, and greases waste. The waste water cools within the tank permitting the fats, oils, and greases time to congeal and rise to the surface to enable removal and disposal.
Designing an Interceptor System
Proper design, installation, and maintenance of the grease interceptor system is essential for the system to work properly and cost effectively. One important design consideration is determining the proper size of the tank based upon the volume of waste water and fats, oils, and greases generated in the operation. Other design considerations are secondary containment to prevent a spill or leak of fats, oils, and greases into the surrounding area, proper venting to eliminate heat and fumes, proper flexible piping and connections to accommodate tank expansion and contraction, and top or sidewall manway covers to permit easy removal and disposal of the fats, oils, and greases from the tank.
Polyethylene Interceptor Systems
A polyethylene grease interceptor tank offers design flexibility and superior cost advantages over steel or fiberglass tank options. Poly tanks are easy and less expensive to maintain since they are less prone to the pin holes and micro cracks experienced in steel and fiberglass tanks. The lighter weight of polyethylene allows easier, less expensive transport and installation of the tank. However, polyethylene tanks are not recommended for underground installations or for elevated temperatures exceeding 100 degrees Fahrenheit without first being evaluated by our engineering team.