Foodservice operations with kitchen waste water containing fat, oil and grease may likely require grease traps. This is because national plumbing codes don’t allow the dumping of fat, oil or grease, called FOG, in local water systems.
Foodservice operators can choose from a number of different types of grease traps on the market, although some code enforcing authorities now refer to these systems as grease interceptors.
Interceptors isolate grease in a primary tank, in the case of passive systems, that pump-service companies clean out. Operators generally use interceptors in conjunction with three-compartment and hand sinks.
More traditionally known as under-the-sink passive interceptors, Hydromechanical grease interceptors work with flow rates of less than 50 gallons of water per minute. Any application with 300 gallons or less of total liquid capacity may find this classification suitable.
Gravity grease interceptors are larger interceptors, usually located outside a facility. These units have capacities larger than 300 gallons, with most accommodating 750, 1,000 or 1,500 gallons.
Automatic Grease Removal Devices (AGRD) can either capture the effluent from a single fixture or an entire kitchen. Unlike other interceptors, these systems trap grease and then isolate it into a collection vessel. Operators then dispose of the grease by whatever means the local municipality permits.
Automatic systems also can have interceptor baskets built into the unit for the removal of solids. This enables operators to avoid the costs that come with frequent cleanings or pumpouts, but also will require regular maintenance to ensure efficient operation. An automatic grease removal device will cost more up front and require regular interaction by a foodservice operation’s kitchen staff, but tend to be less messy and typically do not cost as much to operate relative to some other options.
The construction of these systems depends on the type. In the past, hydromechanical grease interceptors traditionally were made out of stainless steel, but more recent designs use polyethylene or, in some cases, fiberglass. Gravity grease interceptors most often feature concrete construction, although foodservice operators can also choose from steel, polyethylene and fiberglass GGIs. Automatic Grease Removal Devices (AGRD) typically feature stainless steel construction or a combination of plastic and stainless steel.
In recent years, some manufacturers have started to move away from steel/concrete interceptors to more durable materials such as polyethylene. Additionally, larger hydromechanical grease interceptors that accommodate 100 to 250 gallons keep gaining traction over the use of larger concrete gravity grease interceptors due to their flexibility, ease of installation and improved total cost of ownership. AGRDs continue to offer advancements in technology with higher quality materials and more intuitive user interfaces.
Operators should keep in mind a number of factors when choosing a grease interceptor, with the most important being the requirements of local codes. Because sewer districts can choose from literally thousands of different ways to deal with fats, oil and grease coming from kitchen wastewater, understanding local ordinances represents an important starting point.
Space represents another key consideration. Hydromechanical and AGRD interceptors require extra back-of-house space, while gravity grease systems require a designated outside area.
Even those foodservice facilities that do not create a lot of grease, such as coffee shops or ice cream parlors, must install a large interceptor. Most local codes require this because low water turnover and a lack of grease generation can create high levels of hydrogen sulfide.
Also, some municipalities may force foodservice locations that produce FOG to put in unnecessarily large interceptors. Rather than having 1,500-gallon concrete interceptors for a typical fast-casual restaurant that require pumping out every 90 days, experts recommend considering regular service on a 100- to 200-gallon hydromechanical interceptor made out of more durable polyethylene.