Effluent Grease Recovery – 21st Century Recyclable Product

Our great grandparents recycled meat drippings into soap. Today their great grandchildren recycle meat drippings and waste cooking oil into biodiesel, cosmetics, animal food additives and hundreds of other useful products. Included in the recycling equation are new systems for capturing and recycling kitchen drain water fats and oils.

The past forty years has seen the rapid rise of the restaurant industry. The proliferation of restaurants throughout towns has also created a serious problem: sewer line clogs caused by grease. Wichita, Kansas, a city of 350,000 population found 85% of their sewer line problems were caused by grease accumulation in the piping. As most food service facility managers already know, grease build-up within a building’s plumbing drainage system is also a major cause of sanitation problems. Effluent grease jeopardizes normal operations as well as creating health and safety hazards within the facility.

Increasingly, sewer districts are implementing programs involving financial penalties to make commercial kitchen operators conform to community standards. Grease separators are now being required and documented servicing is being enforced. Existing restaurants have difficulty retrofitting grease separators because of space, plumbing complexity and construction cost issues. Fortunately, there are newer technology products available to economically enable older facilities to meet community code standards. These new products fit into two categories: 1) automatic grease removal units and 2) compact supercapacity grease interceptors.

Automatic Grease Removal Units (GRDs)
These units are specifically engineered for the separation and removal of free-floating (non-emulsified) grease and oils from kitchen drain water flows. Most units are designed to fit beside pot-washing and dishwashing sinks to capture grease. These units are electrically powered and have a skimming and heating mechanism for daily removal of the captured fats and oils. For example, in a high volume hamburger restaurant, the removal of 7 to 10 pounds (3.2 to 4.6 kg) of grease by an automatic grease removal unit servicing the three- compartment pot-washing sink is typical. Because it is removed on a daily basis, the recovered grease is fresh, water-free and is suitable for recycling into biodiesel and cosmetic products. The grease is kept out of the facility’s piping, reducing maintenance costs and preventing costly downstream blockages.

Automatic GRDs offer the simplest installation and lowest operation costs with the restaurant staff routinely emptying the grease container and solids strainer basket. Annual electricity cost is usually less than $25.00. Automatic GRDs cost more than non-automatic grease traps, but pay for themselves in one to four years with lower maintenance and servicing costs. Additionally, many Automatic GRDs like the popular Big Dipper® have sanitary stainless steel and polymer construction which, can last three to four times longer than painted steel grease traps that eventually rust out and are prone to unsanitary stains.

Automatic GRDs are particularly suited to servicing very high grease effluent output cooking appliances like wok ranges, rotisserie ovens and combi-ovens. A high volume rotisserie oven may discharge 15 gallons (57 liters) of water and chicken drippings in one day. Typically, this liquid is 70% fat which means 10.5 gallons (40 liters) of pure fat can be profitably recovered while also saving the facility’s and the city’s piping from congealed grease. In these applications, an Automatic GRD may pay for itself in less than 6 months.

Compact Supercapacity Grease Interceptors (CSGIs)
Many sites have trench and other floor drain receptacles receiving flows from tilt kettles and other grease discharging appliances. There are other sites that do not generate much grease such as ice cream shops, downtown grills and sandwich shops but are required to have high capacity grease separators to protect the city’s sewer piping. With available space being a serious constraint, compact supercapacity grease interceptors are increasingly being installed in these sites. Supercapacity grease interceptors such as the Trapzilla® feature corrosion-resistant polymer construction and are small enough to be carried by two men through a commercial width doorway but large enough to hold 150 kg to 275 kg of retained grease. These supercapacity grease separators have evolved into product lines having solid separator modules, engineered designs that can be mounted between floors and site adaptable extension collars.

Recycling Pays in the 21st Century
The recovered grease from one high volume supermarket rotisserie oven may recover $7500/year in biodiesel grade fats. The recovered grease from a high volume hamburger restaurant’s pot washing sink may be worth $750/year and another $1200/year in avoided facility maintenance costs. With petroleum costs soaring above $100/barrel and predicted to reach $200/barrel in seven years (2015), capturing effluent grease becomes a profitable enterprise. Like our great grandparents, we, too, recycle waste grease for worthwhile products.