Everybody likes to eat at a restaurant once in a while. We love our carne asada and pasta with pesto and all the things that taste better somehow when somebody else prepares them. There’s one small problem, though. Commercial kitchens prepare a boatload more food than a residential facility. That means more food waste, more water used and more fats, oils and greases doing down the drain.
   Left alone long enough, these FOGs can get into a municipal system and clog it right up with vast quantities of semi-congealed, sticky gunk that costs a fortune to remove. Enter the grease interceptor. Think of them as “rest stops” along the drain line where the outgoing water/FOGs emulsion can rest a minute and take advantage of the old “oil and water don’t mix” thing for the water to shed the FOGs before heading on down the line.
   “They’re required by code for commercial kitchens,” said Charlie Ismert of Schier Products, a manufacturer of drain line purity products based in Edwardsville, Kan. “They get installed downstream of the kitchen waste lines and the waste water goes into the grease interceptor. The two biggest differences between the Uniform and the International codes when it comes to grease interceptors are the UPC doesn’t allow garbage disposals or dishwashers to discharge through a grease interceptor.” [This may have changed-IAPMO said the 2012 editions of its Uniform Plumbing and Uniform Mechanical Codes were set to be available Mar. 1. See pg. 23. -Ed.]
   Basically, Ismert said, “It gives the flow enough time and space to let Mother Nature do what she wants to do.”
   Michael Whiteside, president of MIFAB, a manufacturer of commercial and industrial plumbing and drainage products based in Chicago, said the whole thing is based on the old “oil and water don’t mix,” thing. 
   “Oil and grease will rise to the surface in the grease interceptor, just as if you were on a lake or ocean and you spill some gasoline onto the water,” he said. “The idea is to size the interceptor to be big enough to hold the water long enough so there’s time for the FOGs to rise to the surface. If not, and FOGs are emulsified into the incoming water, it won’t have time to separate and will blow right out the other end.”
   Grease interceptors are commonly made of rolled steel, stainless steel or one of two types of plastic, polyethylene or polypropylene. There are even interceptors made of Fiberglas, Ismert said. Each material has its own application. “Most of the automatic recovery units are stainless steel, but the regular units are mostly 10-gauge hot rolled steel,” Whiteside said. “That’s because most people don’t want to pay stainless steel’s cost, but stainless is better because it lasts longer in the long haul.”
   Plastic interceptors, Whiteside said, are becoming more popular and MIFAB, like most companies, offers plastic versions. “When you get into custom sizes and really large units they tend to be (rolled) steel,” he said. There is a lot of automatic recovery grease interceptors sold in Atlantic City, for example, because they want to know it will automatically remove the grease as it comes in.
   The market, Ismert said, caters to two different strategies or grease removal. 
   Most new construction markets where there is still real estate available will want the grease interceptor to be installed outside: “For the more landlocked markets and more Midwestern markets, they’re used to seeing indoor, typically smaller, grease interceptors. These will be under the sink or buried in the floor of the kitchen. We make both.”
   But, he said, if he were a restaurant owner, he would “want that thing out of my kitchen.” Grease interceptors at work are, by their very nature, some nasty, nasty things. With an in-kitchen installation the cooks run the risk of a seal going bad and then having bad smells come up into the environment. “And you do have to pump these things out when they get filled up,” he said.
   “The biggest problem with grease interceptors is they’re not cleaned enough,” Whiteside added. “That’s because they’re horrible things. Nobody wants to clean them so they get full and everything just passes right through. There are also cases of plumbing lines becoming blocked-filled with grease-because grease interceptors aren’t being maintained or aren’t even there in the first place.”
   One way to make sure the interceptor is cleaned regularly is through the installation of an automatic recovery interceptor. In drastic cases, such as recently in relatively tiny-but restaurant-rich-San Francisco, automatic recovery units are mandated by law. “We know these things aren’t cleaned-nobody wants to clean them and as much as we talk about it it’s not happening,” Whiteside said. “The city doesn’t have the resources to go around and inspect them so now you either have an automatic recovery unit or you don’t get the permit to open the restaurant.”
   Automatic recovery grease interceptors, which are offered by most manufacturers, often use an internal skimmer wheel to nudge the FOGs out of the unit and into a portable container for easier removal.
Which begs the question, removal to…where, exactly? “At best they’re probably throwing it in a dumpster,” Ismert said. “At worst they’re probably taking it and dumping it by the side of the building or in a floor drain that bypasses the interceptor. Our recommendation is to have a professional come and pump it out, whether it’s inside or out. Pump-out charges vary from region to region, but I’d say a minimum of $100 to pump out a grease interceptor, depending on where you are in the country.”
   OK, so some companies accept money to cart the goop away. Other companies will pay the restaurant for the stuff: “It has multiple uses, Ismert said. “Brown grease from grease traps, I believe, can be made into biogas by catching the methane from the decomposition process. They’ll turn it into animal feed. They’ll spread it on agricultural fields in a certain mix with lime and other things. Some treatment plants are geared up for treating it. I don’t know exactly what that means, but they dewater it and sell some sort of fertilizer cakes or something.”