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The problems that FOG can cause are significant – as food service industry professionals know. No matter how well kitchen staff follow procedures for diverting pan drippings, food scraps and other oils, fats and greases into used cooking oil containers or waste bins, some of this stuff ends up going down the drain when equipment is cleaned. Then travels through a device called a grease trap or a grease interceptor, where the FOG is captured in a series of baffles while most of the water is flushed to sewage lines, bound for municipal wastewater treatment. In a perfect world before the grease trap is filled to capacity, a waste collector is periodically called to clean out the grease trap and carry the FOG away in a tanker.

The frequency of these visits is determined by municipal requirements, the size of the tank and the daily output of FOG. Grease traps are sometimes not well maintained and overflow. When that happens, restaurants and building managers pay the price in high cleanup costs and fees. Restaurants, food production facilities, cafeterias and any buildings that produce food-based products are ultimately responsible for the FOG they create. And each grease trap overflow has the potential to send chemicals and other pollutants inside the traps into nearby rivers, lakes or other bodies of water. In fact, beach closures due to sewage overflows are commonplace in Los Angeles, which was sued in 2001 over a rash of 800 sewage overflows due to pipes clogged with FOG. In much the same way that fat and grease clog human arteries over time, they also clog sewage arteries.

FOG, that gets collected in grease traps at restaurants and food service or industrial kitchens, unlike yellow fryer grease, is tough to refine into biofuel due to high water content and impurities. Unattended FOG could cause dangerous and costly sewage overflows. Food service and facility managers can employ microbes to eat away at the FOG that collects. Bioremediation may also be an eco-friendly solution to FOG. And a few start-ups are working to develop biofuel feedstock from FOG. The acidity of the FOG eats away at pipes over time, which leads to major failures in sewage infrastructure. Aside from the environmental hazards of a spill, having grease traps pumped is expensive and getting costlier for eateries or building managers, as collectors pass on the rising fees they pay to get rid of the FOG. And collectors often have to drive far outside urban centers to reach a wastewater treatment plant or landfill that will accept the stuff. This is where Grease Reduction Systems (GRS) introduce microscopic organisms to a grease trap and use an air pump and specialized telemetry equipment mounted inside the tank to balance the amount and type of microbes injected into the tank.

The microbes consume the FOG, in order to eliminate or at least slow the FOG accumulation inside the tank. The process is called in-situ bioremediation. While bioremediation is a common tool for degrading effluent at wastewater treatment plants (which is where collectors often bring the FOG pulled out of traps), it had not been successfully deployed directly within grease traps.

This is a greener solution than pumping, because it benignly reduces waste at its point of generation, rather than trucking the FOG out and passing the problem along the waste stream. The GRS system can earn a facility up to 10 LEED credits. And once the lower hauling fees are factored in, the GRS system should cost 25% less per month than using traditional trap cleaning services.

FOG’s Potential Benefits

Bioremediation might be a sustainable solution for eliminating FOG, but just as fryer grease or yellow grease has transitioned from an expensive waste problem for restaurants and food producers to a valuable feedstock for biofuels (and, as competition for it grows, even a new revenue source) the FOG that collects in traps is also beginning to emerge as an energy source. In fact, some biofuel start-ups would argue that there’s gold in the FOG. Nevertheless, converting FOG to fuel would involve collecting FOG from restaurant grease traps and bringing it to a wastewater treatment facility, where existing resources will be used in refining it. Firstly, it costs money to bring something so thick and yucky (FOG) to something that is fuel feedstock, and secondly, this is an arduous process that cuts into the bottom line.

Source: www.greenbuildings.com

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