Issue: 5/04

Grease problems are making headline news. For years local papers from New York to Los Angeles have reported on how FOG (fats, oils and grease) have gummed up their municipal sewer lines. In June of 2001, the Wall Street Journal cited the enormity of the problem: "American sewers are in a bad way. Three-quarters are so bunged up that they work at half capacity, causing 40,000 illegal spews a year into open water. Local governments already spend $25 billion a year to keep the sewers running, and the Water Infrastructure Network, a coalition of the waste water-aware groups, warns that it will cost $20 billion a year for the next 20 years to keep them from falling apart." According to the National Restaurant Association, total restaurant-industry sales have grown every year for the last 12 years, generating revenues of approximately $426 billion dollars, and the industry generates over three billion pounds of grease every year. With Americans spending more money annually on eating fast food than on higher education, our appetite for fried foods and our love affair for eating out will continue to fuel the grease goblins in our sanitary sewer infrastructure.

Besides the spiraling cost issues, sanitary sewer overflows threaten the health, safety and welfare of the public. Blockages of municipal sewer lines can result in raw sewage backing up into the basements of homes and businesses, and many times this raw sludge seeps into our water tables, polluting our waterways, rivers and oceans.

From a regulatory standpoint, the Environmental Protection Agency (EPA) has been addressing the problem at the municipal sewage treatment plant level since the mid-70s. Gary Duren, a member of the Florida Building Commission Plumbing Technical Advisory Committee, recently wrote an article pointing out that the EPA recommended the adoption of a national discharge limit of no more than 100 milligrams of FOG per liter of effluent. Although the proposed standard was issued for public comment, it was never promulgated, and the current stance by the EPA is that pretreatment limits should be developed on a case-by-case basis and should be based on the ability of the Water Reclamation Facilities to remove this pollutant in the treatment process. Duren goes on to point out that the Water Pollution Control Federation's manual of practice states that wastewater treatment plants have the responsibility to accept and treat any compatible wastes that can be successfully treated in such volumes as the treatment plant can handle. This appears to make sense, as individual municipalities' treatment of FOG can vary depending on their facilities treatment abilities, population size and use. Therefore, FOG discharge requirements can vary from municipality to municipality, from a stringent mandate of 50mg/l (milligrams per liter) to as much as 600mg/l.

The Real Root of the FOG Problem

It is important to note that all national plumbing model codes and a majority of local authorities currently require the installation of some type of grease interceptor in commercial kitchens or food preparation facilities. Most municipalities also adopt ordinances and policies that mandate the proper handling and disposal of grease. Failure to comply with local requirements brings an array of sanctions not limited to just imposing fines on violators. Many municipalities, such as Pima County, AZ; New York City, and Kansas City have gone to great lengths to initiate public educational awareness programs to assist in their efforts to deal with the elimination of the high costs associated with treating the problems caused by FOG.

It is the writer's opinion that all of these efforts are admirable and essential, but it is obvious that the problem persists to a level of epidemic proportions and the fight to control FOG continues to be a losing battle, or at best, should be considered a fight that the authorities are not winning. The biggest culprit of this process is not the local authority's inability to find effective solutions to remedy the problem after the fact, but that a majority of kitchen facilities simply do not maintain their manual grease interceptors adequately and therefore create the adverse waste stream in the first place. This is a combination of poor education as to how the grease removal process in the community works, its impact on the environment and a lack of understanding of the level of maintenance required to properly clean a manual grease interceptor.

The Plumbing Drainage Institute PDI-G101 standard has been a widely recognized standard since 1949, and it is included as the basic testing and rating requirement of Military Specification MIL-T-18361 and most recently has become the basis for the new ASME A112.14.3 consensus standard. However, PDI states in its Guide to Grease Interceptors that even the best designed interceptors, properly installed, will fail if they are not maintained. The precise requirements for maintenance are not possible to define since conditions at each installation vary. In terms of the typical code, maintenance must be performed before the grease in the waste water downstream from the interceptor exceeds 100 parts per million (100 milligrams per liter) or whatever the local standard is. While that is a simple statement to make, it is impossible for the user of a grease interceptor to determine when those limits have been exceeded.

The PDI-G101 standard is not designed to test for the amount of FOG that is present in effluent that leaves the grease interceptor. The test is designed to test the FOG retention capacity of the interceptor. A PDI-approved grease interceptor must retain at least 90% of the grease that entered the unit up to its rated capacity. The majority of products tested to the PDI-G101 standard retain considerably more FOG than required at their rated capacities. Despite this achievement, the best of the units will pass more than 100mg/l of FOG at only 35% of their rated capacity. Some units pass more than 100mg/l of FOG at 10% of their rated capacity. For example, a 25 gpm interceptor is rated to hold 50 lbs. of grease. At 100% of its rated capacity, the 25 gpm unit will have an average discharge of 2,325 mg/l of FOG in the effluent. This statement is based on an analysis by PDI of accumulated test data. That data was collected at full rated flows and does vary from product to product. However, it's safe to assume that this principle is valid whether an indoor interceptor is as small as a 25 gpm unit or as large as an outdoor concrete interceptor with the capacity to hold 15,000 gallons of effluent. Regardless of the local requirements, all manual passive interceptors should be cleaned well before they reach 100% of their rated capacities.

An Answer to the Impossible Dream

Several manufacturers currently market Grease Removal Devices (GRDs) which are intended to separate and remove grease by a variety of methods. These methods include timer-controlled devices, sensor-controlled devices, devices that measure grease levels and automatically discharge FOG into reclaim tanks, and other units that automatically inject bacteria to digest grease, fat and oils into the drainage system. Although all of these devices theoretically work as intended, they are also subject to proper maintenance and care in order for them to be consistently effective.

A new technology that offers a potential solution to the problem of knowing when to clean a manual grease interceptor is a sensing device that, in conjunction with a microprocessor, can be fitted into any new manual interceptor or retrofitted into any existing manual indoor or outdoor interceptor. This electronic grease level detector is the first generation of product that targets the hundreds of thousands of existing manual grease interceptors and offers an effective solution by constantly measuring the grease level activity within the interceptor and notifying the facility personnel when their grease interceptor is about to exceed local effluent code requirements. An optional modem feature can monitor the grease level within an interceptor from a remote location via a standard telephone line. The data on the level of grease in an interceptor is now accessible on a 24/7 basis via the Internet, or if required, the facility manager can receive an instant e-mail message when the interceptor requires servicing. For the facility manager, the guessing game of knowing when to clean the grease interceptor is history, and compliance with local effluent code requirements is assured, because the device can be calibrated to the local authority's mg/l requirements. The real attraction of this technology is its ability to monitor, detect and inform.

Cleaning the interceptor is perhaps the most unpleasant task in any kitchen environment. This job is usually subcontracted to a third party or left to the lowest paid employee in the kitchen facility. No wonder it often goes neglected! Prior to the development of this technology, PDI was correct when it stated that the user was blind to when the interceptor needed to be cleaned in order to comply with local code. When an electronic grease level detector is installed in the unit, the facility owner or manager has an instant alarm or message that informs him when the cleaning task needs to be performed. This device answers PDI's impossible dream by making it possible for the user of a grease interceptor to determine when those limits are about to be exceeded.

A compelling reason why local authorities should embrace this new technology is the ability for their code enforcement officials to monitor grease interceptors within their jurisdiction prior to sanitary sewer overflows. Now most grease policing and tracing of the grease discharge violators is a laborious and expensive chore, often done after the fact, when the blockages to the municipality sewer have already occurred. With grease interceptor monitoring via the Internet now a reality, effective and inexpensive code enforcement is a feasible option.

Electronic grease level detection offers many benefits to everyone in the FOG food chain. The facility is alerted and reminded ahead of time to its responsibility not to neglect to clean its grease interceptor and keep its FOG out of our public sewer systems. The local authorities now have a reasonable chance of getting ahead of the game by monitoring the installations within their jurisdictions and preventing sanitary sewer overflows caused by unnecessary grease blockages. Grease haulers and maintenance personnel can conceivably benefit by monitoring their clients' interceptors. Grease haulers can effectively manage their clients' pump-outs based on real demand, not routine routes, and maintenance personnel can monitor interceptors and spot interceptor malfunctions prior to sewer overflows that are costly for the facility owner, the municipality and the taxpayers.

The new electronic grease level detector technology offers the real possibility, if properly mandated and administered by local authorities and embraced by manufacturers and users alike, that we can begin to win the battle against our old, slippery and elusive enemy, fats, oils and grease.