WRc explains effective catering grease management systems

07/10/2010 - 00:00
By Andy Drinkwater and Malgorzata Dolata, The WRc Group

Typically at least half of sewer blockages are caused by fats, oils and greases (FOG). This can also result in sewer flooding, odours and vermin problems. The cost to Water and Sewerage Companies (WaSCs) is significant. Similar problems are also found in private drainage systems close to property and this can be very expensive to rectify. The drainage from food service establishments (FSEs) such as takeaways, public houses and restaurants can be particularly prone to FOG. Most FOG related blockage problems can be avoided by reducing the volume of FOG discharged to the drains. There are number of ways in which the volume can be reduced and these can be very effective. However, there have been a number of examples where FOG reduction initiatives have not worked. This article sets out to examine the reasons why grease management sometimes works and sometimes does not. One of the findings of a three year water industry FOG research programme, lead by WRc, was the need to more effectively manage FOG in the kitchen at FSEs. This will always include good kitchen practice and may include either a grease separator and/or dosing system. These devices either stop or digest FOG entering the drainage system and, as such, should minimise the number of blockages and associated problems. Many FSEs already have some form of grease management system in place but it is not always effective. Experience at WRc, through visits to many FSEs, has shown that a product may work in one location but not in another. The reason for this is not always clear because there are many issues that can affect the performance of the system. When installing a grease management system it is not simply a matter of choosing a grease separator/dosing system. The following needs to be taken into consideration when developing an effective grease management system: • Volume and type of FOG produced in a kitchen; • Kitchen layout – location of sinks, dishwashers etc and internal drainage layout; • Location where a grease separator or dosing system can be successfully installed; • Size of the device; • Access to the device, for cleaning and maintenance; • Maintenance procedures; and • Training of kitchen staff. Good kitchen practice is also essential. This requires as much food waste and FOG to be removed from food plates/cooking utensils before being washed. WaSCs are also concerned and want to make sure that they only give a good advice to solve the problem. It is also in the interest of suppliers of grease separators/dosing systems that these devices are effective. A good equipment supplier should ask sufficient questions in order to understand the kitchen environment. This will enable a suitable grease management system, including an appropriate grease separator/dosing unit, to be selected. It is important that FSE owners do not buy the first grease separator/dosing system that is offered to them. FSEs owners should be aware of suppliers who sell only one product and will try to sell it regardless of its suitability. A reputable supplier should consider all the above issues and suggest a device that is best suited to the particular kitchen environment. WRc has seen many examples of grease management systems that are very effective and these are not necessarily the most expensive systems. However, there are many examples of the grease management systems that do not work. These include grease separators that are: • Too close or too far away from hot wash water discharges. In this case, grease will settle either before or after the separator and not in it; • Too small– the wash water will flow through the separator too quickly and not enable the FOG to settle out; and • In an inaccessible location. The grease separator can not be cleaned out and will be a maintenance headache. Likewise, WRc has seen dosing systems in the wrong place. These include the systems that are located immediately downstream of: • a dishwasher (hot discharge will kill the dosing compound); •

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