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CESA guide: waste management

12 February 2010
CESA guide: waste management

Waste management is increasingly becoming a major issue in food service operations. Following the outbreak of foot-and-mouth in 2001, the feeding of catering waste to livestock was banned, so operators have had to sort out alternative arrangements.

FOOD WASTE DISPOSAL UNITS - GRINDERS OR MACERATORS

These grind the waste food and mix it with water so it can be safely emptied into the drains. Sizes are usually specified by horsepower and larger grinders of between 0.5 and 3 horsepower are recommended for general kitchen use, depending on the number of covers.

WATER EXTRACTION SYSTEMS AND WASTE PULPERS

Some restaurants and hotels are serviced by old and dilapidated sewer pipes that may find it difficult to cope with a large volume of macerated food waste, so it can be beneficial to use water extraction systems that separate out the ground food waste from the water before it is emptied down the drain. Some manufacturers offer both maceration and de-watering in one unit.

Third-stage, integrated systems either turn all the food waste into compost for on-site use or pipe the food waste into a storage tank prior to collection by a tanker to go to a biogas plant. Although the capital cost of these systems is higher, the savings on disposal make them viable investments.

In some sites it is not practical to use food waste macerators which discharge to the sewer. As a result, systems are available that decompose or de-water food waste on-site using micro-organisms and only dirty water is then discharged in the sewage system.

HOW TO PREVENT BLOCKAGES

Bio-remediation is available to prevent blockages that are caused by a build-up of grease and fat through the disposal of fats, gravy, custard, etc down the drain. Regular dosing with bio-enzyme compounds that "eat" the grease ensure the pipes are kept clear. Automatic systems dispense specially formulated fluids into the drains to degrade fats, oils and greases.

Another requirement is to install a grease trap through which the liquid waste passes on its way to the main drain pipes. Grease traps provide a mechanical means of separating grease from water before it enters the sewer, or they can contain microbes to create a sustainable grease-eating biomass.

Every kitchen is different so it is important to get expert advice to ensure the waste management element of any site's operation is effective for your individual needs.

LATEST DEVELOPMENTS

Composting is hardly a new concept but in commercial kitchens it is a relatively new procedure. Many kitchens now keep vegetable matter separate from meats and cooked waste so it can be turned into compost. Country establishments can easily set up an outdoor conventional composting area or a wormery as long as the waste has not been in contact with animal by-products.

Other sites can invest in in-vessel composters that rapidly turn kitchen waste into compost and allow all food waste to be composted - including animal by-products and plated waste. These reduce the food waste volume by about 90% and produce a rich, high-energy compost.

Q&A

Q If we install a pulper/extractor system in our fast-food restaurant, will there be any cost savings that we can offset against capital investment?

A Yes, the volume reduction in your food waste can be up to 70%, which in turn dramatically reduces collection/landfill costs. These units also recycle some of the grey water, reducing the water bill. Plus, as waste does not need to be physically carried from the kitchen so often, there are cost savings in labour. An additional benefit is that there is a reduction of odour in the kitchen and around the rubbish area.

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