News Article

Feb 7, 2012

Category: Resource Efficiency

Recycling Waste Fat and Oil

By Laura Hobbs

Disposing of used cooking oil and fats can be messy and unpleasant, and if you put them down the sink they can quickly block your drains. According to the Chartered Institute for Environmental Health, an estimated 10% of the sewerage network (170,000 tonnes) is filled with waste fats, oils and grease (FOG) [1], and in 2010 they found that despite being legally required to do so, around one third of businesses inspected were failing to dispose of their waste FOG correctly [2]. However, rather than sending used cooking oil or waste fats to landfill, there are several ways they can be recycled or reused.

Liquid cooking oil

Some cooking oil can be reused for cooking, if the heat is turned off immediately and the oil is filtered, but this will depend on a variety of factors. The oil cannot be used if it smokes when heated, foams on the surface, has gone dark in colour, does not bubble when food is added, or smells rancid [3]. Many local authorities provide recycling collection points for used cooking oil; details of the availability of these sites can be found through the cooking oil section of recycling.co.uk [4] or in the general information supplied by recyclenow.com [5].

Living Fuels [6] collects oil from the public and private sectors, by providing recycling points and free oil collection to some businesses. They recycle all the oil they collect into a patented carbon neutral biofuel, which they run all their collection vehicles on. They calculated that 1 litre of used cooking oil can generate 4.5 kWh of electricity, equivalent to making 240 cups of tea, or running a 20 W energy saving bulb for 225 hours [7].

Another way to recycle cooking oil, if it’s clean, is to make it into soap. There are various ways of doing this, but the simplest recipes use oil, lye (sodium hydroxide, also known as caustic soda, which should be handled with care), water and scents. Lemon juice can be used as a natural fragrance [8].

Solid fat waste

The fat that comes from meats will quickly clog drains, as it solidifies at room temperature. After draining it, leave it to cool so that it can be disposed of or used. While other foods can be cooked in it, it should be used sparingly for this, and not allowed to go off. In areas that collect food waste for composting, it may be possible to dispose of solid fat in this way.

Less Mess Ltd have developed a range of Fat Trap products which allow fat to be safely stored in a plastic, sealable tub, which can be recycled or reused when it’s emptied. (While the Fat Trap products are affordable, you could also use something like an empty jam jar for this, as long as you clean it thoroughly after each use). One use for the fat that Less Mess Ltd suggest, once the tub is full, is adding dried fruit and seeds to it to make a solid bird feeder, which is similar to the recipes supplied by the RSPB [9, 10].

Tallow candles are made from animal fat. It is essential that the fat is very clean – the rendering process that separates the fat from the meat occurs when it is cooked, and impurities can be skimmed off or strained out while the fat is liquid, or scraped off when it is solid. Melting the fat with water, then allowing it to solidify, can help separate out impurities [8]. Candles can be made by repeatedly dipping wicks into the fat (tallow) so that layers build up, or by using candle moulds [11]. They will be very hot when they are burnt. And like cooking oil, tallow can also be used to make soap [8].

[1] http://www.cieh.org/ehn/ehn3.aspx?id=16410

[2] http://www.cieh.org/ehn/ehn3.aspx?id=33766

[3] http://www.angus.gov.uk/atoz/pdfs/KitchenSafetyLeaflet.pdf

[4] http://www.recycling.co.uk/cooking-oil

[5] http://www.recyclenow.com

[6] www.livingfuels.co.uk

[7] http://www.livingfuels.co.uk/facts/one_litre_of_oil

[8]http://chemistry.about.com/cs/howtos/ht/makesoap.htm

[9] http://www.rspb.org.uk/youth/makeanddo/activities/birdcake.aspx

[10] http://www.rspb.org.uk/advice/helpingbirds/feeding/whatfood/index.aspx

[11] http://www.ehow.com/how_2311987_make-tallow-candles.html

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