Composting food waste



Globally about one third of food produced is wasted, most of which could have been eaten, according to research by WRAP (Waste and Resources Action Programme).


Sending food waste to landfill is not only wasteful and expensive, but also produces emissions of methane as anaerobic bacteria break down the compressed waste. Methane is a potent greenhouse gas which, molecule for molecule, traps 30 times more of the sun’s heat in the atmosphere than carbon dioxide.

EU regulations mean that the amount of biodegradable waste going to landfill in the UK is reducing, and many local councils now have green waste recycling schemes. This is an excellent solution, but you can’t dispose of any leftover meat, fish or cooked food waste this way, so those items still have to go to landfill or for incineration.

If you have a garden a better way is to compost all your kitchen waste at home, including cooked waste, producing rich fertile compost for the garden.


Home composting has always been a good way of recycling uncooked kitchen waste such as vegetable peelings, tea bags and coffee grounds, but there is a problem dealing with meat and fish, dairy products and leftover cooked food. If you mix this waste in with your ordinary compost it smells and attracts flies and rats, so it needs to be composted in a different way. There are several systems for doing this.


Food waste digesters


These are the simplest way to recycle all food waste, cooked or uncooked. There are three main types of digester available in the UK, the Green Cone, the Green Johanna, and the Hotbin, all of which use natural processes to break the food down without producing methane.


*The Green Cone is a small food waste digester which needs to be partially buried in the ground in a sunny, well drained part of the garden.


You can put about three-quarters to one kilogram of any cooked or uncooked food waste into the Green Cone each day, which is the average amount produced by a family of four to five. It's not intended to be used for garden waste.


It's easy to set up, very simple and clean to use, rarely needs emptying, and will dispose of most cooked and uncooked food waste. It doesn't produce any garden compost.


*The Green Johanna will recycle the kitchen waste produced by a household of up to five people together with the compostable waste from an average garden.


The unit must be installed in a shady part of the garden and is designed to be filled with two parts food waste mixed with one third garden waste. If you don't have much garden waste, other carbon rich material such as leaves, sawdust, cardboard or straw can be used.


Waste is broken down by micro-organisms in a hot composting method producing good rich compost which is ready after about four to six months, depending on the time of year and temperature.


*The Hotbin is a highly insulated 200 litre capacity bin designed to operate at between 40 to 60 degrees C. The makers claim it will compost kitchen and garden waste 32 times faster than a traditional cold bin, producing finished compost in 90 days or mulching compost in 30 days.


It will take all cooked and uncooked kitchen scraps, pet waste, and general garden waste including grass clippings. To operate at high temperatures a Hotbin needs regular feeding of at least 5 kg of waste per week, mixed with shredded woody waste and/or torn up corrugated cardboard, or shredded paper. The average family of four produces about 3-5 kg per week.


See also the 100 litre *Hotbin Mini for smaller households.


There is more detailed info on all these systems in our post Food Waste Digesters


Wormeries


Worms are very effective and hygienic composters, and a wormery will compost most types of leftover food scraps, producing especially rich compost and concentrated liquid fertiliser.These are really good efficient systems, although not everyone is happy dealing with worms.


For more detailed information see our posts on Worm composting.


Bokashi bins


This is a very simple two-step system in which the food waste is firstly fermented and then composted. The waste is mixed with a special culture of micro-organisms mixed into wheat bran, then sealed into an airtight container for about two to three weeks. The fermented waste is then added to an ordinary compost bin or a wormery or buried in the garden where it very quickly breaks down into compost.


See our posts on Bokashi composting for much more in-depth information on using this system.


See also How to eat green


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© 2019 by Turning To Green

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