Category Archives: food

Food waste digesters

A food waste digester will dispose of all biodegradable kitchen waste, cooked or uncooked, such as meat, fish, bones, bread, dairy products, vegetable peelings and fruit.

There are two main types of digestor, the Green Cone and the Green Johanna. They are installed in the garden and look very similar to normal compost bins. Both use natural processes to break the food down without producing methane.

Green Cone

This small food waste digester needs to be partially buried in the ground in a sunny, well drained part of the garden.

green cone food waste digesterThe unit uses solar heat to raise the temperature of the waste in the underground digestion chamber. The surrounding soil insulates the chamber. Food waste is broken down into water and carbon dioxide and a little organic residue. Accelerator powder can be added if needed to speed up the process.

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. It’s not intended to be used for garden waste.

The Green Cone works all year round. As it produces very little waste residue it should only need to be emptied once a year at most, usually longer.

Available to buy from

Green Johanna

This is a more expensive option, but in my view it’s the best of all. It’s a very simple, easy to use compost bin which will dispose of all food waste and garden waste too.turning2green - green johanna hot composter It 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 which produces good rich compost. To maintain food waste recycling all year round a thermal jacket is needed when average temperatures drop below 5°C. No accelerator powder or chemicals are added.

There are two doors at the base to easily remove the finished compost which, depending on the time of year and temperature, will be ready after about four to six months.

The Green Johanna is available to buy from Great Green Systems and also from Amazon


Note: Larger scale food waste composters are available for schools, restaurants and commercial food waste – see Ridan Composters

Composting food waste

Research by WRAP (Waste and Resources Action Programme) shows that in the UK we are throwing away about one quarter of the food we buy, most of which could have been eaten. In effect, for every four bags of shopping we bring home, we put one straight into the bin.

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 over a century, 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 is reducing, and many local councils now have green waste recycling schemes. This is an excellent solution, although you can’t dispose of any leftover meat, fish or cooked food waste this way, so those items still have to go to landfill.

If you have a garden a better way is to compost all your kitchen waste at home, producing rich fertile compost for the garden. Home composting has always been a good way of recycling uncooked kitchen waste such as vegetable peelings, egg shells, 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 now several systems for doing this.

Food waste digesters

These are the simplest way to recycle all food waste, cooked or uncooked. There are two types of digester, the Green Cone and the Green Johanna, and both use natural processes to break the food down without producing methane. - green cone food waste digester
Green Cone – this small food digester needs to be installed in a sunny part of the garden as it uses solar heat to break down food waste into water, carbon dioxide, and just a small residue of solids. It isn’t suitable for garden waste, and doesn’t produce any compost. It’s easy to set up, very simple to use, rarely needs emptying, and it will dispose of most cooked and uncooked food waste. See Great Green Systems for more information or to buy.

Green Johanna food waste composterGreen Johanna. This is a more expensive option, but in my view it’s the best of all. It’s a very simple, easy to use compost bin which will dispose of all waste food and garden waste too.
It must be sited in a shady part of the garden and is designed to be filled with two parts food waste mixed with one third garden waste, working by a ‘hot composting’ method which produces good rich compost.

See also my post on Food waste digesters.

For more information or to buy see Great Green Systems or Amazon

 Wormeries - wormery for composting food wasteWorms are very effective and hygienic composters, and a wormery will compost most types of leftover food scraps, shredded newspapers, or even the contents of your vacuum cleaner, producing especially rich compost and concentrated liquid fertiliser. There are various designs available – the easiest to use have several layers of trays which the worms move up through leaving compost ready for use in the lower trays.

These are really good efficient systems, although the idea of dealing with worms doesn’t appeal to everyone. For more information see my page on Worm composting.or have a look at the different types available on Amazon

 Bokashi binsturning2green - bokashi bin for composting cooked food waste

This is a two step system in which the waste is firstly fermented in airtight bins and then composted, so it works along with a normal composting system, turning leftover meat, fish, bread, etc into nutrient rich compost without creating smells or attracting  flies or vermin.  As the materials are collected they are sprinkled with a bran based material, bokashi, which contains a culture of friendly micro organisms.  When the bokashi bin is full it is closed up and left for two weeks to ferment. Generally two containers are used so one can be left fermenting while the other is being filled. After fermentation the waste needs to be added to an ordinary compost bin or wormery or buried in the garden to complete the composting process.

There is more information on using this system on my Bokashi page, or see the equipment available at Amazon