Food waste

Reduce or home compost your food waste

Everyone produces some food waste that can’t be avoided (for example tea bags, banana skins, vegetable peelings and chicken bones) but throwing away edible food costs you money and wastes energy and resources. Find out ways to reduce your food waste or compost food waste at home.

Recycle your food waste at the kerbside

Every household in Oxfordshire receives a food waste collection from their district council. Recycling food waste reduces your carbon footprint, saves the council money on mixed waste disposal, generates green electricity and a fertiliser that is used on farmland across Oxfordshire.

About a fifth of all household waste collected at the kerbside is food. Oxfordshire residents already separate half of this for recycling – thank you. If the other half that ends up in the general waste bin was also recycled, it would save the council around £2m a year in disposal costs.

All cooked and raw food can be put into your food caddy for recycling, including meat, fish, vegetables, dairy products, tea bags and coffee grounds.

Video about food waste

Watch our film to find out how your food waste is recycled'

Read video transcript

Separately collected food waste from the kerbside is brought to an Anaerobic Digestion facility for recycling. The first stop is the weighbridge, where the vehicle full of food waste is weighed so we know how much food is being recycled.

The vehicle then drives into an enclosed reception building where it tips the food into a large bunker. Business waste from supermarkets, restaurants, and even liquid waste from factories, breweries and dairies is mixed with household food waste. It is passed through the mouth of the plant where it is chewed, any contamination removed, and the food waste soup is created, ready for digestion.

Before digestion this needs to be pasteurised, to kill off any bad bacteria. This is like cooking the soup. It is held in giant vats where it is heated to 70oc for one hour. They are heated by using recycled heat from the gas engines. The pasteurised soup is then fed to one of the digestion tanks. There are five tanks on site. Each tank is like a giant stomach, where good bacteria eat the food, converting it into biogas, or methane, and a fertiliser called digestate.

The food waste is pumped through the five tanks, and this takes around 100 days.

Like the bacteria in our stomachs, the good bacteria break down the food waste to extract as much energy as possible. Once all the biogas has been extracted, we are left with a nutritious organic fertiliser.

Because the digesters are like giant stomachs, they have to be tested every day , in our lab, to keep them healthy.

The digesters have to be kept at body temperature, and are heated by using recycled heat from the gas engines.

The biogas is stored in the roofs of the tanks. It is then fed into two large engines which, just like a car converting fuel into energy, converts the biogas into electricity. This is fed into the national grid through transformers on site. The engines produce enough energy to power 4,200 homes.

The nutritious organic fertiliser is a black liquid which is taken from the plant and spread as a valuable fertiliser on local farmland. This helps improves crop yield, and replace artificial fertilisers.

Vehicles bring in approximately 120 tonnes of food waste every day. This means, in addition to powering our homes and helping to grow crops, over 40,000 tonnes of food waste is kept out of landfill.

Your questions answered

Why can I put cooked food waste in my food waste collection but not in my home composter?

The food waste collected by your district council will be taken to one of three composting or anaerobic digestion sites provided by Oxfordshire County Council and our contractor, Severn Trent Green Power Ltd.

These sites are highly controlled to stop smells escaping and ensure birds and vermin are not attracted to the facilities. The facilities reach the correct temperature to ensure any bad bacteria is killed off. This means that the facilities can compost cooked and uncooked food including meats, oils and fats.

Can I use plastic bags to line my food waste bin?

If you live in Oxford City, South Oxfordshire, Vale of White Horse and West Oxfordshire you can use a plastic bag to line your food waste bin – consider reusing a bread bag or other food packaging rather than buying liners.  If you live in Cherwell, you need to use compostable bags. In all districts you can also line your food bin with newspaper or put the food in loose but you will need to clean your bin more often if you don’t use a liner.

What about home composting?

Making your own compost at home is the most environmentally friendly way of dealing with your vegetable peelings and other uncooked food waste. You can produce your own compost which is beneficial for your garden. However, meat and fats and cooked food waste cannot be composted at home. It is likely to create nasty smells and attract vermin.

How is the food waste processed?

Severn Trent Green Power operates three plants within the county, using two different technologies: In-Vessel Composting and Anaerobic Digestion.

In-Vessel Composting (IVC)

IVC used to process food waste where it is collected in the same bin as garden waste. It is shredded and treated in large tunnels for three weeks. Air is pumped through the tunnels to speed up the decomposition process. The waste is then transferred to another set of tunnels and the process is repeated to ensure that all waste has fully broken down into compost. This compost is stored in a maturation area and is then refined on-site to sell to the farming industry.

The IVC plant at Ashgrove Farm, Ardley accepts mixed food and garden waste collected in Cherwell.

Anaerobic Digestion AD)

Separately collected food waste is processed in a series of large sealed vats, or 'digestors', where it is heated and stirred for 72 days. This process releases methane and converts the food waste to a valuable fertiliser, which is pasteurised and stored on site for up to six months and then sold to the farming industry.

The methane gas produced by the process is piped to an on-site engine to generate electricity which is fed into the National Grid.

The AD plant at Cassington accepts food waste from West Oxfordshire and Oxford. The AD plant at Wallingford accepts food waste from South Oxfordshire and Vale of White Horse. The electricity generated from each plant is enough to power almost 5,000 homes – equivalent to a town the size of Kidlington.