Food waste recycling is not a new concept, however, as we see more and more the damaging effects of improper food waste management on the environment, authorities have made steps to reduce the amount of food waste going to landfill, and instead divert it into more sustainable processes.
Local councils are finding ways to improve their food waste management services to encourage residents to take a more active role in preserving the environment. The main way is through providing food waste caddies and collection services as part of their overall waste management.
Recycling your food waste, no matter how much or how little goes into your caddy, is a great way to reduce the amount of food waste going to landfill and contribute to environmental initiatives.
If your local council provides a home food waste collection then it is important to partake in food waste recycling services.
Why is Food Waste Recycling Important?
Food waste that is not recycled is often sent to landfill. As the food decomposes under anaerobic conditions, it releases a harmful greenhouse gas called methane that is 25-28 times more potent than carbon dioxide. Releasing these gases into the atmosphere is a key contributor to global warming.
In the UK alone, nearly 20 million tonnes of food is being wasted every year. This waste totals more than 25 million tonnes of greenhouse gas emissions, as reported by the Waste and Resources Action Programme (WRAP).
How is Food Waste Recycled in the UK?
Food waste recycling in the UK is a highly efficient, sustainable process that transforms food waste into valuable resources, primarily through a method known as anaerobic digestion. Other methods include in-vessel compositing and mechanical biological treatment (MBT).
Anaerobic Digestion
This closed-loop system is a key contributor to a circular economy, as it maximises the recovery of nutrients and energy which can then be reused in agriculture and as an alternative to fossil fuels.
Once the food waste has been collected by councils in dedicated food waste caddies, the organic material is transported to specialised anaerobic digestion plants. Before entering the main system, the food waste undergoes pre-treatment where any contamination such as plastic bags, stickers, or packaging that has managed to infiltrate the organic waste is separated and removed.
The cleaned food waste is then often ground up and mixed with water to create a liquid “slurry.” This slurry is pumped into large, sealed, airless tanks called digesters.
Inside these digester tanks, naturally occurring micro-organisms (bacteria) get to work. The “anaerobic” environment (meaning without oxygen) triggers a biological process where the bacteria consume and break down the organic matter over a period of weeks. As this organic material decomposes, it releases a gas which rises to the top of the tank. This collected gas is known as biogas.
The anaerobic digestion process yields two extremely valuable outputs:
Renewable Energy: Biogas is a highly versatile renewable fuel. It is either used in combined heat and power (CHP) units to generate renewable electricity (which is fed into the national grid) or it is cleaned and upgraded into bio-methane and injected directly into the national gas grid to heat homes and businesses.
This method is far more efficient than incinerating food waste (which is 70% water) and prevents the potent greenhouse gas, methane, from escaping into the atmosphere, as happens in landfills.
Bio-Fertiliser (Digestate): The nutrient-rich material left over after the digestion process is called digestate. This liquid and solid residue is carefully treated (often pasteurised to eliminate pathogens) and stored.
This valuable digestate is supplied to farmers and agricultural land as a sustainable, organic substitute for chemical fertilisers, supporting the growth of new crops and completely closing the recycling loop.
In-Vessel Composting (IVC)
In-Vessel Composting (IVC) is another method specifically used for treating mixed food waste, which includes materials like cooked food, meat, dairy, and domestic kitchen waste.
This method is legally required because these materials are classified as animal by-products and must be processed under strict regulations to ensure public and environmental health.
IVC takes place inside a sealed, enclosed system such as tunnels, silos, or agitated bays where conditions are meticulously controlled. The waste is first shredded, mixed with a bulking agent such as wood chips, and then loaded into the vessel.
The naturally occurring microorganisms break down the waste, generating high temperatures typically between 60°C and 70°C. This heat is carefully maintained for a minimum period to kill all pathogens and weed seeds, ensuring the material is fully sanitised.
After this intense, enclosed phase which lasts 1–3 weeks, the material is then transferred to an open area for a period of maturation.
Mechanical Biological Treatment
The process of Mechanical Biological Treatment (MBT) for food waste recycling is an advanced waste processing technology primarily designed to extract value and stabilise mixed residual waste, the “black bag” rubbish that hasn’t been separated for recycling at home.
When applied to food waste, MBT ensures that organic material is not wasted, contributing to both energy recovery and recycling goals.
MBT is not a single technology but a combination of both mechanical and biological processes, usually applied to Municipal Solid Waste:
Mechanical Pre-treatment (Sorting): This is the physical stage, often similar to a Material Recovery Facility. It involves using automated technologies like screens, magnets, and eddy current separators to rapidly sort the mixed waste stream.
The purpose here is to separate the non-biodegradable components. Metals are pulled out for traditional recycling, and hard plastics/paper are isolated to create a high-calorific solid fuel suitable for incineration or gasification. What remains after this stage is a wet, highly concentrated biodegradable fraction (slurry) rich in organic materials, which includes food waste.
Biological Treatment (Stabilisation): The organic-rich slurry then proceeds to the biological stage. For food waste recovery, this almost always involves Anaerobic Digestion (AD). The food waste slurry is pumped into sealed, oxygen-free tanks where microorganisms break it down.
MBT’s primary role regarding food waste is two-fold: it provides a method for recovering value from unsorted waste (food that ends up in the black bin), and it acts as a pre-treatment step. By isolating the food waste component from plastics and metals before digestion, the MBT process ensures a cleaner feedstock for the AD process.
This diversion aligns with the UK’s mandate to reduce biodegradable waste sent to landfill and contributes to renewable energy targets. Increasingly, however, the MBT process is being simplified in favour of source-separated collections (like the brown food caddy) to achieve higher quality and cleaner recycling streams.
Open Windrow Composting
Another method called open windrow composting, or open-vessel composting, is used to recycle waste, but this is exclusively reserved for ‘green waste’ referring to garden materials such as grass clippings and leaves that have not been mixed with food waste or animal by-products.
This process is carried out in the open air, where shredded waste is arranged in long, large, triangular heaps called ‘windrows’.
To ensure the process remains aerobic and breaks down efficiently, these windrows are turned regularly. Turning them incorporates oxygen, distributes heat more evenly, and regulates moisture.
The overall process is much slower than in-vessel composting, often taking several months for the material to naturally stabilise and form compost. Once both in-vessel composting and open windrow materials are mature, they are screened by sieving to remove any remaining contaminants and graded before being sold as quality soil improvers or used in agriculture.
What Can Go in a Food Waste Caddy?
So, what can go in the food waste caddy to be recycled?
- Uneaten food and plate scrapings
- Bread and pastries
- Cooked and raw meat
- Fish and bones
- Fruit and vegetables and their peelings
- Mouldy and out of date food that is removed from packaging
- Non-liquid dairy products
- Eggs and eggshells
- Rice, pasta, beans and lentils
- Tea bags and coffee grounds
What Cannot Go in a Food Waste Caddy?
- Any material that is not food waste
- Packaging of any kind
- Liquids including milk and cooking oil
If you have any questions regarding what can go in your food waste caddy, always check your council’s website.
How Bartec Can Help Councils with Food Waste Management
At Bartec, our innovative Collective waste management software empowers councils across England, Scotland, and Wales to enhance their waste management services.
Our intelligent routing, scheduled collections, and improved resident communication streamline processes and ensure reliable garden and food waste recycling, aligning with new recycling legislation.
To discover how Collective can transform your municipality’s public services and food waste recycling initiatives, contact our experts today.
