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Getting help to digest your food

08 June 2017

Few would disagree that there are clear financial and environmental benefits to reducing food waste. But, what can be done with unavoidable food waste? Charlotte Morton believes that anaerobic digestion is the way forward.

According to the Waste and Resources Action Programme (WRAP), estimated annual food waste within UK households and the hospitality, food service, food manufacture, retail and wholesale sectors is around 12 million tonnes (Mt) – equivalent to filling 25,000 Olympic-sized swimming pools. Around 3.4 Mt of waste are disposed of in the food sector alone each year.

Why does this matter? Firstly, the economic impact of food waste is enormous. Food waste costs businesses operating in England £2.6 billion a year: the labour cost to businesses constitutes £0.96 billion, and avoidable food waste yield loss constitutes an average of 13.2% of labour costs across all hospitality and food service subsectors. Secondly, producing food requires a lot of vital resources and can have a significant impact on the environment. 

The food waste hierarchy tells us that food waste should be eaten by humans or animals if safe and appropriate. If this is not possible, the next best option is recycling through anaerobic digestion (AD), which extracts the energy contained in food waste to produce renewable heat and power, green transport fuel, and organic biofertiliser that restores essential nutrients and organic matter back to our depleted soils.

AD plants in England already process around two million tonnes of food waste from households and businesses each year. British businesses generate almost six million tonnes of food waste every year (over one-third of all UK food waste) which costs more than £8 billion to deal with. With landfill tax rising sharply, businesses are increasingly finding it a financial necessity to find an alternative to throwing organic waste into landfill. By either treating waste on-site in their own AD plant or source-segregating their waste and arranging to have it collected separately to be treated through AD, this financial burden can be cut.

This saving is likely to grow as waste controllers adjust from charging businesses by volume to weight as they modernise practices in response to high landfill charges. Pay-by-weight pricing will mean that even small food producers will be able to make savings by introducing separate food waste collections. 

“Sending food waste to landfill is not only bad for the environment, but is now increasingly a very expensive option,” said Iain Pickles, head of sales at Biogen, a company that recycles food waste for local authorities and businesses. “The Government has introduced a tax on landfill disposal which increases every year. Sending food waste to AD, however, is significantly less costly and helps produce renewable energy and a valuable fertiliser.”

Businesses that produce a large amount of organic waste can treat it in their own AD plant to produce energy to heat and power their site. “Food and drink manufacturing sites can be an ideal location for bioenergy plants,” said Richard Gueterbock, director at Clearfleau, a company that provides AD systems for on-site treatment of liquid bio-waste. “These sites produce a range of bio-degradable process residues that are ideally suited to bio-digestion.”

Environmental impact
Businesses are also increasingly aware of the environmental impact of their activities, and as a consequence more committed to reducing their carbon footprint. Integrating AD can help to realise huge carbon savings and demonstrates a business’s green credentials and commitment to sustainability. AD can also help to minimise the financial burden that falls under the Government’s CRC Energy Efficiency Scheme.

The wider benefits of AD for the UK economy and the environment offer a great way for businesses to meet their sustainability and corporate social responsibility goals.

AD produces renewable energy. Treating all of the UK’s inedible food waste through AD would produce over 9TWh of green gas every year, which is enough baseload energy to power around 800,000 homes and reduce fertiliser imports by 10%. 

AD also contributes to decarbonisation. Sending the waste disposed of by the food sector each year to AD would abate 3.86 Mt CO2e per year, further helping the UK achieve its renewable energy targets and meet decarbonisation thresholds required under the Climate Change Act. 

Treating organic waste through the AD process also offers carbon benefits compared to landfill use or incineration. Methane emissions from landfill currently account for 3% of the UK’s total greenhouse gas emissions, while incinerating organic waste to generate electricity produces 27 times more CO2 than treating it through AD. Unlike AD, incineration of food waste fails to return any of the nutrients back to the land, wasting the nutritional and organic matter content of the soil used for growing food. 

AD therefore has an important role to play in improving the UK’s soil health. The biofertiliser produced from recycling organic material such as food waste through AD can be used instead of carbon-intensive alternatives. Known as ‘digestate’, this biofertiliser helps maintain pH and soil fertility and improves soil quality, crop yields, and the availability of nutrients (principally nitrogen, potassium and phosphorus) while also replacing the organic matter component.

There are co-benefits to recycling food waste through AD. Malt and malted ingredients producer. Muntons, for example, has found antibiotics in their AD plant that could be developed to combat Micrococcus and drug-resistant E. coli and the company is actively involved in researching other medical uses.

While the UK Government recognises AD as the treatment option for food waste that achieves the greatest environmental benefit, only 12% of food and drink waste is currently recycled this way. 

The Government will not be able to meet its recycling targets without separate food waste collections, which are mandatory in the devolved nations for both households and businesses but still not in England. A lack of consistency in food waste collections perpetuates the traditional linear economy of food waste where it is made, used, and disposed of.

“The regulatory framework should incentivise manufacturing decarbonisation and greater resource efficiency, encouraging smaller food companies to generate bioenergy,” continued Gueterbock, who also points out the need for the economic case to be made to food processing companies. “Apart from trust in the technology, the key challenge is to show that AD is cost-effective with an attractive payback. The priority is development of an efficient on-site digestion process with an attractive return on investment.”

Overcoming practical considerations is also key for food processors. “One of the main barriers the food and drink industry experiences is finding space both within the factory and outside for the food waste bins,” said Pickles. “We have worked with a number of customers to develop site-specific solutions which work for them. This has included daily collections, pick-ups at night and bespoke containers such as dolavs, bulkers and skips.”

An attractive option
While there is a lot more that Government could do, AD is increasingly being seen as a no-brainer for food processing companies who see the advantages of saving money on sending waste to landfill and improving their environmental credentials, benefiting both the business itself and wider society. The Anaerobic Digestion and Bioresources Association (ADBA) continues to work with the food and drink industry and other partners to help reduce the barriers to recycling food waste through AD so we can all profit today while protecting tomorrow.


Charlotte Morton is chief executive of the Anaerobic Digestion & Bioresources Association.


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