Food for thought in recovering best value
Unwanted food remains an untapped resource in the household waste stream, so how can local authorities best maximise its value? Maxine Perella reports
If you can ride the media storm around alternate weekly collections by introducing separate kerbside collections of food waste, you could become a hero – that was the message driven home to recycling officers in London last month.
Speaking at London Remade’s local authority network meeting ‘Dealing with London’s food waste’, David Stowe, recycling project officer at Preston City Council, told delegates: “If you’re going to start collecting food waste, do it now. You can possibly ride this media wave of negative AWC publicity – what a hero you will look if you’re getting food out of it.”
Stowe, who joined Preston City Council in 2005, has been responsible for implementing a separate weekly food waste collection scheme and composting trial. The success of the award-winning scheme has led nearly 200 council officers and consultants to visit Preston to find out more.
Firstly, Stowe advised delegates against mixing food waste with green waste. “If you commingle collections, it’s going to make a mess of your green rounds. It’s not only going to make a mess of your bins, but it will also change participation rates. So if you’ve already got RCVs out there collecting garden waste, think carefully before you take any decisions.”
The food waste scheme in Preston uses a 7.5 tonne RCV to collect food waste from 25-litre containers at the kerbside. Residents were also supplied with 7-litre kitchen caddies and corn starch liner bags which Stowe said were “absolutely brilliant”. He added: “I don’t think I could drive past 1,853 houses on the round if I wasn’t collecting food in a corn starch bag. They really do speed up the collection. It’s at a cost though, budget for around £2.50 a house – each house in our area uses about three bags every week.”
Get the public on your side
Participation rates are high, due to a highly visual literature promotional campaign accompanied by door-stepping. “You have to bang on doors, especially with the contamination issue,” said Stowe who added, “right from day one, we got huge tonnages”. Reiterating the initiative’s success, he said: “One of the only sources of complaint I see is from people in neighbouring areas where the scheme doesn’t operate, complaining that they can’t do it – that’s a lovely complaint to get.”
Echoing Stowe’s argument for introducing a separate food waste collection, Mary Corin, director of recycling development at Grosvenor Waste Management, said: “AWCs – what’s the argument against it once you’ve removed the food element? It’s a phenomenal opportunity to capture the public’s enthusiasm”.
Grosvenor is one of the UK’s largest dry recyclables reprocessors and Corin told delegates that contamination was crucial if maximum value is to be derived from materials, including food. “Food waste has the most horrendous ability to contaminate dry recyclables – half-eaten pizza thrown away in paper is seriously frowned upon by my paper mill who is buying that material … grease is an absolute disaster within paper making.” She added that although food waste was small volumes compared to other waste streams, the industry was waking up to the fact that valuable products such as energy or soil fertiliser can be recovered from it.
Continuing this theme, Michael Chesshire, director of Greenfinch, spoke about the benefits of anaerobic digestion (AD) in recovering value from food waste. Greenfinch is a specialist AD company and has carried out research and development into this area for the past 10 years.
AD works by taking biomass (such as food waste) and converting it into either biogas or bio-fertiliser. Biogas is 60% methane and 40% CO2 and can be used to feed combined heat and power units for electricity and heat, while bio-fertiliser is rich in nutrients and can be used as a soil conditioner. “Unlike other renewable energies, AD is a low carbon process. We can reduce carbon and greenhouse gas emissions through four ways,” explained Chesshire.
“First, by avoiding uncontrolled emissions of methane to the atmosphere. Second by converting biomass into bio-fertiliser we displace nitrogen so farmers can reduce their dependency upon mineral nitrogen – one tonne of artificial nitrogen results in the emission of two tonnes of CO2 to the atmosphere in its manufacture so this is a very important CO2 avoidance exercise. Third, AD lends itself to local solutions so we can reduce waste miles and therefore CO2 emissions from waste, and fourth is the production of renewable energy and heat from AD.”
Digesting the facts
Chesshire added that food waste has a high moisture content so lends itself to a biological process, in particular AD. In partnership with South Shropshire District Council, Greenfinch has designed and built the UK’s first full-scale biowaste digester that is currently operating on 100% food waste collected from households. It is generating 150kW continuously from 70 tonnes a week of food waste – a figure that will shortly be ramped up to 100 tonnes.
WRAP, which has recently rolled out food waste kerbside collection schemes with 17 local authorities, has carried out a significant amount of research on how best to capture this particular waste stream. While LAs are diverting around 65% of garden waste from landfill and composting it into product, only 4% of food waste is currently being recycled.
“The big challenge facing local authorities is to design schemes that collect this material in a cost and environmentally efficient way that maximises capture rates, but also delivers a good quality service to residents,” said Louise Hollingworth, WRAP’s supply programme manager for organics.
She went onto outline some recommended approaches. These included intensively promoting home composting as a starting point, to minimise the amount of food getting into the waste stream in the first place. Once kerbside collections are introduced, she said, try to avoid mixing food and garden waste: “This isn’t very effective at collecting food waste and can increase the processing costs of that stream which then has to be treated through some sort of in-vessel system.”
Weekly rounds suit urban areas
Hollingworth added that weekly collections of food waste could work particularly well in urban areas where there is less opportunity for home composting and garden waste collections. “There is the potential here to process it through anaerobic digestion and use the renewable energy,” she said.
Legislation surrounding food waste was also touched upon by Alice Cohen, policy officer for Defra’s waste licensing unit. She mentioned that the recent Waste Strategy for England is looking to increase the scope of new technologies and that “support has been put in place for anaerobic digestion through the new technologies programme, the renewable obligations system, PFI and the development of a digestate standard”.
Cohen also told delegates that while the strategy proposes strong voluntary agreements across the industry to reduce food waste, the Government would not dismiss putting regulation in place if necessary to achieve this goal.
An appetite for action
· London produces approximately 1.3M tonnes of household food waste each year
· Kitchen and garden waste accounts for about a third of the waste collected from London households and these volumes are likely to increase
· London is home to half of England’s restaurants and commercial food outlets
· There are no facilities in London to recover and reprocess the food waste stream yet
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