What about food waste?

We all work towards diverting organic waste away from landfill sites, and innovative solutions are cropping up all the time.

We all work towards diverting organic waste away from landfill sites, and innovative solutions are cropping up all the time. Here, Karen Wilde presents the work of Aardvark Recycling a UK-based company that collects and processes food waste on a compact inner-city site using Accelerated Compost Ltd’s Rocket® In-Vessel Composter

Waste recycling has grown exponentially over the last few years, yet food waste still presents a major problem. Concerns over global warming and sustainable living have helped with the recycling revolution, yet the majority of food waste generated throughout the world still ends up in landfill food waste decomposing in landfill sites generates methane, a greenhouse gas 20 times more damaging to the environment than CO2.

Susan Antler, executive director of the Composting Council of Canada reveals that 38% of Canada’s methane gas emissions come from landfill: ‘This is coming from organics ... we’ve got to get them out of landfill.’

Figures for worldwide food waste are few and far between, but estimates for developed countries range from 25%40%, with some US estimates increasing to a staggering 50%. According to the University of Arizona, this is due to the large amount of food thrown out by supermarkets each year which, although edible, is considered below par in looks this totals around $30 billion (£20 billion) worth. Is the environment too high a price to pay for ‘pretty’ food?

‘Well over 30% of fruit and vegetables in North America are tossed out before they hit the supermarket because they are cosmetically challenged,’ says Toronto Food Policy Council’s Wayne Roberts. ‘The carrot may be crooked or the apple too small or simply not the right colour. People want food to meet high cosmetic standards,’ he claims.

In the UK about a third of food bought is thrown away, a pattern repeated through much of Europe. Sweden is reported to throw away around a quarter of its purchased food. In 2004 a report by the Australian Food and Grocery industry showed that 40% of their household waste was unwanted food. Estimates in Canada suggest that in Toronto alone approximately 275kg is thrown away per family per year though at least 75% of their food waste is recovered for an organics composting programme.

There are solutions of course. Anaerobic digestion with energy recovery can play a part in reducing the mountains of food waste while contributing to the sustainable energy mix, but the costs and logistics involved with setting up a collection service, transporting the waste to the processing site and building the plant to process the material, can be prohibitive. In high-density population areas with land space at a premium, it is not always a viable economic option. So what can be done?

Inner-city food waste a solution?

Squeezing through the parked cars on a narrow road in South London, UK, can have many pitfalls, even for the compact car owner. It’s hard to imagine what the road must be like on waste collection days. Tucked away on a small business park in the heart of this densely populated area is a social enterprise that is achieving huge successes in terms of food waste recycling.

‘Recycling collections in high-density areas are labour intensive, and therefore costs are higher for kerbside collections,’ explains Joe Tanner, managing director of Aardvark Recycling. So how do they stay afloat?

Joe continues, ‘When Aardvark was set up we were in the right place at the right time to access the pots of funding for the initial capital outlay and education programme. But now that funding has come to an end we are finding that commercial contracts are the way forward.’

Showing that Aardvark could cut the costs of other Local Authority services, they secured £400,000 worth (approx US$595,000) of funding from the UK Treasury through DEFRA (Department for Environment, Food and Rural Affairs) which, along with other schemes run by the London Development Agency and the National Lottery community recycling program, increased to nearly £1 million ($1.5 million) enough to get the project up and running for the first three years without any cost to residents or authorities. Now that funding has ceased, all of the profits generated from the commercial contracts go back into the community biowaste recycling programme, which at the moment only achieves around 30% participation.

‘Expanding the commercial contracts to generate finances will give us the money to increase the education programme. This is the key to increasing resident participation rates. We are a fairly new and different type of services and residents find change hard, so right now, the commercial contracts are providing the funding for our future we can’t have one without the other.’

The cost per tonne on a small- to medium-scale collection service like Aardvarks is high around £22 per household per week, but lower than the £30£40 per tonne that an out-of-town anaerobic digestion site could cost. But this figure of £22 per tonne will decrease significantly as more residents come on board. The food waste collection service for the residents of the London Borough of Lambeth is promoted through Aardvark’s website, Residents’ Association meetings, leaflet drops, the Local Authority website, community events and word-of-mouth.

‘We found the service is bringing the community together and the keeping-up-with-the-Joneses effect has increased participation. But excellent service is the key ingredient to maintaining and increasing participation rates among the residents,’ Joe says.

Food waste collection system makes it easy for residents

The Aardvark team have thought about every aspect of their ‘personalized’ service: there’s not usually a lot of space in high-rise households so the lockable caddies, supplied by Peter Ridley Waste Systems, are small enough to be unobtrusive yet large enough to safely contain the average 2.5kg3kg of food waste that each family throws away every week.

The high costs of such a service have priced out a lot of local authorities and private sectors, leaving a gap for social enterprises like Aardvark to have a significant impact on food waste recycling rates.

Supplied by Accelerated Compost, the eight Rocket® In-Vessel Composters of varying sizes used to process the food waste (including five of the largest A1200 models) have the combined capacity of around 700 metric tonnes per year. Aardvark’s team use small vans to increase access ability for ‘near entry’ collections and local tree surgeons supply the woodchip necessary for the composting process to work efficiently in the Rocket® composters.

Small scale how it works

Biodegradable caddie liners are supplied to residents, and replacement liners can be ordered by telephone or direct from the collection staff as and when they are needed. The filled liners are collected and transferred to wheeled bins for easier off-loading at the Aardvark processing site, empty caddies are left for the resident.

All food waste is shredded before entering the Rocket® composting system to increase particle surface area and the composted product is screened before maturation. Any oversized material is put back through the Rocket®.

Figure 1. Keeping it simple speeds up the process rather like rocket science Click here to enlarge image

Ten years ago keen gardener and inventor John Webb wanted to find a way of speeding up the composting process the Rocket® In-Vessel Composter was therefore developed in 1998 as a solution for John’s green waste problem on his smallholding.

Huw Crampton, general manager at Accelerated Compost Ltd (ACL), explains how it works: ‘The Rocket® is a continual process system, designed to be fed with wastes as frequently as possible ideally daily. Food and organic waste is simply placed into the hopper on the top of the machine with an equal quantity of woody material. The process from then on is automated.

‘As the blades of the internal shaft turn they aerate the material, moving it along the body of the machine so providing loading space at the input end of the machine, and pushing finished material out from the exit of the machine. The Rocket® is simply a controlled environment in which harmless composting microbes thrive.’

Temperatures inside the Rocket® can reach 70°C+ (158°F), enough to kill off pathogens such as Salmonella and E. coli. After around 14 days the composted product exits the Rocket® and enters the maturation phase for six to eight weeks.

Myth busting

Joe Tanner from Aardvark says: ‘The pong associated with compost is a myth and one of the things we are keen to educate residents about. The compost we produce at Aardvark has all the right ingredients for active plant growth and is shown to be pathogen-free. We’ve sent samples for analysis and are still waiting for the results, but it’s likely we will meet the Association for Organics Recycling PAS 100 certification.’

Matured compost ready for landfeeding, not landfilling! Click here to enlarge image

The food waste processing areas are already compliant with the UK’s Animal By-Products Regulations (ABPRs) and if Aardvark’s compost does achieve PAS 100 then the compost can be sold to all-comers. At the moment demand outstrips supply for the compost. During the processing, the material is reduced by around 50% volume and the finished commodity is being used in residents’ window boxes, allotments and for landscaping.

‘The Aardvark system is adaptable and scalable to around 20,000 plus households, and for inner-city areas it’s probably the only way forward unless you have large AD sites far out of town. Being locally based reduces the carbon impact of the service. A mini Aardvark site could be set up in basements of high-rises this is one thing we are looking closely at for the future.’

The problems with waste disposal in high-rise, high-density population areas are well documented. Rubbish disposal chutes can become blocked and any food waste begins to rot leading to possible bad odours and vermin. Take food waste away from these chutes and bad odours decrease significantly, as do vermin, while the volume of actual waste decreases by around 35%.

For the Local Authority the recycling system is still in the experimental stage and low participation rates and high running costs is currently preventing them from rolling it out across the whole Borough. However, it won’t be long before legislation dictates that all authorities in the UK will be forced to look at food waste collections and processing in high-density areas.

Composted food waste discharges from the Rocket® Click here to enlarge image

Participation rates for another project are already hitting 50%. The project started as a pilot initiated by EC1 New Deal for Communities (NDC) with funding of around £190,000. Food waste was collected and processed in a pilot scheme that operated from the basement of a high-rise. The pilot was a success, and Islington Council in partnership with Aardvark took over and continue to run the service today.

Food waste is collected by the recycling team, macerated and de-watered before being processed through an A700 Rocket® Composter. The compost is then used around the surrounding grounds and for residents’ window boxes, flowerpots and planters.

Bringing the community together

As a not-for-profit organisation, Aardvark Recycling has brought more to the community than recycling food waste. Their Real Nappies Laundering service collects dirty reusable nappies and delivers clean ones in the same visit, helping to reduce the number that end up in landfill each year. In another scheme, Aardvark is providing locally sourced fruit boxes to Stockwell’s Resource Centre Breakfast Club. The scheme hopes to encourage healthy eating while also promoting the environmental benefits of locally sourced food.


When it comes to food waste recycling in high density population areas (although the initial costs can seem high) there are many benefits that a social enterprise, like Aardvark Recycling, can bring; educating and encouraging local residents to change their shopping habits; reducing waste-to-landfill; reducing harmful greenhouse gas emissions; bringing the community together; and providing a valuable resource from an environmentally damaging waste product an added value that a local authority or private enterprise would have a hard time achieving.

In a world where economies of scale prevent the collection and recycling of food waste from many high-density population areas, there is a need for local, small-scale collection and processing plants. These could provide a much needed solution to a problem that we are only just beginning to address.

Karen Wilde works in sales and marketing for Accelerated Compost Ltd e-mail: info@quickcompost.co.uk