Without a firm idea of exactly where biowaste should be going, most countries in the EU are doing the best they can with the options available – such as AD and co-mingled collection. But are there alternative options which are being overlooked? Claudine Capel looks at the benefits of home treatment of biowaste...
The problems presented by biowaste will not disappear, instead we need to learn how to turn them into advantages. Credit: WRAP
The global waste industry is flooded with reports giving shocking figures on the amount of food that is wasted every year. Recent WRAP reports have stated that the UK throws away one third of the food it buys1, while Scotland throws away 570,000 tonnes of food and drink per year2. A 2004 study produced by the University of Arizona (UA) in Tucson stated that the USA was wasting 40%-50% of its food. When one considers the number of developing countries that have a shortage of food, and the rise of climate change, which is being exacerbated by the irresponsible disposal of food waste, these figures put us to shame.
In an ideal world we would only purchase and produce the amount of food we need, and there would be no reason to find new and more effective ways to dispose of it. But in practice, developed world societies have become used to the throwaway culture, and food is a cheap and disposable resource. The problem will not go away so we need to find the best way to manage it.
The main methods we have of disposing of our food waste – landfill, biodegradation or composting and, the latest technology, Anaerobic Digestion (AD) – all have their pros and cons. Europe is struggling to control its food waste, and until a Biowaste Directive is implemented, the situation must just be managed in the best way each local authority can offer. This usually involves a mix of two or more of these methods, but is determined by the financial restrictions the municipality has to work to, rather than by what has been deemed to be best for each country overall.
Who is doing what?
All member states in the EU are committed to reducing the amount of organic or biodegrable waste they send to landfill, and are working towards targets which mean they must continue to divert increasing amounts. This means that more and more biowaste is being dealt with, or will have to be dealt with, in other ways. Some countries took a proactive approach to this situation years ago, while others did not, or have joined the EU more recently and therefore had less time and resources to work on their waste management targets.
The UK is one country which cannot be said to have been leading the way when it comes to biowaste, although it is starting to make the necessary changes and work towards a better system. AD is rising in popularity, though the number of facilities is still very small, and some local councils have now taken the alternative route of encouraging residents to compost or treat their own food waste at home.
John Cockram, MD of Green Cone, who has spent many years looking into the global market for home treatment of food waste, says, 'Personal experiences of Canada indicate the country to be far more conscious of the need to segregate household waste into its various components, and peer pressure ensures that the residents actually do so. Germany appears to have a more disciplined approach and is largely reliant on incineration, while the UK continues to lag behind other European countries. New Zealand with its zero waste approach is probably the most advanced country and also the easiest in which to implement waste initiatives.'
The gaps between countries getting it 'right' and 'wrong' are broad. But one good example from Europe is Sweden, which perhaps can provide some inspiration for the rest of us. 'The readiness of people in Swedish society to protect the environment is very high,' says Gunnar Brundin, environmental consultant.
The case of Gothenburg
During the early 1990s, councils all over Sweden started looking at household composting as a serious part of their biowaste strategy. After the Agenda 21 conference in Rio de Janeiro in 1992, there was a lot of activity in various regions, and one of the more proactive councils was Gothenburg. Residents were offered a financial incentive to take care of their own organic household waste in the form of a reduction in waste collection fees.
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Home management of biowaste could be one solution. Credit: WRAP |
Gothenburg already had high recycling rates, and its residents are clearly environmentally aware. This can-do attitude when it comes to waste management has meant that residents have been willing to adopt new methods of dealing with biowaste, even if it means they have to put more effort in. The possibility of saving money offered by the council has been another catalyst to the resounding success of home treatment in this region.
Over the past few years the council has replaced old waste bins with wheelie bins in order to be able to weigh the waste and charge people per kg. It has also offered the residents a variety of different waste collection fee options, based on what type of fractions are handed over, how much and how often.
There will always be a need for centralized composting or biogas facilities in the area – or indeed anywhere – as home treatment is not feasible in every single home. But it seems to be working very well in Gothenburg – a city which has created a good balance when it comes to biowaste.
Benefits of the food waste digester
There are certain obvious benefits when considering the humble food waste digester as a treatment method: the waste is dealt with at home which saves collection costs for local authorities, it gives people a greater awareness of the amount of food they are actually wasting and encourages them to buy less, and it can provide a source of compost which can be used in the garden, or simply make the food waste vanish altogether.
The first step in any good waste management strategy is minimization, and home treatment gives people a cheap and easy way to reduce the amount of waste they put out to be collected by up to a third. This makes life easier for the council collecting the waste, which will not only have less to deal with, but will also have eliminated certain contamination problems in the waste stream.
Environmental consultant Alan Knipe says, 'Centralized treatment, whereby waste is whisked away, leads consumers to produce increasing mountains of it. It has been proven time and time again that the consumer needs to take ownership of their waste to reduce it. Centralized systems do not help people reduce waste arisings, any more than daily collections do.' So in terms of raising awareness and educating people to reduce their waste, home food waste digestion systems seem to be a good option. And in fact if these systems were more frequently used, the need for large-scale AD facilities would obviously be reduced somewhat, and the process would be streamlined.
Perhaps the only solution – and this could probably be said for most areas – is for the two systems, along with large-scale composting where is it most cost-effective, to be used in tandem? Collection costs would be reduced if those in rural areas made use of home food waste digestion systems, and centralized collection systems and AD facilities would still be there to aid those residing in blocks of flats, or homes without gardens.
A combination approach
A new study, called 'Managing Biowastes from Households in the UK: Applying Life-cycle Thinking in the Framework of Cost-benefit Analysis', conducted by research consultancy Eunomia, in association with the UK's WRAP, concludes:
In Eunomia's view there may be benefits if WRAP orientated its programmes increasingly around:
- Promotion of home composting to a wide audience,
- Targeted collection, at high frequencies, of food waste,
- The treatment of the collected food waste using suitable in-vessel composting/anaerobic digestion systems, preferably (from an environmental point of view) digesters,
- With garden waste, where it is collected, the quantity being 'constrained' in some way (either through charging, as modelled here, or through limits on container size or numbers of sacks collected) so as to reduce the potential for attracting new material into the collection system.
This study sees home composting as a much bigger part of the ideal balance of biowaste treatment, than has previously been considered in the UK. Having looked at costs and weighed up the benefits of the other processes available, it concludes that they all have a part to play, and that home treatment's role is significant.
Environmental challenge
Appendices to the study by Eunomia raised the also very important question of greenhouse gas emissions from home treatment equipment. It stands to reason that any method of dealing with food waste is going to produce CO2 and that we must find way to decrease or eliminate it for the method to play a role in the future of waste management.
Facilities that tap landfill emissions and turn them into energy provide a brilliant 'two birds with one stone' solution, but it is obviously not possible for a person to tap greenhouse gas from his food waste digester at home.
'The rate of emissions from home composting facilities is likely to be much slower than at larger facilities,' says the study. 'Furthermore, the ratio of the surface area to the volume is likely to be much greater. These two factors suggest that it may be the case that emissions from home compost heaps are more likely to be subject to "biofilter-type" abatement as the outer layers act in this way to abate, at least to some extent, the emissions from the degrading material.'
The study showed no significant levels of emissions from home composting equipment, and says, 'It seems possible that the outer layers of the composting mass act as an oxidation layer, so reducing emissions to the atmosphere.'
Conclusion
For now, the tackling of food waste at home remains a relatively small part of the wider waste management strategy, with Anaerobic Digestion facilities gaining popularity. AD certainly provides benefits that home food waste digesters cannot, such as the total elimination of greenhouse gas and the production of energy. But it also faces problems that home food waste digesters do not, such as the need for centralized collection of food waste which can be costly and time consuming.
As with most good waste management solutions, a combination of the best technologies, dependent on geographical location, will give the best results. While food waste digesters may fall short of giving us an entire solution as to what to do with our biowaste, we can see that they are working for those in rural or semi-rural areas and helping to educate people. They can certainly therefore work alongside composting, AD and other available methods to provide a significant part of the bigger solution.
References
- The Food we Waste, July 2008, WRAP
- The Food we Waste in Scotland, September 2009, WRAP
Claudine Capel is editor of Waste Management World
e-mail:claudinec@pennwell.com
Case Study – Green Cone
The company Green Cone was established in the early 1990s, and produces a home food waste digester that completely eliminates the waste put into it. Its sister product, the Green Johanna, works in similar way but creates compost which can be spread on the garden. John Cockram, MD, tells us more:
WMW: To what do you attribute the success of home food waste treatment options such as Green Cone?
JC: These products are popular with local authorities who are faced with no alternative other than to reduce the amount of food waste going to landfill, and who are facing ever rising costs associated with the collection of food waste. They find the capital expenditure is always repaid in under four years. In addition, the public is becoming more aware of the need to help the environment and is increasingly eager to play its part.
WMW: How did you come up with the idea for this product?
JC: The product was invented in Canada by a resident of Ontario who spent considerable time up-country, keen to identify a way of disposing of his food waste that didn't attract bears, racoons and other beasties. He developed the concept behind the Green Cone (i.e. a system that maintains the best possible air flow over waste), and also, by empirical research, then identified the optimum shape and volume of the unit that handled approximately 200kg a year – which is the typical amount of the waste generated by one family.
WMW: Do you think these things will remain a secondary option as long as we are without legislation which states we must treat our own food waste at home?
JC: Whilst it is considered that the Green Cone will always remain a secondary option, it is set to become a significant option. However, for food waste produced in major urban areas, there is little doubt that peer pressure and empowering individuals to deal with their own waste, will ensure the use of food waste digesters continue to gain momentum.
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The Green Cone is simple to use. |
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