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Anaerobic Digestion of Food Waste

recycle food waste for digestionThe anaerobic digestion of food waste is an important application for AD technology, and it is predicted by many waste management experts that many EU nations will soon place legal requirements on local authorities to make them collect it and dispose of it in biogas plants, to create energy. Indeed, in some countries (for example Wales) collecting authorities are already required to do this.

Why Food Waste is Important

Food waste disposal and treatment has become a big issue in most industrialized countries. Relative to other recycling methods using AD for this purpose is relatively new, but many areas are now sending it to anaerobic digestion. It was once expensive, with one UK local authority stating that their (2013/14) cost per tonne for their collected domestic food waste is £267/tonne (including all collection and transport costs to the AD plant).

However, now (in 2016) the gate fee has dropped as many new Food Waste AD Plants have been commissioned in the UK. Now, the choice of whether or not to collect food waste and treat it in AD plants is much easier as there may be savings to be achieved for local authorities, and for businesses. In many areas, where a food waste biogas plant is available, the cost of disposal may be below the cost of landfilling and of the Landfill Tax.

As the other “easier to achieve” waste reductions have been gradually picked-off, more and more attention is having to be paid to the anaerobic digestion of these household food waste streams. This is to comply with European Regulations on waste diversion from landfill and increasingly more onerous recycling targets.

The quantity of food waste is large! The image below explains that point very effectively:

food waste infographic pre anaerobic digestion

© Copyright GDS Infographics licensed for reuse under CC BY 2.0 https://www.flickr.com/photos/gdsdigital/4138675384/

But to look at it from the point of view of a biogas plant operator, Food waste is an excellent feedstock for the new generation of anaerobic digestors. Food waste is readily digested within them. Anaerobic Digestion technology based Waste Treatment Plants which accept a high proportion of food waste will also be, in principle, more economic to run than the equivalent non-food waste fed plants such as biomass, food crop, and manure fed plants, due to the high methane gas producing potential and thus the revenue potential of these plants.

Why has the Food Waste Quantity Grown?

food Waste Anaerobic digestion ebook 3D cover

Download Free Food Waste eBook – Click on the image above!

Food waste volumes increased greatly in industry after foot and mouth, and other incidents related to the spread of disease vectors raised public and regulatory awareness to the need for stringent measures to prevent the use of food materials in a way which could jeopardize health.

As a result, new regulations were brought in, such as the Animal By-Products Regulations to prevent of recurrence of these problems, and these measures eliminated many traditional methods for the re-use of many waste foods

At the same time rising affluence, the tendency for people to live alone and cook less, and the increase in the number of working mothers with less time to cook at home has increased the amount of pre-processed food bought and wasted.

As a result of this, coupled to a greater casualness to the waste of food, the amount of food waste in our waste has risen faster than overall waste tonnages.

Are You Personally a Part of the Problem?

Householders should only shop for what they need – they need to take responsibility for what they buy and what they waste. But, in fact the records show that they are not – and all this has contributed to food waste now being a major component, at 15% to 20%, of our municipal solid waste (MSW) by weight.

The first course of action should of course be minimisation – reduce the amount of food becoming waste in the first place. Even in areas where householders willingly participate in source segregation in the form of paper and packaging recycling schemes, separate collections for food waste are considerably less popular and less well supported than others.

Food has always represented a much bigger percentage of the total weight of waste thrown out by households compared to packaging, but has proved more difficult to get the public to segregate. As a result despite the many advantages of the source separation of food waste, food waste collection has been a long way down the priority list for most local authorities.

In fact separate food waste collection is often seen as a problematic area for waste managers and councillors, and few want to promote it, as they see that residents are quick to rebel against it, due to the perceived barriers to its hygienic and odour free collection.

US Dept of Agric Food waste anaerobic sm

© Copyright US Dept of Agriculture licensed for reuse under CC BY 2.0 https://www.flickr.com/photos/usdagov/15032644782

Collection Trends

No wonder that the trend within most LA’s Waste Manager’s Depts. was to start by collecting green and/or garden waste for the tonnage it can generate, while food waste remained largely ignored until the start of this decade.

When it comes to food waste, until the end of the noughties (2010) a great deal of attention was placed upon developing the uptake of relatively cheap home compost units. But, even in areas that provided the type of bin that can handle meat, fish and bones, UK uptake by home composters was poor. Nowadays, it is generally understood that home composting does not, and will not in the future, make a large impact on the amount of food waste thrown out in the mixed waste (black bag). The emphasis is now all toward collection of all food waste and its digestion.

A Business Opportunity for You?

If you ever thought of running your own biogas plant in a local authority area which is about to start collecting food waste, what are you waiting for? Get thinking about setting up your own biogas plant and tendering for the contract to treat the collected local food waste. A large part of the future of Anaerobic Digestion lies in food waste processing. There will be a big demand for all sizes of biogas plants for the anaerobic digestion of food waste. Start experimenting and develop your own proprietary AD Food waste processing system now!

Anaerobic Sludge Digestion

2 Responses to Anaerobic Digestion of Food Waste

  1. Scott Gomez December 21, 2014 at 5:27 pm #

    Cut out this waste of uneaten food (£11 billion) and the government could fund the money it needs to keep the NHS going! Looking forward to reading more.

  2. Cynthia Davies March 14, 2015 at 12:14 am #

    Say, you got a nice article post, overall but I think you could have explained fermentation related things in simpler language.

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