Anaerobic digestion reduces waste and generates electricity

Nina Sweet: Commentary

For those of us who get excited about waste-treatment technology, anaerobic digestion really is the way forward — you put rubbish in one end and get valuable products out of the other.
Quite simply, we are running out of places suitable for burying the rubbish we generate and any initiative — whether it be new technology or changes in behaviour — has to be worth considering if it reduces the quantity of waste we throw away.
Anaerobic digestion is tried and tested on the Continent but we have been slow to take it up in Britain. Now, with local authorities having to meet targets to reduce the biodegradable waste that we send to landfill, and sustainability being such a hot issue, the technology is being given serious consideration.
Surprisingly, until recently little attention has been paid to reducing the vast quantity of food that is thrown away annually. It forms one of the biggest elements of landfill, yet only 3 per cent is sent for composting or to anaerobic digesters. Of the 6.7 million tonnes that is estimated to be binned each year by households, only 2.6 million tonnes could not have been eaten — the potato peelings, the apple cores, the eggshells and so on.

The rest is wasted, and a staggering proportion isn't leftovers — it is food that has been bought, allowed to go off and then thrown away without a single bit being taken. Shocking.
And that's just the waste in our homes. There's plenty more in other sectors of society, including an estimated 1.5 million tonnes that is put out by supermarkets because it is past its sell-by date.
A range of technological options to process the food that we throw away are being assessed, and anaerobic digestion has performed well. Thanks to the demonstration plant at Ludlow we can show that it works well in that type of location. The technology definitely is part of the solution to the challenge we face in getting food waste out of landfill.
It's a win-win-win scenario. You get rid of your food waste and at the same time you make good fertiliser and generate renewable electricity.
Dr Nina Sweet is a technical expert at the Waste Resources Action Plan