Anaerobic Digestion of Food Waste

In order to expand its range of food waste recycling servicesl, PDM Group has joined forces with one of Europe's leading food-chain recycling businesses, SARIA Bio-Industries, to introduce its market-leading anaerobic digestion (AD) operation to the UK.

ReFood UK combines SARIA's expertise in operating AD facilities with PDM's UK food waste recycling capabilities.

There are currently 10 ReFood plants operating in Europe - 5 in Germany, 4 in France amd 1 in the UK. A further 5 plants are being built in Germany and 2 in France.

The ReFood AD plants operate as integrated recycling units, processing a variety of food wastes to produce renewable electricity, heat and DynAgro, a nutrient-rich fertiliser for local farms. The plants also recycle the food waste packaging. The plants provide an environmentally-sustainable solution for all waste producers looking for a safe method of diverting food waste from landfill.

ReFood's first UK AD plant opened in September 2011 in Doncaster, South Yorkshire. The new plant processes approximately 45,000 tonnes of food waste per annum, collected from local shops, restaurants and cafes as well as residues from PDM Group's petfood production plant.

The new ReFood plant generates over 2.8MWh of renewable energy, which is used to power the Doncaster site and supply the national grid.

The second ReFood plant in the UK is now under construction at Widnes and and a third site in East London is now under development.

What is anaerobic digestion?

Anaerobic digestion (AD) is the term applied to the process of the biological breakdown of organic material in the absence of oxygen.

During the process organic matter such as food waste is broken down biologically and this generates large amounts of biogas - a mixture of methane and carbon dioxide.

The process is similar to that which takes place during composting, however it is done in the absence of oxygen and the methane generated is captured and utilised as a biogas rather than being lost to the atmosphere.

The biogas generated by ReFood's AD plants is used as a fuel for combined heat & power engines to generate heat for the processing site and for the generation of renewable electricity. The electricity is used on the site in place of imported power and the excess exported to the national grid.

By using biogas from the AD process as a fuel the ReFood plant is displacing the use of fossil fuels; this in turn reduces the amount of carbon dioxide released into the atmosphere.

As well as producing biogas for the combined heat and power units, the AD plants also produce DynAgro, a nutrient-rich liquid fertiliser for use by local arable farms.