AD plants reject food waste from supermarkets

Supermarket food waste is proving problematic for anaerobic digestion (AD) plants due to the high levels of contamination found in the feedstock.

A leading AD operator has voiced concerns over the quality of food waste collections arising from major retailers and in some cases, has had to reject the feedstock.

Speaking at an Associate Parliamentary Sustainable Resource Group meeting on sustainable food in London this week (March 20), BiogenGreenfinch chief executive Richard Barker said that the company had experienced problems with some supermarket suppliers.

“We take supermarket waste and that tends to come overnight when the shelves are being restacked from the ambient aisles, take food waste off it and we process it,” he told delegates. “But one of the issues we’ve seen is that you get very high levels of contamination.”

Barker said the problem often occurs when individuals accidentally place inappropriate items in food waste collections.

“We’ve dropped some supermarkets who cannot get their own internal supply chains in order because the cost of us dealing with the level of contamination means that it’s just not economic.”

Barker told delegates that on the whole the supermarket supply chain was very efficient and that the main opportunities for AD growth were in the municipal, manufacturing and the hospitality sectors.

He added that BiogenGreenfinch runs an R&D innovation centre where local authority food waste collections are analysed to get an idea of the energy content and levels of contamination.

Barker said he had been struck by the high volume of tea bags in household collections, which made up 9.7% by weight.

“The thought that local authorities are spending 10% of their waste allowance on getting rid of tea bags is quite a frightening prospect but culturally we as a country like the ritual of dunking a tea bag and creating our cup of tea rather than instant tea,” he said.

“Clearly, we could make an impact of 10% theoretically if we went straight to instant tea.”

Barker called for more source-segregated food waste collections in the municipal sector. He estimated that there were around 3m households producing 300,000 tonnes of food waste and argued that this figure needs to rise to 20m households.

Nick Warburton

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