Veolia has demonstrated a new way of treating the 25% of green waste that is sent for disposal or re-composting.
Veolia currently processes over 500,000 tonnes of green and food waste annually, derived from a nationwide network of 11 composting sites that produce over 250,000 tonnes per year.
Previously, around 25% of green waste ended up as oversize after composting, as some green waste bins contain physical contaminants such as plastic and metal, mistakenly discarded by customers. Even after careful processing, this contamination ends up in the compost oversize which is the larger, woody fraction remaining after the valuable compost product fraction is removed. If a site runs out of storage space, or if the oversize is too contaminated to re-circulate, there is a cost for landfilling, which in turn contributes to greenhouse gas emissions.
The new process required a £1 million (€1.16 million) investment for a bespoke fixed cleaning line to remove the contamination from the 30,000 tonnes of compost oversize arising annually across four sites in southern England. This transforms the material into a clean wood product such as PAS100 approved mulch for gardening and landscaping, or a renewable biomass fuel for electricity and heating, which replaces virgin alternatives, such as woodchip and bark.
By using this efficient form of processing, these products can reduce the number of trees cut down for wood products, Veolia said, and the process also removes contamination from the composting sites and enhances the quality of composts spread to land.
Veolia said the process means that composting sites will be much more efficient, disposal costs will be lowered and greenhouse gas impact reduced. To date, more than 55,000 tonnes of contaminated compost oversize has been processed in this way, and the plant is aiming to find an alternative use for all contaminants removed to achieve zero waste to landfill.
Donald Macphail, chief operating officer of treatment at Veolia, said: “Composting sites provide the perfect example of a circular economy, and the need to efficiently process this material is likely to increase with the prospect of green waste becoming free to collect and on a more regular basis, as pledged in the government’s Resources and Waste Strategy.
“By backing this new innovation, we have increased the effectiveness of operations and will provide additional high-quality sustainable wood mulch and renewable fuels. This will help horticulture and renewable energy generation, and is another key step that we are taking to reduce environmental impact and advance towards a lower-carbon economy.”