Sustainability

‘World-first’ enzyme treatment for household waste coming to England

Enzymes will be used to sort waste in the North-West of England after Danish company Novozymes announced a partnership to provide the materials to convert unsorted residual waste into biogas and recyclable materials at a plant development.

The company will deliver the enzymes to DONG Energy’s REnescience plant in Northwich in Cheshire as part of a long-term, non-exclusive contract. It says that the facility will be the first full-scale ‘bio plant’ in the world to use technology based on enzymes – biological catalysts made up of proteins – to break down household waste.

How enzymes can sort waste

The REnescience technology has been functional since 2009 and is capable of converting unsorted waste into biogas and recyclable materials. 

The process involves mixing unsorted household waste wetted and warmed to temperatures appropriate for enzymatic hydrolysis. Enzymes are then added to the waste stream in a specially-designed reactor. All organic waste, including food waste and even labels, is dissolved by the enzymes into a liquid that can then be converted into biogas.

All remaining material is predominantly made up of plastics and metals, which can then be recycled, and the remainder of the waste can be converted to fuel.

DONG says that the processing of the unsorted MSW is ‘robust’, with no requirement for shredding, giving it a high capture rate of biomass and recyclable of materials.

The plant is expected to come online in early 2017, and, once operational, DONG says that it will be able to sort 120,000 tonnes of waste per year, the amount created from around 110,000 homes in the UK.  Initially this will be supplied by FCC Environment, which already collects household waste in the Northwich region.

As well as a stream of recyclables, the process will produce around five megawatts of electricity from biogas, enough to power around 9,500 households.

The plant will be financed, built and managed by DONG Energy before opportunities for expanding to other countries are explored. Novozymes also says that the partnership will be used to further develop the enzymes for the technology.

‘Excellent example of circular economy in practice’

Commenting on the partnership and plans, Thomas Dalsgaard, Executive Vice President at DONG Energy, said: “It’s important to extract as many resources as possible from waste, and the enzymes are an important part of the process where we convert waste into green energy and recyclable material. We’re pleased to enter into a partnership with Novozymes on setting up this type of plant.

‘World-first’ enzyme treatment for household waste coming to England
The facility is currently under construction
“The further development of the enzymes will help us to continuously optimise the process and, at the same time, extract even more valuable products from the waste. This is both good for the environment and useful in terms of reducing the costs of waste management. I’m pleased that together we’re also looking at the future prospects for this technology.”

Thomas Schrøder, Vice President at Novozymes, said: “Waste is a major problem for many urban areas around the world, but this technology turns the problem into a resource. Biorefineries like this, where trash is transformed into value, is an excellent example of circular economy in practice.”