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From popular button mushrooms to beefy portobellos or earthy shiitakes, fungi are a major global agricultural crop. However, their production involves a substantial amount of compost that is currently disposed of after use – creating costs and logistical concerns for farmers.
The BIORESCUE project, funded by the Bio-based Industries Joint Undertaking (BBI JU), a public-private partnership between the EU and industry, is developing methods to turn this compost into valuable bioactive compounds and bio-products. These include environmentally friendly fertilisers and pesticides or even natural pill casings and capsules for drug delivery as a replacement for fossil fuel-derived coatings. In the process, the removal of waste compost from farms will cease to be an expense and instead become a valuable recyclable by-product of mushroom farming, providing financial benefits for farmers that will generate jobs and investment in the sector.
‘Total fresh mushroom production in Europe amounts to approximately 1 million tonnes per year. For every tonne of mushrooms harvested, approximately 3 tonnes of mushroom compost are produced,’ says BIORESCUE project coordinator Inés del Campo at CENER, Spain’s National Renewable Energy Centre. ‘The compost is currently collected from farms for a fee associated with transport and disposal, creating significant economic and logistical problems for farmers.’
Turning rubbish into a resource
BIORESCUE aims to enable the recovery of the vast majority of spent mushroom compost from farms through the development of a novel waste conversion system to extract and transform valuable organic components. The concept is initially being implemented at a mushroom farm in Ireland operated by Monaghan Mushrooms, one of the world’s largest mushroom producers, which is being retrofitted to become a sustainable and efficient biorefinery.
Supported by novel mathematical modelling methods to rapidly analyse the composition of biomass waste, the biorefinery will extract organic components from both liquid and solid fractions of the compost and other agricultural feedstock such as wheat straw. These components include natural compounds that can be used as targeted bio-pesticides and fertilisers, and lignin, an organic polymer that forms the cellular structure of most plants and offers an alternative to fossil fuel-derived plastics.
From compost to pill casings
Different project partners, among them universities, research institutes and innovative SMEs, are developing cutting-edge applications for these by-products of agricultural waste, focusing on the concept of cascading use in which each step in the conversion process generates a valuable resource.
For example, lignin is being transformed into non-toxic polymer membranes. This naturally-sourced material could be used to make pill casings and capsule coatings for medical, pharmaceutical and nutritional applications, as well as in agriculture as fully biodegradable carriers for the progressive and controlled release of bio-pesticides and fertilisers.
In turn, some of these bio-pesticides and fertilisers will also be derived from the mushroom compost refining process, providing a naturally occurring and sustainable source of products that are less environmentally harmful than conventional ones.
‘BIORESCUE is creating a critical opportunity to unlock the potential of mushroom compost conversion and support the transition to a circular economy in the mushroom industry. With wider reaching aims, this methodology could be extrapolated to other agricultural industries that generate large amounts of biomass waste,’ says del Campo. ‘The bio-based products developed within BIORESCUE will be capable of replacing many fossil-based ones currently on the market and generate new income streams for mushroom producers and, in turn, the industry’s feedstock and equipment suppliers.’