Italian firm Aquafil has patented a method to recover copper impregnated into the netting used in aquaculture cages.
Copper alloys are an important aid in the fishing industry, although reuse has long been considered impossible as they are labelled ‘hazardous waste’. An estimated 300 tonnes of copper a year are recovered from nets across across Europe, mostly by Nofir in Norway, which is owned by Aquafil.
With Aquafil’s patent, the recovered copper can be used in its pure form or as an additive in industrial processes. Nylon recovered is already being recycled into yarn to produce sheets, new nets and clothing. Recycled materials serve high-end sectors, including the automotive industry.
At the start of the process, the copper alloy material is carefully analysed. If pollution levels do not exceed 25% of the whole mass, the nets are cut into the three-metre length strips and sewn together. These are then washed in a closed stainless-steel camera with water from eight high-pressure blades.
Waste water is filtered via a chemical magnetic-mechanic process which allows the operator to reuse the water needed to wash the nets. This yields a sludge, which is passed to waste handlers. The process minimises foul odours while avoiding the generation of microplastics.
‘The fact that the copper from aquaculture cages can now be recovered is a major victory both from a sustainability and a business perspective,’ says Nofir’s general manager Øistein Aleksandersen. Nylon cages are seen as a great resource, he adds, but EU rules introduced in 2018 have caused great difficulties for recyclers. ‘It took time to adapt to the requirements. But we are now collecting full-time and are delighted that both the nylon and the copper can be recycled.’