W&J Knox Ltd, based in Ayrshire, is the largest UK manufacturer and servicing agent of Aquaculture nets. The company provides cage nets primarily to the salmon farming industry and on a biannual basis they transport the nets back to its servicing facility for washing, repairing and drying before returning them to the fish farm.
Aquaculture nets have to be washed regularly to remove the marine plants and animals that attach to the netting restricting the flow of water to the fish contained within.
Washing the commercial fishing nets from the salmon farming industry produces several hundred tonnes per year of a solid material rich in nitrogen, phosphorus, fish oil proteins and calcium from mussel shells and includes copper which is dried into cake.
Following a referral from North Ayrshire Council, Interface worked with the company to identify suitable academic support to analyse this waste product and suggest a use for the nutrient rich solid cake produced from the process. The ‘cake’ which goes to an approved landfill site may have value in the nutrients contained within it which could be used to create a new product and thus reducing the volume and cost of the material going to landfill.
The School of Applied Sciences at the University of Abertay were able to support the company due to their experience in handling such waste materials, extraction of bioactive ingredients and quantification of bioactive compounds.
Through a feasibility study, funded through a Scottish Funding Council Innovation Voucher, the university were able to analyse the waste product and its potential use.
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Following the initial feasibility study, a researcher has now been employed by Abertay University, through the Innovate UK Knowledge Transfer Partnership programme (KTP), to investigate how the useful materials can be extracted from the waste cakes. Instead of being sent to landfill, tonnes of salvaged protein and oil will now be turned into livestock feed for the likes of fish, pigs and chickens.