Studying the application of fish-farming net-cleaning waste as fire-retardant for Scots pine (Pinus sylvestris L.) sapwood

Optimising the exploitation of available waste resources for the recovery of their intrinsic value will be vital in the future circular economy society. Recovery of energy, nutrients and metals from waste streams is in focus today. This study aimed to evaluate the use of an aquaculture waste, i.e. the dried-solid waste discharge that generates by cleaning the fishing-nets, as a potential fire-retardancy promoter for Scots pine sapwood. As-received dried-solid waste from salmon-farming was calcined at different temperatures to evaluate material phase transformation and achieve homogeneous phase distribution. Thermal degradation of waste powders was studied by TG-FTIR gas analysis when annealing the material to temperatures up to 800°C, and the crystallinity, phase composition, morphology, elemental composition and particle sizes of as-received and calcined-waste materials at different temperatures were evaluated by XRD, FTIR, SEM/EDS, and TEM analyses. The flammability studies using cone calorimeter of Scots pine sapwood blocks treated with as-received and processed material is also reported and discussed. Results were promising, indicating that the aquaculture waste could be employed as an effective fire-retardant. The possibility of value-creation from waste discharges is enforced in this study so to promote the way towards waste valorisation and circular economy.