Green Hydrolysis as an Emerging Technology to Turn Wool Waste into Organic Nitrogen Fertilizer

Abstract

Management of waste wool is a problem related to sheep farming and butchery in Europe. Since the primary role of European flock is meat production, sheep are crossbreds not graded for fine wool production. Their wool is very coarse and contains a lot of kemps (dead fibres), so that it is practically unserviceable for textile uses, and represents a by-product which is mostly disposed off. Green hydrolysis using superheated water is an emerging technology to turn waste wool into amendment-fertilizers for the management of grasslands and other cultivation purposes. In this way wool keratin (the wool protein) is degraded into simpler compounds, tailoring the release speed of nutrients to plants. Wool, when added to the soil, increases the yield of grass grown, absorbs and retains moisture very effectively and reduces run off of contaminants such as pesticides. Moreover, the closed-loop cycle grass–wool–grass is an efficient form of recycling, because the wool-grass step is solar powered and grazing sheep increases soil carbon sequestration on grasslands and fertilisation, if not over-used, can enhance the carbon sequestration rate. Economical results of using hydrolysed wool as a fertilizer are expected from the increase of the management yield and the extension of the pasture lands that may contribute to employment and profit of sheep farming, increase European sheep population, and reduce European dependency of imported meat which is forecast to rise in the next years.