GREENWOOLF: GREEN HYDROLYSIS CONVERSION OF WOOL WASTES INTO ORGANIC NITROGEN FERTILIZERS

Green hydrolysis with superheated water is an emerging technology to turn waste wool into amendment-fertilizers for the management of grasslands, organic horticulture and other cultivation purposes. Raw wool was treated with water at high temperature (up to 170 °C) in order to convert keratin (the wool protein) into simpler compounds such as oligo-peptides and amino-acids. Tuning the hydrolysis temperature and time, allowed to control the degree of conversion of the wools into solid slow-release or liquid fast-release fertilisers, tailoring the release speed of nutrients to plants. On the other hand, wool contains elements such as carbon, nitrogen, sulphur and microelements which play an essential role in plant nutrition. Laboratory trials demonstrated that hydrolysed wool, when added to the soil, increases the yield of plant grown and absorbs and retains moisture very effectively. Hydrolysed wool displays bio-stimulant properties of the soil microbial activity, is suitable for foliar feeding and chelating/complexing agents for trace elements (i.e. Fe, Cu, Zn), and represents a sustainable option in organic agriculture. The economical effectiveness of converting wool wastes into amendment fertilisers has been demonstrated also for small-scale, local hydrolysis plants, thus reducing transportation and disposal costs.