PROJECT DESCRIPTION
BACKGROUND
Coarse wool from EU sheep farming and slaughter is a valueless by-product that cannot be used by the textile sector. However, since sheep shearing, which is necessary for the animal welfare, generates some 200 000 tonnes per year of coarse wool, this waste material could present significant economic opportunity.
Each tonne of raw wool contains around 150 kg of lanolin (wool wax), 40 kg of suint (soluble contaminants such as potassium salts from sweat and faeces), 150 kg of dirt (soil), 20 kg of vegetable matter, and residues of insecticides, leaving 640 kg of wool fibre. Insecticides or insect growth regulators are used to protect sheep from ecto-parasites (lice, mites, blowfly, etc.); their presence in wool is variable and depends on the permitted legal use pattern in each country.
Factory or industrial scouring consists of the immersion of the greasy wool in a series of baths of warm water (about 50C), soap and sodium carbonate (soda) and is one of the recommended procedures for eliminating the foot-and-mouth disease virus present in the wool. The effluent discharged from wool scouring contains high concentrations of soil particles picked up by the sheep during grazing as well as lanolin and sweat (the source of potassium) produced by the sheep. It also contains additives used in the scouring and related processes, such as detergent and pesticide residues.
The resulting chemical oxygen demand (COD) reaches 100 000 mg/l and the biochemical oxygen demand (BOD) varies from 20 000 to 40 000 mg/l. This makes the disposal of the sludge generated by the effluent treatment very difficult to manage.
OBJECTIVES
The overall objective of the LIFE+GREENWOOLF project was to demonstrate the viability of converting waste wool into fertiliser using small-scale, local hydrolysis plants. The process would reduce transportation costs and eliminate the need for the scouring and disposal of the coarse wool. Specifically, the project aimed to:
RESULTS
The GREENWOLF project designed a system for the hydrolysis of waste wool and carried out a detailed study of the kinetic process involved. It assembled three prototypes: a pilot plant at laboratory scale to be used for testing the hydrolysis process of wool samples; a mobile plant (intermediate-scale) for the demonstration initiatives to be held in Italy; and a large-scale unit, which is the final version of the plant and intended to be commercialised.
The prototype overcame initial difficulties related to the hydrolysis of the wool and was able to produce 500 kg of fertiliser. A chemical and agronomic analysis of the fertiliser was then carried out and a business plan for the prototypal plant was drawn up. For this step of the project, it was necessary to directly approach farmers and their organisations in order to get over initial scepticism and raise their interest in the project activities. A key lesson to be learned from the project is the importance of involving local and European stakeholders. It carried out extensive dissemination activities aimed at farmer associations, chambers of commerce and research institutions focused on livestock.
Key messages focused on the possible savings of applying the GREENWOLF system. By re-using wool wastes from sheep farming and butchery facilitates, the system reduces the amount of organic waste disposed of in landfills and illegal practices of storage, transportation and disposal. The system also prevents soil contamination from sulphur contents and insecticides present in raw wool, while reducing environmental contamination due to the illegal practice of leaving the wool on soil after shearing. Research has shown that treatment with superheated water (150-180C), such as that of the project system, kills off infections and degrades pesticides and agrochemicals possibly present in the raw wool.
Furthermore, the project demonstrated that greasy wool can be converted into amendment-fertilisers that are effective for grasslands and biological agriculture. This type of fertilisation can increase carbon sequestration of soils, especially in grasslands where sheep are bred. The organic matter provided by the fertiliser improves soil characteristics, enhancing the biogeochemical nutrient cycles. Moreover, hydrolysed wool absorbs and retains moisture very effectively, facilitating the water retention of soils and preventing erosion on slopes.
According to estimates for the Piedmont region, the recycling of around a third of the annual wool clips would save the disposal of around 50 tonnes (equivalent of 800 -1000 m3). This result scales up to savings of 80 000 m3 of waste wool in Italy, and 900 000 m3 in EU. Such recycling of raw wool offers an economic advantage, avoiding the costs of disposal. The cost for the scouring of wool, entailing the immersion of the greasy wool in a series of baths of warm water, soap and sodium carbonate, amounts to around 1 per kg. Moreover, due to the restrictions imposed by ongoing European legislation, the costs for the transportation of waste wool are quite high and amount to about 0.01 per km per kg. However, the project demonstrated the feasibility of transforming such matter into a high value fertiliser with an estimated minimum sale price of 0.24/kg.
Finally, the project contributed to the implementation of Commission Regulation for Class 3 Materials concerning the restrictions on transportation of animal derived products, as well as the Thematic Strategy for Soil Protection. Moreover, the system proposed is in line with the Circular Economy Action Plan and the Waste Directive. The project beneficiary contacted Italian authorities to argue for the inclusion of this type of organic fertiliser in the official lists of approved fertilisers. Such an inclusion could lead to a revision of Italian and EU legislation.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
