PROJECT DESCRIPTION
BACKGROUND
Sheep wool contains high levels of impurities, as much as 60% by weight. The major impurity is grease (lanolin), a waxy substance secreted by the animals to repel water from their coats. Wool also contains varying amounts of dirt, dead skin, sweat residue, pesticides and vegetable matter, often in the form of wool dust. Before wool can be used commercially, it must be cleaned by hot aqueous scouring. Depending on the properties required for the final product, this can involve a complicated process using detergents and alkali, which generates large quantities of wastewater with a high organic content.
For every kg of clean wool produced by aqueous cleaning, some 17 litres of effluent, with a high Chemical Oxygen Demand (COD) value (0.3-2.4 kg) is generated. Consequently, aqueous wool scouring has a high environmental impact, since it consumes large amounts of water and energy, and generates large quantities of highly polluted effluents. Moreover, the wastewater requires several treatment stages before disposal, consuming additional resources.
OBJECTIVES
The objective of the Wooldryscouring (WDS) project was to demonstrate an innovative process of “wool dry scouring”, based on closed-loop processing and total waste recovery. The aim was to determine whether it is possible to achieve quality improvements in the clean wool, to reduce wastewater consumption and to increase the recovery and valorisation of by-products.
The project aimed to recover lanolin and wool dust by means of solvent extraction and purification technologies in a prototype dry process. After this process, it was expected to obtain cleaner wool which would require just a simple rinsing process with low water and energy consumption to produce clean showing better quality than the one produced by water scouring. The WDS process was designed to optimise the overall wool scouring through: 1. Reducing the volume of effluents generated and chemicals in the scouring process (detergents). 2. Minimising the contaminants in water effluents through the recovery of wool grease, which can find application in the cosmetic industry, and wool dust, which can find application as fertiliser.
RESULTS
The Wooldryscouring (WDS) project demonstrated an innovative wool scouring cleaning process to remove impurities in the early stages of wool manufacturing, which resulted in a cleaner product and reduced environmental impacts in terms of water and energy consumption and polluted wastewater generated. The consortium created with LEITAT and CSIC as research centres, RMT as an industrial partner and Tavares as a scouring plant, designed, built, tested and demonstrated at pilot scale the new technology, which uses organic solvents instead of the hot water with alkalis and detergents used in conventional wool scouring. In this way, grease (mainly lanolin) can be extracted at an earlier stage, for example, for use in the cosmetic industry. To achieve this, the WDS approach uses a batch production process rather than the conventional continuous production process in water. This new approach is highly innovative in the sector.
As a result of the pilot demonstration, the project team produced wool that was whiter, cleaner, smoother and with larger fibres, than conventionally scoured wool. The project’s wool was practically free of grease content, with 95% of wool grease (lanolin) being recovered for use as a valuable by-product. In addition, nearly 100% of the wool dust was recovered, which can be used as an agricultural fertiliser.
The new dry scouring process resulted in several environmental benefits:
WDS technology has lower environmental impact (Life Cycle Assessment, LCA) than the traditional wool scouring process. The low fugitive emissions of solvent measured at the pilot plant due to the solvent manipulation and vacuum suction pump could be reduced significantly at industrial scale when implementing mechanization and automation.
The technology developed also produces economic benefits. Reductions in waste generation and water, energy and chemical consumption using the WDS technology resulted in important cost savings, compared to the costs of conventional wool scouring. The Economic Assessment conducted by the project team showed that the WDS process should be economically viable in Europe and holds a high replicability potential. The project’s technology represents a significant step towards achieving a closed loop concept where all the current wastes streams are recovered as by-products, in line with EU circular economy policy and the Europe 2020 Strategy for smart, sustainable and inclusive growth.
Policy-wise, due to the valorisation of the dust and grease recovered using the WDS process, the project is in line with the Waste Framework Directive (2008/98/EC), which prioritises valorisation rather than waste disposal. Furthermore, reductions in water consumption together with the improvements in the quality of the process’s final effluent contribute to the implementation of the Water Framework Directive (2000/60/EC), aiming to achieve a good status of all EU water bodies.
The project proved the environmental and economic viability of the new technology. The project beneficiaries are therefore looking for partners who wish to implement WDS at semi-industrial scale in order to boost confidence in the sector since the implementation of the WDS process would mean to change the process substantially, replacing the traditional continuous scouring process using water with a batch scouring process using solvent.
The process has the potential to increase the competitiveness of the European wool industry. Many European wool scouring companies cannot afford wastewater treatment costs (accounting for nearly 28% of total production costs). Wool scourers cannot find other viable alternatives to scour wool and they close progressively. In fact, in Europe there are only 18 wool scouring manufactures left. So, wool traders sell greasy wool to other countries to be scoured where the scouring costs are lower. The WDS process could reverse this trend, to help maintain and recover the wool industry in Europe, as a result of being 25% cheaper (with further benefits possible through lanolin valorisation). New jobs could be created after industrial implementation, with worker health benefits due to reductions of odour and dust. Around 18 industries requested to receive updated information after the project end date.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
