Wool Environment part--II
Environmental Wool Science Developments
Pesticides are used to keep sheep healthy but their residues can remain in the fleece only to be released when the shorn wool is scoured - a process in which dirt and grease are washed from the raw wool. In the past, the wastewater from wool scouring containing these residues has added to contamination of rivers. Although all scouring effluent is treated before discharge into rivers, traces of "hard" pesticides entering rivers, such as lindane, exceeded environmental quality standards.

All The Woolmark Company member countries have effective bans on the use of toxic and persistent organochlorine and arsenic based pesticides. Only biodegradable chemicals are permitted and these are applied in a controlled way which minimises residues. The bans on organochlorines and arsenic are policed by the wool authorities in each member country through random testing and 'traceback' schemes. In Australia, the program has been very successful and has led to the effective elimination of organochlorine and arsenic in the wool clip.

Chemical treatments are still required to protect sheep from infestation by parasites but efforts are made to reduce the frequency of treatments and to encourage use of more controlled ways of administering these chemicals. Only biodegradable chemicals are licensed for use in The Woolmark Company Member countries. Jetting, showering or striping are commonly used treatments today in The Woolmark Company member countries. Older, less precise methods such as immersion dipping are rarely used.

Apart from pesticide bans, improvements in scouring technology have been developed alongside alternative methods of cleaning the effluent on site and some scouring plants produce very little effluent at all.

Wool, like all other fibres, is usually dyed. Some dyes include heavy metals which do not break down in the environment. The problem of unacceptable levels of these heavy metals in dyeing effluent is common to all textile fibre dyeing.

Dyes containing chromium are used extensively in the wool textile industry because of their high colour fastness and the wide range of colours available at an economic cost. In some cases there are no alternative dyes which give equally high performance especially for the popular fashion shades of black and navy blue.

The Woolmark Company and major dyestuff manufacturers developed low chrome effluent dyeing techniques which are now used commercially. The effluent from these new techniques meet existing and proposed limits for chromium residues in dyeing effluent.

In addition, developments improving dyeing techniques for pre-metallised dyes have reduced the residual levels of heavy metals in these effluents.

In 1991, The Woolmark Company developed and implemented a Guide to Good Environmental Practice in wool dying which is available to Woolmark licensees and their dyers around the world. Recently, there has been renewed interest in the use of natural dyes for wool. These Techniques were used to colour wool for centuries before the invention of modern, synthetic dyestuffs. The Woolmark Company has examined these old methods of application using environmentally acceptable ways to fix the natural colours to the fibre. The range of shades is more limited and the dyes are less colour fast but interesting effects are possible with natural dyes on natural wool fibre.

   Shrink Resistance

To prevent wool felting and shrinking when washed, shrink-resist processes were developed where the outer scale layer of each wool fibre is chemically modified and covered by a thin film of polymer. This enables the fibres to slide smoothly over one another when wet.

One shrink-resist process produced unacceptably high levels of organohalogens (AOX) in effluent. The main source of AOX arose from chlorine used in the pre-treatment stage. Smaller quantities arose from the chlorine-containing polymers also used in the process. German regulations control the levels of AOX permitted in industrial effluent including those from the wool textile industry. In the UK, industrial use of chlorine is also regulated and processors are required to obtain licenses to operate.

The Woolmark Company, in conjunction with wool research laboratories (CSIRO in Australia) and chemical manufacturers, is developing pre-treatments and polymers which do not use chlorine. Already, low or zero AOX polymers are available and work is continuing on developing commercial pre-treatment alternatives to chlorine.

Non- chlorine based shrink resist processes are commercially available for batch treatments. These do not produce AOX in the treatment bath and are therefore environmentally acceptable.

Wool's natural protein composition makes it vulnerable to some moths and beetles and mothproofing has been an integral part of quality wool carpet manufacturing for many years. It is a mandatory requirement for Woolmark wall to wall carpeting.

While mothproofing carpets are totally safe in use, investigations have shown that effluent produced from conventional mothproofing processes may exceed permitted discharge concentrations and pollute rivers.

The Woolmark Company has developed two new processes for the industrial application of mothproofing agents. These recycle the chemicals and permit vertically no effluent discharge. "Enviroproof" is commercially available and is capable of mothproofing wool with a discharge of only one quarter of a gram of mothproofing agent per tonne of wool treated.

The second process, currently at the industrial prototype stage, achieves even better performance. Mothproofing agent discharges are down to one twentieth of a gram per tonne of wool processed. Both processes meet current and proposed industrial discharge concentrations for mothproofing agents.

The Woolmark Company has also worked with a machinery manufacturer developing a process for foam application of mothproofing agents during the carpet backing process. Applying the mothproofing to the carpet rather than to the yarn avoids contamination of wastewater yet produces a fully mothproofed carpet.

   Wool Production and the Environment

In Australia, The Woolmark Company has its own environmental research program covering the management of sheep and use of land. The program examines ways to minimise the environmental impact of woolgrowing.

In addition, Landcare groups of sheep farmers have initiated tree planting programs to improve land quality.

Caring for the Future
All fibres, both natural and synthetic, must be processed to fit them to their chosen uses.

Environmental excellence can only be achieved at the processing stage by selecting the best raw materials, using best practices during manufacturing and carefully considering the environmental impacts of products during use and disposal.

The Woolmark Company will continue to commit resources to developing new processing technologies for the wool textile industry which will reduce the potential for pollution.