Professional guide

Water issues

As China's water pollution comes under scrutiny and India's Minister of Environment is looking in to untreated waste-water and closing factories, another worrying news-item gives rise to concern: Silver in the form of nano-particles can be deadly for fish in very low concentrations.

A Greenpeace report has linked several major Western apparel brands to chemical residues in the effluent of a Chinese dye-house. While most people may think that pollution from dye-houses for the most part is unfixed dyes coloring the waterways in bright hues - but things are not as simple as that. 

Waste-water can consist of dyes, oils and waxes from natural fibers, sizes used for weaving, oils used in knitting, bleaches, acids, alkalis and synthetic, man-made chemicals designed to fascilitate processing. The waste-water may also be hot and contain microscopic pieces of dust, fiber and particles that are damaging to the aquatic environment.

Very recent findings from NIVA (Norwegian Institute for Water Research) has looked at nanosilver, and found that even 20 micrograms pr liter water can kill fish. Nanosilver is widely used in running-shoes, in socks and sports-clothes to avoid smell. When we wash items containing nanosilver, it is released in to the water-ways; so this is not a factory-related problem. Besides hurting the fish-gills, the nano-silver also affects the salt-balance. The silver acts like a Trojan horse and kills the fish from the inside. 

But something as harm-less as salt kan create havoc for fish. Most aquatic damage is done by non-toxic, biodegradable chemicals, according to Phil Patterson, NICE advisory board member. One of the major issues with effluent is the presence of chemicals that can deplete oxygen in water. This can be caused by using some very simple "safe" chemicalsm such as starch used in weaving size. We all eat it on a daily basis, but pumped into rivers in large quantities it will deplete oxygen and kill aquatic species. 

In some areas of the world it is not permitted to realease the salt used in cotton jet-dyeing directly in to water courses, but in order to get the salt out of the waste-water one needs to emply a rather energy-intensive reverse osmosis, thus bringing up the green-house gas emissions. 

Dyers can chose salt-free cold pad patch dyeing, and enzymes can drastically reduce the chemical loading and the temperatures of many processes. And one can always ask the pertinent question: Why do we need nanosilver in f ex wool socks. One only has to air them to get rid of the smell... And if what was produced was of better quality and lasted longer, there would be a lot less pollution over-all.