4. Environmental aspects

4.1 Toxicity of textile dyeing effluents

The amount of water used each year worldwide for textile dyeing represents more than 126,000 liters every second, or 4,000 billion liters per year. As a result, a huge amount of polluted or heavily soiled effluent is generated every day. In textile dyeing effluents, heavy metals such as iron, lead, nickel, copper, zinc and chromium are present in trace amounts. Synthetic azo dyes are carcinogenic and toxic, and present a serious health risk. These effluents find their way into waterways, agricultural fields, irrigation canals, and ultimately into rivers, seas and oceans... Effluents from the textile and finishing industries can cause physical, chemical and biological variations in the aquatic environment, through continuous alterations in turbidity,...