Problems Caused by Textile Dyes in the Environment

Problems of Dye in the Environment:
Dyes cause a lot of problems in the environment. The problems which are caused in environment by dyes are given below:

1. Depending on exposure time and dye concentration, dyes can have acute and/or chronic effects on exposed organisms.

2. The presence of very small quantities of dyes in water (less then 1 ppm) is highly visible due to their brilliance.

3. The greatest environmental concern with dyes is their absorption and reflection of sunlight entering the water. Light absorption diminishes photosynthetic activity of algae and seriously influence on the food chain.

4. Dyes can remain in the environment for an extended period of time, because of high thermal and photo stability. For instance, the half-life of hydrolysed Reactive Blue 19 is about 46 years at pH 7 and 25 °C.

5. Many dyes and their breakdown products are carcinogenic, mutagenicand/or toxic to life. Dyes are mostly introduced into the environment through industrial effluents.

There is ample evidenc of their harmful effects. Triple primary cancers involving kidney, urinary bladder and liver of dye workers have been reported. Most of the dyes, used in the textile industry are known only by their trade name, while their chemical nature and biological hazards are not known. Mathur et. al. studied the mutagenicity of textile dyes (known only by their trade name, used in Pali, identified as one of the most polluted cities in India) and the effluents containing these dyes, and the influence on the health of textile dyeing workers and the environment. The dyes were used in their crude form and no following purification was attempted, because they wanted to test the potential danger that dyes represent in actual use. The results clearly indicated that most of the used dyes are highly mutagenic. Brow net. al, published an article, to show it is possible to predict the toxicity of new azo dyes. The systematic backtracking of the flows of wastewater from textile-finishing companies led to the identification of textile dyes as a cause of strongly mutagenic effects. The textile dyes used in the textile-finishing companies in the European Union were examined for mutagenicity. According to the obtained results the dyes that proved to be mutagenic have been replaced with less harmful substances.

The degradation product of dyes could be carcinogenic. The formation of Decoloration of Textile Wastewaters 177 carcinogenic aromatic amine o-tolidine from the dye Direct Blue 14 by skin bacteria has been established.

6. Textile dyes can cause allergies such as contact dermatitis and respiratory diseases, allergic reaction in eyes, skin irritation, and irritation to mucous membrane and the upper respiratory tract. Reactive dyes form covalent bonds with cellulose, woollen and PA fibres. It is assumed that in the same way reactive dyes can bond with –NH2 and –SH group of proteins in living organisms. A lot of investigations of respiratory diseases in workers dealing with reactive dyes have been made. Certain reactive dyes have caused respiratory sensitisation of workers occupationally exposed to them.

Public perception of water quality is greatly influenced by the colour. So, the removal of colour from wastewater is often more important than the removal of the soluble colourless organic substances. Removal of the dyes from the textile wastewater is often very costly, but a stringent environmental legislation has stimulated the textile sector in developing wastewater treatment plants.


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