Effluents from Textile Industry and It Impacts on Environment

Effluents in Textile Industry:
Textile industry discharge a variety of effluents. These effluents are considered to be the most polluting element emitted from the textile industry. It affects the environment very badly. Before disposal, textile mills need to be treated to certain tolerance limits, since pollution control is strict all over the world. The proper effluent treatment is receiving an increasing attention.

Textile industry effluents are a major source of water pollution because of dyes, detergents, and other contaminants present in the wastewater undergo chemical and biological changes, consume dissolved oxygen, destroy aquatic life, and pose a threat to human health as many of these contaminants are highly toxic in nature.

Fig: Textile effluents drain out from textile mill

Textile chemical processing is using more than 8000 chemicals to make readymade garments. The large volumes of wastewater generated also contain a wide variety of hazardous and toxic chemicals used throughout processing, which persists in the environment. Among the various processes, coloration is the major source of pollution in the textiles; it contains dyes, dyeing additives, and other chemicals. Obviously, dyes contain heavy metals which are highly toxic. These pollutants are aquatic toxicity, which includes various toxic elements such as salts, surfactants, ionic metals and their complexes, formaldehyde, toxic organic chemicals, biocides and toxic anions, detergents, emulsifiers, and dispersants. Therefore, wastewater from the textile industry is highly polluted and dangerous, especially when it gets mixed with other chemicals and disposed of untreated. The characteristics of the wastewater from this industry are high pH, biological oxygen demand (BOD), chemical oxygen demand (COD), high concentrations of total dissolved solids (TDS), suspended solids (SS), chlorides, sulfates, and phenols. Most of these chemicals and dyes are not readily biodegradable and they cause severe health and environmental issues.

Dyeing effluents contain several types of pollutants, such as dispersants, leveling agents, salts, carriers, acids, alkali, and various dyes; wastewater quality is variable and depends on the kind of process that generates the effluent. Most environmental concern relates to the effluents of the dyeing and finishing processes that contain a variety of contaminations of higher concentration of chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solids, organic nitrogen, and some heavy metals. Color is usually noticeable at dye concentrations above 1 mg/L and has been reported in effluent from textile manufacturing at exceeding concentrations mainly because 10-15% of the dye is lost into wastewater during the dyeing processes.

Effluents from Textile Industry and It Impacts on Environment:
Following effluents are emitted from textile industry and their impacts on environment.

1. Dyes: Change color of water, high BOD, high COD, lead to cancer, disabilities, and disorders.

2. Acids: It lowers the pH, cause corrosion, help in the liberation of Na₂S, destroy microorganism, and destroy self-purification system of water.

3. Alkalis: Alkali increases the pH, help in the liberation of hydrogen ions, destroy microorganisms, and destroy self-purification of water.

4. Dissolved solids: Chlorides, sulfates, nitrates, bicarbonates of various inorganic metals; plants and vegetable kingdom affected by osmotic changes, affect biological organisms, BOD.

5. Suspended matter: Insoluble wastes, destroy self-purification of streams, reduce the photosynthetic activity of plants, choke the gill of fish, organic solids undergo purification giving rise to solids buoyed by gas, lead to floating masses, bad odor results.

6. Oils: Absorption of O₂ from air into water affected, destroy the animal, plant life in water, high BOD.

7. Synthetic detergents: Lower biodegradability, add on to toxicity, accelerate chain reactions, increase floating masses and affect natural aeration.

8. Toxic metals: Self-purification of streams destroyed, cause skin diseases, disabilities and disorders, destroy microorganism aquatic plants and animals are killed, compounds containing mercury affect the food chain.

9. Gaseous pollutants: Free chlorine, hydrogen sulfide, etc. increase toxicity, add on to oxygen demand, kill microorganism, destroy animals and plant kingdom.

10. Heated effluents: Reduce dissolved oxygen concentration, aquatic life gets affected, destroy animal and plant kingdom, and affect the entire ecosystem because of temperature.

11. Radioactive wastes: Its effects are numerous; induce metabolic changes, disorders, disabilities, genetic damage, chronic diseases, cancer, and the abnormal birth of human beings which are also common to plants and animals.

Some Facts Regarding Environmental Issues in Textile Industry:
Some facts, we should all know regarding the environmental issues in this industry, are:

Treatment is essential before discharge of effluents.
Small units cannot afford sophisticated technologies such as reverse osmosis.
ETP (effluent treatment plant) is installed in a few units only.
Honesty of functioning of ETP is a matter of concern (total dissolved solids, chemical oxygen demand, biochemical oxygen demand, are generally not within the prescribed limits.
ETP maintenance, replacement of corroded parts, etc., is not well done regularly.
Low priority for environmental technologies by the entrepreneurs.
Enforcement of legislation is not strict.
Govt’s attention and support is also not acting as sufficient incentive for adopting environmental technologies.
Awareness and education have to be increased.

References:

Environmental Friendly Textile Processing by Aravin Prince Periyasamy, Samson Rwahwire, and Yan Zhao
Characterization and Treatment of Textile Wastewater By Himanshu Patel and R.T. Vashi
Pollution Control in Textile Industry By S. C. Bhatia
Treatment of Textile Processing Effluents By N.Manivasakam
Handbook of Textile Effluent Remediation By Mohd Yusuf

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Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.