Chennai: The Indian Institute of Technology, Madras (IIT Madras) has developed and deployed an advanced new technology for efficiently processing wastewater from the textile industry.
The discharge from this industry not only affects the aesthetic value and water clarity but also reduces photosynthetic activity and poses toxic risks to humans, aquatic organisms and other life forms.
This project focuses on improving the techno-economic feasibility of Zero Liquid Discharge (ZLD) plants by developing an innovative electrochemical-based methodology.
To mitigate the environmental impacts, textile industries are mandated to implement ZLD systems, which aim to recover and reuse wastewater and salts. However, the conventional ZLD process is associated with high capital and operating costs, significant energy consumption and a large carbon and area footprint.
The technology was developed through comprehensive lab-scale studies using synthetic wastewater ranging from small volumes of 500 ml to larger volumes of 50 litres for the Electrochemical Ozone Oxidation System (ECOOP) for removal of organic dyes.
Led by Prof Indumathi M Nambi of IIT Madras, this pilot project was implemented at Kunnakalpalayam Common Effluent Treatment Plant (CETP) in Tamil Nadu's Tirupur district in 2023. This plant showed a significant reduction in harmful compounds in ECOOP-treated samples compared to chlorinated samples from the CETP. Also, it has successfully achieved 96 percent colour removal and 60 percent COD removal for dyebath effluent
Based on the results obtained from the initial deployment, the research team scaled up the system to process 400 litres per day. These trials aim to optimise the system for real-world application.
Advantages compared to existing technologies:
- Segregation of dyebath effluent for colour removal which reduces 75 percent load on RO system
- Reduction in capital infrastructure cost for RO and reject evaporators and hence lower carbon foot print
- Chlorine free colour removal process which avoids formation of carcinogenic chlorinated compounds
Elaborating on the innovative and high-impact project, Prof Indumathi M Nambi, Environmental and Water Resources Engineering (EWRE) Division, Department of Civil Engineering, IIT Madras, said, “This innovative approach reduces the number of RO units required in the treatment plant, ultimately lowering the total treatment cost by 25 percent and cuts down the RO infrastructure cost by 75 percent. It efficiently removes colour and organic pollutants without the use of Chlorine which is reported to produce harmful byproducts. Our treatment system promotes cleaner water resources and supports healthier ecosystems, advancing environmental responsibility in the textile industry.”
Envisioning upcoming plans, Prof Nambi said optimising the pilot plant to enhance its efficiency, versatility and adaptability to treat wastewater from multiple units is in the pipeline. "Additionally, we are working towards propagating the adoption of the Electrochemical Ozone Oxidation System by smaller dyeing industries which do not have RO systems.” Prof Nambi added.
Textile industry in India:
In India, the textile industry contributes significantly to the nation's economy, accounting for 5 percent of the GDP, 7 percent of industrial output by value, and 12 percent of export earnings. However, this revenue comes with a steep environmental cost, as the industry is responsible for 20 percent of global clean water pollution, particularly from dyeing and finishing processes. The textile industry wastewater contains a variety of harmful chemicals, both biodegradable and non-biodegradable, including dyes, dispersants, heavy metals, acids, and alkalis.
