Industries such as textiles, dyeing and printing produce a large amount of coloured chemical waste that poses a risk to human health. While conventional water-treatment technologies are expensive and consume a large amount of energy, they also generate secondary waste streams.
India’s textile and apparel industry is the second largest globally, valued at nearly $190 billion, and it is the world’s largest producer of cotton. This innovation assumes significance as it could help industries tackle one of the country’s most persistent environmental challenges.
The research team, led by Sunipa Bhattacharyya, an associate professor in the Ceramic Engineering Department, has developed a water-based ceramic adsorbent by combining fly ash, ground granulated blast-furnace slag (GGBS) and kaolin clay, a naturally occurring white clay used in industrial applications to form strong ceramic materials.
Fly ash is a by-product of coal combustion in thermal power plants, while GGBS is generated during iron and steel manufacturing. Both materials are produced in large quantities across India and pose disposal challenges of their own.
The technology developed by the NIT Rourkela team addresses this challenge by utilising these by-products generated by coal-fired power plants and steel industries as a value-added environmental solution. This ceramic adsorbent has been specifically designed to remove methylene blue dye, a commonly used dye found in industrial wastewater.
“A key innovation of the technology is the use of raw kaolin clay instead of metakaolin, a heat-treated material commonly used in geopolymer-based adsorbents. Eliminating the energy-intensive heating stage significantly reduces production costs and environmental footprint, making the process more sustainable and commercially viable,” said Bhattacharyya.
The innovation comes at a time when India is grappling with growing concerns over industrial pollution of rivers and groundwater. Conventional treatment technologies are often expensive, making them difficult to deploy widely, particularly among small and medium enterprises.
Laboratory tests showed that the material achieved more than 95 per cent removal efficiency for methylene blue dye, a performance level comparable with many advanced treatment technologies. More importantly, the production cost of the ceramic adsorbent is estimated at only Rs 25 to Rs 50 per kg, making it an affordable option for large-scale industrial wastewater treatment.
India’s textile sector alone generates millions of litres of dye-laden wastewater every day, and compliance with increasingly stringent environmental regulations has become a major challenge for manufacturers. The technology can be beneficial for industries seeking cost-effective wastewater-treatment solutions while protecting water resources.
“This low-cost and scalable treatment technology could help industries improve compliance while reducing operational costs. We have plans to develop porous shaped adsorbents made from waste materials and test their ability to remove different pollutants,” said Susant Mohapatra, a research scholar.
The findings of their study using the new technology have been published in the scientific journal ChemistrySelect and align with the United Nations’ Sustainable Development Goals on clean water and sanitation as well as responsible consumption and production.
 "(From left) Susant Mohapatra, Research Scholar, NIT Rourkela; Sourav Ranjan Satpathy, Research Scholar, NIT Rourkela; Prof Sunipa Bhattacharyya, Associate Professor, NIT Rourkela")