Sustainable Treatment of Textile Processing Wastewater in Resource Challenged Economies: Utilizing Calcium Hypochlorite Oxidation Followed by Sand Filtration with Waste Blast Furnace Iron Slag for Repurposing Treated Effluent in Wet Processing

The textile industries are essential to the economy of Bangladesh. This sector is the largest foreign exchange earner for the country, employing over three million women. However, the unplanned and rapid clustering of industries harms the environment. Unabated untreated textile wastewater discharge is plaguing the water bodies. Compliance issues arise due to the high treatment costs associated with expensive imported chemicals and energy-intensive systems. In the pursuit of a sustainable solution, a pilot-scale technology development project was initiated at an operational textile wastewater treatment plant. The process involved the chemical oxidation of treated wastewater using calcium hypochlorite, followed by rapid sand filtration with the assistance of waste blast furnace iron slag. This approach resulted in the complete removal of colour and further reductions of 95% for COD, 93% for TDS, and 89% for TSS, ensuring that the treated water met Bangladesh's discharge standards. Consequently, this water can be reused in textile wet processes. Fabrics dyed with recycled water exhibited comparable colour fastness in dry and wet conditions. The developed tertiary treatment process, relying on locally available resources and technology within the regional supply chain, holds the potential to serve as a sustainable wastewater treatment option for textile industries in resource-challenged economies. This approach aligns with the objectives of sustainable development by embracing circular economy principles.