Performance of gas chlorination in decolourization of textile dyeing wastewater: a pilot study

This study presents performance of gas chlorination in decolourization/degradation of textile dyeing wastewater, optimisation of operating parameters and process kinetics of gas chlorination since it eliminates the generation of hazardous sludge and economical treatment method. The pH, contact time and chlorine dosage were found optimised at 9, 30 min and 300 ppm, respectively. Colour (m⁻¹) of raw effluent was found in the range of 17–85, 14–52 and 15–24 and after the treatment, it was 3–7, 2–4 and 1–3 complying with the International colour standards at 436, 525 and 620 nm wavelengths, respectively. The percentage of colour removal and COD degradation were in the range of 89–95 and 28–45, respectively. Rate of reaction on colour removal and COD degradation were behaved in first order with kinetic rate constant ranged from 0.274 to 0.373 (min⁻¹) and 0.046 to 0.103 (min⁻¹), respectively. Performance of colour removal was achieved better than COD degradation.