Decolorization and decontamination of textile wastewater by gamma irradiation in presence of H2O2

Gamma irradiation is a contemporary concept for the treatment of textile wastewater. The organic pollutants and coloring materials of wastewater can be decomposed acceptably by gamma irradiation. However, the process efficiency can be improved significantly by integrating H2O2 as an additive with wastewater during irradiation. The treatment of combined textile wastewater collected from a knit dyeing industry was carried out using a Cobalt-60 gamma radiation source at 10 kGy irradiation dose with a dose rate of 13 kGy/h in presence of 0.5, 1.0, 2.0, and 3.0% concentrations of H2O2. Then the change in pH and decoloration percentage, reduction in total suspended solids (TSS), five-day biological oxygen demand (BOD5), and variation of chemical oxygen demand (COD) were extensively investigated. It was observed that colored wastewater become almost colorless due to destruction of the chromophore group of the dye molecules by irradiation. Moreover, the alkaline pH of wastewater is also reduced to neutral condition by fragmentation of larger dye macromolecules resulting in the formation of smaller acidic organic compounds. The degradation of the solid particles and refractory organic matters leads to a considerable reduction in TSS and BOD5 values and consequently the COD of wastewater after irradiation. However, the COD values were found to increase in presence of H2O2 by dichromate method as it behaves as a reductant and oxidized by potassium dichromate resulting in a significant increment in COD reading. So it can be summarized that the application of gamma irradiation with the incorporation of H2O2 is a promising tool for the treatment of textile wastewater by decontaminating its organic pollutants effectively. This effectual degradation of organic matter can eliminate environmental hazard significantly after discharging a large volume of irradiated wastewater to the environment with the minimum concentration of perilous organic matters and coloring substances.