Electron beam irradiation post treatment for degradation of non biodegradable contaminants in textile wastewater

Wet processing is one of the major streams in textile engineering refers to textile chemical processing. Textile wet processing involves three stages mainly pre-treatment or preparation (desizing, scouring), colouration (dyeing and printing) and finishing. In desizing and scouring processes sizing material (starch/ PVA) and natural impurities (oil/wax/fat) are removed respectively. Dyeing and printing are the processes for colouration of fabric with natural or synthetic dye and for producing any pattern on the fabric respectively. Textile wet processing produces high load of pollutants to textile effluent treatment plant (ETP) of which aim is to safely discharge of water to meet the consent limits provided by environmental regulatory authority. In this paper, the degradation of simulated textile waste water arising from various processes viz. desizing, scouring, dyeing and printing was evaluated by treatability study with activated sludge process. The results show desizing, dyeing and printing processes mainly to be contributing to non biodegradable contaminants in textile effluent treatment plant (ETP). In this study, electron beam radiation technology was applied to enhance the biodegradability of simulated textile effluent (mixed) pre-treated by activated sludge process. This mixed effluent comprises of all constituents related to scouring, desizing, dyeing and printing process with known concentrations has never been considered before, in any of the available literature on EB irradiation of Textile waste waters. Most of the studies on EB irradiation on wastewater showed focus on single pollutant. The results showed that E-beam irradiation pre-treatment did not improve the biodegradability of textile effluent even when it was irradiated up to 80 kGy. However, in contrast, a-beam irradiation as post treatment to biologically treated sample could significantly enhance the biodegradability at very low dose 1 kGy where hydroxyl radical (OH) played a very active role. The values of COD, BOD, and BOD/COD ratio were compared before and after E-beam treatment. The absorbance spectra in UV-Visible range were obtained for mixed effluent.