Comparison between BOD and COD of auxiliaries used in conventional and enzymatic pretreatment of textiles polluting the aquatic environment

Textile production is estimated to be responsible for about 20% of global clean water pollution from dyeing and finishing products. Textile wastewater discharge is one of the most hazardous pollutants which has a strong possibility to be mixed with freshwater bodies making the clean water unfit for further utilization. Chemical oxygen demand (COD) and biological oxygen demand (BOD) are the important indicators that describe the pollution level of the water. Pretreatment of textiles using hazardous chemicals boosts the toxicity of water due to the release of chemicals from textile fibrous surfaces into clean drinking water polluting the aquatic environment. This research aimed to develop a correlation between COD and BOD concerning auxiliaries used in the conventional and bio-pretreatment of textiles, so that the wastewater load can be traced back to the pretreatment method applied in upstream procedures. Furthermore, a comparison was established between COD and BOD of conventional and enzymatic processes. At first, the desizing of gray fabric was done, followed by scouring and bleaching. Then, scouring and bleaching were performed by conventional and enzymatic methods to examine their association with the rise in COD and BOD levels of effluent. Results confirmed that auxiliaries used in traditional and bio-pretreatments of textiles are significantly responsible for wastewater load. However, COD and BOD values of effluent obtained after enzymatic pretreatments were substantially less compared to conventional pretreatment methods. Therefore, enzymatic pretreatment application in textile chemical processing will help reduce effluent pollution and promote sustainable practices (SDG 6) with less environmental impact.

Graphical Abstract