Characteristics of textile dyeing wastewater
Organic matter pollution is mainly characterized by COD and BOD values. It is worth noting that the more synthetic fibers are used in the raw materials, the more organic substances of the COD group must be used in the finishing treatment, which means that chemicals and dyes are more difficult to biodegrade. much. For example, wastewater from a process that uses reactive dyes (eg Cibarcon Blue P-3R) for floral printing may have a BOD around zero, but COD reaches the upper body less than 900 mg/L. The ratio of COD/BOD on the one hand represents the organic pollution characteristics of textile dyeing wastewater, and at the same time shows the feasibility of microbiological technology in the later treatment stage.
The third characteristic of textile dyeing wastewater is heavy metal pollution mainly due to the use of bleaching chemicals and dyes in the form of metal compounds. One of the sources of metal pollution is pigments, which are now commonly used pigments mostly based on halogenated organometallic compounds (e.g. copper phthalate loxiamin chloride).
High conductivity or high total dissolved solids (TDS) is also characteristic of textile dyeing wastewater due to the use of relatively large soluble salts, such as Na2SO4, NaCl.
Another characteristic of textile dyeing wastewater, especially dyeing and printing, is color. Color contamination depends on the degree of color binding between the dye and the textile fiber.