A large amount of waster streams or effluents is produced during dyeing knitted fabrics. Water streams produced in different sector of dyeing knitted fabrics pollute environment. Desizing, souring, bleaching, mercerizing, dyeing, printing, finishing, washing and other process can produce waste streams which contains harmful chemicals. For that, waste streams need to be purified before discharge to the environment.
Characteristics of waste streams: the followings are the characteristics of waste streams.
Desizing: Size materials are used on the surface of yarn during weaving. The process removing size materials form the fabric is called as desizing. Possible pollutant in water is Starch, Glucose, CMC, PVC, Resins, Fats, and Oils etc. Waste streams have high BOD (35-50%).
Scouring: Scouring can remove impurities of textile materials. Waste water contains NaOH, Na2CO3, Waxes, Grease, Fragments of cotton etc. Nature of waste water is strongly alkaline, dark color, high BOD (30%) of total.
Bleaching: Bleaching can remove natural color of the textile materials which also causes waste streams containing Na(0Ocl)Cl, NaOH, Cl2, H2O2, Na2O2, acids etc. Nature of waste stream is alkaline, BOD (5%) of the total.
Mercerizing: The process can improve the physical properties of the fiber, producing waste streams. Pollutant in water is NaOH, H2SO4, Na2CO3 etc. Nature of waste water is strongly alkaline, BOD (less than 1%).
Dyeing: The process can produce a large number of waste water. Possible pollutant is various types of dyes, salts, acids, alkalis, soap and detergent etc. Nature of waste streams is strongly colored, fair BOS (6%) of the total.
Printing: Printing forms carious types of decorous design. Possible pollutant is colors, pigments, gums, oils, acids, different salts and other auxiliaries. Waste water is highly colored, oily appearance, BOD (6 to 10%) of the total.
Finishing: Possible pollutant in water is Traces of Starch, Resins, Softeners, and Stiffeners etc. Nature of waste water is low BOD (2 to 4%) of the total.
Effluent treatment plant (ETP) should be set up for protecting the environment from the influence of the waster streams.
Post: Characteristics of Waste Streams Caused by Dyeing Knitted Fabrics
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