Why do we use NaOH in BOD

Products for lower wastewater pollution


Wastewater pollution in textile finishing

Wastewater from textile finishing often has a high chemical load. The severity of the wastewater pollution is indicated, among other things, with COD (chemical oxygen demand) and BOD (biochemical oxygen demand) values. The polluting chemicals in wastewater can be attributed, among other things, to products that were applied to the textile goods in upstream processes. These include smelting, spin finishes, finishing agents, knitting oils and sizes. In some cases, however, substances with a high COD or BOD load are also introduced by substances accompanying the fibers in the fiber material. These chemical substances are removed from the textiles in the pretreatment and thus end up in the wastewater.

 

Solutions to reduce COD and BOD loads

Raw cotton has a high COD and BOD load, which is detached from the goods during pretreatment processes, during washing, bleaching, causticizing or bio-scouring and ends up in the wastewater. The typical COD load is 40 - 80 g / kg raw cotton. The accompanying substances in cotton mainly consist of dirt, fats, wax and pectins. If these chemical substances are only removed from the raw material to the extent necessary for optimal product and color failure, the waste water pollution can be reduced significantly. We offer various textile-chemical solutions for this purpose:

  • For dark colors on yarn or knitwear made of cotton we recommend one Raw dyeing with PERLAVIN NDA..
  • For medium and darker colors on cotton yarn or knitted fabric, we suggest an enzymatic process before dyeing Pectinase treatment with PERIZYM LOW to be carried out in combination with a mild peroxide bleach.

 

Raw dyeing with PERLAVIN NDA

By raw dyeing with PERLAVIN NDA you can reduce the COD and BOD load of your wastewater. When using PERLAVIN NDA a separate bleaching step can be dispensed with for yarns or knitted fabrics made of cotton. Due to the very good washing, dispersing and sequestering effects PERLAVIN NDA Well suited for one-bath washing and dyeing of raw cotton for dark colors. The COD and BOD pollution of the wastewater through detached waxes, pectins, etc. is reduced.

PERLAVIN NDA is added before the dyeing process. After a short lead time, the dyeing process is carried out as usual. The addition of other dyeing auxiliaries, such as wetting agents or deaerators, is not necessary.

PERLAVIN NDA

PERLAVIN NDA is a multifunctional tool for one-bath washing and dyeing of raw cotton. The product has good wetting, washing, dispersing and sequestering properties.

 

Bio-scouring with PERIZYM LOW

Compared to the classic pretreatment with high amounts of alkali, Bio-Scouring also offers PERIZYM LOW numerous advantages for unsized cotton goods such as knitted goods or yarns: In addition to the smoother handle of the goods, lower weight loss and the reduced COD and BOD in wastewater, no chemical and water-intensive neutralization of core alkali is necessary. For medium and dark colors on cotton goods, we recommend a single-bath, two-stage pretreatment process that includes pectinase treatment and mild peroxide bleaching. The mild conditions lead to a softer handle than a pretreatment with caustic soda. In addition, relatively good hydrophilicity is achieved through bio-scouring. A high degree of whiteness, which would be necessary for very light colors or white goods, cannot be achieved in this process.

The bio-scouring with subsequent bleaching is included in the discounting process PERIZYM LOW and PERISTAL EPJ conc. carried out. After the enzymatic pectinase treatment at 60 to 70 ° C, peroxide and soda are added to the liquor and bleached at 90 to 98 ° C. After draining and rinsing, the dyeing process takes place immediately afterwards.

PERIZYM LOW

PERIZYM LOW is a multifunctional pretreatment agent for the enzymatic bio-scouring of yarns and knitted fabrics made of cotton. In a one-bath, two-stage process, the pectinase treatment can be combined with a mild peroxide bleach.

PERISTAL EPJ conc.

PERISTAL EPJ conc. is a silicate-free, multi-functional product for peroxide bleaching. It acts as a bleach stabilizer, sequestering agent, deaerator, wetting agent and detergent and is used in the hot bleaching of cellulose fibers with peroxide and their mixtures with synthetic fibers in the yarn or piece.

 

Contact us

We would be happy to advise you on how you can reduce wastewater pollution in your processing plant and give you tips on in-house wastewater treatment. Our specialists for textile chemistry and environmental protection will be happy to help you with any questions. Write us an email at contact [at] drpetry.de or use our online contact form.

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