Is Decolorization of Printing and Dyeing Wastewater a Problem? Look Here

China is a major textile printing and dyeing country, so treating printing and dyeing wastewater well is a difficult problem that all printing and dyeing factories must solve to survive. Due to the different water quality caused by different dyes, the chemicals required for treatment are also different, so decolorization has become the most difficult problem in the treatment of printing and dyeing wastewater.

1. The generation of chromaticity in printing and dyeing wastewater

Printing and dyeing wastewater, as a type of surface treatment wastewater, has a very high chromaticity. The main reason for the high chromaticity of printing and dyeing wastewater is the residual dyes in the wastewater, which mainly come from the dyeing and printing processes. In addition, certain suspended solids, slurries, and additives may also produce color. At present, the most commonly used dyes in the market include reactive dyes, acid dyes, alkaline dyes, dispersed dyes, azo dyes, reducing dyes, water-soluble dyes, and sulfide dyes. Among them, reactive dyes and acid dyes are widely used water-soluble dyes. Below are several common methods for decolorizing printing and dyeing wastewater.

2.  Oxidation-reduction decolorization method

Redox decolorization is a relatively common method. For example, strong oxidants such as chlorine oxidation, ozone oxidation, hydrogen peroxide and electrolysis, and photooxidation are effective methods for treating printing and dyeing wastewater by destroying the color dye conjugated system or chromophore groups in the wastewater. These oxidants have a certain selectivity towards different dyes, such as ozone. They have high decolorization rates for water-soluble dye wastewater such as reactive, direct, cationic, and acidic dyes, but have poor decolorization effects on other suspended reduction, sulfurization, and coatings present in the wastewater. At the same time, these processing methods all have a problem of relatively high operating costs.

3.  Fenton decolorization method

Fenton reagent is a strong oxidizing agent composed of H2O2 and FeSO4 mixed in a certain proportion. The Fenton method has a strong removal effect on substances that are difficult to degrade and precipitate in wastewater. Due to its coagulation effect, it has a high decolorization efficiency in the treatment of printing and dyeing wastewater. At present, traditional H2O2 oxidation mostly occurs in the form of Fenton reagent.

4. Coagulation decolorization

The coagulation decolorization method is to adsorb and precipitate colloidal and suspended dyes in water, thereby achieving a decolorization effect of over 90%, and the cost is controllable. Chemical coagulants can be divided into two categories: inorganic and organic. The currently available inorganic coagulants include metal salts and inorganic polymer electrolytes, which have good decolorization effects on dyes present in colloidal or suspended form in wastewater.

Haipu Company Technology

Haipu special adsorbent achieves decolorization through adsorption, which belongs to the physical decolorization method. Adsorbent modification is an important way to improve the adsorption performance of adsorbents. Haipu special adsorbents use techniques such as additional crosslinking, imprinting pore formation, and chemical liquid-phase directed deposition to achieve precise adjustment of pore size in porous materials. One of the main advantages of using adsorption method to treat printing and dyeing wastewater is to reduce secondary pollution.

Compared with other processing methods, Haipu has the following advantages:

• Efficiently remove organic and colored substances from wastewater to achieve water reuse;

• Special adsorbent materials have high absorption capacity and high concentration ratio, low equipment investment, and low operating costs;

• Automated control, easy operation, convenient maintenance, and long service life.

The decolorization method for printing and dyeing wastewater using Haipu functional materials has certain advantages in terms of economy, decolorization effect, and practicality. Customers are welcome to come and consult for free.