Printing and dyeing wastewater treatment equipment

The printing and dyeing wastewater treatment equipment is mainly designed and developed for printing and dyeing wastewater with high chromaticity and difficulty in decolorization, and high COD, which can effectively solve the technical difficulties in the previous printing and dyeing wastewater treatment process. The printing and dyeing wastewater can be discharged up to standard after treatment.

The water quality of printing and dyeing wastewater varies depending on the type of fiber used and processing technology, and the pollutant components vary greatly. Printing and dyeing wastewater generally has the characteristics of high pollutant concentration, multiple types, toxic and harmful components, and high chromaticity. Generally, the pH value of printing and dyeing wastewater is 6-10, CODCr is 400-1000mg/L, BOD5 is 100-400mg/L, SS is 100-200mg/L, and the chromaticity is 100-400 times.

But when the printing and dyeing process, the types of fibers used, and the processing technology change, the sewage quality will have a significant change. In recent years, due to the development of chemical fiber fabrics, the rise of imitation silk, and the advancement of dyeing and finishing technology, a large number of difficult to degrade organic compounds such as PVA size, alkali hydrolysates of artificial silk (mainly phthalates), and new additives have entered printing and dyeing wastewater. The CODCr concentration has also increased from hundreds of mg/L to over 2000-3000mg/L, BOD5 has increased to over 800mg/L, and the pH value has reached 11.5-12, This reduces the CODCr removal rate of the original biological treatment system from 70% to around 50%, or even lower.

The amount of desizing wastewater in printing and dyeing wastewater is relatively small, but the concentration of pollutants is high, which contains various sizes, size decomposition products, fiber chips, starch alkali, and various additives. The sewage is alkaline with a pH value of around 12. The desizing wastewater with starch as the main sizing agent (such as cotton fabric) has high COD and BOD values and good biodegradability. The desizing wastewater with polyvinyl alcohol (PVA) as the main sizing agent (such as polyester cotton warp yarn) has high COD and low BOD, and the biodegradability of the wastewater is poor.

Printing and dyeing wastewater has a large amount of boiling wastewater and a high concentration of pollutants, including cellulose, citric acid, wax, oil, alkali, surfactants, nitrogen-containing compounds, etc. The wastewater is strongly alkaline, with high water temperature and a brown color.

Printing and dyeing wastewater has a large amount of bleaching wastewater, but the pollution is relatively light, which contains residual bleaching agents, small amounts of acetic acid, oxalic acid, sodium thiosulfate, etc.

Printing and dyeing wastewater mercerizing wastewater has a high alkali content, with NaOH content ranging from 3% to 5%. Most printing and dyeing plants recover NaOH through evaporation and concentration, so mercerizing wastewater is generally rarely discharged. After repeated use, the final discharged wastewater is still highly alkaline, with high BOD, COD, and SS.

The amount of dyeing wastewater in printing and dyeing is relatively large, and the water quality varies depending on the dyes used. It contains slurries, dyes, additives, surfactants, etc., and is generally strong alkaline with high chromaticity. The COD is much higher than BOD, and its biodegradability is poor.

The amount of printing and dyeing wastewater is relatively large. In addition to the wastewater from the printing process, it also includes the soaping and water washing wastewater after printing. The concentration of pollutants is high, including slurry, dyes, additives, etc., and the BOD and COD are all high.

The amount of wastewater from printing and dyeing wastewater treatment is relatively small, which contains fiber chips, resins, oil agents, and slurries.

Printing and dyeing wastewater alkali reduction wastewater is generated from the alkali reduction process of polyester imitation silk, mainly containing polyester hydrolysates such as terephthalic acid and ethylene glycol, with a terephthalic acid content of up to 75%. Alkaline reduction wastewater not only has a high pH value (generally>12), but also has a high concentration of organic matter. The CODCr in the wastewater discharged from the alkali reduction process can reach up to 90000 mg/L. High molecular organic compounds and some dyes are difficult to biodegrade, and this type of wastewater belongs to high concentration and difficult to degrade organic wastewater.

The printing and dyeing wastewater treatment equipment utilizes the life activities of anaerobic and aerobic bacteria to consume organic pollutants in the wastewater. At the same time, the biological flocculents formed by microorganisms destabilize and flocculate suspended and colloidal organic pollutants, adsorb on the surface of activated sludge, degrade organic matter, and ultimately achieve the effect of purifying wastewater.

The equipment is equipped with underwater aeration, which is pushed by water flow to form dual function aeration. When treating sewage, the sewage flows into the aeration zone from the top of the device, and the aerator undergoes underwater aeration and pushes the flow to stir the sewage. The incoming sewage quickly mixes fully with the original mixture, adapting to the changes in inlet water quality to the maximum extent possible. The aerator has dual functions of water flow propulsion and underwater aeration, enabling the sewage in the aeration zone to circulate regularly and increase the dissolved oxygen content in the sewage. Due to the continuous circulation and flow of sewage in the aeration zone, the water quality at each point in the zone is relatively uniform, and the number and properties of microorganisms are basically the same. Therefore, the working conditions of each part of the aeration zone are almost consistent. This controls the entire biochemical reaction under good and identical conditions. Organic matter is gradually degraded by microorganisms, and wastewater is purified. The purification efficiency is high, and all indicators of the effluent meet the emission standards of the national "Emission Standards for Pollutants in the Textile Dyeing and Finishing Industry" (GB 4267-92). According to customer requirements, further supporting facilities can be provided for ozone strong oxidation deep treatment to meet the "Water Quality Standards for Urban Wastewater Recycling and Landscape Environment Water" (GB/T 18921-2002) standards for recycling and utilization.印染污水Applicable scope of processing equipment:

This integrated printing and dyeing wastewater treatment equipment is suitable for the treatment of various high, medium, and low concentration printing and dyeing wastewater, such as knitted printing and dyeing wastewater, wool dyeing and finishing wastewater, silk dyeing and finishing wastewater, chemical fiber dyeing and finishing wastewater, woven cotton and cotton blended fabric dyeing and finishing wastewater.

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Post time: Jun-05-2023