Treatment Method of Printing and Dyeing Industrial Wastewater
May 04, 2022
According to the water quality characteristics of cotton printing and dyeing wastewater, the main targets of wastewater treatment are organic matter, dye pigments and toxic substances that are not easy to biodegrade or biodegrade very slowly. Domestic cotton and cotton textile dyeing wastewater mostly adopts aerobic treatment-based treatment process. The biological treatment effect of pure cotton fabric dyeing wastewater is better, while the treatment effect of cotton blended fabric dyeing wastewater and purified fiber fabric dyeing wastewater is poor. Because there is no desizing wastewater for knitted products, the biological treatment effect of wastewater is better than that of the same woven products. Cotton spinning industrial wastewater generally fails to meet the discharge standard after biological treatment. Usually, different types of chemical treatment devices are connected in series after the biological treatment device for further treatment. In the above process, various types of activated sludge methods can be used in the biochemical treatment process. The residence time of wastewater is more than 3h. The biofilm method mostly adopts two-stage biological contact oxidation method, and the wastewater residence time is 2.5-4h. The residence time of the wastewater in the hydrolysis and acidification tank is 5-8h or longer. The residence time of the wastewater in the regulating tank should be more than 8h.
The CODcr removal rate of the biological treatment unit is about 60%, the BOD5 removal rate is 80% to 90%, and the chromaticity is about 50%. The removal rate of the subsequent chemical treatment unit (coagulation sedimentation or air flotation), CODcr is 50%-60%, BOD5 is about 50%, and chromaticity is 60%-90%. The coagulant is mostly made of polyaluminum. The dosage needs to be determined experimentally.
It is possible to discharge pollutants such as COD, BOD and chroma of dyeing wastewater in the printing and dyeing industry to meet the standards through biochemical treatment. Based on various technical conditions, biological fluidized bed, contact oxidation and surface exposure should be preferred, and treatment plans can be selected according to the specific conditions of each factory. It is generally believed that: when the amount of wastewater is small (less than 500 m3/d), contact oxidation-coagulation sedimentation is used; when the amount of wastewater is large (more than 500 m3/d), it is recommended to use biological fluidized bed-mixing to save floor space. coagulation sediment.
In the treatment of cotton spinning printing and dyeing wastewater, in addition to the above-mentioned typical processes, some special treatment technologies should be adopted for the water quality characteristics of specific discharge objects, such as alkalinity, chroma and the removal of certain toxic substances.
https://www.biocell-enviro.com/
