1, printing and dyeing processing of the four processes must be discharged from the wastewater, the pretreatment stage to discharge desizing wastewater, cooking wastewater, bleaching wastewater and mercerizing wastewater, dyeing process discharge dyeing wastewater, printing process discharge waste water and soap waste water, finishing process The waste water is discharged. Dyeing wastewater is the mixed wastewater of various types of waste water, or integrated wastewater other than bleaching wastewater.
2, water quality and water
The water quality of the printing and dyeing wastewater varies greatly depending on the type of fiber used and the processing technology. General printing and dyeing wastewater pH value of 6 ~ 10, COD 400mg / l ~ 1000mg / l, BOD 100 ~ 400mg / l, SS is 100 ~ 200mg / l, color is 100 ~ 400 times. However, when the printing and dyeing process and the use of fiber types and processing technology changes, the water quality will have a greater change. For example, when the waste water containing polyester silk dyeing process in the production of alkali reduction waste water, the wastewater COD will increase to 2000 ~ 3000mg / l or more, BOD increased to 800mg / l or more, pH value of 11.5 ~ 12, And the quality of waste water with the polyester silk screen printing and dyeing reduction of the amount of waste water increased and deteriorated. When the amount of COD in the effluent is less than 20% of the COD in the wastewater, the biochemical treatment will be difficult to adapt. Different manufacturers or the same manufacturer of different production periods, different water quality, water quality will be beyond the scope of the above.
(1) desizing wastewater: water is small, but the pollutant concentration is high, which contains a variety of pulp, pulp decomposition products, cellulose, starch, alkali and various additives. Desizing wastewater into alkaline, pH value of 12 or so. (COD), such as polyester and cotton warp, desulfurization wastewater, COD, BOD value is high, biodegradability is better; sizing to polyvinyl alcohol (PVA) High and BOD low, waste water can be biochemical poor.
(2) boiled wastewater: water, high concentration of pollutants, which contains cellulose, acid, wax, grease, alkali, surfactant, nitrogen compounds, the wastewater was strong alkaline, high water temperature, brown The
(3) bleaching wastewater: water, but lighter pollution, which contains residual bleach, a small amount of acetic acid, sodium thiosulfide and so on.
(4) mercerized wastewater: high alkali content, NaOH content of 3% to 5%, most of the printing and dyeing plants are concentrated by evaporation and recovery, so mercerized wastewater is generally rarely discharged, after repeated use of the final discharge of wastewater is still strong alkali Sex, BOD, COD, SS are higher.
(5) Dyeing wastewater: water is high, the water quality varies with the dyes used, including slurry, dyes, additives, surfactants, etc., generally strong alkaline, high color, COD higher than BOD More biodegradable.
(6) printing waste water: water, in addition to the printing process of waste water, but also after printing soaping, washing wastewater, high concentrations of pollutants, which contains pulp, dyes, additives, etc., BOD / COD are more high.
(7) finishing wastewater: water is high, including fiber debris, resin, oil, slurry and so on.
The characteristics of printing and dyeing wastewater can be summarized as: organic matter concentration medium, complex composition, biodegradability is poor, color depth, alkaline, high pH, water quality changes. Printing and dyeing industry is a large industrial waste water discharge, the national emissions of 300 to 400 million m3 / d.
(8) alkali reduction waste water: is the polyester simulation of alkali reduction process, mainly containing polyester hydrolyzate on dicarboxylic acid, ethylene glycol, etc., of which the content of dibasic acid up to 75%. Alkali reduction of waste water is not only high PH, but also high concentrations of organic matter, alkali reduction process effluent CODcr up to 90,000, polymer organic and some dyes are difficult to be biodegradable, this waste is a high concentration of organic wastewater degradation.
3, the characteristics of printing and dyeing wastewater
(1) color, high content of organic matter, in addition to pollutants and additives and other pollutants, but also contains a lot of slurry, waste water sticky;
(2) COD changes, high up to 2000 ~ 3000mg / l, BOD is also up to 2000 ~ 3000mg / l;
(3) alkaline, such as sulfur dyes and vat dyes wastewater pH value of up to 10 or more;
(4) water temperature and water changes, due to processing varieties, production changes, can lead to large changes in water temperature and water.
4, the choice of treatment methods
Processing Technology of Cotton and Cotton Blended Printing and Dyeing Wastewater
(1) mixed wastewater treatment process grid - pH adjustment - regulating pool - hydrolytic acidification - aerobic biological treatment - physical and chemical treatment
(2) wastewater treatment of water treatment, desizing and other high concentrations of waste water by anaerobic or hydrolytic acidification, and then mixed with other waste water treatment; alkali reduction of waste alkali by alkali recovery and reuse, and then with other waste water Mixed treatment.
Wool dyeing wastewater treatment process
Grill - conditioning pool - hydrolytic acidification - aerobic biological treatment scouring waste water should be recycled lanolin, and then anaerobic biological treatment + aerobic biological treatment, and then mixed with the whole wastewater treatment or into the urban sewage treatment plant.
Treatment Technology of Silk Dyeing and Finishing Wastewater
Grille - Leaf Regulating Pool - Hydrolysis Acidification - Aerobic Biological Treatment Silk Spinning Refining Wastewater The treatment process to be used is: grill - cold water tank (recoverable heat) + regulating pool - anaerobic biological treatment aerobic Biological treatment.
Reeling wastewater should be recycled and other valuable substances and then to deal with the treatment process: grille, grid - regulating pool - aerobic biological treatment - precipitation or flotation.
Processing wastewater treatment process
According to the biological degumming wastewater, chemical degumming wastewater, the water quality of the jellyfish wastewater and the actual water quality after mixing with the dyeing and finishing wastewater, the treatment process should be: grille + grit chamber pH adjustment - anaerobic biological treatment - Hydrolysis Acidification - Aerobic Biological Treatment - Physicochemical Treatment - Biofilter.
If the proportion of hemp degumming wastewater is high, it should be anaerobic biological treatment alone, or physical and chemical treatment and then mixed with the dyeing wastewater treatment.
Polyester - based chemical fiber dyeing and finishing wastewater treatment process
(1) waste water containing alkali reduction of polyester dyeing wastewater
Grille - pH adjustment - Regulating pool - Physicochemical treatment - Aerobic biological treatment. Among them, the alkali reduction waste water should be first recovered terephthalic acid and then mixed with dyeing wastewater.
(2) polyester dyeing wastewater
Grille - pH adjustment - conditioning pool - aerobic biological treatment - physical and chemical treatment.
Batik wastewater treatment process
The amount of urea should be reduced during the batik process. As the concentration of pollutants in waste water is high, and the nitrogen content is also high, usually using hydrolytic acidification + with denitrification function of the oxygen, aerobic biological treatment process, the specific parameters should be determined by experiment.