Printing and dyeing wastewater is wastewater discharged from printing and dyeing factories that mainly process cotton, linen, chemical fibers and their blended products. The amount of printing and dyeing wastewater is large. Each ton of textile printing and dyeing consumes 100 to 200 tons of water, of which 80 to 90% becomes wastewater. Textile printing and dyeing wastewater has the characteristics of large water volume, high content of organic pollutants, high alkalinity, and large changes in water quality. It is one of the industrial wastewaters that is difficult to treat. Wastewater contains dyes, slurries, additives, oils, acids and bases, fiber impurities, sand materials, inorganic salts, etc.
We all know that wastewater treatment has the characteristics of large water flow, high water content of chemical pollutants, deep saturation, high alkalinity, and large changes in water body. It is a difficult-to-treat chemical wastewater. As we all know, polyacrylamide is generally divided into three types. According to our company's experience, cationic polyacrylamide has absolute advantages in wastewater treatment. Wastewater treatment comes from each manufacturing process, and the composition of air pollutants is also different.
At present, printing and dyeing wastewater at home and abroad mostly adopts a combination of physicochemical and biochemical treatment processes. In principle, biochemistry is mainly used for the removal of COD and BOD, and physicochemistry is mainly used for the removal of decolorization, suspended solids and non-biodegradable COD. At present, printing and dyeing wastewater decolorization technologies generally include the following types.
Chemical methods Commonly used chemical methods for decolorization include coagulation, chemical oxidation, electrolysis and photochemical methods.
Different chemicals are used in each process of printing and dyeing wastewater treatment, but for sludge treatment, the following aspects should be considered comprehensively
Pharmaceuticals are widely available and easy to purchase;
The price is cheap;
pH has a wide applicable range;
The agent is less corrosive;
Good flocculation effect and low consumption;
Returning the filtrate to the sewage treatment system will not have any negative impact.
Polyaluminium Chloride (Polyaluminium Chloride) is referred to as PAC. The appearance is yellow, light yellow, dark brown, gray brown, resin powder solid. Polyaluminum chloride is a water treatment coagulant. It is a water-soluble inorganic polymer between ALCL3 and AL(OH)3. Its effective substance content is mainly aluminum oxide (AL2O3). . The coagulant polyaluminium chloride has a high degree of electrical neutralization and bridging effect on colloids and particulate matter in water, and can powerfully remove slightly toxic substances and heavy metal ions with stable properties. Similar products include white polyaluminum chloride, basic aluminum chloride, composite aluminum chloride, etc.
Micro-electrolysis process for treating printing and dyeing wastewater
The micro-electrolysis process is a method for treating wastewater using galvanic cell reactions, and is particularly suitable for treating high-concentration organic wastewater, such as printing and dyeing wastewater. This method effectively removes organic pollutants, chromaticity and improves the biodegradability of wastewater through electrochemical and redox reactions of iron-carbon fillers in wastewater.
The specific steps for treating printing and dyeing wastewater with the micro-electrolysis process are as follows:
Pretreatment: The printing and dyeing wastewater first passes through a grid to remove large particle impurities, and then enters a regulating tank to adjust the pH value to conditions suitable for micro-electrolysis reactions.
Micro-electrolysis reaction: Under acidic conditions, the iron-carbon filler undergoes electrochemical and redox reactions with the wastewater, and the generated new ecological hydrogen and ferrous ions react with organic matter and chromatic substances in the wastewater, destroying the chromogenic groups, achieving decolorization and degradation of organic matter.
Flocculation and precipitation: After adjusting the pH value, iron ions react with hydroxide to generate ferrous hydroxide and ferric hydroxide. These floccules adsorb suspended matter and organic matter in the wastewater and are removed by precipitation.
Subsequent treatment: The micro-electrolysis effluent enters the buffer tank and is then pumped to the photochemical oxidation reaction tank or biological contact oxidation tank to further remove residual pollutants and finally meet the emission standards.
The advantages of micro-electrolysis process in treating printing and dyeing wastewater include:
High-efficiency degradation: Micro-electrolysis reaction can effectively degrade the difficult-to-degrade organic matter and color substances in printing and dyeing wastewater.
Improving biodegradability: By destroying the structure of organic matter, the biodegradability of wastewater is improved, which is conducive to subsequent biological treatment.
Easy to operate: The process flow is simple, the investment is small, and it is suitable for industrial application.
Strong adaptability: It is suitable for printing and dyeing wastewater of different types and concentrations.
In summary, the micro-electrolysis process is an effective method for treating printing and dyeing wastewater, which can purify and treat wastewater through electrochemical and redox reactions.
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