Printing and dyeing wastewater treatment method

Abstract

The invention discloses a printing and dyeing wastewater treatment method which comprises the following steps of: firstly mixing the printing and dyeing wastewater with domestic sewage; stirring at a certain pH value; and mixing intrinsic iron irons, magnesium ions, calcium ions and hydroxides of magnesium ions in the wastewater and the components such as suspended particles and the like in the domestic sewage to form a composite flocculating body with a synergistic effect. The composite flocculating body removes chromaticity in the printing and dyeing wastewater through the effects such as electrostatic adsorption, adhesion, bridging, sweeping and the like, and the domestic sewage is purified at the same time. The method disclosed by the invention is applicable to water-soluble and non-water soluble single kind or more kinds of mixed wastewater, and can be matched with a biological method or other physical and chemical methods for further treatment. The method has the characteristics of high decoloration degree, remarkable reduction of COD (chemical oxygen demand), suspended solids and total phosphorus and nitrogen, short treatment flow, simplicity in operation and management, only need for acid-base agents, low equipment investment and operation cost, no need of changing the original treatment facilities, wide application range, convenience in popularization and application and the like.

Description

technical field [0001] The invention belongs to the field of industrial wastewater treatment, in particular to a treatment method for printing and dyeing wastewater. Background technique [0002] The printing and dyeing industry is one of the industrial sectors with large water consumption and large discharge in my country. According to statistics, my country's textile industry discharged 1.26 billion tons of wastewater in 2000, and it increased year by year. In 2002, textile wastewater discharged 7 billion tons, of which 80% was printing and dyeing wastewater. Generally speaking, organic dyes have poor biodegradability, and have been degraded in the natural environment for more than a hundred years. Some are even carcinogenic, mutagenic, and distortion-inducing organic substances, which are increasingly threatening and harmful to the environment, especially the water environment. In addition, with the rapid development of the dye industry and the advancement of finishing t...

AI Technical Summary

Problems solved by technology

[0007] Disadvantages: high investment cost, short membrane life, high water quality requirements and easy clogging, difficult cleaning, low membrane flux, and about 20% salt accumulation water that is difficult to handle

[0010] Disadvantages: basically no effect on water-soluble dyes

[0014] Disadvantages: due to insufficient oxidation potential, the mineralization rate is poor, and by-products that are harmful to the environment may be generated

[0017] Disadvantages: The reaction conditions are harsh, and the requirements for equipment are very high. The reaction equipment must be resistant to high temperature and high pressure, and the fuel consumption is large.

[0020] Disadvantages: the reaction pH is narrow (pH<3.5), the reaction rate is relatively slow, the amount of hydrogen peroxide added increases the treatment cost, and it is easy to produce iron-containing sludge. The effluent has a special color of iron ions and cannot be directly recycled used in dyeing process

[0022] Disadvantages: Ionic liquids have certain selectivity and are difficult to apply in large-scale wastewater treatment

[0025] Disadvantages: It is difficult for this system to effectively use sunlight as a UV light source

[0029] Disadvantages: certain selectivity, difficult regeneration, generally used in dye wastewater treatment or advanced treatment process with low concentration

[0032] Disadvantages: Due to the generation of oxide film, the electrode is passivated, and the consumption of electric energy and power consumption is large

[0035] Disadvantages: Difficult to remove water-soluble dyes, produces a large amount of chemical sludge that is difficult to dispose of

[0038] Disadvantages: The saturated adsorption capacity is limited, and the inorganic salts in the wastewater have a certain inhibitory effect on it

[0042] Disadvantages: long hydraulic retention time, weak ability to remove chroma, poor resistance to organic load and inorganic salt impact

Xu Kun[Xu Kun, Jia Zhiping, Jiang Zhaochun. Study on the decolorization of water-soluble anionic dye wastewater by magnesium hydroxide. Environmental Chemistry. 1998,17(1):94-99.], Ji Ming[Ji Ming, Zhao Yijiang, Zhang Yan, et al. Magnesium hydroxide decolorizes printing and dyeing wastewater. Water Treatment Technology, 2000, 26 (4): 245-248.] et al. found that the time for magnesium hydroxide to precipitate and adsorb dyes should not exceed 1.5min, otherwise it will occur Desorption affects the decolorization effect, and it is difficult to achieve solid-liquid separation in such a short period of time in practical applications, and the sedimentation effect of magnesium hydroxide flocs is also poor

In addition, most of the literature is aimed at the application of water-soluble dyes, and the magnesium salt method is less effective for the removal of disperse dyes, vat dyes, and other insoluble dyes

[0045] Conventional flocculants such as iron salts / aluminum salts / calcium salts / organic polymers have better removal effects on water-insoluble dyes, but poorer removal effects on water-soluble dyes

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