Methods For Textile Industry Wastewater Treatment
Physical Method For Textile Industry Wastewater Treatment
The most popular Physical method for textile industry wastewater treatment is the adsorption method, which is to mix the powder or particles of porous materials such as activated carbon, clay, kaolin and wastewater, or to pass the wastewater through a filter bed composed of its granular materials. Contaminants in the wastewater are adsorbed on the surface of the porous material or removed by filtration. At present, many countries mainly use activated carbon adsorption (mostly for tertiary treatment), which is very effective for removing dissolved organic matter in water, but it can not remove colloid and hydrophobic dye in water, and it only applies to cationic dyes and direct dyes. Water-soluble dyes such as acid dyes and reactive dyes have good adsorption properties. Adsorbents used in adsorption treatment are various. In engineering, the selectivity of the adsorbent to dyes should be considered. The adsorbent should be selected according to the quality of the wastewater.
Chemical Method For Textile Industry Wastewater Treatment
The basic principle of the coagulation method is to put a coagulant into the wastewater, form a micelle in the wastewater, and electrically neutralize the colloidal substance in the wastewater to form a flocculation group. The coagulation method not only removes fine suspended particles with a particle size of 10-3 to 10-6 mm in the wastewater, but also removes organic matter such as color, oil, microorganisms, BOD, and COD. The coagulation method mainly includes the coagulation sedimentation method and the coagulation air flotation method. Most of the coagulants used are mainly aluminum or iron salts, and the adsorption performance of basic aluminum chloride (PAC) is better. Recently, the use of high-molecular coagulants has increased, and there is a tendency to replace inorganic coagulants. Polymer coagulants are most commonly used in polyacrylamide (PAM), anionic, cationic and nonionic.
The chemical oxidation method is a treatment method for intensifying oxidation of chromaticity, bacterial microorganisms, organic matter (COD, BOD) and the like in wastewater by using a strong oxidizing agent. In the chemical treatment of textile wastewater, chemical solid oxide agents are often not used due to restrictions on operating costs and environmental acceptance. The ozone oxidation method is used more in foreign countries, and the mathematical model of ozone decolorization of textile wastewater has been summarized. The ozone oxidation method can obtain a good decolorization effect for most dyes, but it has poor decolorization effect on water-insoluble dyes such as vulcanization, reduction, and coating.
The electrolysis method has a good treatment effect on the treatment of textile wastewater containing acid dyes, and the decolorization rate is 50% to 70%, but the treatment effect on wastewater with deep color and high CODCr is poor. The electrochemical properties of dyes show that the CODCr removal rates of various dyes in the order of electrolysis are: sulfur dyes, vat dyes > acid dyes, reactive dyes > neutral dyes, direct dyes > cationic dyes. At present, this kind of processing method is being promoted and used in some engineering practices.
Physical Method, Chemical Method, Biological Method. For Textile Industry Wastewater Treatment
From the current situation, the aerobic biological treatment of textile wastewater in China is dominated by surface accelerated aeration and contact oxidation. In addition, blast aeration activated sludge process, jet aeration activated sludge process and biological turntable process are also applied. Biological treatment is effective for removing organic matter such as BOD, but the chroma removal rate is not high, generally about 50%, so when the chroma requirement is relatively high, it needs to be supplemented by physical or chemical treatment.
Aerobic biological treatment has a significant effect on the removal of BOD, generally up to 80%, but the chroma and COD removal efficiency is not high, especially the wide application of chemical pulp, surfactant, solvent and pebble-base reduction technology such as PVA. Not only the COD of textile wastewater is as high as 2000mg/l~3000mg/l, but also the ratio of BOD/COD is significantly lower than before. The simple aerobic biological treatment is more and more difficult, and the effluent is difficult to reach the standard. Based on the above situation, the anaerobic biological treatment technology of textile wastewater has been paid more and more attention by people. It is increasingly important to explore new technologies for printing, dyeing and water treatment with high efficiency, low consumption and investment.