Nowadays, dye wastewater has become a major source of pollution in industrial wastewater, which contains a large number of refractory organic matter, salt and a variety of heavy metal ions, which not only seriously damages the ecological balance of water bodies, but also threatens human health and water security.
1. Characteristics of dye wastewater and treatment difficulties.
The main characteristics of dye wastewater are high color, high chemical oxygen demand (COD), significant biological toxicity, and contains a wide variety of organic dye molecules with complex structure, which are difficult to effectively remove by conventional physical and biochemical methods. In addition, some wastewater may also contain multivalent metal ions such as copper and chromium, which further increases the difficulty of treatment.
2. Detailed explanation of dye wastewater treatment process.
Pre-treatment phase.
Coagulation and sedimentation method**: The suspended particles and colloidal substances in the wastewater are condensed into larger particles by adding flocculants, and then separated by precipitation.
Air flotation method**: The use of tiny bubbles to adsorb fine particles and oils in wastewater to form a "gas-water-solid" three-phase mixture, so that it floats up to achieve solid-liquid separation.
Activated carbon adsorption method**: The strong adsorption performance of activated carbon is used to adsorb the color and some organic matter in the wastewater.
Physicochemical treatment stage.
Advanced oxidation technologies**: such as fenton oxidation, ozone oxidation, photocatalytic oxidation, etc., these methods can produce strong oxidizing free radicals, break the chain or mineralize the organic dye molecules in the wastewater, reduce their toxicity and improve biodegradability.
Electrochemical method: including electrolysis, electrodialysis, etc., through the action of electric current to promote the redox reaction of dye molecules on the surface of the electrode, and at the same time, the ** of heavy metal ions can also be realized.
Biochemical processing stage.
Activated sludge method**: Converts organic pollutants in wastewater into microorganisms and harmless final metabolites through microbial colonies.
Anaerobic biological treatment**: such as UASB, EGSB, etc., which decomposes part of the organic matter under anaerobic conditions, produces biogas and reduces COD concentration.
Aerobic Biological Contact Oxidation**: Efficient degradation by immobilized biofilms, especially suitable for the treatment of refractory dye wastewater.
Deep processing stage.
Reverse osmosis, nanofiltration and other membrane separation technologies**: It can efficiently intercept dye molecules to ensure that the effluent quality meets the standard.
Adsorption and regeneration technology**: new adsorption materials (such as modified activated carbon, nano adsorbents) are used for adsorption treatment, and regeneration and recycling are carried out after adsorption saturation.