Polyaluminium chloride in water treatment
The discharge of industrial wastewater and papermaking wastewater is large.
After pretreatment, the black liquor produced by the papermaking industry will be mixed with the middle water for common treatment, so as to increase the harmful substances of papermaking wastewater. Polyaluminium chloride(pac) is used to treat the middle water in papermaking. Due to the increase of salinity, the removal rates of COD and Ss will also increase. However, when the salinity reaches 75%, the removal rate will not increase but decrease. The salinity of polyaluminium chloride with temperature of 250 ℃ and 0.6gl is 75%, which can make the effluent meet the national discharge standard. When papermaking wastewater is treated with polyaluminium chloride, the price of polyaluminium chloride is low, and its sediment can also be returned to the papermaking process as raw materials. There is no secondary pollution, and it can also produce practical economic benefits. The experiment shows that under the condition of alkaline (pH 7-9), when the input amount of coagulant is higher than 750mgl, the removal rate of suspended solids can reach more than 95% and 20-50% of CODCr can be removed.
Treat the wastewater generated by daily domestic water and washing wastewater.
Oil and dust particles interact with a large number of surfactants in water to form negatively charged colloidal particles, which are easy to be fixed in water. Adding an appropriate amount of polyaluminium chloride in wastewater will produce positively charged cations and polynuclear high charge coordination ions, which can make the charge suspended on the surface of colloidal particles have the ability of adsorption, electric neutralization and compression of electric double layer, destabilize colloidal particles, adsorb and precipitate and separate water bodies.
Printing and dyeing wastewater contains a large amount of COD, pH value and chromaticity.
Although polyaluminium chloride has good coagulation effect and low dosage in the process of use, the neutralization ability of polyaluminium chloride to printing and dyeing wastewater with high alkalinity is poor, and its application will also be limited. Taking advantage of their complementary advantages and the synergistic effect of the same ion effect, the treatment of printing and dyeing wastewater with two coagulants can not only reduce the treatment cost, but also improve the treatment effect.
4. Oily wastewater treatment oily wastewater refers to oily wastewater discharged from oilfield production water, oil refineries and petrochemical plants. It can be treated by oil separation sedimentation, air flotation and biochemistry. When modified cationic polyacrylamide and polyaluminium chloride are used together, the treatment effect is particularly obvious. The relative molecular weight of modified cationic polyacrylamide should not be too high, and it is easy to compound with polyaluminium chloride, so as to achieve the ideal effect.
Polyaluminium chloride as a water treatment agent is mainly used in the following industries.
Urban water supply and drainage purification: River water, reservoir water and groundwater.
Industrial water purification.
Urban sewage treatment.
Recovery of useful substances in industrial wastewater and waste residue, promotion of pulverized coal sedimentation in coal washing waste water and recovery of starch in starch manufacturing industry.
Various industrial wastewater treatment: printing and dyeing wastewater, leather wastewater, fluorine-containing wastewater, heavy metal wastewater, oily wastewater, papermaking wastewater, coal washing wastewater, mining wastewater, brewing wastewater, metallurgical wastewater, meat processing wastewater F, sewage treatment.
Wrinkle proof cloth.
The content of polyaluminium chloride is different, and the use range is also different. Users can select the corresponding polyaluminum chloride according to their different uses.
Polyaluminium chloride with a content of more than 30%. Suitable for drinking water industry. Specific industries include: waterworks, purified water plants, pharmaceutical plants, food processing plants and other industries with high water quality treatment requirements.
Polyaluminium chloride with a content of 28% is suitable for industrial sewage treatment. Specific industries include: oily sewage, printing and dyeing plant, papermaking sewage, steel plant sewage, coal washing plant, plastic plant and other industries with high turbidity water quality.
Polyaluminium chloride with content of 26% and below is suitable for urban domestic sewage treatment. Polyaluminium chloride with such content is suitable for the treatment of municipal sewage with low turbidity.
Usage and precautions of polyaluminium chloride
First, dissolve solid polyaluminium chloride into liquid. Generally, the dosage of water purification is about 5-100g / T of liquid product and 2-30g / T of solid, and dilute to the appropriate proportion. When preparing, it can be directly added into water. After adding water, it can be put into use after mixing evenly. The dosage should not be too small, which is easy to reduce the use effect, nor too much, which is easy to cause waste.
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