Application of magnesium hydroxide in water treatment
Magnesium hydroxide products are widely used in major industries, such as unsaturated polyester, epoxy resin, rubber, paint flame retardant filler. In fact, magnesium hydroxide can also be applied to the water treatment industry, what is the specific situation? The following is a small introduction to the application of magnesium hydroxide in the decolorization of sewage.
1)Acid wastewater treatment
Acid-containing wastewater and waste liquid mainly from machinery, electrical appliances, tools and other factories, acid wastewater and waste liquid discharged from the pickling workshop, waste acid in addition to containing sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, etc., but also contains a large number of metal ions, the traditional acidic wastewater treatment method is usually used first lime milk or limestone, soda ash, caustic soda and other alkaline substances and neutralization, in order to ensure that metal ions precipitation completely, there is often a pH difficult to control problem. The use of magnesium hydroxide for wastewater treatment, to better than caustic soda or limestone, because the wastewater biochemical treatment, must ensure that there is a suitable pH, nutrient conditions and alkalinity, with caustic soda or limestone is difficult to control its alkalinity, magnesium hydroxide as acidic wastewater treatment agent is widely used, in addition it is also suitable for acid waste gas (SO2, HCl, NO2).
2)Heavy metal removal
In the heavy metal wastewater, electroplating wastewater is more typical, electroplating wastewater water quality is complex, the composition is not easy to control, which contains chromium, nickel, copper, zinc, gold, silver and other heavy metal ions and cyanide and other toxic. Magnesium hydroxide has a large specific surface area, strong adsorption, easy to adsorb and remove heavy metal ions from various different industrial waste streams that cause harm to the environment, the application can be used alone magnesium hydroxide, can also be used with other agents, its treatment effect is better than most existing flocculants, compared with calcium hydroxide, also has the production of sludge small size, dense structure easy to separate and filter and other characteristics. Magnesium hydroxide in the neutralization of acid in the wastewater at the same time, can make chromium, nickel, cadmium ions to form precipitation, and through the adsorption of magnesium hydroxide to further remove the ions in the wastewater, the removal rate of up to 98% or more, the treated magnesium hydroxide can also be used for wastewater treatment many times after light burning.
3)Wastewater removal of phosphorus, ammonia
Wastewater nitrogen, phosphorus content is too high will cause the water eutrophication and promote the excessive growth of algae, causing fish hypoxia, endangering the survival of marine life, so the wastewater discharge before the general should be de-phosphorus nitrogen. Although the cost of magnesium hydroxide phosphorus removal and ammonia removal is slightly higher, but the phosphorus removal rate is above 90%.
4)Dyeing wastewater decolourisation
Printing and dyeing wastewater is large, extensive, complex in composition and deep in colour, mainly containing dyes, dyeing auxiliaries, slurry, fibre impurities and inorganic salts, etc., of which the pollution of dyes in particular is the most serious. Among all kinds of dyestuff, reactive dyestuff is water-soluble and difficult to biochemical degradation, its COD removal and decolourisation is extremely difficult. Magnesium hydroxide for dyeing wastewater decolourisation treatment, has a good decolourisation effect, decolourisation rate of 98% or more, magnesium hydroxide for high concentration reaction dye wastewater treatment effect is better than the equivalent amount of ferrous sulphate, polymeric ferric sulphate, polymeric aluminium chloride iron.
