Chemical and method for treatment of waste water contg. heavy metals

Abstract

The invention discloses a composite medicament for treating heavy metal wastewater and a method for purifying heavy metal wastewater by sedimentation and flocculation using the medicament, belonging to the field of water treatment industry and technology. Using a sodium aluminate waste liquid or metal aluminum scrap and sodium hydroxide produced in the manufacturing process as the main raw material, adding an appropriate amount of solid sodium sulfide to compound it, to prepare a product containing Al 2 o 3 8%-9%, NaOH 28%-32%, S 2- 4% to 9% sodium sulfoaluminate liquid product, and the corresponding solid product can be prepared from this liquid. Since this product contains both divalent sulfur and hydroxide which can be precipitated as heavy metals, it can very effectively remove heavy metals in water by precipitation. At the same time, because the agent contains a considerable amount of aluminum, it can carry out synchronous coagulation and flocculation of heavy metals in water and the sulfide or hydroxide precipitates produced, and has the effect of synergistic effect of the three substances. Using this agent to treat heavy metal wastewater requires only adding one agent to achieve the purpose of effective removal of heavy metals, and the joint action of sulfur and aluminum makes the pH of the treated water meet the requirements without adding acid to adjust.

Description

Invention field [0001] The invention relates to a medicament for treating heavy metal wastewater, which belongs to the field of water treatment industry. Background technique [0002] There are many ways to remove heavy metals in wastewater. For example, the ion exchange method uses a positive resin exchanger to pass the waste water to be treated and remove heavy metals in the water. However, the disadvantage of this method is that the resin is expensive, the operating cost is high, and the resin is difficult to regenerate, and the concentrated water is not easy to handle. The electrodialysis method uses ion exchange membranes and separates and removes water and metal ions when energized. However, this method requires a large investment in the equipment system, high processing costs, difficult membrane maintenance, and difficult to promote and apply in wastewater treatment. The reverse osmosis method uses reverse osmosis membranes to separate heavy metal ions from water, but ther...

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Problems solved by technology

However, the disadvantage of this method is that the resin is expensive, the operating cost is high, and the regeneration of the resin is difficult, and the concentrated water is not easy to handle. , but the equipment system investment of this method is large, the treatment cost is too high, the membrane maintenance is difficult, and it is difficult to popularize and apply in wastewater treatment; the reverse osmosis method uses the reverse osmosis membrane to separate the heavy metal ions in the water from the water, but there are The same problem of the electrodialysis method; the organic chelation method is to use a kind of chelating fiber resin to carry out chelation adsorption to remove heavy metal ions in water, and then regenerate the resin material by desorption, but this method also has high cost and regeneration Difficulties and other issues; the electrocoagulation method uses an electrolytic cell to cause redox precipitation or chemical precipitation of heavy metals in water, which can be removed through the flocculation process. The removal efficiency of heavy metals in water has an important relationship with wastewater quality, power parameters, electrodes and other factors; At present, the most widely used heavy metal wastewater treatment method is the method of adding alkali to adjust, flocculation, sedimentation and separation. The treatment equipment is relatively simple, the effect is easy to control, and the cost of treatment and equipment investment is relatively low.

But the disadvantage is that it is necessary to add the agent in stages, and the precipitation efficiency of some heavy metals is low by only using hydroxide