Treatment method for coalescence demercuration of mercury-containing wastewater and application

Abstract

The invention provides a treatment method for coalescence demercuration of mercury-containing wastewater and application, and relates to the technical field of water demercuration treatment. On the basis of the action principle that alkyl mercaptan can change the surface charge of the mercury element and can generate surface adsorption-bridging-coalescence with the mercury element, the mercury element in the wastewater is selectively removed. The treatment method comprises the following steps of: adding a solution A containing a sulfydryl compound into mercury-containing wastewater for mixing reaction, and coalescing the sulfydryl compound and the mercury element to form a mercury coalescence; and then carrying out solid-liquid separation on the mercury coalescence and the mercury-removed wastewater through air flotation (or filtration) to obtain the mercury coalescence and the mercury-removed wastewater. According to the treatment method, the interference on a solution system is small, the coalescence degree of other metals except mercury is low, the mercury removal effect is good, and the formed mercury coalescence is high in mercury content and easy to recycle subsequently.

Description

technical field [0001] The invention relates to the technical field of water body mercury removal treatment, in particular to a treatment method and application of mercury-containing wastewater coalescence and mercury removal. Background technique [0002] Mercury-containing wastewater mainly comes from industries such as metal smelting, chlor-alkali chemical industry, petrochemical industry, paper making, printing and dyeing, electronic instrumentation, and pharmaceutical / paint / coal power generation. Mercury elements in wastewater mainly exist in the form of elemental mercury (zero-valent mercury or colloidal mercury) and mercury compounds (+1 and +2-valent ion mercury), which are highly toxic, and directly discharged into water without treatment will cause environmental pollution. The mercury-containing substances in the water body form highly toxic methyl compounds under the action of bacteria and other microorganisms, pollute seafood such as fish, shrimp and shellfish in...

AI Technical Summary

Problems solved by technology

[0003] At present, the mercury removal process of wastewater mainly includes physical and chemical precipitation method, metal reduction method, activated carbon adsorption method, ion exchange method, solvent extraction method, adsorption method, electrolysis method and microbial method, etc. However, different processes are only effective for specific wastewater, and each method has certain limitations. There is a lack of process methods that can take into account multiple treatment effects, especially in the efficient removal of multiple mercury at the same time. ; directional and selective single coalescence to remove mercury; the produced mercury slag is easy to recycle; there are problems that cannot be taken into account in the aspects of no significant impact on the system before and after treatment.

[0004] For example, the physical and chemical precipitation method has a good treatment effect for high-mercury wastewater, but it needs to pretreat the wastewater, and the addition of a large amount of precipitant (50%-80% more than the theoretical amount) can achieve a higher removal rate, and It also needs to add coagulants such as iron salts and aluminum salts, and the process flow is long. In addition, the composition of the sedimentation residue is complex and difficult to use efficiently. A large amount of low-concentration, high-activity gypsum slag and neutralization slag, these mercury-containing gypsum slags will cause secondary pollution; the metal reduction method has a limited scope of application and is only suitable for a single mercury-containing wastewater, and it is difficult to obtain good treatment effects when it contains other impurity ions , and the operating cost is high, and the economy is insufficient; the ion exchange method and activated carbon adsorption method are suitable for low-concentration mercury-containing wastewater, but are easily affected by other impurities in the wastewater, and the treatment depth is not high enough (generally only 1mg / L); electrolysis The method can treat mercury-concentrated mercury-containing wastewater, but it consumes a lot of energy and mercury is easy to evaporate and cause secondary pollution.

[0005] In order to solve the above existing problems, some scholars have provided targeted solutions, such as publication (announcement) date: 20110427, publication (announcement) number: CN102030440A patent disclosed "Mercury Polluted Water Treatment Process", the mercury content after treatment It can reach the mercury discharge limit value of 0.5μg / L, but this method has high requirements on the water body, and the water body needs to be pretreated to ensure that the suspended solids concentration is ≤100mg / L; the treatment process is relatively long, and there are many treatment procedures (pretreatment -Adsorption mercury removal-secondary adsorption mercury removal), adding a wide variety of reagents (ammonium sulfide, coagulant, flocculant)

Another example is the Chinese patent with publication (announcement) date: 20150325 and publication (announcement) number: CN104445675A, which discloses a method for treating mercury-containing wastewater by using a mercury-removing adsorbent material. However, mercury slag resources have not been recycled, and the adsorption materials will cause secondary pollution

[0006] It can be seen that although several technical methods for removing mercury from wastewater have been disclosed in the prior art, none of the methods can take into account the following aspects at the same time: ①Simultaneous and efficient removal of ionic mercury and colloidal mercury; ②Removal of mercury by directional coalescence ③ Mercury slag is easy to recycle and has no secondary pollution to the environment; ④ Chemicals and processes before and after treatment have no obvious impact on the system; ⑤ The process flow is simple and easy to connect upstream and downstream processes; ⑥ Adaptability strong, wide range of applications

[0007] For this reason, a process method for highly efficient and deep removal of mercury in mercury-containing wastewater has been developed to achieve rapid, efficient and deep selective coalescence of mercury, and overcome the difficulty of high-efficiency and deep removal of mercury in wastewater and the long removal process. Insufficient: to obtain stable high-quality mercury concentrates that are easy to recycle, overcome the difficulty of recycling mercury resources in wastewater, and achieve the dual purposes of efficient and selective removal of mercury in wastewater and recycling of mercury residue resources. Safe and healthy life has important practical significance and good application prospects