What should I do if the heavy metal of wastewater is over?

The neutral precipitation method is separated by adding alkali to the wastewater containing heavy metals to the neutral and neutral reactions so that the hydroxide sedimentation of heavy metals to generate insoluble water is separated. In the actual wastewater treatment, the following three problems should be paid attention to:! The pH value of the heavy metal wastewater in the meridian and the sedimentation treatment is high, and it needs to be processed to discharge; the actual wastewater in the wastewater can almost exist alone, often a variety of heavy metal ions coexist, and When the wastewater contains bisexual metals such as zinc, lead, chromium, tin, and aluminum, there is a tendency to dissolve at a high pH value. When dealing with the operation, the pH value must be strictly controlled to implement the segmented sedimentation method; Cyanocyan, humidic acid, and rotten implantation can be formed with heavy metal ions, which has a greater impact on neutralization and law, sometimes not even formed, and pre -treatment before neutralization; Frequent flocculants need to be added to assist sedimentation. In actual operation, crystal circulation method is also applied to make the sedimentation crystal large and easy to settle.
At present, the method of heavy metal wastewater treatment can be roughly divided into three categories: (1) chemical method; (2) physical treatment method; (3) biological treatment method.
The chemical method
The chemical method mainly includes the chemical precipitation method and electrolytic method. It is mainly suitable for the treatment of higher concentration of heavy metal ion wastewater. The chemical method is currently the main method for treating heavy metal wastewater at home and abroad.
2.1.1 Chemical precipitation method
The principle of chemical precipitation method is to transform the heavy metal compounds that are dissolved in wastewater in the wastewater through chemical reactions. Including neutralization method, sulfide precipitation method, and iron oxygen co -precipitation method. Due to the influence of the precipitation and environmental conditions, the precipitation method often does not meet the requirements. It is necessary to be treated further. The precipitated substances must be treated and handled well, otherwise it will cause secondary pollution.
2.1.2 Electrolysis
The electrolytic method is to use the electrochemical properties of the metal. Metal ions can be separated from a relatively high concentration solution during electrolytes and then used. The electrolytic method is mainly used for the treatment of electroplating wastewater. The disadvantage of this method is that the concentration of heavy metal ions in the water cannot be reduced. Therefore, the electrolytic method is not suitable for handling wastewater containing heavy metal ions with lower concentrations.
The physical treatment
The physical treatment method mainly includes solvent extraction separation, ion exchange method, membrane separation technology and adsorption method.
2.2.1 Solidation of solvent
The solvent extraction method is commonly used by separation and purification substances. Due to liquid contact, it can be continuously operated and the separation effect is better. When using this method, you need to choose a higher selective extracting agent. The heavy metals in the wastewater generally exist in the form of yang ions or anion. For example, under acidic conditions, an alternative reaction with the extracting agent will occur. Then, under alkaline conditions, the water phase is obtained to make the solvent regenerate to recycle. This requires choosing water phase acidity when extraction operations. Although the extraction method has a great superiority, the loss of energy during the extraction process and the great energy consumption during the extraction process, which has a certain limitations of this method, and the application is greatly restricted.
2.2.2 ion exchange method
ion exchange method is the exchange of heavy metal ions and ion exchanges to achieve the method of removing heavy metal ions in the wastewater. Commonly used ion exchanges include cation exchange resin, anion exchange resin, chelated resin, etc. Over the past few years, domestic and foreign scholars have opened a lot of research on the development and development of ion exchanges. With the continuous emergence of ion exchanges, the ion exchange method has increasingly showed its advantages in the depth treatment of electroplating wastewater and recycling of high -priced metal salt. Ion exchange method is an important method of electroplating wastewater. It has a large processing capacity, good water quality, and recycling heavy metal resources. It has no secondary pollution to the environment.
2.2.3 Film separation technology
Mascular separation technology is to use a special semi -diaphragm. Under the influence of external pressure, the solvents and solutions are separated or soluble based on the chemical form in the solution. The concentrated method includes electrolyte and electrolytic electrolysis. Electrodialysis is a kind of physical chemistry process that uses yin and yang ion exchanges to use yin and yang ion exchanges to select the solution yin and yang ions to separate the heavily metal ions in the aquatic solution. The electrolytic method of the diaphragm is an electrolytic method for the anode and cathode of the membrane to separate the electrolyte. In fact, it is a method that combines electrolysis and electrolytic. The above methods encountered problems such as electrode polarization, scaling and corrosion during operation.
2.2.4 adsorption method
The adsorption method is an effective way to use porous solid -state absorption to remove heavy metal ions in water. The key technology of adsorption method is the choice of adsorption agents. Traditional adsorbents are activated carbon. Activated carbon has a strong adsorption capacity, high removal rate, but the activated carbon regeneration efficiency is low, it is difficult to meet the reuse requirements, the price is expensive, and the application is limited. In recent years, a variety of adsorption materials with adsorption ability have been developed. Related studies have shown that shells and derivatives are good adsorption agents for heavy metal ions. After the cross -crossing of shell polycanic resin, it can be reused 10 times, and the adsorption capacity has not been significantly reduced. The use of modified sea bubbles to control heavy metal wastewater has a good adsorption ability for PB2 , HG2 , and CD2 . After treatment, the heavy metal content in the wastewater is significantly lower than the comprehensive discharge standard of sewage. Another literature reports that Mongolian stone litter is also a kind of good clay mineral adsorption agent. The aluminum pillar supports the removal rate of CR 6 under acidic conditions, and the CR 6 content in the water is lower than national emissions than national emissions. Standards, with practical application prospects.
The biological treatment method
The biological treatment method is to remove heavy metals in wastewater with the functions of microorganisms or plants, including the functions of flocculation, absorption, accumulation, and enrichment, including biological adsorption, biological flocculation, plant repair and other methods.
2.3.1 Bio adsorption
The biological adsorption method refers to the method of adsorbing metal ions with the help of chemical effects. The algae and microbial bacteria have a good adsorption effect on heavy metals, and have the advantages of low cost, good selectivity, large adsorption amount, and wide concentration scope. It is a relatively economical adsorption agent. With the study of biological adsorbing laws to remove heavy metals from wastewater, the United States and other countries have initially seen results. Some researchers pre -processed the fungus cluster of the fake monolma, fixed it on the fine -grained magnetite ore to adsorb the CU in the industrial wastewater, and found that when the concentration is as high as 100 mg/L, the removing rate can reach 96%. Use it to use. Acidized suction can recover 95%of copper, pre -processing can increase the adsorption capacity. However, there are also some shortcomings of biological adsorption laws, such as adsorption capacity is easily affected by environmental factors. Microbial adsorption of heavy metals is selective, while heavy metal wastewater often contains a variety of harmful heavy metals. You need to conduct further research.
2.3.2 Bioccoly
The bioconentity method is a method of removing the use of metabolites produced by microorganisms or microorganisms. Although the development of the bioconentity method is less than 20 years, more than 17 microorganisms have been found to have a good flocculation function, such as mold, bacteria, threading bacteria, and yeast, and most of the microorganisms can be used to deal with heavy metals. The biological flocculation method has the advantages of safe and non -toxic, high flocculation efficiency, and easy to separate flocculans, and has broad development prospects.
2.3.3 Plant repair method
Pylast repair method refers to the use of higher plants through absorption, precipitation, enrichment, etc. to reduce the heavy metal content of contaminated soil or surface water to achieve pollution and repair the environment the goal of. The plant repair method is an effective way to use the ecological engineering governance environment. It is an extension of biotechnology to deal with wastewater in enterprises. The use of plants to deal with heavy metals, mainly three parts:
(1) Use metal to accumulate plants or overcreae plants from being absorbed, precipitated or rich in toxic metals from wastewater: (2) Use metal to accumulate plants or overcreae plants to reduce toxic toxicity. Metal activity can reduce heavy metals being filtered underground or spread through air carrier: (3) Use metal to accumulate plants or overcurrent plants to extract the heavy metals in the soil or water in the soil or water by using metal The harvested part of the roots and the on -planting parts of the plant. By harvesting or moving the branches that have accumulated and enriched heavy metal plants, the heavy metal concentration in the soil or water body is reduced. Plants that can be used in plant repair technology include algae plants, herbaceous plants, woody plants, etc.
The capacity of algae purification heavy metal wastewater is mainly manifested in having strong adsorption for heavy metals. The absorption of AU’s absorption of AU reaches 400mg/g. Under certain conditions, the removal rate of heavy metal ions such as CU, PB, LA, CD, and HG under certain conditions reaches 80%to 90%. Hao Yuntao and other separate screening obtained a high -heavy metal resistant elliptical algae (Chlorella), and studied the effects of heavy metal copper, zinc, nickel, cadmium on the growth of the algae and its absorption of heavy metal ions with different concentrations. Extract. The results showed that the algae Zn and CD had high tolerance. The tolerance of four heavy metals is zinc> cadmium> nickel> copper. The algae has a good removal effect. 15 μmol/L CU2 , 300 μmol/L Zn2 , 100 μmol/L Ni2 , 30 μmol/L CD2 concentration 72h treatment, the removal rate reaches 40.93%, 98.33%, 97.62%, and 86.88%. It can be seen that this algae can be treated with heavy metal wastewater.
The application of herbal plant purification heavy metal wastewater has been reported. Eichhoria Crassipes Somis is an internationally recognized and commonly used aquatic floating plant. It has the characteristics of rapid growth, which can be resistant to low temperature and high temperature resistance. PB, HG, Ni, AG, CO, CR and other heavy metals. The research results of Zhang Zhijie and others show that the windy eye lotus of the dry LKG can absorb lead 3.797g and 3.225g of cadmium in 7 ~ L0D. Studies from Zhou Fengfan and others found that the absorption of cobalt and zinc was as high as 97%and 80%, respectively. Typhao Ritealis Pres1 is also an excellent herbaceous plant that purifies heavy metals. It has special structures and functions such as meat quality and developed fence tissue. The long -term growth of Mugang plants in high concentration of heavy metal wastewater forms a special structure to resist the harsh environment and can self -regulate certain physiological activities to adapt to pollution and poison. Zhaowen Rui and others studied the stability of the wide -leaf lotus artificial wetland system to deal with the stability of the 凡 口 矿 ore ore -filled wastewater in Shaoguan, Guangdong. The 10 -year monitoring results show that the system can effectively purify lead -zinc ore wastewater. Unprocessed wastewater contains high concentrations of harmful metal lead, zinc, and cadmium after artificial wetlands, and the water quality of the water outlet has improved significantly. Among them, the purification rates of lead, zinc, and cadmium reached 99.0%, 97.%and 94.9%, and they were all in it, and they were all in Under the discharge standards of national industrial sewage. In addition, there are many herbal plants that have purification effects, such as Xilian Seed grass, water dragon, thorns, duckweed, and Indian mustard.
The use of wooden plants to deal with pollution water body. It has the advantages of good purification effect, large treatment volume, small affected by the climate, and is not easy to cause secondary pollution. It is more and more valued by people. The results of the tests such as Hu Huanbin showed that the two plants of reeds and Kisoto have strong enlightenment capabilities for heavy metal lead and cadmium, while the woody plant pilotmiper has a better purification effect than herbal reeds. Zhou Qing and others have studied the response of 5 kinds of evergreen trees on cadmium pollution. The experimental results show that under high concentration of cadmium coercion, the chlorophyll content of the 5 trees and leaves, cellular diaphragmist, peroxide activity, and cadmium rich album The physiological and biochemical characteristics of quantity have changed significantly. Among them, the poplar and tungs and fir cadmium anti -cadmium pollution capacity is better than that of camphor and winter green. The heavy metal wastewater treatment technology with wooden plants as the main body can cut off toxic and harmful substances into the food chain of the human body and livestock, avoid secondary pollution, can be cultivated or targeted. It is an ideal environmental repair method.

There are relatively common processing, including electrolytic, adsorption, ion exchange method, and directly cast heavy metal capture agents. I hope to help you ~