Arsenic containing wastewater treatment method

Abstract

The invention provides an arsenic containing wastewater treatment method.The arsenic containing wastewater treatment method includes steps: (1) adding a ferrous salt and an oxidizing agent into arsenic containing wastewater to obtain a solution A; (2) adding a ferric salt into the solution A, controlling a pH value of the arsenic containing wastewater to be 8-12 to obtain a solution B; (3) adding an organic flocculating agent and an inorganic flocculating agent, stirring, standing, and performing primary solid-liquid separation to separate a residue phase from a liquid phase.The arsenic containing wastewater treatment method has the advantages of low equipment requirement, simple technical process and low cost, the arsenic content of the treated wastewater completely reaches the national industrial wastewater discharge standards, residues of the treated wastewater are stable, and further hazards of arsenic toxicity are reduced.

Description

technical field [0001] The invention relates to a wastewater treatment method, in particular to a treatment method for arsenic-containing wastewater. Background technique [0002] Arsenic compounds are highly toxic and easily accumulate in the human body, causing chronic arsenic poisoning. Arsenic pollution poisoning incidents (acute arsenic poisoning) or public nuisance diseases (chronic arsenic poisoning) caused by arsenic pollution are not uncommon. Among them, drinking water arsenic poisoning is a common endemic disease. my country's high-arsenic water drinking areas involve about 30 counties (banners) in 10 provinces (regions) including Taiwan, Xinjiang, Inner Mongolia, Tibet, Yunnan, Guizhou, Shanxi, and Jilin. Endemic arsenic poisoning patients have appeared in these areas, and most of them are Few, marginal, poor and lack of low-arsenic water source areas. Arsenic is mainly in the form of inorganic arsenate (AsO 4 3- ) and arsenite (AsO 3 3- ), or exist in natur...

AI Technical Summary

Problems solved by technology

However, the above methods all require the addition of a large amount of chemical agents, resulting in a large amount of waste residue, and there is no good disposal method for these waste residues at present, and there is a problem of secondary pollution

The sulfide precipitation method uses a sulfurizing agent (Na 2 S, NaHS, etc.) react with arsenic ions in wastewater to form arsenic sulfide precipitation, so as to achieve the purpose of removing arsenic, but the sulfide precipitation method has very strict requirements on the pH value, and improper pH value control will cause arsenic to enter the water again and form Hydrogen sulfide, hydrogen sulfide is highly toxic, it will harm people and cause secondary pollution

[0005] Chinese patent (Application No.: 201310385447.0) discloses a treatment method for high-arsenic wastewater from copper smelting. An oxidant is introduced into the wastewater after precipitation to oxidize. After adding lime milk and flocculant to react, the solid-liquid is separated, and the clear liquid after treatment is The pH value is relatively high (9-12), and the arsenic concentration may not meet the industrial wastewater discharge standard (GB25466-2010), so it needs to be diluted with water before being discharged, and the amount of hydrogen peroxide is large (H 2 o 2 The ratio of the quality to the volume of high-arsenic wastewater from copper smelting is (0.1-10): 100g / ml), and the cost is relatively high

Chinese patent (application number: 201210090680.1) discloses a coupling treatment method for acidic high-arsenic wastewater, including precipitation of sulfate, oxidation precipitation, primary inclined plate sedimentation separation, oxidation stirring, secondary inclined plate sedimentation separation, iron salt coagulation, In steps such as air flotation and separation, pH adjustment and oxidation treatment are performed twice in the process, which requires a large amount of alkaline precipitant and oxidant, and the cost is relatively high

Chinese patent (Application No.: 96116742.4) provides a method for treating arsenic-containing wastewater. Using calcium compounds to adjust the pH value of wastewater to 12 or higher requires a large amount of slaked lime, which increases the cost and calcium hardness of the effluent, and the follow-up cost is relatively high. High, ferric chloride is selected as the iron salt, so that the chloride ion content in the effluent is also high

Chinese patent (Application No.: 201010165722.4) proposes a treatment method for low-concentration arsenic-containing wastewater. In its operation process, caustic soda solution is used to adjust the pH value and filter with a clean membrane, which greatly increases the cost.

Chinese patent (application number: 201110304407.X) discloses a treatment method for high-concentration arsenic-containing wastewater, involving pH neutralization adjustment, oxidation precipitation (I), oxidation precipitation (II), iron salt coagulation, air flotation separation, etc. step, which uses a large amount of lime milk and oxidant, and multiple solid-liquid separations, increasing the input of raw materials and equipment

Chinese patent (application number: 201310025352.8) discloses a treatment method for arsenic-containing wastewater. Continuous treatment is performed by adding sulfide in multiple stages to remove metalloid arsenic in wastewater, and the wastewater is deeply treated by electrochemical and aeration oxidation precipitation. Treatment, the use of sodium sulfide to remove arsenic may cause the escape of hydrogen sulfide gas, which will cause personal injury to the operator and cause secondary pollution, and the price of sodium sulfide is relatively expensive, and the subsequent electrochemical method and aeration precipitation will increase the cost

Chinese patent (application number: 201110308990.1) proposes an advanced treatment method for arsenic-containing wastewater and arsenic-contaminated groundwater or drinking water. The arsenic content in the treated water can reach the drinking water standard stipulated by the World Health Organization, but it is only for lower concentrations. Arsenic-containing wastewater (according to the embodiment, the highest arsenic concentration is only 102ppm), for high-concentration arsenic-containing wastewater, the arsenic removal effect is not ideal enough

Chinese patent (application number: 200910312545.5) proposes a treatment method for high-arsenic and high-alkali wastewater, adding ferrous sulfate and oxidant under aeration conditions, adding polymerized ferric sulfate to the clear liquid after solid-liquid separation to flocculate, and controlling the concentration of the solution pH, solid-liquid separation after standing, clear liquid is discharged, the arsenic concentration after treatment can reach the national surface water level III water standard, but it needs aeration and artificial acid addition to control the pH of the effluent, which greatly increases the cost

Chinese patent (Application No.: 201510212060.4) relates to a treatment method for industrial arsenic-containing wastewater. It adopts a two-stage treatment method. First, it is neutralized with lye until the pH end point of the wastewater is greater than 5 to obtain a section of treated water, and then to a section of treated water. Add polyferron and oxidant to control the end point of the second-stage treatment water to be greater than 5, but it is only limited to the treatment of low-arsenic wastewater (4-30ppm), no experiment has been conducted on high-arsenic wastewater, and the arsenic content in the second-stage effluent may still be higher than 0.3 ppm (embodiment one, three, five), failed to meet emission standards

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