A combined treatment process for treating acidic mine wastewater with high manganese content

Abstract

This invention discloses a combined treatment process for treating acidic mine wastewater with high manganese content. First, the acidic mine wastewater is transported to a pre-precipitation tank where hydrogen sulfide gas is introduced for pre-precipitation. The supernatant from the pre-precipitation tank is then transported to a biomineralization tank for biomineralization treatment. The effluent from the biomineralization tank is fed into a pH adjustment tank for neutralization. The mixed wastewater, after pH adjustment, is then fed into a flocculation sedimentation tank for further treatment. The supernatant from the flocculation sedimentation tank is fed into a settling tank where oxalic acid is added to adjust the pH to between 7 and 8. Finally, the effluent from the settling tank is fed into a deep desulfurization tank for deep desulfurization. This invention utilizes a physical-chemical-biological-micro-electro-coupled process for wastewater treatment, which overcomes the shortcomings of acidic mine wastewater effluent failing to meet heavy metal standards and high desulfurization costs. Simultaneously, it can recover byproducts such as styrene minerals and heavy metal sulfides, ensuring efficient and energy-saving maintenance of stable effluent compliance from mine acidic wastewater treatment facilities.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a combined treatment process for acidic mine wastewater, suitable for applications with pH values ​​between 2.6 and 3.9, containing Mn, Cu, Fe, Zn, Al, and SO4. 2- This treatment method is particularly suitable for acidic mine wastewater with excessive levels of certain substances, especially those with pH values ​​between 2.6 and 3.9, Mn content between 250 and 350 mg / L, Cu content between 12 and 30 mg / L, Fe content between 50 and 95 mg / L, Zn content between 0.5 and 4.5 mg / L, Al content between 200 and 400 mg / L, and SO4 content between [unclear - possibly related to a specific concentration or level]. 2- Treatment of acidic mine wastewater with concentrations of 4000~7000 mg / L. Background Technology

[0002] Acid mine wastewater (AMD) is a common environmental problem in mining activities. It is mainly caused by the oxidation of sulfide minerals (such as pyrite FeS2) when exposed to air and water, producing sulfuric acid, iron ions, and heavy metal pollutants. This wastewater is highly acidic (pH typically 2-4) and contains high concentrations of heavy metals such as copper, lead, and zinc, causing serious harm to the ecological environment, soil quality, and infrastructure. For example, it poisons aquatic life, damages soil structure, and corrodes metal facilities. Due to its acidity, high heavy metal content, and high sulfate content, if not properly treated, acid mine wastewater not only pollutes water bodies but also restricts or reduces biodiversity. Heavy metals can also enter the ecosystem through bioaccumulation, thus accumulating in the human body through the food chain and causing chronic heavy metal poisoning. Furthermore, excessive sulfate levels can lead to soil degradation, reducing crop yields or even causing crop failure.

[0003] For the treatment of acidic mine wastewater, two main types of technologies are currently employed: passive and active. Passive treatment technologies include constructed wetlands and limestone neutralization ditches, which utilize natural or semi-natural systems to reduce pollution through sedimentation, adsorption, and neutralization. These technologies are suitable for low-flow, long-term treatment scenarios. Active treatment technologies rely on chemical agents (such as lime and sodium hydroxide) to rapidly neutralize acidity and remove heavy metals through precipitation, or utilize microorganisms (such as sulfate-reducing bacteria) to convert sulfates into sulfides under anaerobic conditions, while simultaneously immobilizing heavy metals. In addition, resource recovery technologies such as selective precipitation and membrane separation can extract valuable metals from wastewater, but these are costly.

[0004] Lime neutralization is currently the mainstream technology for treating acidic mine wastewater, and it can simultaneously remove most heavy metals and sulfate ions. Its principle is to increase the pH value of the acidic wastewater through acid-base neutralization by adding lime, while simultaneously allowing heavy metal ions to react with OH- ions. - A reaction occurs, forming a sparingly soluble hydroxide precipitate, and some SO42-. 2- With Ca 2+Wastewater is purified by the precipitation of waste gypsum. However, since the solubility of calcium sulfate at room temperature is approximately 2.4 g / L, the sulfate concentration in the effluent from acidic mining wastewater treated by lime neutralization is typically in the range of 2000-3000 mg / L. Currently, the commonly used methods for removing sulfate are chemical precipitation and biological methods. Chemical precipitation mainly removes sulfate by adding barium or aluminum salts to generate barium sulfate or ettringite, but barium and aluminum salts are expensive, and barium salts are highly toxic. Biological methods remove sulfate using sulfate-reducing bacteria, but biological treatment requires the addition of a large amount of carbon source, is slow, and results in high treatment costs.

[0005] Chinese patent application 202010173123.0 discloses a process and system for treating acidic mine wastewater. The process includes the following steps: adjusting the water quality and quantity of the acidic mine wastewater to be treated in an equalization tank; aerating the effluent from the equalization tank in an aeration tank to react the first part of the metal elements in the effluent into metal oxides; removing the metal oxides from the effluent from the aeration tank through sedimentation in a sedimentation tank; and removing at least part of the second part of the metal elements from the effluent from the sedimentation tank through a permeable reactive barrier. However, the wastewater treated by this process is mine inflow water, with a manganese content that is only slightly above the standard (manganese concentration of 4.5 mg / L). The content of metal ions such as Cu, Fe, Zn, and Al is low, making it easily treatable acidic wastewater. If the manganese concentration exceeds 50 mg / L, the content of Cu, Fe, Zn, Al, and SO42- in the wastewater will increase significantly. 2- This process cannot effectively treat acidic mine wastewater that exceeds the standards.

[0006] Therefore, there is an urgent need to develop a low-cost, high-efficiency, and stable effluent treatment method capable of efficiently treating Mn, Cu, Fe, Zn, Al, and SO4. 2- Methods for addressing acidic mine wastewater with severely excessive levels of certain substances. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies, such as difficulty in treating acidic mine wastewater with high manganese content, difficulty in achieving heavy metal standards in the treated wastewater, large amounts of reagents used, high treatment costs, and large amounts of sludge generated. This invention provides a combined treatment process for treating acidic mine wastewater with high manganese content. This combined treatment process can not only ensure stable compliance of the effluent from the mine acidic wastewater treatment facility with high efficiency and energy saving, but also recover by-products such as styrene minerals and sulfide heavy metals.

[0008] To achieve the above-mentioned objectives of this invention, a combined treatment process for treating acidic mine wastewater with high manganese content is provided, which is implemented by the following steps:

[0009] (1) Pre-precipitation: Pre-precipitate the soil with pH 2.6~3.9, Mn concentration ≥100mg / L, and SO42-.2- Acidic mining wastewater with a concentration ≥3000 mg / L is transported to a pre-precipitation tank where hydrogen sulfide gas is introduced for pre-precipitation. The wastewater retention time in the pre-precipitation tank is 20-40 minutes. The amount of hydrogen sulfide gas introduced depends on the pH of the acidic mining wastewater and the concentrations of Mn, Cu, Fe, Zn, Al, and SO42-. 2- The concentration is determined by calculation. During pre-sedimentation, some heavy metal ions, such as copper and mercury, can be removed from the wastewater. Heavy metal sulfides generated at the bottom of the tank can be sent to the flotation process for heavy metal recovery.

[0010] (2) Biomineralization: The supernatant in the pre-sedimentation tank is transferred to the biomineralization tank for biomineralization treatment. The biomineralization tank contains uniformly suspended carbon fiber packing material with good electrical conductivity, and an aeration disc is installed at the bottom. The supernatant stays in the biomineralization tank for 30-50 minutes, and the dissolved oxygen level is controlled at 1.5-4 mg / L. The carbon fiber packing material is pre-treated with *Thiobacillus ferrooxidans* (At.f.). During this process, under the influence of oxygen and At.f., the ferrous iron in the wastewater is oxidized to ferric iron or Scheringer's mineral (an iron hydroxyl sulfate mineral) or other iron oxide precipitates. Scheringer's mineral or other iron oxide precipitates can be recycled as adsorbents or pigments.

[0011] (3) pH control: The effluent from the biomineralization tank is fed into the pH control tank for neutralization reaction. The pH value is raised to above 10 by adjusting the dosage of alkaline drugs. The effluent from the biomineralization tank stays in the pH control tank for 40-60 minutes.

[0012] (4) Flocculation and sedimentation: The mixed wastewater, after being adjusted by the pH control tank, is fed into the flocculation and sedimentation tank. A pipeline mixer is installed at the inlet end of the flocculation and sedimentation tank, and flocculant polyacrylamide (PAM) is added to the pipeline mixer. After sedimentation in the sedimentation zone of the flocculation and sedimentation tank, the fed mixed wastewater is divided into an upper clear water layer, a middle sludge layer, and a bottom sludge layer. A sludge outlet is provided at the bottom of the sedimentation zone of the flocculation and sedimentation tank. In this process, most of the heavy metals and some sulfate can be removed from the wastewater.

[0013] (5) Acid adjustment: Add oxalic acid to the supernatant of the flocculation sedimentation tank into the adjustment tank to adjust the pH value to between 7 and 8.

[0014] (6) Deep desulfurization: The effluent from the return tank is fed into the deep desulfurization tank for deep desulfurization. The effluent from the return tank stays in the deep desulfurization tank for no less than 20 hours, achieving a pH of 7-9, and the concentrations of each pollutant are Mn 0.08-1.5 mg / L, Cu < 0.006 mg / L, Fe 0.04-0.2 mg / L, Zn < 0.006 mg / L, Al 0.27-0.98 mg / L, SO42-0.27 mg / L, and SO42-0.27 mg / L. 2-The effluent concentration is ≤1300 mg / L; the deep desulfurization tank is uniformly filled with carbon fiber packing material with good conductivity, and an exhaust pipe is installed at the top of the deep desulfurization tank. The hydrogen sulfide gas generated in the deep desulfurization tank is circulated to the pre-sedimentation tank in step (1) through the exhaust pipe; the carbon fiber packing material is pre-treated with sulfate-reducing bacteria for microbial biofilm formation. Under anaerobic conditions, sulfate-reducing bacteria reduce sulfate to divalent sulfur ions through dissimilatory reactions, thereby generating sulfides or hydrogen sulfide. This step can deeply remove sulfate ions and residual heavy metals from the wastewater.

[0015] Furthermore, in step (2), the top of the packing material in the two reaction chambers of the biomineralization tank is connected to the anode and cathode of the micro power supply by electric wires, respectively. The micro power supply provides a small DC current of 5~30mA. There is a connection hole between the side walls of the two reaction chambers of the biomineralization tank. There is also a connection hole on the side wall of the deep desulfurization tank in step (6). A proton exchange membrane is installed in the two connection holes.

[0016] Furthermore, in step (6), the tops of the packing material in the two reaction chambers of the deep desulfurization tank are respectively connected to the anode and cathode of the micro power supply by electrical wires, and the micro power supply provides a small amount of DC current of 5~30mA.

[0017] Furthermore, 28% to 36% of the sediment in the bottom sediment layer of step (4) is returned to the pH adjustment tank of step (3) to improve the utilization rate of alkaline agents; the remaining sediment is discharged into the sludge tank for subsequent pressure filtration treatment.

[0018] Furthermore, in step (3), the pH control tank is equipped with a stirring device with a rotation speed of not less than 400 r / min; the alkaline agent is any one or any two or more of quicklime, hydrated lime, and sodium hydroxide.

[0019] Preferably, the acidic mine wastewater fed in step (1) has a pH of 2.6-3.9, a Mn content of 250-350 mg / L, a Cu content of 12-30 mg / L, a Fe content of 50-95 mg / L, a Zn content of 0.5-4.5 mg / L, an Al content of 200-400 mg / L, and an SO4 content of [missing information]. 2- The content is 4000~7000mg / L; step (6) obtains a pH of 7~9, and the concentrations of each pollutant are Mn 0.08~1.5mg / L, Cu <0.006mg / L, Fe 0.04~0.2mg / L, Zn <0.006mg / L, Al 0.27~0.98mg / L, SO4 2- 800~1300 mg / L of effluent.

[0020] Compared with existing technologies, this invention provides a combined treatment process for treating acidic mine wastewater with high manganese content. Through a physicochemical-biological-micro-electrostatic coupling process, it addresses the shortcomings of acidic mine wastewater treatment, such as difficulty in achieving heavy metal standards and high desulfurization costs. Simultaneously, it can recover byproducts such as styrene minerals and heavy metal sulfides, ensuring efficient and energy-saving maintenance of stable effluent compliance from mine acidic wastewater treatment facilities. Specifically, it offers the following beneficial effects:

[0021] (1) The present invention adopts a physical-chemical-biological micro-electric coupling process, which can effectively increase the pH value of wastewater and remove heavy metals and sulfate from the water. On the other hand, the styrene minerals and heavy metal sulfides generated in the process of treating wastewater can be used as recyclable resources, thereby improving resource utilization and reducing desulfurization costs.

[0022] (2) The present invention adopts a micro-electrochemical catalytic process, which can provide oxygen in the biomineralization stage, reduce the aeration volume, and reduce the energy consumption of the blower. On the other hand, it can catalyze the reduction process of sulfate-reducing bacteria in the deep desulfurization stage, reduce the total amount of organic matter required for the sulfate reduction process, and the power consumption required by the micro-current power supply is quite small and can be ignored. Therefore, the water treatment facility using the process of the present invention can reduce the treatment cost and the amount of reagent used is small, which is especially suitable for the treatment of acidic mine wastewater with high sulfate concentration.

[0023] (3) The sludge generated by the flocculation sedimentation tank of the present invention is returned to the pH control tank, which can improve the utilization rate of alkaline agents and reduce the consumption of alkaline agents, sludge amount and sludge moisture content compared with the traditional neutralization method.

[0024] (4) Experimental studies have shown that when the pH of the fed acidic mine wastewater is 2.6~3.9, the Mn content is 250~350mg / L, the Cu content is 12~30mg / L, the Fe content is 50~95mg / L, the Zn content is 0.5~4.5mg / L, the Al content is 200~400mg / L, and the SO4 content is high, the water quality is suitable for the following conditions: 2- With a concentration of 4000-7000 mg / L, the final results showed a pH of 7-9 and concentrations of each pollutant as follows: Mn 0.08-1.5 mg / L, Cu < 0.006 mg / L, Fe 0.04-0.2 mg / L, Zn < 0.006 mg / L, Al 0.27-0.98 mg / L, and SO42-0.98 mg / L. 2- 800~1300 mg / L of effluent. Attached Figure Description

[0025] Figure 1 This is a schematic flowchart of a combined treatment process for treating acidic mine wastewater with high manganese content, according to the present invention. Detailed Implementation

[0026] To further understand the content of this invention, it is described in detail below with reference to the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] Example

[0028] The embodiments utilize the method of the present invention to treat acidic mine wastewater. The present invention will be further illustrated below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The process of this invention was used to treat acidic mine wastewater from a certain mine. The specific treatment process is as follows, and the influent and effluent water quality are shown in Table 1.

[0030] (1) Pre-precipitation: Acidic mine wastewater is transported to a pre-precipitation tank for pre-precipitation, and hydrogen sulfide gas is introduced into the pre-precipitation tank. The wastewater retention time in the pre-precipitation tank is 30 minutes.

[0031] (2) Biomineralization: The supernatant in the pre-sedimentation tank is transferred to the biomineralization tank for biomineralization treatment. The biomineralization tank contains uniformly suspended carbon fiber packing material with good electrical conductivity, and an aeration disc is installed at the bottom. The wastewater retention time in the biomineralization tank is approximately 30 minutes, and the dissolved oxygen is controlled at 1.5~4 mg / L. The carbon fiber packing material is pre-treated with *Thiobacillus ferrooxidans* (At.f.) for microbial biofilm formation. The top of the packing material is connected to the anode of a micro-power source via an electrical conductor.

[0032] (3) pH control: The effluent from the biomineralization tank enters the pH control tank for neutralization reaction. An alkaline agent is added to the pH control tank to raise the pH value of the wastewater to above 10. The pH control tank is equipped with a stirring device with a rotation speed of not less than 400 r / min and the wastewater retention time is about 40 min. The alkaline agent used is slaked lime.

[0033] (4) Flocculation and sedimentation: The mixed wastewater from the pH control tank enters the flocculation and sedimentation tank. A pipeline mixer is installed at the inlet of the flocculation and sedimentation tank, and polyacrylamide (PAM) is added to the pipeline mixer. One-third of the sludge from the flocculation and sedimentation tank is returned to the pH control tank. The sedimentation time is 2 hours.

[0034] (5) Acid adjustment: Add 5% oxalic acid solution to the supernatant of the flocculation sedimentation tank into the adjustment tank to adjust the pH value to between 7 and 8.

[0035] (6) Deep desulfurization: The effluent from the return tank enters the deep desulfurization tank for deep desulfurization. The wastewater retention time is not less than 20 hours. The deep desulfurization tank is uniformly filled with carbon fiber packing material with good conductivity. An exhaust pipe is installed at the top of the deep desulfurization tank, and the hydrogen sulfide gas generated in the deep desulfurization tank is vented to the pre-precipitation tank through the exhaust pipe. The carbon fiber packing material is pre-treated with sulfate-reducing bacteria to form a microbial biofilm. The top of the packing material is connected to the cathode of the micro power supply by an electric wire. There is a connection hole between the side walls of the two reaction chambers of biomineralization and deep desulfurization. A proton exchange membrane is installed in the connection hole. The micro power supply provides a micro DC current of 20mA.

[0036] Comparative Example

[0037] To better compare treatment effects, the traditional lime neutralization method was used as a control to treat the acidic wastewater from the mine. The treatment steps for the control were as follows:

[0038] Wastewater is pumped by a peristaltic pump to a neutralization reaction bottle for neutralization. The stirring rate is set to 400 r / min, and the dosing rate of the alkaline neutralizing agent is adjusted to stabilize the pH of the effluent between 9.8 and 10.2. The alkaline agent is 10% quicklime slurry, and the neutralization residence time is 0.5 h. The effluent then enters a flocculation bottle for flocculation. The flocculant dosage is 2 mg / L, and the stirring rate is set to 100 r / min. The effluent then enters an inclined plate sedimentation tank for sedimentation, with a residence time of 2 h. The effluent then enters the neutralization bottle for neutralization. A 5% oxalic acid solution is used for acid correction. The dosing rate of the dilute acid peristaltic pump is set to maintain the pH of the effluent from the acid correction bottle between 6 and 9. The effluent then enters an effluent tank.

[0039] Table 1. Influent and Effluent Water Quality of Examples and Comparative Examples

[0040]

[0041] As shown in Table 1, the acidic mine wastewater treated in the examples had a pH of only 2.8-3.3, while the Mn content was as high as 270-296 mg / L, and SO4 content was also high. 2- The concentration of pollutants is as high as 4500-6000 mg / L, with high levels of other elements such as Cu, Fe, Zn, and Al, making it an extremely difficult-to-treat acidic mine wastewater. In the examples, the method of this invention was used to treat a certain acidic mine wastewater, ultimately yielding a solution with a pH of 7-9 and the following concentrations of pollutants: Mn 0.08-1.5 mg / L, Cu < 0.006 mg / L, Fe 0.04-0.2 mg / L, Zn < 0.006 mg / L, Al 0.27-0.98 mg / L, and SO42-0.98 mg / L. 2-The effluent concentration of 800-1300 mg / L exceeded the requirements of the emission standard for pollutants from iron ore mining and beneficiation industry, GB 28661-2012, achieving unexpected technical results. In contrast, the traditional lime neutralization method resulted in effluent with Mn content frequently exceeding the standard, and the sulfur reduction effect was not significant.

Claims

1. A combined treatment process for treating acidic mine wastewater with high manganese content, characterized in that... The following steps are to be taken: (1) Pre-precipitation: Pre-precipitate the soil with pH 2.6~3.9, Mn concentration ≥100mg / L, and SO42-. 2- Acidic mining wastewater with a concentration ≥3000 mg / L is transported to a pre-sedimentation tank where hydrogen sulfide gas is introduced for pre-sedimentation. The wastewater retention time in the pre-sedimentation tank is 20-40 minutes, and the amount of hydrogen sulfide gas introduced is determined based on the pH of the acidic mining wastewater and the concentrations of Mn, Cu, Fe, Zn, Al, and SO42-. 2- The content level is determined by calculation. (2) Biomineralization: The supernatant in the pre-sedimentation tank is transported to the biomineralization tank for biomineralization treatment. The biomineralization tank is filled with carbon fiber packing material with good conductivity. An aeration disc is set at the bottom of the biomineralization tank. The residence time of the supernatant in the biomineralization tank is 30-50 min. The dissolved oxygen in the biomineralization tank is controlled at 1.5-4 mg / L. The carbon fiber packing material is pre-treated with microbial biofilm by Acidithiobacillus ferrooxidans. (3) pH control: The effluent from the biomineralization tank is fed into the pH control tank for neutralization reaction. The pH value is raised to above 10 by adjusting the dosage of alkaline drugs. The effluent from the biomineralization tank stays in the pH control tank for 40-60 minutes. (4) Flocculation and sedimentation: The mixed wastewater that has been adjusted by the pH adjustment tank is fed into the flocculation and sedimentation tank. A pipeline mixer is installed at the inlet end of the flocculation and sedimentation tank. Flocculant polyacrylamide is added to the pipeline mixer. After the mixed wastewater is settled in the sedimentation zone of the flocculation and sedimentation tank, it is divided into an upper clear water layer, a middle sludge layer and a bottom sludge layer. A sludge outlet is provided at the bottom of the sedimentation zone of the flocculation and sedimentation tank. (5) Acid adjustment: Add oxalic acid to the supernatant of the flocculation sedimentation tank into the adjustment tank to adjust the pH value to between 7 and 8; (6) Deep desulfurization: The effluent from the return tank is fed into the deep desulfurization tank for deep desulfurization. The effluent from the return tank stays in the deep desulfurization tank for no less than 20 hours, achieving a pH of 7-9, and the concentrations of each pollutant are Mn 0.08-1.5 mg / L, Cu < 0.006 mg / L, Fe 0.04-0.2 mg / L, Zn < 0.006 mg / L, Al 0.27-0.98 mg / L, SO42-0.27 mg / L, and SO42-0.27 mg / L. 2- The effluent concentration is ≤1300mg / L; the carbon fiber filler with good conductivity is evenly suspended in the deep desulfurization tank, and an exhaust pipe is set at the top of the deep desulfurization tank. The hydrogen sulfide gas generated in the deep desulfurization tank is circulated to the pre-sedimentation tank in step (1) through the exhaust pipe; the carbon fiber filler is pre-coated with sulfate-reducing bacteria.

2. The combined treatment process for treating acidic mine wastewater with high manganese content as described in claim 1, characterized in that: In step (2), the top of the packing is connected to the anode of the micro power source by an electric wire. In step (6), the top of the packing is connected to the cathode of the micro power source by an electric wire. There is a connection hole between the side walls of the two reaction chambers of biomineralization and deep desulfurization. A proton exchange membrane is installed in the connection hole. The micro power source provides a micro DC current of 20mA.

3. The combined treatment process for treating acidic mine wastewater with high manganese content as described in claim 2, characterized in that: 28% to 36% of the sediment in the bottom sediment layer of step (4) is returned to the pH adjustment tank of step (3), and the remaining sediment is discharged into the sludge tank for subsequent pressure filtration treatment.

4. The combined treatment process for treating acidic mine wastewater with high manganese content as described in claim 3, characterized in that: In step (3), the pH control tank uses a stirring device with a rotation speed of not less than 400 r / min.

5. The combined treatment process for treating acidic mine wastewater with high manganese content as described in claim 4, characterized in that: In step (3), the alkaline agent is any one or any two or more of quicklime, hydrated lime, and sodium hydroxide.

6. The combined treatment process for treating acidic mine wastewater with high manganese content as described in claim 5, characterized in that: Step (1) The acidic mine wastewater fed in has a pH of 2.6-3.9, a Mn content of 250-350 mg / L, a Cu content of 12-30 mg / L, a Fe content of 50-95 mg / L, a Zn content of 0.5-4.5 mg / L, an Al content of 200-400 mg / L, and an SO4 content of [missing information]. 2- The content is 4000~7000mg / L; step (6) obtains a pH of 7~9, and the concentrations of each pollutant are Mn 0.08~1.5mg / L, Cu <0.006mg / L, Fe 0.04~0.2mg / L, Zn <0.006mg / L, Al 0.27~0.98mg / L, SO4 2- 800~1300 mg / L of effluent.

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