Pretreatment method of high-salt organic matter heavy metal wastewater

Abstract

The invention provides a pretreatment method of high-salt organic matter heavy metal wastewater. The pretreatment method comprises the following steps: S1, carrying out catalytic ozonation on the heavy metal wastewater, and carrying out solid-liquid separation to obtain oxidized effluent; the heavy metal wastewater contains sulfate ions, chloride ions and nickel ions, the COD (Chemical Oxygen Demand) of the heavy metal wastewater is 500-1000mg / L, and the TOC (Total Organic Carbon) of the heavy metal wastewater is 100-300mg / L; the pH value of the heavy metal wastewater is 4-5; the catalytic ozonation comprises the following steps: adding an ozone catalyst into the heavy metal wastewater, and introducing ozone into the heavy metal wastewater; and S2, neutralizing and precipitating the oxidized effluent, and carrying out solid-liquid separation to obtain precipitated effluent. On the basis of the high-salt organic matter heavy metal wastewater, heavy metal nickel and organic matter can be removed in advance, COD and TOC values are reduced, and nickel is greatly removed under the condition that the dosage of chemicals is small.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and more particularly to a pretreatment method for high-salt organic and heavy metal wastewater. Background Technology

[0002] The extraction wastewater from the ternary lithium battery industry is complex, classified as high-salt, organic, and heavy metal wastewater. Its treatment process is lengthy and challenging, and conventional biological methods are insufficient for effective treatment. With increasingly stringent environmental regulations, the recovery of inorganic salt resources and achieving zero wastewater discharge are gradually becoming necessary conditions for industry access or environmental impact assessment approval in the ternary lithium battery industry. Organic matter and heavy metals in the wastewater can affect the crystal form, yield, and whiteness of inorganic salt products, and can also cause scaling in evaporation and salt extraction equipment. Therefore, it is essential to conduct proper pretreatment of the extraction wastewater from the ternary lithium battery industry to remove heavy metals and organic matter.

[0003] High-salt organic heavy metal wastewater originating from the extraction wastewater of the ternary lithium battery industry contains large amounts of sulfate ions, chloride ions, and heavy metal nickel ions. Pretreatment of nickel ions in this wastewater is necessary. Neutralization precipitation is a conventional method for removing nickel from wastewater. Generally, adjusting the pH to above 9 with an alkaline precipitant and performing a precipitation reaction can achieve a nickel removal rate of over 90%. However, due to the complex composition of high-salt organic heavy metal wastewater, excessive alkaline precipitants are often required for nickel removal, and even with excessive precipitants, it is still difficult to achieve the same nickel removal rate as conventional neutralization precipitation. Furthermore, during the pretreatment of high-salt organic heavy metal wastewater, a large amount of organic matter also needs to be removed beforehand to ensure subsequent advanced treatment.

[0004] Therefore, it is necessary to provide a pretreatment method for high-salt organic heavy metal wastewater to solve or at least alleviate the technical problem of how to pre-remove heavy metal nickel and organic matter from high-salt organic heavy metal wastewater. Summary of the Invention

[0005] The main objective of this invention is to provide a pretreatment method for high-salt organic heavy metal wastewater, aiming to solve the aforementioned technical problem of how to pre-remove heavy metal nickel and organic matter from high-salt organic heavy metal wastewater.

[0006] To achieve the above objectives, the present invention provides a pretreatment method for high-salt organic heavy metal wastewater, comprising the following steps: S1, ozone catalytic oxidation of heavy metal wastewater, followed by solid-liquid separation to obtain oxidized effluent; The heavy metal wastewater contains sulfate ions, chloride ions, and nickel ions. The COD of the heavy metal wastewater is 500~1000 mg / L, the TOC is 100~300 mg / L, and the pH of the heavy metal wastewater is 4~5. The ozone catalytic oxidation includes: adding an ozone catalyst to the heavy metal wastewater, and introducing ozone into the heavy metal wastewater; S2, neutralize and precipitate the oxidized effluent, and obtain precipitated effluent after solid-liquid separation; The neutralization precipitation includes: adjusting the pH of the oxidized effluent to 10-12 using an alkaline precipitant before carrying out the precipitation reaction.

[0007] Furthermore, in the heavy metal wastewater, the concentration of sulfate ions is 50~150 g / L, the concentration of chloride ions is 5~20 g / L, and the concentration of nickel ions is 100~500 mg / L.

[0008] Furthermore, the ozone is introduced into the heavy metal wastewater for 0.5 to 3 hours.

[0009] Furthermore, during the process of introducing ozone into the heavy metal wastewater, the ozone introduction rate is 10~100 mg / min; During the process of introducing ozone into the heavy metal wastewater, the circulation of the heavy metal wastewater is controlled.

[0010] Furthermore, the ozone catalyst includes a support and an active component supported on the support; the active component includes one or more of a single metal and a composite metal.

[0011] Furthermore, the solid-liquid ratio of the ozone catalyst and the heavy metal wastewater is 0.02~0.4 g / mL.

[0012] Furthermore, the alkaline precipitant includes lime milk; the mass concentration of the lime milk is 8-12%.

[0013] Furthermore, the lime slurry is prepared using calcium oxide; the ratio of calcium oxide to the heavy metal wastewater is 1~2 g / L.

[0014] Furthermore, the pH of the oxidized effluent is adjusted to 11-12 using the alkaline precipitant before the precipitation reaction is carried out.

[0015] Furthermore, the precipitation reaction takes 0.5 to 2 hours.

[0016] Compared with the prior art, the present invention has at least the following advantages: This invention addresses high-salt, organic-laden, and heavy-metal wastewater, enabling the pre-removal of heavy metals like nickel and organic matter, reducing COD and TOC values, and achieving significant nickel removal with relatively low reagent dosage. The invention utilizes ozone catalytic oxidation followed by neutralization and precipitation. This not only pre-removes organic matter but also significantly raises the pH of the oxidized effluent to 8-9, reducing the required pH increase for neutralization and precipitation and conserving alkaline precipitant dosage. Furthermore, ozone catalytic oxidation also breaks down complexes, further improving heavy metal removal and reagent utilization. After ozone catalytic oxidation, the invention allows for significant nickel removal at even lower pH conditions, further reducing the amount of alkaline precipitant needed and increasing the nickel removal rate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This invention analyzes the calcium oxide dosage comparison between directly adding lime slurry to raw water and first catalytically oxidizing (oxidizing the water) and then adding lime slurry in Example 1. In the figure, lime neutralization corresponds to directly adding lime slurry to raw water, and oxidation-lime neutralization corresponds to first catalytically oxidizing ozone and then adding lime slurry. Figure 2 This invention analyzes the nickel removal effect of adding lime slurry directly to the raw water versus first catalytic oxidation with ozone (oxidizing the water) followed by adding lime slurry in Example 2. In the figure, lime neutralization corresponds to adding lime slurry directly to the raw water, while oxidation-lime neutralization corresponds to first catalytic oxidation with ozone followed by adding lime slurry. Figure 3 The change of pH with ozone catalytic oxidation reaction time was analyzed in Example 3 of this invention.

[0019] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0021] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0022] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0023] As an illustration of other prior art, Chinese invention patent application CN103043834A discloses a wastewater treatment process for rare earth smelting, which belongs to the treatment scheme for high-salt organic heavy metal wastewater from rare earth smelting. It employs a combined wastewater treatment process of "micro-electrolysis-dephosphorization-heavy metal removal-advanced oxidation," achieving compliant wastewater discharge. However, this process generates a large amount of slag and wastes valuable metals and inorganic salts in the wastewater. Chinese utility model patent CN221166322U discloses a wastewater treatment system for ternary lithium battery recovery, which uses a "oil removal-biochemical treatment-adsorption-fluoride recovery-evaporation" process to effectively reduce COD and fluoride in the wastewater and recover fluoride and sodium sulfate resources. However, biochemical treatment is easily affected by water quality fluctuations and has limited effectiveness for wastewater with excessively high salinity. Therefore, current treatment processes for high-salt organic heavy metal wastewater have limitations, and there is an urgent need to develop a short-process technology that balances cost and resource recycling.

[0024] This invention provides a pretreatment method for high-salt organic heavy metal wastewater, comprising the following steps: S1, ozone catalytic oxidation of heavy metal wastewater, followed by solid-liquid separation to obtain oxidized effluent.

[0025] In this invention, the heavy metal wastewater contains sulfate ions, chloride ions, and nickel ions. The COD of the heavy metal wastewater is 500~1000 mg / L, more specifically 800~850 mg / L; the TOC is 100~300 mg / L, more specifically 150~250 mg / L; and the pH of the heavy metal wastewater is 4~5, more specifically 4~4.5.

[0026] In some embodiments of the present invention, the concentration of sulfate ions in the heavy metal wastewater is 50-150 g / L, more specifically 90-110 g / L; the concentration of chloride ions is 5-20 g / L, more specifically 8-10 g / L; the concentration of nickel ions is 100-500 mg / L, more specifically 250-350 mg / L; and the concentration of other heavy metals (cobalt, manganese, copper, zinc) is <0.5 mg / L.

[0027] The ozone catalytic oxidation includes: adding an ozone catalyst to the heavy metal wastewater, and introducing ozone into the heavy metal wastewater.

[0028] In some embodiments of the present invention, the ozone catalyst includes a support and an active component supported on the support; the active component includes one or more of a single metal and a composite metal; the support includes or is activated carbon, and the single metal includes or is iron; the mass fraction of the single metal loaded on the support is 1 to 2%, more specifically 1.4 to 1.5%.

[0029] The solid-liquid ratio of the ozone catalyst and the heavy metal wastewater is 0.02~0.4 g / mL, further 0.1~0.4 g / mL, 0.16~0.32 g / mL, 0.15~0.17 g / mL, or 0.3~0.35 g / mL.

[0030] In some embodiments of the present invention, ozone is introduced into the heavy metal wastewater for 0.5 to 3 hours, more specifically 1.5 to 2 hours, 1.4 to 1.6 hours, or 1.9 to 2.1 hours; the ozone catalytic oxidation of the present invention is carried out at room temperature.

[0031] In some embodiments of the present invention, during the process of introducing ozone into the heavy metal wastewater, the ozone introduction rate is 10~100 mg / min, and more specifically 20~30 mg / min; in the present invention, the ozone generator may be a gas source generator or an electrochemical generator.

[0032] In this invention, during the process of introducing ozone into the heavy metal wastewater, the circulation of the heavy metal wastewater is controlled; specifically, the water circulation reaction is achieved through a pump.

[0033] In this invention, after ozone catalytic oxidation, the pH of the oxidized effluent is 8-9, further 8.5-9, and further 8.5-8.7; compared with the heavy metal wastewater, the pH is significantly increased.

[0034] S2, the oxidized effluent is neutralized and precipitated, and the precipitated effluent is obtained after solid-liquid separation.

[0035] In this invention, the neutralization precipitation includes: adjusting the pH of the oxidized effluent to 10-12 using an alkaline precipitant before carrying out the precipitation reaction.

[0036] In some embodiments of the present invention, the alkaline precipitant includes lime milk or sodium hydroxide; preferably, the alkaline precipitant includes or is lime milk; the mass concentration of the lime milk is 8-12%. The lime milk is prepared using calcium oxide; the ratio of the calcium oxide to the heavy metal wastewater is 1-2 g / L, further 1-1.6 g / L, 1-1.2 g / L, or 1.5-1.6 g / L.

[0037] In some embodiments of the present invention, the pH of the oxidized effluent is adjusted to 11-12 (further 11-11.2, 11.5-12, or 11.8-12) using the alkaline precipitant before the precipitation reaction is carried out.

[0038] In some embodiments of the present invention, the precipitation reaction time is 0.5-2 h, more specifically 0.5-1 h, and more specifically 0.5-0.6 h; the precipitation reaction is carried out under stirring conditions, such as magnetic stirring or mechanical stirring; the precipitation reaction of the present invention is carried out at room temperature.

[0039] In the precipitated effluent of the present invention, the nickel content is less than 30 mg / L, further 0.8~29 mg / L, further 0.8~21 mg / L, or 20~29 mg / L, or 0.8~0.9 mg / L; in the present invention, compared with the heavy metal wastewater, the nickel removal rate is greater than 90%, further greater than 99%, and further 99.7-99.75%.

[0040] In this invention, organic matter and heavy metal nickel can be removed after the pretreatment. Specifically, COD removal is achieved by adjusting the catalyst solid-liquid ratio and reaction time; heavy metal nickel removal is achieved by using chemical precipitation to remove the effluent from the oxidation process and adjusting pH and reaction time. The process of this invention is simple, the reagents are readily available, and the precipitated residue can be reused.

[0041] The following are specific examples of the present invention: Example 1 The actual high-salt organic heavy metal wastewater from the ternary lithium battery industry (hereinafter referred to as raw water) was taken. The wastewater had a pH of 4.2, a COD concentration of 813 mg / L, a TOC concentration of 200 mg / L, a nickel concentration of 300 mg / L, other heavy metals (cobalt, manganese, copper, zinc) concentrations of <0.5 mg / L, a sulfate concentration of 100 g / L, and a chloride ion concentration of 9 g / L.

[0042] This embodiment describes a pretreatment process for high-salt organic heavy metal wastewater from the ternary lithium battery industry, comprising the following steps: (1) Raw water was directly subjected to ozone catalytic oxidation. The ozone introduction rate was 20 mg / min. The catalyst used was activated carbon as the carrier and iron as the active component (the iron loading mass fraction was about 1.44%). The solid-liquid ratio of the catalyst was 0.16 g / mL, and the reaction was carried out for 90 min. After solid-liquid separation, the effluent (denoted as oxidation effluent) was obtained. The COD removal rate was 75.54%, the TOC removal rate was 79.11%, the nickel concentration in the effluent was 289.25 mg / L, and the pH of the effluent was basically 8.61.

[0043] (2) Add lime milk with a mass concentration of 10% to the oxidized effluent to adjust the pH of the oxidized effluent to 11, which is equivalent to a ratio of calcium oxide (in this invention, calcium oxide is used to prepare lime milk) and raw water of about 1 g / L. Then stir and react for 30 min. After solid-liquid separation, the nickel concentration in the precipitated effluent was measured to be 28.55 mg / L, and the nickel removal rate was 90.48%.

[0044] Example 2 The actual high-salt organic heavy metal wastewater from the ternary lithium battery industry (hereinafter referred to as raw water) was taken. The wastewater had a pH of 4.2, a COD concentration of 813 mg / L, a TOC concentration of 200 mg / L, a nickel concentration of 300 mg / L, other heavy metals (cobalt, manganese, copper, zinc) concentrations of <0.5 mg / L, a sulfate concentration of 100 g / L, and a chloride ion concentration of 9 g / L.

[0045] This embodiment describes a pretreatment process for high-salt organic heavy metal wastewater from the ternary lithium battery industry, comprising the following steps: (1) Raw water was directly subjected to ozone catalytic oxidation. The ozone introduction rate was 20 mg / min. The catalyst used was activated carbon as the carrier and iron as the active component (the iron loading mass fraction was about 1.44%). The solid-liquid ratio of the catalyst was 0.16 g / mL, and the reaction was carried out for 90 min. After solid-liquid separation, the effluent (denoted as oxidation effluent) was obtained. The COD removal rate was 75.54%, the TOC removal rate was 79.11%, the nickel concentration in the effluent was 289.25 mg / L, and the pH of the effluent was basically 8.61.

[0046] (2) Add lime milk with a mass concentration of 10% to the oxidized effluent to adjust the pH of the oxidized effluent to 12, which is equivalent to a ratio of calcium oxide (in this invention, calcium oxide is used to prepare lime milk) and raw water of about 1.6 g / L. Then stir and react for 30 min. After solid-liquid separation, the nickel concentration in the precipitated effluent was measured to be 0.87 mg / L, and the nickel removal rate was 99.71%.

[0047] Example 3 The actual high-salt organic heavy metal wastewater from the ternary lithium battery industry (hereinafter referred to as raw water) was taken. The wastewater had a pH of 4.2, a COD concentration of 813 mg / L, a TOC concentration of 200 mg / L, a nickel concentration of 300 mg / L, other heavy metals (cobalt, manganese, copper, zinc) concentrations of <0.5 mg / L, a sulfate concentration of 100 g / L, and a chloride ion concentration of 9 g / L.

[0048] This embodiment describes a pretreatment process for high-salt organic heavy metal wastewater from the ternary lithium battery industry, comprising the following steps: (1) Raw water was directly subjected to ozone catalytic oxidation. The ozone introduction rate was 20 mg / min. The catalyst used was activated carbon as the carrier and iron as the active component (the iron loading mass fraction was about 1.44%). The solid-liquid ratio of the catalyst was 0.32 g / mL, and the reaction was carried out for 120 min. After solid-liquid separation, the effluent (denoted as oxidation effluent) was obtained. The COD removal rate was 80.68%, the TOC removal rate was 89.88%, the nickel concentration in the effluent was 286.42 mg / L, and the pH of the effluent was basically 8.63.

[0049] (2) Add lime milk with a mass concentration of 10% to the oxidized effluent to adjust the pH of the oxidized effluent to 11, which is equivalent to a ratio of calcium oxide (in this invention, calcium oxide is used to prepare lime milk) and raw water of about 1 g / L. Then stir and react for 30 min. After solid-liquid separation, the nickel concentration in the precipitated effluent was measured to be 20.32 mg / L, and the nickel removal rate was 93.23%.

[0050] Comparative Example 1 The actual high-salt organic heavy metal wastewater from the ternary lithium battery industry (hereinafter referred to as raw water) was taken. The wastewater had a pH of 4.2, a COD concentration of 813 mg / L, a TOC concentration of 200 mg / L, a nickel concentration of 300 mg / L, other heavy metals (cobalt, manganese, copper, zinc) concentrations of <0.5 mg / L, a sulfate concentration of 100 g / L, and a chloride ion concentration of 9 g / L.

[0051] This comparative example describes a pretreatment process for high-salt organic heavy metal wastewater from the ternary lithium battery industry, the steps of which are as follows: (1) Take raw water and add lime milk with a mass concentration of 10% to adjust the pH of the raw water to 11, which is equivalent to a ratio of calcium oxide (in this invention, calcium oxide is used to prepare lime milk) to raw water of about 1.8 g / L. Then stir and react for 30 min. After solid-liquid separation, the nickel concentration in the precipitated water was measured to be 66.47 mg / L, and the nickel removal rate was 77.84%.

[0052] (2) The precipitated water was subjected to ozone catalytic oxidation at an ozone introduction rate of 20 mg / min. The catalyst used was carried by activated carbon and the active component was iron (the loading mass fraction of iron was about 1.44%). The solid-liquid ratio of the catalyst was 0.32 g / mL, and the reaction was carried out for 120 min. After solid-liquid separation, the effluent was obtained with a COD removal rate of 78.03%, a TOC removal rate of 78.25%, a nickel concentration of 46.24 mg / L, and a nickel removal rate of 84.59% (relative to the raw water).

[0053] Comparative Example 2 The actual high-salt organic heavy metal wastewater from the ternary lithium battery industry (hereinafter referred to as raw water) was taken. The wastewater had a pH of 4.2, a COD concentration of 813 mg / L, a TOC concentration of 200 mg / L, a nickel concentration of 300 mg / L, other heavy metals (cobalt, manganese, copper, zinc) concentrations of <0.5 mg / L, a sulfate concentration of 100 g / L, and a chloride ion concentration of 9 g / L.

[0054] This comparative example describes a pretreatment process for high-salt organic heavy metal wastewater from the ternary lithium battery industry, the steps of which are as follows: (1) Take raw water for Fenton process to remove organic matter: adjust the pH of wastewater to 3 with dilute sulfuric acid, add 5.4 g / L of ferrous sulfate heptahydrate, mix evenly and slowly add 40 ml / L of 30% hydrogen peroxide, react for 60 min and filter. The pH of the effluent (referred to as oxidized effluent) is 4~4.5, the COD removal rate of the effluent is 48.35% and the TOC removal rate is 67.59%.

[0055] (2) Add lime milk with a mass concentration of 10% to the oxidation effluent to adjust the pH of the oxidation effluent to 11, then stir the reaction for 30 min, and after solid-liquid separation, precipitated effluent is obtained; compared with the original water, the nickel removal rate is 86.76%.

[0056] Comparative Example 3 The actual high-salt organic heavy metal wastewater from the ternary lithium battery industry (hereinafter referred to as raw water) was taken. The wastewater had a pH of 4.2, a COD concentration of 813 mg / L, a TOC concentration of 200 mg / L, a nickel concentration of 300 mg / L, other heavy metals (cobalt, manganese, copper, zinc) concentrations of <0.5 mg / L, a sulfate concentration of 100 g / L, and a chloride ion concentration of 9 g / L.

[0057] This comparative example describes a pretreatment process for high-salt organic heavy metal wastewater from the ternary lithium battery industry, the steps of which are as follows: (1) Removal of organic matter from raw water by electrochemical oxidation: The pH of the raw water is adjusted to 7 with sodium hydroxide, and the raw water is introduced into the electrochemical reaction tank. The anode used in the electrochemical reaction is an iridium-tantalum-titanium electrode plate, and the cathode is a 304 stainless steel electrode plate. The electrode spacing is 2 cm, and the current density is 90 mA / cm. 2The reaction was carried out for 120 min; the pH of the effluent (denoted as oxidation effluent) was between 7 and 8, the COD removal rate was 72.02%, and the TOC removal rate was 40.49%.

[0058] (2) Add lime milk with a mass concentration of 10% to the oxidation effluent to adjust the pH of the oxidation effluent to 11, then stir the reaction for 30 min, and after solid-liquid separation, precipitated effluent is obtained; compared with the original water, the nickel removal rate is 81.80%.

[0059] Comparative Example 4 Simulated nickel-containing wastewater, free of organic matter, was used. The nickel concentration was 300 mg / L, the sulfate concentration was 100 g / L, and the chloride ion concentration was 9 g / L.

[0060] The simulated nickel-containing wastewater treatment process in this comparative example involves the following steps: 10% lime slurry is added to the simulated nickel-containing wastewater to adjust the pH to 8, 9, 10, 11, and 12, respectively. The mixture is then stirred and reacted for 30 minutes. After solid-liquid separation, precipitated effluent is obtained. Compared to the raw water, the nickel removal rates are 48.31%, 96.25%, 99.77%, 99.88%, and 99.93%, respectively.

[0061] Comparative Example 5 The actual high-salt organic heavy metal wastewater from the ternary lithium battery industry (hereinafter referred to as raw water) was taken. The wastewater had a pH of 4.2, a COD concentration of 813 mg / L, a TOC concentration of 200 mg / L, a nickel concentration of 300 mg / L, other heavy metals (cobalt, manganese, copper, zinc) concentrations of <0.5 mg / L, a sulfate concentration of 100 g / L, and a chloride ion concentration of 9 g / L.

[0062] This comparative example describes a pretreatment process for high-salt organic heavy metal wastewater from the ternary lithium battery industry, the steps of which are as follows: (1) The raw water was directly subjected to ozone oxidation at an ozone introduction rate of 20 mg / min and a reaction time of 90 min. The pH of the effluent (referred to as the oxidized effluent) was 4-4.8, the COD removal rate was 17.55%, and the TOC removal rate was 21.39%.

[0063] (2) Add lime milk with a mass concentration of 10% to the oxidation effluent to adjust the pH of the oxidation effluent to 11, then stir the reaction for 30 min, and after solid-liquid separation, precipitated effluent is obtained; compared with the original water, the nickel removal rate is 80.92%.

[0064] Analysis example 1 1. Take the same raw water as in Example 1, add lime milk with a mass concentration of 10% to the raw water to adjust the pH, and analyze the ratio of calcium oxide (in this invention, calcium oxide is used to prepare lime milk) to raw water at different pH levels.

[0065] 2. Obtain the same oxidized effluent as in Example 1, add lime milk with a mass concentration of 10% to the oxidized effluent to adjust the pH, and analyze the ratio of calcium oxide (in this invention, calcium oxide is used to prepare lime milk) to raw water at different pH levels.

[0066] See Figure 1 As shown, it can be seen that after ozone catalytic oxidation, adding lime milk to adjust the pH can reduce the amount of calcium oxide required.

[0067] Analysis example 2 1. Take the same raw water as in Example 1, add lime milk with a mass concentration of 10% to the raw water to adjust the raw water to different pH values, then stir and react for 30 min. After solid-liquid separation, precipitated water is obtained. Compared with the raw water, the nickel ion removal rate corresponding to different pH values ​​is analyzed.

[0068] 2. The same oxidation effluent as in Example 1 was obtained. Lime slurry with a mass concentration of 10% was added to the oxidation effluent to adjust the pH of the oxidation effluent to different pH values. The reaction was then stirred for 30 min. After solid-liquid separation, precipitated effluent was obtained. The nickel ion removal rate corresponding to different pH values ​​was analyzed compared with the original water.

[0069] See Figure 2 As shown, it can be seen that after ozone catalytic oxidation, adding lime milk to adjust the pH can achieve a nickel ion removal rate of over 90% at a lower pH.

[0070] Analysis example 3 Raw water (same as in Example 1) was directly subjected to ozone catalytic oxidation. The ozone introduction rate was 20 mg / min. The catalyst used was activated carbon as a carrier and iron as the active component (the iron loading mass fraction was about 1.44%). The solid-liquid ratio of the catalyst was 0.16 g / mL. The pH of the oxidized water was measured after different reaction times.

[0071] See Figure 3 As shown, it can be seen that compared with the raw water, the pH of the oxidized water increases significantly after ozone catalytic oxidation, reaching 8.5~9.

[0072] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for pretreating high-salinity organic heavy metal wastewater, characterized by comprising the steps of: The method comprises the steps of: ​ S1, catalytic ozonation of heavy metal wastewater, solid-liquid separation to obtain oxidized effluent; The heavy metal wastewater contains sulfate ions, chloride ions and nickel ions, and the COD of the heavy metal wastewater is 500-1000 mg / L, and the TOC is 100-300 mg / L; the pH of the heavy metal wastewater is 4-5; The catalytic ozonation comprises adding an ozone catalyst to the heavy metal wastewater and introducing ozone into the heavy metal wastewater; S2, neutralization and precipitation of the oxidized effluent, solid-liquid separation to obtain precipitated effluent; The neutralization and precipitation comprises adjusting the pH of the oxidized effluent to 10-12 with an alkaline precipitant and then performing a precipitation reaction.

2. The pretreatment method of high-salt organic heavy metal wastewater according to claim 1, characterized by, In the heavy metal wastewater, the concentration of sulfate ions is 50-150 g / L, the concentration of chloride ions is 5-20 g / L, and the concentration of nickel ions is 100-500 mg / L.

3. The pretreatment method for high-salt organic heavy metal wastewater according to claim 1, characterized in that, The time for introducing ozone into the heavy metal wastewater is 0.5-3 h.

4. The pretreatment method for high-salt organic heavy metal wastewater according to claim 1, characterized in that, During the process of introducing ozone into the heavy metal wastewater, the ozone introduction rate is 10-100 mg / min. During the process of introducing ozone into the heavy metal wastewater, the heavy metal wastewater is controlled to circulate.

5. The pretreatment method for high-salt organic heavy metal wastewater according to claim 1, characterized in that, The ozone catalyst comprises a carrier and an active component loaded on the carrier; the active component comprises one or more of a single metal and a composite metal.

6. The method of claim 1, wherein the high-salinity organic heavy metal wastewater is pretreated by the method of claim 1. The solid-liquid ratio of the ozone catalyst to the heavy metal wastewater is 0.02-0.4 g / mL.

7. The method of claim 1, wherein the high-salinity organic heavy metal wastewater is pretreated by the method of claim 1. The alkaline precipitant comprises lime milk; the mass concentration of the lime milk is 8-12%.

8. The pretreatment method for high-salt organic heavy metal wastewater according to claim 7, characterized in that, The lime milk is prepared by using calcium oxide; the ratio of the calcium oxide to the heavy metal wastewater is 1-2 g / L.

9. The method of claim 1, wherein the high-salinity organic heavy metal wastewater is pretreated by a method comprising: The pH of the oxidized effluent is adjusted to 11-12 with the alkaline precipitant before the precipitation reaction. ​ 10. The method for pretreatment of high-salinity organic-heavy-metal wastewater according to any one of claims 1-9, characterized in that, The time for the precipitation reaction is 0.5-2 h.

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