A beneficiation wastewater advanced oxidation-biological collaborative treatment system and treatment method

Abstract

This invention relates to an advanced oxidation-biological co-treatment system and method for mineral processing wastewater. The advanced oxidation-biological co-treatment method for mineral processing wastewater of this invention includes the following steps: S1: Introducing polymetallic mineral processing wastewater into a pretreatment tank and adjusting the pH value for initial sedimentation treatment; S2: Introducing the supernatant into a coagulation sedimentation tank and adding a coagulant for secondary sedimentation treatment; S3: Introducing the supernatant into an ozone catalytic oxidation tower, adding a catalyst, and performing oxidation treatment to remove toxic and recalcitrant substances, and then removing residual ozone; S4: Introducing the wastewater into a biochemical reactor for biological treatment, followed by sludge settling, and discharging the supernatant after it meets the standards. The advanced oxidation-biological co-treatment method for mineral processing wastewater of this invention selectively catalytically oxidizes the wastewater before biological treatment, thereby improving the biodegradability of the wastewater.

Description

Technical Field

[0001] This invention relates to the field of mineral processing wastewater treatment technology, and in particular to an advanced oxidation-biological synergistic treatment system and method for mineral processing wastewater. Background Technology

[0002] Industrial wastewater containing heavy metal ions mainly originates from iron and steel and non-ferrous metal smelting, machining, mining, and some chemical enterprises. During mining, because most non-ferrous metal ore concentrates contain complex associated elements, the separation and extraction process often requires the addition of many mineral processing reagents. Therefore, the resulting mineral processing wastewater generally contains multiple heavy metal elements such as mercury, cadmium, arsenic, lead, copper, zinc, cobalt, and tin, as well as recalcitrant and toxic organic matter. The complex composition, high heavy metal content, high suspended solids, and large volume of polymetallic mineral processing wastewater further increase the difficulty of its treatment.

[0003] Currently, mineral processing plants both domestically and internationally primarily treat wastewater using natural sedimentation, coagulation sedimentation, and neutralization methods. Natural sedimentation and coagulation sedimentation can remove some heavy metal ions and suspended solids from wastewater, but coagulation treatment is less effective at removing residual organic flotation reagents, resulting in treated water that still doesn't meet reuse requirements. For organic matter in wastewater, photocatalysis and advanced oxidation technologies can achieve better treatment results, but their high cost makes widespread adoption difficult. In contrast, biological methods offer advantages such as cost-effectiveness, environmental friendliness, and no reuse barriers, making them the most promising approach.

[0004] However, the beneficiation wastewater from polymetallic ores is highly complex due to the lengthy beneficiation process and the numerous types of reagents added. The pollutants in this complex polymetallic beneficiation wastewater primarily originate from residual tailings and various beneficiation reagents. The addition of some of these reagents complicates the wastewater composition, making it difficult to separate and eliminate certain organic compounds. Furthermore, some toxic substances can harm microorganisms. Applying biological methods to treat these toxic and recalcitrant substances is impractical, and a single biological treatment method cannot completely remove the organic matter from the wastewater. Therefore, there is an urgent need to develop an environmentally friendly and efficient method for treating complex polymetallic ore beneficiation wastewater to address this problem. Summary of the Invention

[0005] Based on this, one of the objectives of the present invention is to provide an advanced oxidation-biological co-treatment method for mineral processing wastewater. For complex polymetallic mineral processing wastewater, before biological treatment, a catalyst with a large number of active sites and functionalized ligands is used to catalytically oxidize the wastewater, so that ozone selectively and preferentially reacts with biotoxic mineral processing agents, decomposing toxic and recalcitrant substances in the wastewater. Then, the wastewater is subjected to biological treatment to improve its biodegradability.

[0006] Another objective of this invention is to provide an advanced oxidation-biological co-treatment system for mineral processing wastewater, which has strong selectivity and can enable ozone to react directly and specifically with toxic and recalcitrant substances under the action of catalysts and modified graphite, thereby detoxifying and breaking down the chains of these substances, decomposing the toxic substances, and allowing these organic compounds to be degraded by microorganisms, thus improving the efficiency of biological treatment.

[0007] A method for the advanced oxidation-biological co-treatment of mineral processing wastewater, characterized by comprising the following steps:

[0008] S1: Primary sedimentation treatment: The polymetallic mineral processing wastewater is introduced into the pretreatment tank and the pH value is adjusted for primary sedimentation treatment.

[0009] S2: Secondary sedimentation treatment: The supernatant from step S1 is introduced into a coagulation sedimentation tank, and coagulant is added for secondary sedimentation treatment.

[0010] S3: Ozone oxidation treatment: The upper liquid from step S2 is introduced into the ozone catalytic oxidation tower, a catalyst is added, and oxidation treatment is carried out to remove toxic and difficult-to-degrade substances, and then the residual ozone in the mineral processing wastewater is removed.

[0011] S4: Biological treatment: The wastewater treated in step S3 is introduced into a biochemical reactor in which the microorganisms have been domesticated for biological treatment. Then it is introduced into a secondary sedimentation tank for sludge settling. The supernatant is discharged after it meets the standards.

[0012] Further, in step S1, the pH value is adjusted to 10-11 according to the condition of the mineral processing wastewater to precipitate most of the metal ions and heavy metal ions. After mechanical stirring until the reaction is complete, the mixture is allowed to stand until precipitation is complete. Then, the supernatant flows into the next process, and the lower precipitate is discharged through the bottom outlet of the pretreatment tank.

[0013] It should be noted that in this step, lime slurry can be used to adjust the pH. A pH value between 10 and 11 can precipitate most of the metal ions, achieving the purpose of removing most of the metal ions. In addition, maintaining a higher pH in this process can significantly reduce the amount of alkali added in the subsequent biological treatment process, thereby reducing the introduction of calcium ions in the subsequent biological treatment process, and thus reducing the generation of calcium sulfate, calcium carbonate, etc. in the bioreactor.

[0014] Preferably, the mechanical stirring time in this step is 10-20 minutes, and the standing time is 1-2 hours.

[0015] Furthermore, in step S2, a coagulant is added to the coagulation sedimentation tank, stirred, and allowed to stand for secondary sedimentation of the mineral processing wastewater. This process can bind and aggregate the colloidal microparticles in the wastewater together, causing impurities to coagulate and flocculate, thereby further removing heavy metal ions and suspended solids from the mineral processing wastewater. This ensures the turbidity of the influent in subsequent steps and reduces the impact of heavy metals on subsequent biological treatment.

[0016] Preferably, in this step, the coagulant is a compound of inorganic and organic polymeric coagulants, which fully utilizes the bridging effect to adsorb colloidal particles in the mineral processing wastewater system, thus significantly improving the wastewater treatment level. In this invention application, the coagulant is prepared by mixing 10-25% polyaluminum ferric chloride, 12% polyferric sulfate, 5-10‰ polydimethyldiallyl ammonium chloride, and 3‰ disodium ethylenediaminetetraacetate with water according to their mass percentages.

[0017] It should be noted that excessive coagulant dosage will increase economic costs and raise the COD level in the wastewater, causing secondary pollution. Insufficient coagulant dosage will result in incomplete sedimentation, allowing heavy metal ions to enter subsequent steps and affecting their efficiency. Preferably, the coagulant dosage is 1-5 mL / L; after stirring for 3 minutes and allowing to stand for 30-60 minutes, the supernatant enters the next step. At this point, most heavy metal ions and suspended solids in the mineral processing wastewater have been removed.

[0018] Further, in step S3, the ozone catalytic oxidation tower contains modified graphite. The modified graphite is prepared by mixing 25% flake graphite, 20% magnesium nitrate solution (10% concentration), and sodium dodecylbenzenesulfonate (3‰ by mass percentage), and then adding hot water for thermal modification. The filling rate of the modified graphite is 20-25%. Preferably, in this invention, hot water at 180°C is used to thermally modify the graphene.

[0019] It should be noted that the filling rate of the modified graphite refers to the ratio of the bulk volume of the modified graphite to the volume of the impregnation liquid, which is expressed as a percentage in this invention; wherein the bulk volume includes the volume of the modified graphite itself and the volume of the voids formed between the modified graphite pieces.

[0020] Further, in step S3, the ozone catalytic oxidation tower is equipped with a communicative reaction chamber and an ozone chamber, the ozone chamber being controlled by an inlet valve. An ozone generator is installed in the ozone chamber to produce ozone; the ozone generator's gas source is air. Modified graphite is installed in the reaction chamber. The ozone catalytic oxidation tower also has a water inlet at the lower end and a water outlet at the upper end. During the oxidation process, mineral processing wastewater enters the reaction chamber through the water inlet. At this time, the inlet valve opens, allowing ozone to enter the reaction chamber. Simultaneously, a catalyst is added. Under the catalysis of the modified graphite and the catalyst, the ozone decomposes the toxic substances in the mineral processing wastewater.

[0021] Specifically, the catalyst is prepared by mixing anhydrous sodium carbonate, potassium dihydrogen phosphate, 5% ferric chloride hexahydrate solution, tert-butanol, and water in a mass ratio of 2:1:1:5:2; the dosage of the catalyst is 30-60 mg / L.

[0022] It should be noted that the catalyst described in this invention is specifically designed for toxic mineral processing reagents in mineral processing wastewater. This catalyst possesses numerous active sites and functionalized ligands, giving it highly flexible catalytic activity. It allows ozone to selectively and preferentially remove mineral processing reagents that are toxic to organisms, creating conditions for subsequent biological treatment. Compared to conventional ozone treatment processes that directly oxidize and remove all organic matter in mineral processing wastewater, this invention uses a targeted catalyst for catalytic oxidation treatment that is more specifically aimed at mineral processing reagents toxic to organisms, resulting in lower treatment costs.

[0023] It should be noted that the purpose of ozone oxidation in step 3 is not to remove organic matter, but to detoxify and break down chains under the influence of catalysts and modified graphite, decompose toxic substances, break long chains and open rings, so that this part of the organic matter can be degraded by microorganisms in the subsequent biological treatment process, improve the biodegradability of wastewater, and at the same time control the cost of advanced oxidation stage.

[0024] Preferably, in step S3, the ozone dosage is 100-200 mg / L, and the ozone reaction time is 15-30 min.

[0025] Furthermore, in step S3, after the mineral processing wastewater is oxidized with ozone, it is introduced into a stripping tank to remove residual ozone from the wastewater.

[0026] Specifically, the stripping tank is equipped with an aerator to remove residual ozone from the mineral processing wastewater through aeration, so as to prevent negative impact on microorganisms in the next step.

[0027] Furthermore, in addition to discharging excess ozone, the stripping tank adjusts the pH value of the mineral processing wastewater system to be within the range of 7-9, in order to facilitate subsequent biological treatment steps.

[0028] Specifically, the pH value of the mineral processing wastewater system can be adjusted by adding alkaline solutions, such as clear limewater or sodium hydroxide solution, or by aerating carbon dioxide.

[0029] Furthermore, the mineral processing wastewater after ozone catalytic oxidation in step S3 is introduced into the acclimated bioreactor after stripping, where it undergoes biological treatment with the aerobic sludge. The microorganisms can remove the toxic substances and residual organic matter from the process.

[0030] Specifically, in the biochemical reactor described in step S4, the sludge inoculation amount is 25-35%, the dissolved oxygen value is 3-5 mg / L, the pH is 7.5-8.5, and the hydraulic retention time is 6-12 h.

[0031] Furthermore, after biological treatment, the mineral processing wastewater flows into the secondary sedimentation tank through the reactor outlet for sludge settling. After the settled sludge is concentrated, part of it is returned to the biological system, with a sludge return ratio of 50%-70%. The supernatant is discharged after being tested and found to meet the standards.

[0032] A mineral processing wastewater advanced oxidation-biological co-treatment system includes the following components arranged in sequence:

[0033] Pretreatment tank is used to adjust the pH value of mineral processing wastewater to settle metal ions;

[0034] Coagulation sedimentation tanks are used to remove heavy metal ions and suspended solids from mineral processing wastewater;

[0035] Ozone catalytic oxidation tower is used to oxidize and decompose toxic substances in mineral processing wastewater introduced from the sedimentation zone;

[0036] Stripping tanks are used to remove residual ozone from mineral processing wastewater;

[0037] A biochemical reactor is used to remove organic matter from mineral processing wastewater introduced from the oxidation treatment area;

[0038] Secondary sedimentation tanks are used to settle sludge from biologically treated mineral processing wastewater.

[0039] The advanced oxidation-biological synergistic treatment system for mineral processing wastewater adopts the advanced oxidation-biological synergistic treatment method for mineral processing wastewater described in this invention.

[0040] The beneficial effects of this invention are as follows:

[0041] (1) By setting up a pretreatment tank, a coagulation sedimentation tank, and adding targeted coagulants, heavy metal ions and suspended solids in complex polymetallic mineral processing wastewater can be effectively removed, resulting in good effluent quality.

[0042] (2) By adding a catalyst with a large number of active sites and functionalized ligands, the flexibility is very high, allowing ozone to selectively and preferentially react with biotoxic mineral processing agents, creating conditions for subsequent biological treatment.

[0043] (3) By adding modified graphite as a catalyst, ozone oxidation is catalyzed, which has strong selectivity and can degrade toxic organics and some recalcitrant organics, greatly improving the ozone oxidation performance, increasing its utilization rate, saving costs and improving efficiency.

[0044] (4) By combining advanced oxidation treatment with biological treatment, it is highly adaptable to changes in the quantity and quality of mineral processing wastewater, has a high pollutant removal rate, good effect, and the treated water sample meets the requirements for discharge or reuse, making it highly practical for industrial applications.

[0045] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0046] Figure 1 A flowchart of an advanced oxidation-biological synergistic treatment method for mineral processing wastewater provided in this application embodiment;

[0047] Figure 2 This is a schematic diagram of an advanced oxidation-biological co-treatment system for mineral processing wastewater provided in an embodiment of this application. Detailed Implementation

[0048] 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 some embodiments of the present invention, and not all embodiments. 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.

[0049] Unless otherwise specified, the reagents used in this invention refer to commercially available conventional reagents. The following examples are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0050] The pollutants in complex polymetallic ore beneficiation wastewater mainly originate from residual tailings and beneficiation reagents. The addition of some of these reagents complicates the wastewater composition, making it difficult to separate and eliminate certain organic compounds. Furthermore, some toxic substances can harm microorganisms. Applying biological methods to treat these toxic and recalcitrant substances is impractical, and a single biological treatment method cannot completely remove the organic matter from the wastewater. Therefore, there is an urgent need to develop an environmentally friendly and efficient method for treating complex polymetallic ore beneficiation wastewater to address this problem.

[0051] Example 1

[0052] The wastewater discharged from a large lead-zinc mine beneficiation plant was used as the treatment target. The treated water sample was to be reused, requiring the effluent organic pollutant COD to be below 80 mg / L, suspended solids (SS) below 50 mg / L, and pH to be neutral. Since the treated water sample was the plant's production wastewater, its physical and chemical composition changed during production. The water quality analysis before treatment is shown in Table 1.

[0053] Table 1. Water quality analysis of mineral processing wastewater to be treated in Example 1 (unit: mg / L)

[0054] Testing items pH COD SS Zn Pb Cu Fe Content (mg / L) 8-9 150-300 320-550 600-720 150-300 8-15 10-20

[0055] A coagulant is prepared by mixing 10% polyaluminum ferric chloride, 12% polyferric sulfate, 5‰ polydimethyldiallylammonium chloride, and 3‰ disodium ethylenediaminetetraacetate with water according to the mass percentage.

[0056] Modified graphite is obtained by mixing 25% flake graphite, 20% magnesium nitrate solution with a concentration of 10% and sodium dodecylbenzenesulfonate with a mass percentage, and then adding hot water at 180℃ for thermal modification.

[0057] The catalyst was prepared by compounding anhydrous sodium carbonate, potassium dihydrogen phosphate, 5% ferric chloride hexahydrate solution, tert-butanol, and water in a mass ratio of 2:1:1:5:2.

[0058] The wastewater to be treated flows into the pretreatment tank, lime milk is added to adjust the pH to 10.5, and after stirring for 15 minutes, it is allowed to stand for 2 hours for the first sedimentation treatment.

[0059] After initial sedimentation with lime, 3.5 ml / L of a self-made high-efficiency coagulant was added to the wastewater sample. The mixture was stirred for 3 minutes and then allowed to stand for 1 hour to further remove heavy metal ions and suspended solids from the mineral processing wastewater (see Table 2 for details). Thus, the heavy metal ions such as SS, Zn, Pb, Cu, and Fe in the treated wastewater were essentially removed.

[0060] Table 2. Water quality analysis of mineral processing wastewater after secondary sedimentation in Example 1 (unit: mg / L)

[0061] Testing items pH SS Zn Pb Cu Fe Content (mg / L) 8-9 15 0.06 0.18 0.12 0.21

[0062] After sedimentation, the supernatant enters the reaction chamber from the inlet at the bottom of the ozone catalytic oxidation tower. The reaction chamber is filled with self-made modified graphite and 35 mg / L of self-made catalyst is added. The ozone inlet valve is opened and the ozone flow rate is adjusted to 115 mg / L. The reaction is carried out for 30 minutes. The ozone reacts directly with the organic matter in the water, especially the toxic organic matter. After treatment, the water sample flows into the stripping tank through the outlet at the top of the ozone catalytic oxidation tower.

[0063] After ozone oxidation treatment, the water sample is placed in a stripping tank and aerated for 30 minutes. At the same time, the pH in the tank is measured. If it is lower than 7, clear lime water is added to adjust it to 7.5-8. If it is higher than 9, CO2 is introduced to lower the pH to 8-9.

[0064] The mineral processing wastewater sample is introduced into a biochemical reactor in which the microorganisms have been domesticated, and biological treatment is carried out with the aerobic sludge. The sludge inoculation amount is 30%, the pH in the biochemical reactor is controlled within the range of 7.5-8.5, the dissolved oxygen value is 3-5 mg / L, and the hydraulic retention time is 8 hours. Organic matter will be effectively removed.

[0065] After biological treatment, the water sample flows into the secondary sedimentation tank through the outlet of the biochemical reactor for sludge settling. After the settled sludge is concentrated, 70% of the sludge is returned to the biochemical system. The supernatant is sampled and tested multiple times. The COD is in the range of 25-50 mg / L and the pH is neutral, which meets the reuse requirements. See Table 3 for details.

[0066] Table 3. Water quality analysis of effluent from mineral processing wastewater after advanced oxidation-biological synergistic treatment in Example 1 (unit: mg / L)

[0067] Testing items pH COD SS Zn Pb Cu Fe Content (mg / L) 7-8.5 25-50 8-20 <0.05 <0.20 0.06 0.10

[0068] A closed-circuit mineral processing test was conducted on the effluent after advanced oxidation-biological co-treatment and the original production water. The specific comparison results are detailed in Table 4.

[0069] Table 4. Effects of different water usage on lead-zinc beneficiation parameters

[0070]

[0071]

[0072] As can be seen from Table 4, the recovery rate, grade, and metallic aluminum of the effluent from mineral processing wastewater after advanced oxidation-biological co-treatment are close to those of the water used in production. This indicates that the advanced oxidation-biological co-treatment method for mineral processing wastewater provided in this application can effectively treat mineral processing wastewater, meet the reuse requirements, and effectively solve the problem of recycled water in mineral processing production.

[0073] Example 2

[0074] This embodiment is the same as Embodiment 1, using mineral processing wastewater discharged from a large lead-zinc mine as the treatment target. The treated water sample is reused, and the requirements are that the organic pollutant COD of the effluent is less than 80 mg / L, the suspended solids SS is less than 50 mg / L, and the pH is neutral. The water quality analysis before treatment is shown in Table 1.

[0075] A coagulant is prepared by mixing 25% polyaluminum ferric chloride, 12% polyferric sulfate, 10‰ polydimethyldiallylammonium chloride, and 3‰ disodium ethylenediaminetetraacetate with water according to the mass percentage.

[0076] Modified graphite is obtained by mixing 25% flake graphite, 20% magnesium nitrate solution with a concentration of 10% and sodium dodecylbenzenesulfonate with a mass percentage, and then adding hot water at 180℃ for thermal modification.

[0077] The catalyst was prepared by compounding anhydrous sodium carbonate, potassium dihydrogen phosphate, 5% ferric chloride hexahydrate solution, tert-butanol, and water in a mass ratio of 2:1:1:5:2.

[0078] The wastewater to be treated flows into the pretreatment tank, where lime slurry is added to adjust the pH to 11. After stirring for 15 minutes, the mixture is allowed to stand for 2 hours for initial sedimentation treatment.

[0079] After initial sedimentation with lime, 5 ml / L of a self-made high-efficiency coagulant was added to the wastewater sample. The mixture was stirred for 3 minutes and then allowed to stand for 50 minutes to further remove heavy metal ions and suspended solids from the mineral processing wastewater (see Table 5 for details). At this point, heavy metal ions such as SS, Zn, Pb, Cu, and Fe in the treated wastewater were essentially removed.

[0080] Table 5. Water quality analysis of mineral processing wastewater after secondary sedimentation in Example 2 (unit: mg / L)

[0081] Testing items pH SS Zn Pb Cu Fe Content (mg / L) 8-9 10 0.05 0.18 0.12 0.20

[0082] After sedimentation, the supernatant enters the reaction chamber from the inlet at the bottom of the ozone catalytic oxidation tower. The reaction chamber is filled with self-made modified graphite and 60 mg / L of self-made catalyst is added. The ozone inlet valve is opened and the ozone flow rate is adjusted to 200 mg / L. The reaction is carried out for 20 minutes. The ozone reacts directly with the organic matter in the water, especially the toxic organic matter. After treatment, the water sample flows into the stripping tank at the top of the oxidation tower.

[0083] After oxidation treatment, the mineral processing wastewater sample was placed in a stripping tank and aerated for 30 minutes to adjust the pH to 7-9.

[0084] The mineral processing wastewater sample is introduced into a biochemical reactor in which the microorganisms have been domesticated, and biological treatment is carried out with the aerobic sludge. The sludge inoculation amount is 35%, the pH in the biochemical reactor is controlled in the range of 7.5-8.5, the dissolved oxygen is 3-5 mg / L, the hydraulic retention time is 12h, and the organic matter will be effectively removed.

[0085] After biological treatment, the water sample flows into the secondary sedimentation tank through the outlet of the biochemical reactor for sludge settling. After the settled sludge is concentrated, 50% of the sludge is returned to the biological system, and the supernatant is tested multiple times. The COD is in the range of 25-50 mg / L, and the pH is neutral, meeting the reuse requirements, as detailed in Table 6.

[0086] Table 6. Water quality analysis of effluent from mineral processing wastewater after advanced oxidation-biological co-treatment in Example 2 (unit: mg / L)

[0087] Testing items pH COD SS Zn Pb Cu Fe Content (mg / L) 7-8.5 25-50 8-20 <0.05 <0.20 0.05 0.10

[0088] Example 3

[0089] Wastewater from a polymetallic mine was used as the treatment target. The water quality analysis before treatment is shown in Table 7. The treated water sample was used for sweeping and cleaning in the factory area, and the requirements were that COD be less than 50 mg / L, SS less than 25 mg / L, pH 7-8.5, and heavy metal ions meet the special emission limits for water pollution in the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB25466-2010).

[0090] A coagulant is prepared by mixing 20% ​​polyaluminum ferric chloride, 12% polyferric sulfate, 10‰ polydimethyldiallylammonium chloride, and 3‰ disodium ethylenediaminetetraacetate with water according to the mass percentage.

[0091] Modified graphite is obtained by mixing 25% flake graphite, 20% magnesium nitrate solution with a concentration of 10% and sodium dodecylbenzenesulfonate with a mass percentage, and then adding hot water at 180℃ for thermal modification.

[0092] The catalyst was prepared by compounding anhydrous sodium carbonate, potassium dihydrogen phosphate, 5% ferric chloride hexahydrate solution, tert-butanol, and water in a mass ratio of 2:1:1:5:2.

[0093] The wastewater from the mineral processing plant overflows from the thickener and enters the pretreatment tank, where lime is added to adjust the pH to 11 and the water is left to stand for 1 hour.

[0094] The supernatant in the pretreatment tank is introduced into the coagulation sedimentation tank, 4.2 ml / L of self-made high-efficiency coagulant is added, and the mixture is stirred for 3 minutes and then allowed to stand for 1 hour.

[0095] The supernatant from the coagulation sedimentation tank is drawn out and enters the reaction chamber containing the ozone catalytic oxidation tower through the inlet at the bottom of the ozone catalytic oxidation tower. Modified graphite with a filling rate of 25% is placed in the chamber. At the same time, a self-made catalyst of 30 mg / L is added, and the ozone flow rate is 100 mg / L. After reacting for 30 minutes, the ozone flows into the stripping tank through the outlet at the top of the ozone catalytic oxidation tower and is aerated for 30 minutes to remove residual ozone from the mineral processing wastewater.

[0096] Next, the mineral processing wastewater was introduced into a biochemical reactor in which the microorganisms had been domesticated, and biologically treated with the aerobic sludge inside. The sludge inoculation amount was 25%, the pH in the biochemical reactor was controlled within the range of 7.5-8.5, the dissolved oxygen was 3-5 mg / L, and the hydraulic retention time was 6 hours.

[0097] After biological treatment, the water sample flows into the secondary sedimentation tank through the outlet of the biochemical reactor for sludge settling. After thickening, 70% of the settled sludge is returned to the biological system, and the supernatant is taken for testing. The raw water and effluent water quality are shown in Table 7. COD is in the range of 25-50 mg / L, SS is below 25 mg / L, and pH is in the range of 7-8, meeting the treatment requirements.

[0098] Table 7. Water quality analysis of raw water and effluent in Example 3 (unit: mg / L)

[0099] Testing items pH COD SS <![CDATA[NH3-N]]> Cu Fe Cd Pb raw water 9.8 1120 450 35 960 550 10 20 Out of water 7.5 45 10 12 0.33 0.1 0.05 0.08

[0100] The water sample after advanced oxidation-biological co-treatment met the requirements, and the heavy metal ions met the special emission limits for water pollution in the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB25466-2010). This indicates that the method can effectively treat mineral processing wastewater, meet the reuse requirements, and can be used as water for sweeping and cleaning in the plant area.

[0101] Example 4

[0102] This embodiment is the same as Embodiment 3, using wastewater from a polymetallic mine as the treatment target. The water quality analysis before treatment is shown in Table 7. The treated water sample is used for sweeping and cleaning within the factory area, requiring COD below 50 mg / L, SS below 25 mg / L, pH between 7 and 8.5, and heavy metal ion levels meeting the special emission limits for water pollution in the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB25466-2010).

[0103] The preparation methods of the coagulant, catalyst and modified graphite in this embodiment are the same as in Example 3.

[0104] The wastewater from the mineral processing plant overflows from the thickener and enters the pretreatment tank, where lime is added to adjust the pH to 10 and the water is left to stand for 1 hour.

[0105] The supernatant in the pretreatment tank is introduced into the coagulation sedimentation tank, 1 ml / L of self-made high-efficiency coagulant is added, and the mixture is stirred for 3 minutes and then allowed to stand for 1 hour.

[0106] The supernatant in the coagulation sedimentation tank is drawn out and enters the reaction chamber containing the ozone catalytic oxidation tower through the inlet at the bottom of the ozone catalytic oxidation tower. Modified graphite with a filling rate of 25% is placed in the chamber. At the same time, a self-made catalyst of 30 mg / L is added, and the ozone flow rate is 200 mg / L. After reacting for 15 minutes, the ozone flows into the stripping tank through the outlet at the top of the ozone catalytic oxidation tower and is aerated for 30 minutes to remove residual ozone in the mineral processing wastewater.

[0107] Next, the mineral processing wastewater was introduced into a biochemical reactor in which the microorganisms had been domesticated, and biologically treated with the aerobic sludge. The sludge inoculation amount was 25%, the pH in the biochemical reactor was controlled within the range of 7.5-8.5, the dissolved oxygen was 3-5 mg / L, and the hydraulic retention time was 10 h.

[0108] After biological treatment, the water sample flows into the secondary sedimentation tank through the outlet of the biochemical reactor for sludge settling. After thickening, 70% of the settled sludge is returned to the biological system, and the supernatant is taken for testing. The effluent quality after advanced oxidation-biological co-treatment is shown in Table 8: COD is in the range of 25-50 mg / L, SS is below 25 mg / L, and pH is in the range of 7-8, meeting the treatment requirements.

[0109] Table 8. Water quality analysis of effluent after advanced oxidation-biological synergistic treatment in Example 4 (unit: mg / L)

[0110] Testing items pH COD SS <![CDATA[NH3-N]]> Cu Fe Cd Pb Out of water 7.5 41 10 13 0.42 0.15 0.05 0.10

[0111] The water sample after advanced oxidation-biological co-treatment met the requirements, and the heavy metal ions met the special emission limits for water pollution in the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB25466-2010). This indicates that the method can effectively treat mineral processing wastewater, meet the reuse requirements, and can be used as water for sweeping and cleaning in the plant area.

[0112] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0113] (1) By setting up a pretreatment tank, a coagulation sedimentation tank, and adding targeted coagulants, heavy metal ions and suspended solids in complex polymetallic mineral processing wastewater can be effectively removed, resulting in good effluent quality.

[0114] (2) By adding a catalyst with a large number of active sites and functionalized ligands, the flexibility is very high, allowing ozone to selectively remove biotoxic mineral processing agents, creating conditions for subsequent biological treatment.

[0115] (3) By adding modified graphite as a catalyst, ozone oxidation is catalyzed, which has strong selectivity and can degrade toxic organics and some recalcitrant organics, greatly improving the ozone oxidation performance, increasing its utilization rate, saving costs and improving efficiency.

[0116] (4) By combining advanced oxidation treatment with biological treatment, it is highly adaptable to changes in the quantity and quality of mineral processing wastewater, has a high pollutant removal rate, good effect, and the treated water sample meets the requirements for discharge or reuse, making it highly practical for industrial applications.

[0117] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A method for the synergistic treatment of mineral processing wastewater using advanced oxidation and biological processes, characterized in that, Includes the following steps: S1: Primary sedimentation treatment: The polymetallic mineral processing wastewater is introduced into the pretreatment tank and the pH value is adjusted for primary sedimentation treatment. S2: Secondary sedimentation treatment: The supernatant from step S1 is introduced into a coagulation sedimentation tank, and coagulant is added for secondary sedimentation treatment. S3: Ozone oxidation treatment: The upper liquid from step S2 is introduced into the ozone catalytic oxidation tower, a catalyst is added, and oxidation treatment is carried out to remove toxic and difficult-to-degrade substances, and then the residual ozone in the mineral processing wastewater is removed. The ozone catalytic oxidation tower contains modified graphite, which is prepared by mixing 25% flake graphite, 20% magnesium nitrate solution (10% concentration), and sodium dodecylbenzenesulfonate (3‰ by mass), and then adding hot water for thermal modification. The filling rate of the modified graphite is 20-25%. The catalyst is prepared by mixing anhydrous sodium carbonate, potassium dihydrogen phosphate, 5% ferric chloride hexahydrate solution, tert-butanol, and water in a mass ratio of 2:1:1:5:

2. S4: Biological treatment: The wastewater treated in step S3 is introduced into a biochemical reactor in which the microorganisms have been domesticated for biological treatment. Then it is introduced into a secondary sedimentation tank for sludge settling. The supernatant is discharged after it meets the standards.

2. The method for advanced oxidation-biological co-treatment of mineral processing wastewater according to claim 1, characterized in that: In step S1, the pH is adjusted to 10-11 by adding lime slurry to the pretreatment tank, and then stirred and allowed to stand until precipitation is complete.

3. The method for advanced oxidation-biological co-treatment of mineral processing wastewater according to claim 1, characterized in that: The coagulant in step S2 is prepared by mixing 10-25% polyaluminum ferric chloride, 12% polyferric sulfate, 5-10‰ polydimethyldiallylammonium chloride and 3‰ disodium ethylenediaminetetraacetate with water according to mass percentage; the amount of coagulant added is 1-5 mL / L.

4. The method for advanced oxidation-biological co-treatment of mineral processing wastewater according to claim 1, characterized in that: In step S3, the ozone dosage is 100-200 mg / L.

5. The method for advanced oxidation-biological co-treatment of mineral processing wastewater according to claim 4, characterized in that: In step S3, the amount of catalyst added is 30-60 mg / L.

6. The method for advanced oxidation-biological co-treatment of mineral processing wastewater according to claim 1, characterized in that: In step S3, residual ozone in the mineral processing wastewater is removed by aeration; and the pH of the mineral processing wastewater system is adjusted to 7-9 by adding acid or alkali.

7. The method for advanced oxidation-biological co-treatment of mineral processing wastewater according to claim 1, characterized in that: In the biochemical reactor described in step S4, the sludge inoculum is 25-35%, the dissolved oxygen value is 3-5 mg / L, the pH is 7.5-8.5, and the hydraulic retention time is 6-12 h.

8. The method for advanced oxidation-biological co-treatment of mineral processing wastewater according to claim 1, characterized in that: In step S4, a portion of the sludge settled in the secondary sedimentation tank is returned to the biochemical reactor, with a sludge return ratio of 50%-70%.

9. A mineral processing wastewater advanced oxidation-biological co-treatment system, characterized in that, Including sequential settings: Pretreatment tank is used to adjust the pH value of mineral processing wastewater to settle metal ions; Coagulation sedimentation tanks are used to remove heavy metal ions and suspended solids from mineral processing wastewater; Ozone catalytic oxidation tower is used to oxidize and decompose toxic substances in mineral processing wastewater introduced from the sedimentation zone; Stripping tanks are used to remove residual ozone from mineral processing wastewater; A biochemical reactor is used to remove organic matter from mineral processing wastewater introduced from the oxidation treatment area; Secondary sedimentation tanks are used to settle sludge in biologically treated mineral processing wastewater. The ozone catalytic oxidation tower is equipped with a conductive reaction chamber and an ozone chamber. The ozone chamber is controlled to open and close by an air inlet valve. An ozone generator is installed in the ozone chamber to generate ozone. Modified graphite is installed in the reaction chamber. The ozone catalytic oxidation tower is also equipped with an inlet at the lower end and an outlet at the upper end. During the oxidation process, the mineral processing wastewater enters the reaction chamber through the inlet. At this time, the air inlet valve is opened, and ozone enters the reaction chamber. At the same time, a catalyst is added. Under the catalysis of modified graphite and the catalyst, the ozone decomposes the toxic substances in the mineral processing wastewater. The ozone catalytic oxidation tower contains modified graphite, which is prepared by mixing 25% flake graphite, 20% magnesium nitrate solution (10% concentration), and sodium dodecylbenzenesulfonate (3‰ by mass), and then adding hot water for thermal modification. The filling rate of the modified graphite is 20-25%. The catalyst is prepared by mixing anhydrous sodium carbonate, potassium dihydrogen phosphate, 5% ferric chloride hexahydrate solution, tert-butanol, and water in a mass ratio of 2:1:1:5:2.

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