Standard treatment method for wastewater containing ammonia nitrogen and difficult to treat copper cyanide

Abstract

The invention provides an up-to-standard treatment method for wastewater containing ammonia nitrogen and difficult-to-treat copper-cyanogen, and belongs to the field of wastewater treatment.The wastewater enters a first-stage oxidation reactor at first, the stable structure of a copper-cyanogen complex is destroyed by adding an oxidizing agent, then a copper removal agent and a pH adjusting agent are added into a copper removal reactor, copper ions are precipitated and separated out, and then the wastewater enters a second-stage oxidation reactor; the method comprises the following steps: carrying out oxidation and solid-liquid separation to remove copper sludge, carrying out oxidation and solid-liquid separation on treated overflow liquid and press filtrate after convergence so as to thoroughly remove residual cyanide and organic matters, and finally, conveying purified liquid which is subjected to two-stage oxidation and is subjected to copper cyanide interference removal to a biological reaction system to carry out biochemical reaction. And finally, the effluent reaches the recycling or discharging standard. The method effectively solves the problem of toxicity inhibition of difficult-to-treat wastewater on a biochemical system, realizes step-by-step removal and resource utilization of toxic and harmful substances, ensures stable and up-to-standard reuse or discharge of effluent, and has the advantages of efficient treatment, economy, environmental protection and convenient operation.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for meeting standards for treating wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide. Background Art

[0002] Cyanide gold extraction is the mainstream wet gold leaching process in the gold industry due to its advantages such as simple process and high gold recovery rate. At present, the gold industry generally adopts the process flow of "carbon leaching gold - desorption electrolysis - gold mud smelting". However, in actual production, due to the associated characteristics of metal minerals such as gold and copper, a large amount of copper cyanide complex will be formed during the cyanide leaching process and enter the subsequent treatment link along with the production process. In the cyanide tailings filter press slurry treatment process, conventional cyanide (such as CN - ) can be effectively removed by traditional redox methods such as hydrogen peroxide and sodium metabisulfite. However, for the copper cyanide complex [Cu(CN)4] 3- The oxidizing capacity of these conventional agents is seriously insufficient, making it difficult to destroy their stable coordination structure, resulting in the continuous enrichment of copper-cyanide complexes; at the same time, in the traditional acidic cyanide destruction process, the ammonia nitrogen produced by the destruction of cyanide also continues to accumulate in the circulating liquid, causing a certain concentration of copper-cyanide complexes and copper-ammonia complexes in the entire wastewater system, affecting the treatment indicators of the harmless treatment of cyanide tailings.

[0003] Currently, the commonly used treatment method for ammonia-nitrogen-containing and difficult-to-treat copper-cyanide wastewater is to regularly discharge a portion of the filter press circulating liquid from the system and add new water. However, this method not only fails to fundamentally solve the problem, but also causes waste of water resources and the risk of secondary pollution. The traditional concentrated sulfuric acid acidification method can also break the complex, but this method has low complex breaking efficiency, especially when copper-ammonia complexes are present, making it difficult to completely free and precipitate copper ions. In addition, the strong acidic conditions will cause the release of hydrogen cyanide gas, posing a huge safety hazard.

[0004] In view of this, it is necessary to design a treatment method for ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater to meet the standards in order to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides a method for meeting the standards for treating wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide. By rationally designing the water treatment process, using copper removal agents and regulating parameters, pollutants such as heavy metal ions, COD, ammonia nitrogen, etc. in the wastewater are removed to achieve environmental benefits.

[0006] The present application provides a method for meeting standards for treating wastewater containing ammonia nitrogen and difficult-to-treat copper-cyanide, comprising the following steps: S1. The wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide is input into a primary oxidation reactor, an oxidant is added to obtain a primary oxidation turbid liquid; S2. The primary oxidation turbid liquid obtained in step S1 is input into a copper removal reactor, and a copper removal agent and a pH adjuster are added to obtain a copper removal turbid liquid; adding a flocculant to the copper removal turbid liquid, performing solid-liquid separation to obtain a copper removal underflow and a copper removal overflow liquid; The copper removal underflow is subjected to filter press dehydration treatment to obtain copper removal filter press residue and copper removal filter press liquid; S3. The copper removal overflow obtained in step S2 and the copper removal filtrate are input into a secondary oxidation reactor, an oxidant is added to obtain a secondary oxidation turbid liquid; adding a flocculant to the secondary oxidation turbid liquid, and performing solid-liquid separation to obtain a secondary oxidation underflow and a secondary oxidation overflow liquid; The secondary oxidation underflow is subjected to filter pressing and dehydration treatment to obtain secondary oxidation slag and secondary oxidation filtrate; S4. The secondary oxidation overflow liquid and the secondary oxidation filtrate obtained in step S3 are used as purified liquids and input into a biological reaction system for biochemical reaction, and the effluent is reused in the production process or discharged when it meets the standards.

[0007] As a further improvement of the present application, in step S1, the oxidant is one or more of hydrogen peroxide, ozone, sodium metabisulfite, and sodium sulfite, and the dosage is about the same as that of CN. f The reaction is 6 to 10 times the theoretical value.

[0008] As a further improvement of the present application, in step S2, the dosage of the copper removal agent is 6 to 12 times the copper content in the wastewater, and the copper removal agent includes sodium dimethyldithiocarbamate.

[0009] As a further improvement of the present application, the copper removal agent also includes one or more of sodium ethyl xanthate, sodium polysulfide, diethylenetriamine, and sodium bicarbonate, wherein the mass proportion of sodium dimethyldithiocarbamate is ≥80%.

[0010] As a further improvement of the present application, in step S2, the pH adjuster is a biological oxidation liquid, the reaction pH is controlled to be 6.5~7.0, and the copper removal reaction time is 0.5~1.0h; the biological oxidation liquid is acidic wastewater with an iron ion concentration ≥10000mg / L.

[0011] As a further improvement of the present application, in step S3, the oxidant is one or more of hydrogen peroxide, ozone, sodium metabisulfite, and sodium sulfite.

[0012] As a further improvement of the present application, in step S3, the amount of the oxidant added is the amount of CN remaining after the copper removal reaction. T The sum of 2~5 times of the theoretical removal value and 0.1~0.2 times of the copper removal agent dosage.

[0013] As a further improvement of the present application, in step S4, the biological reaction system includes a regulating system, an anoxic tank, an aerobic tank, a solid-liquid separation device, and a water outlet tank.

[0014] As a further improvement of the present application, the activated sludge concentration in the anoxic tank and the aerobic tank is 3000~12000 mg / L, the dissolved oxygen in the aerobic tank is 2.0~4.0 mg / L, and the dissolved oxygen in the anoxic tank is <0.5 mg / L.

[0015] As a further improvement of the present application, the ammonia nitrogen concentration in the purified liquid is 15~800 mg / L, the copper ion concentration is <5 mg / L, and the total cyanide concentration is <10 mg / L.

[0016] The beneficial effects of this application are: The present application provides a method for meeting the standards for treating wastewater containing ammonia nitrogen and difficult-to-treat copper-cyanide. The method adopts a combined process of chemical pretreatment and biochemical deep treatment. The wastewater first enters a primary oxidation reactor, where a strong oxidant is added to destroy the stable structure of the copper-cyanide complex. Subsequently, a copper removal agent and a pH adjuster are added to a copper removal reactor to precipitate the copper ions. The copper sludge is then completely separated and removed through a solid-liquid separation process. The treated overflow liquid is combined with the press filtrate and then enters a secondary oxidation reactor for re-oxidation and solid-liquid separation to completely remove residual cyanide and organic matter. Finally, the purified liquid that has undergone two-stage oxidation and removed the interference of copper-cyanide is transported to a biological reaction system for biochemical reaction, and microorganisms are used to efficiently degrade ammonia nitrogen, ultimately ensuring that the effluent meets the reuse or discharge standards. The present application effectively solves the toxic inhibition of difficult-to-treat wastewater on the biochemical system, realizes the step-by-step removal and resource utilization of toxic and harmful substances, ensures that the effluent is stably reused or discharged, and has the advantages of efficient treatment, economy, environmental protection and convenient operation.

[0017] The present application sequentially subjects wastewater containing ammonia nitrogen and difficult-to-treat copper-cyanide to primary oxidation treatment, copper removal treatment with a copper removal agent assisted by a biological oxidation liquid, secondary oxidation treatment, and deep biological treatment. The strongly complexed copper-cyanide complex is removed by the copper removal agent and the secondary oxidation action, and the remaining ammonia nitrogen in the wastewater and the ammonia nitrogen produced by the oxidation of cyanide are deeply purified and removed by a biological method; in the copper removal process, a biological oxidation liquid containing a high concentration of heavy metal ions such as iron is used as a pH adjuster to assist in the precipitation and removal of copper and iron-cyanide complexes in the wastewater; the secondary oxidation process can not only remove the cyanide released during the copper removal process, but also remove the residual copper removal agent and its reaction decomposition products, eliminating its negative impact on the back-end biological method.

[0018] This application aims at the pollution characteristics of cyanide-containing wastewater rich in stable copper-cyanide complexes and ammonia nitrogen, and adopts a high-efficiency complex-breaking and copper-precipitating agent. This agent overcomes the safety hazards of the strong acidic reaction conditions of traditional concentrated sulfuric acid acidification for complex-breaking and copper-precipitating. In combination with the current process characteristics of cyanide-containing wastewater treatment, through the use of copper removal agents and the reasonable design of water treatment processes, the ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater is subjected to primary oxidation treatment, copper removal treatment with biological oxidation liquid-assisted copper removal agent, secondary oxidation treatment and biochemical treatment in sequence, so that the treated deep purified liquid can be reused in enterprise production or meet the first-level standard of the "Integrated Sewage Discharge Standard" (GB8978-1996) and then discharged in compliance with the standard, thereby ensuring the normal production operation of the enterprise and achieving the unity of economic and environmental benefits.

[0019] This application successfully overcomes the problem of difficulty in effectively treating wastewater containing ammonia nitrogen and stable complexed copper cyanide by further regulating and controlling parameters such as the oxidant addition point, oxidant addition amount, type, addition point and addition amount of copper removal agent, and type and pH value of pH adjuster in the treatment process. The method for meeting the standards for treating wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide provided by this application is simple in process, safe and reliable in operation, and uses common and inexpensive raw materials for the reagents. It can achieve deep purification of copper cyanide wastewater, reduce the impact of its reuse on the production process, and achieve standard discharge of cyanide-containing wastewater, with significant economic, environmental and social benefits, providing a new approach to the comprehensive treatment of copper cyanide wastewater.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0022] Figure 1 This is a flow chart of the method for meeting the standards for treating ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater provided in the embodiments of the present application. DETAILED DESCRIPTION

[0023] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0025] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] During the cyanide gold extraction process, copper-cyanide complexes are often present in cyanide-containing wastewater due to the coexistence of gold and copper. During the cyanide tailings filter press slurry treatment process, the filter press circulating fluid circulates in a closed loop for a long period of time, leading to the continuous accumulation of stable copper-cyanide complexes that are difficult to treat with conventional cyanide-breaking agents, as well as ammonia nitrogen produced by cyanide decomposition, resulting in difficult-to-treat copper-cyanide wastewater. Traditional methods are either unable to discharge due to "zero emission" requirements, or, while acidification can break the complexes, it carries the significant safety risk of incomplete destruction and leakage of highly toxic hydrogen cyanide gas.

[0028] In order to solve the technical problems of low treatment efficiency, incomplete treatment and high risk in the existing treatment methods for ammonia nitrogen-containing and difficult-to-treat copper cyanide wastewater, the present application provides a method for meeting the standards for the treatment of ammonia nitrogen-containing and difficult-to-treat copper cyanide wastewater, wherein, through a combined process of chemical pretreatment and biochemical deep treatment, the technical effect of meeting the discharge standards of cyanide-containing wastewater can be achieved.

[0029] Please refer to Figure 1 The present invention provides a method for treating wastewater containing ammonia nitrogen and difficult-to-treat copper-cyanide to meet standards, comprising the following steps: S1. The wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide is input into a primary oxidation reactor, an oxidant is added to obtain a primary oxidation turbid liquid; S2. The primary oxidation turbid liquid obtained in step S1 is input into the copper removal reactor, and a copper removal agent and a pH adjuster are added to obtain a copper removal turbid liquid; Adding flocculant to the copper removal turbid liquid, and performing solid-liquid separation to obtain copper removal underflow and copper removal overflow liquid; The copper removal underflow is subjected to filter pressing and dehydration treatment to obtain copper removal filter press residue and copper removal filter press liquid; S3. The copper removal overflow obtained in step S2 and the copper removal filtrate are input into a secondary oxidation reactor, an oxidant is added to obtain a secondary oxidation turbid liquid; Adding a flocculant to the secondary oxidation turbid liquid, performing solid-liquid separation to obtain a secondary oxidation underflow and a secondary oxidation overflow liquid; The secondary oxidation underflow is subjected to filter pressing and dehydration treatment to obtain secondary oxidation slag and secondary oxidation filtrate; S4. The secondary oxidation overflow liquid and the secondary oxidation filtrate obtained in step S3 are used as purified liquids and input into the biological reaction system for biochemical reaction, and the effluent is reused in the production process or discharged when it meets the standards.

[0030] In the technical solution of the embodiment of the present application, in order to solve the two core problems of difficult-to-treat copper-cyanide wastewater and high-concentration ammonia nitrogen, the present application uses a powerful means of chemical oxidation to first destroy the stable structure of the copper-cyanide complex, convert cyanide and heavy metal copper into low-toxic or non-toxic forms and separate them, thereby removing substances that have a highly toxic inhibitory effect on subsequent microorganisms; the pre-treated purified liquid is introduced into the biological reaction system, and the metabolic activity of microorganisms is used to efficiently degrade the remaining ammonia nitrogen and a small amount of residual pollutants, ultimately achieving stable compliance and reuse of wastewater. Specifically, the concentration of copper in the ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater is not less than 30 mg / L, the concentration of cyanide is not less than 100 mg / L, the concentration of ammonia nitrogen is not less than 15 mg / L, the pH value is alkaline, and the wastewater contains a relatively stable copper-cyanide complex ([Cu(CN)4] 3− ).

[0031] Furthermore, in some embodiments, in step S1, the oxidant is one or more of hydrogen peroxide, ozone, sodium metabisulfite, and sodium sulfite, and the dosage is about the same as that of CN. f (Free cyanide) reaction is 6 to 10 times the theoretical value.

[0032] In the technical solutions of the embodiments of the present application, the oxidant can oxidize cyanide to less toxic cyanate, or further to carbon dioxide and nitrogen. The dosage ensures the thoroughness of the oxidation reaction, avoiding residual cyanide due to insufficient oxidant and resource waste or secondary pollution caused by excessive oxidant use. The addition of a pH adjuster, air, or oxygen to aid the reaction is determined based on the type of oxidant (cyanide removal agent). The pH adjuster can be sulfuric acid, acidic wastewater (such as biological oxidation liquid, acidic smelting wastewater with low concentrations of heavy metals and other pollutants), lime, sodium hydroxide, carbide slag, etc. The reaction time is controlled to be 1-2 hours. The specific control parameters can be determined through experiments, but it is necessary to treat all easily treated cyanide. That is, the cyanide removal rate is essentially unchanged by increasing the dosage of the cyanide removal agent.

[0033] Furthermore, in some embodiments, in step S2, the dosage of the copper removal agent is 6 to 12 times the copper content in the wastewater, and the copper removal agent includes sodium dimethyldithiocarbamate.

[0034] In the technical solution of the embodiment of the present application, the dosage needs to take into account the existence form of copper in the wastewater (such as free state, complex state) and the influence of other interfering ions. The dosage of 6 to 12 times ensures sufficient reaction and avoids copper residue due to insufficient reagents.

[0035] Furthermore, in some embodiments, the copper removal agent also includes one or more of sodium ethyl xanthate, sodium polysulfide, diethylenetriamine, and sodium bicarbonate, wherein the mass proportion of sodium dimethyldithiocarbamate is ≥80%.

[0036] In the technical solution of the embodiment of the present application, sodium dimethyldithiocarbamate is used as the main active ingredient, and its high proportion ensures sufficient reaction between the agent and copper ions, while assisting other agents to synergistically enhance efficiency, thereby achieving efficient and stable removal of copper ions in difficult-to-treat copper-cyanide wastewater.

[0037] Furthermore, in some embodiments, in step S2, the pH adjuster is a biological oxidation liquid, the reaction pH is controlled to be 6.5-7.0, and the copper removal reaction time is 0.5-1.0h; the biological oxidation liquid is acidic wastewater with an iron ion concentration ≥10000mg / L.

[0038] In the technical solution of the embodiment of the present application, the biological oxidation liquid is an acidic wastewater with an iron ion concentration of ≥10000 mg / L, and its acidity mainly comes from free H + Ions, in the copper removal reaction, act as a natural pH buffer, neutralizing alkaline conditions and stabilizing the reaction environment. Iron ions in the biological oxidation solution readily form ferric hydroxide (Fe(OH)3) colloids under alkaline conditions. Their large surface area allows them to adsorb copper ions or their complexes in water, forming a coprecipitate and improving copper removal efficiency. A reaction time of 0.5-1.0 hours promotes precipitation equilibrium; prolonged reaction times may lead to excessive flocculation of the colloids and difficulty in settling. Using iron-containing acidic wastewater (such as mining or metallurgical wastewater) as a pH adjuster reduces the cost of chemicals (such as sulfuric acid) and enables wastewater recycling. Compared to traditional strong acid and alkali adjusters, the neutralization products of the biological oxidation solution (such as Fe(OH)3) are easier to dehydrate, reducing the difficulty of sludge disposal. Specifically, the flocculant added to the copper removal turbid solution is a nonionic flocculant, preferably nonionic polyacrylamide (NPAM).

[0039] Furthermore, in some embodiments, in step S3, the oxidant is one or more of hydrogen peroxide, ozone, sodium metabisulfite, and sodium sulfite. The amount of the oxidant added is the amount of CN remaining after the copper removal reaction. T The sum of 2~5 times of the theoretical value of (total cyanide) removal and 0.1~0.2 times of the copper removal agent dosage.

[0040] In the technical solution of the embodiment of the present application, the oxidant is used to remove the remaining cyanide and the residual copper removal agent and the decomposition products of the copper removal agent. Its core goal is to destroy the chemical bonds of cyanide and convert it into low-toxic or non-toxic substances (such as CO2, N2, cyanate (CNO - ), etc.), after the copper removal reaction, free cyanide or copper cyanide complexes (such as [Cu(CN)4] 3- ), the latter is more difficult to decompose and requires a higher oxidant concentration, with a coverage range of 2-5 times to account for water quality fluctuations (such as changes in cyanide concentration) and oxidation efficiency losses (such as temperature and pH effects). Copper removal agents may contain sulfide groups (-CS), which compete with the oxidant and consume some of the oxidant. The remaining sulfide groups can be converted to sulfate under oxidation conditions, avoiding sulfur contamination in subsequent treatments. The oxidation reaction typically requires a pH of 9-11 (such as ozone oxidation) or acidic conditions (such as sodium metabisulfite), which must be coordinated with the pH adjustment in step S2. The reaction time should be 0.5-2 hours to ensure complete cyanide decomposition, which can be controlled by monitoring the cyanide concentration endpoint. Specifically, the flocculant added to the secondary oxidation turbidity solution is a nonionic flocculant, preferably nonionic polyacrylamide (NPAM).

[0041] Furthermore, in some embodiments, in step S4, the biological reaction system includes a conditioning system, an anoxic tank, an aerobic tank, a solid-liquid separation device, and an outlet tank. The activated sludge concentration in the anoxic and aerobic tanks is 3,000 to 12,000 mg / L, the dissolved oxygen in the aerobic tank is 2.0 to 4.0 mg / L, and the dissolved oxygen in the anoxic tank is <0.5 mg / L.

[0042] In the technical solution of the embodiment of the present application, the regulating system is used to homogenize and equalize the amount, buffer the fluctuation of water quality and amount, ensure the stability of subsequent biological treatment, and the residence time is 2~6h. Stirring or aeration is used to prevent precipitation; the anoxic tank is used for denitrification and denitrification, using denitrifying bacteria in the activated sludge to reduce nitrate to nitrogen gas and remove ammonia nitrogen produced by oxidized cyanide. The dissolved oxygen DO is controlled to be less than 0.5mg / L by stirring to avoid oxygen inhibiting the activity of denitrifying enzymes; the pH of the aerobic tank is 6.5~8.5, and the nitrite bacteria in the aerobic tank oxidize NH3-N to NO2 - , nitrifying bacteria further oxidize to NO3 -Aerobic bacteria decompose residual COD and cyanate hydrolysis products. Aeration is used to control dissolved oxygen (DO) to 2.0-4.0 mg / L, ensuring the dominance of nitrifying bacteria and preventing sludge bulking. A solid-liquid separator separates activated sludge from purified water, which is then returned to the anoxic / aerobic tank to maintain a high sludge concentration and control the activated sludge return rate at 30-200%. The effluent tank temporarily stores qualified water and monitors pH, COD, ammonia nitrogen, and other indicators before discharge. This activated sludge concentration increases the volumetric load, reduces the reactor volume, and enhances shock resistance. Specifically, an external carbon source is used to control the activated sludge F / M (organic loading ratio) within the range of 0.1-0.3 kgBOD / (kgMLVSS·d). Phosphorus is added to maintain a nitrogen-phosphorus ratio of 5:1. Activated sludge is rich in Thiobacillus, Nitrospira, norank Saccharimonadale, Denitratisoma and Thauera.

[0043] Furthermore, in some embodiments, the ammonia nitrogen concentration in the purified liquid is 15-800 mg / L, the copper ion concentration is <5 mg / L, and the total cyanide concentration is <10 mg / L.

[0044] In the technical solution of the embodiment of the present application, the ammonia nitrogen range indicates that the system can treat high-load wastewater and adapt to changes by adjusting the sludge concentration and residence time. The low limits of copper and cyanide avoid biological toxicity and ensure system stability.

[0045] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0046] Example 1 This embodiment provides a method for treating ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater to meet standards, and treats easily released cyanide, copper-cyanide complex, heavy metals such as copper, and ammonia nitrogen in ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater (detailed material composition is shown in Table 1). Figure 1 As shown, the following steps are included: S1. Input the wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide into the primary oxidation reactor (cyanide removal reactor), and add 10 mL / L hydrogen peroxide (CN fThe first-stage oxidation reaction was carried out with 10% sodium hydroxide solution (6.57 times of the theoretical value of the reaction), and the pH value of the reaction was controlled to be ≥6.5 during the reaction. The stirring reaction time was 1.5 h. When the amount of hydrogen peroxide was increased, the cyanide content in the wastewater no longer decreased, and a first-stage oxidation turbid liquid was obtained; S2. The primary oxidation turbid liquid obtained in step S1 was introduced into a copper removal reactor, and the pH value was controlled at approximately 6.5 using a biological oxidation solution (approximately 1 mL / L). A copper removal agent (8.01 times the copper content) was added to remove copper. The mixture was stirred for 30 minutes to obtain a copper-removed turbid liquid. The copper removal agent was prepared by mixing sodium dimethyldithiocarbamate, sodium ethylxanthate, diethylenetriamine, and sodium bicarbonate in a molar ratio of 8:0.5:1:1. The composition of the biological oxidation solution is shown in Table 2. Add nonionic polyacrylamide to the copper removal turbid liquid, and obtain copper removal underflow and copper removal overflow liquid after solid-liquid separation in a thickener; The copper removal underflow is subjected to filter pressing and dehydration treatment to obtain copper removal filter press residue and copper removal filter press liquid; S3. The copper-removing overflow liquid and copper-removing filtrate obtained in step S2 were input into the secondary oxidation reactor, and 1.65 mL / L hydrogen peroxide (CN T 3.14 times of the theoretical value of the reaction + 0.15 times of the amount of copper removal agent) for secondary oxidation treatment to obtain a secondary oxidation turbid liquid; Adding nonionic polyacrylamide to the secondary oxidation turbid liquid, and obtaining secondary oxidation underflow and secondary oxidation overflow liquid after solid-liquid separation in a thickener; The secondary oxidation underflow is subjected to filter pressing and dehydration treatment to obtain secondary oxidation filter press residue and secondary oxidation filter press liquid; S4. The secondary oxidation overflow liquid and the secondary oxidation filtrate obtained in step S3 are used as purified liquids and input into the biological reaction system for biochemical reaction. The N / P ratio is controlled to 5:1 through the regulating tank, the anoxic tank, the aerobic tank, and the solid-liquid separation device; the DO in the anoxic tank is controlled to be below 0.5 mg / L, and the DO concentration in the aerobic tank is controlled to be 2.0~4.0 mg / L by aeration; the pH of the aerobic tank is 7.5~8.5; the return rate of activated sludge is controlled to be 100~200%, and the concentration of activated sludge in the anoxic tank and the aerobic tank is controlled to be 3000~6000 mg / L. After sufficient reaction, a deeply purified liquid is obtained, which is reused in the production process or discharged to meet the standards.

[0047] The relevant technical indicators of this embodiment are shown in the following table.

[0048] Table 1 Contents of various substances in ammonia nitrogen and difficult-to-treat copper-cyanide wastewater Table 2 Main substance content of biological oxidation liquid Table 3 Technical indicators of each section of this process Table 4 Removal rate of each pollutant Comparative Examples 1-10 Comparative Examples 1-10 respectively provide a method for meeting the standards for treating ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater. Compared with Example 1, the only difference is the amount of hydrogen peroxide added in step S1, the amount of copper removal agent added in step S2, the type of pH regulator in step S2, and the amount of hydrogen peroxide used in step S3, as shown in Table 5.

[0049] Table 5 Process parameters in Comparative Examples 1-10 After treating the ammonia nitrogen-containing and difficult-to-treat copper-cyanide wastewater according to the methods provided in the above comparative examples 1-10, the effluent obtained was tested, and the results of relevant technical indicators are shown in Table 6.

[0050] Table 6 Comparative Example Test Results It can be seen from the data in Table 6 that if copper removal agent is not added or the amount of copper removal agent is insufficient, and the pH value of copper removal is not well controlled, the complexed and stable copper and cyanide cannot be removed, the copper and cyanide concentrations in the deep purification influent are high, resulting in biological inactivation, ammonia nitrogen cannot be effectively removed, and the cyanide, copper, and ammonia nitrogen in the effluent exceed the standard; excessive copper removal agent will result in a large amount of residual copper removal agent and its decomposition products after treatment, affecting the biological activity of deep purification, resulting in the effluent ammonia nitrogen not meeting the standard; directly adding copper removal agent for copper removal without cyanide breaking pretreatment or insufficient dosage of primary cyanide breaking treatment agent will also lead to incomplete copper removal, low cyanide removal rate, high cyanide and copper concentrations in the deep purification influent, biological inactivation, and ammonia nitrogen cannot be removed The cyanide, copper, and ammonia nitrogen in the effluent do not meet the standards; concentrated sulfuric acid is used instead of biological oxidation liquid to adjust the pH value, and the small amount of ferrocyanide in the wastewater cannot be completely removed; the amount of precipitation after the copper removal reaction is very small, and there is no co-precipitation effect of other metal precipitations such as iron, making it difficult to separate the copper-containing precipitates produced from the water, and the copper removal effect is still not achieved, while affecting the back-end biological method for removing ammonia nitrogen; insufficient addition of secondary oxidation oxidants will lead to incomplete removal of cyanide, residual copper removal agents and decomposition products, affecting microbial activity, and excessive ammonia nitrogen in the effluent; excessive addition of secondary oxidation oxidants will cause the residual oxidants to have a disinfecting and sterilizing effect on microorganisms, reducing the microbial biomass and causing excessive ammonia nitrogen in the effluent. Therefore, the primary oxidation reaction, copper removal reaction, and secondary oxidation reaction all need to control the agent addition point, agent addition amount, pH value and other control conditions according to the treatment process requirements to achieve the ultimate treatment purpose.

[0051] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other methods constructed by applying various modifications that can be imagined by those skilled in the art to the embodiments and combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for treating wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide, characterized in that: The following steps are involved: S1. The wastewater containing ammonia nitrogen and difficult-to-treat copper cyanide is input into a primary oxidation reactor, an oxidant is added to obtain a primary oxidation turbid liquid; S2. The primary oxidation turbid liquid obtained in step S1 is input into a copper removal reactor, and a copper removal agent and a pH adjuster are added to obtain a copper removal turbid liquid; adding a flocculant to the copper removal turbid liquid, performing solid-liquid separation to obtain a copper removal underflow and a copper removal overflow liquid; The copper removal underflow is subjected to filter press dehydration treatment to obtain copper removal filter press residue and copper removal filter press liquid; S3. The copper removal overflow obtained in step S2 and the copper removal filtrate are input into a secondary oxidation reactor, an oxidant is added to obtain a secondary oxidation turbid liquid; adding a flocculant to the secondary oxidation turbid liquid, and performing solid-liquid separation to obtain a secondary oxidation underflow and a secondary oxidation overflow liquid; The secondary oxidation underflow is subjected to filter pressing and dehydration treatment to obtain secondary oxidation slag and secondary oxidation filtrate; S4. The secondary oxidation overflow liquid and the secondary oxidation filtrate obtained in step S3 are used as purified liquids and input into a biological reaction system for biochemical reaction, and the effluent is reused in the production process or discharged when it meets the standards.

2. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 1, wherein: In step S1, the oxidant is one or more of hydrogen peroxide, ozone, sodium metabisulfite, and sodium sulfite, and the dosage is about the same as that of CN. f The reaction is 6 to 10 times the theoretical value.

3. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 1, wherein: In step S2, the amount of the copper removal agent added is 6 to 12 times the copper content in the wastewater, and the copper removal agent includes sodium dimethyldithiocarbamate.

4. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 3, wherein: The copper removal agent also includes one or more of sodium ethyl xanthate, sodium polysulfide, diethylenetriamine, and sodium bicarbonate, wherein the mass proportion of sodium dimethyldithiocarbamate is ≥80%.

5. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 1, wherein: In step S2, the pH adjuster is a biological oxidation liquid, the reaction pH is controlled to be 6.5-7.0, and the copper removal reaction time is 0.5-1.0h; the biological oxidation liquid is acidic wastewater with an iron ion concentration of ≥10000mg / L.

6. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 1, wherein: In step S3, the oxidant is one or more of hydrogen peroxide, ozone, sodium metabisulfite, and sodium sulfite.

7. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 6, wherein: In step S3, the amount of the oxidant added is the amount of CN remaining after the copper removal reaction. T The sum of 2~5 times of the theoretical removal value and 0.1~0.2 times of the copper removal agent dosage.

8. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 1, wherein: In step S4, the biological reaction system includes a regulating system, an anoxic tank, an aerobic tank, a solid-liquid separation device, and a water outlet tank.

9. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 8, wherein: The activated sludge concentration in the anoxic tank and the aerobic tank is 3000-12000 mg / L, the dissolved oxygen in the aerobic tank is 2.0-4.0 mg / L, and the dissolved oxygen in the anoxic tank is <0.5 mg / L.

10. The method for treating wastewater containing ammonia nitrogen and difficult to treat copper cyanide according to claim 9, wherein: The ammonia nitrogen concentration in the purified liquid is 15-800 mg / L, the copper ion concentration is less than 5 mg / L, and the total cyanide concentration is less than 10 mg / L.

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