Method and system for treating acidic wastewater by ultrasonic enhanced H2O2 based on pollutant typing

Abstract

The invention relates to a method and a system for treating acidic wastewater by ultrasonic enhanced H2O2 based on pollutant typing, and belongs to the technical field of hydrometallurgy wastewater treatment. In order to solve the problems that an existing treatment process is single in scheme, poor in adaptability and not thorough in oxidation, consequently, the chemical oxygen demand (COD) of effluent is unstable and prone to rebound and the like, a differential precise treatment method is adopted, pollutant classification is conducted on wastewater, and a high sulfite type and a high organic matter-high sulfite mixed type are distinguished; after pretreatment and pH adjustment, an ultrasonic enhanced H2O2 oxidation process is adopted for the high-sulfite type wastewater, and an ultrasonic, Fe < 2 + > catalysis, H2O2 oxidation and Fe < 3 + > flocculation combined process is adopted for the high organic matter-high-sulfite mixed type wastewater. According to the method disclosed by the invention, the efficient and stable removal of COD (Chemical Oxygen Demand) of different components is realized by matching differentiated working conditions in a parting manner and accurately controlling ultrasonic parameters, H2O2 adding amount and reaction conditions. The total COD removal rate of the two types of wastewater is stabilized at 92%-98%, the COD of the effluent is lower than 50 mg / L, the emission standard is met, and COD rebound of the effluent is effectively inhibited.

Description

Technical Field

[0001] This invention relates to a method and system for ultrasonically enhanced H2O2 treatment of acidic wastewater based on pollutant classification, belonging to the field of hydrometallurgical wastewater treatment technology. Background Technology

[0002] In industrial production, molybdenum is mainly produced by roasting and oxidizing molybdenite (MoS2) to MoO3, which is then used to produce downstream products. The SO2-containing flue gas generated during roasting is used for acid production, resulting in highly acidic (pH=0~1), chemically demanded (COD), and complex acidic wastewater during the flue gas scrubbing process. The high COD primarily originates from reducing inorganic pollutants, mainly sulfites, and some recalcitrant organic pollutants from residual beneficiation reagents and organic additives (such as 1,2-dimethylhydrazine carboxamide and siloxane derivatives).

[0003] Existing COD treatment technologies for acidic wastewater from molybdenum smelting mainly include physical, biological, and chemical methods. Physical methods (such as adsorption and membrane separation) suffer from incomplete pollutant removal, adsorbent regeneration, or membrane fouling issues. Biological methods are limited by factors such as microbial activity, long treatment cycles, and system instability. Among chemical methods, H₂O₂ oxidation and Fenton (H₂O₂ / Fe²⁺) are... 2+ The H2O2 or Fenton process is widely used due to its simplicity and relatively low cost. However, directly applying traditional H2O2 or Fenton methods to acidic wastewater from molybdenum smelting, which exhibits drastic fluctuations in water quality, reveals significant limitations, making it difficult to consistently achieve the required treatment efficiency. Firstly, traditional H2O2 oxidation or Fenton methods typically determine reagent ratios and reaction conditions based on the total COD value of the wastewater. However, the COD composition of acidic wastewater from molybdenum smelting is complex and highly volatile, mainly consisting of easily oxidizable inorganic reducing sulfites and recalcitrant organic pollutants. Faced with significant fluctuations in the ratio of sulfites to organic matter, fixed reagent ratios and reaction conditions cannot simultaneously and efficiently treat both types of pollutants. For wastewater with high sulfite content, H2O2 is easily consumed rapidly and may be ineffectively decomposed; for wastewater with high organic matter content, the oxidation capacity is insufficient, leading to drastic fluctuations in COD removal rate with influent water quality and poor system stability. From a reaction mechanism perspective, inorganic reducing agents such as sulfites undergo rapid, direct chemical oxidation with H₂O₂; however, recalcitrant organic matter reacts slowly with H₂O₂, requiring stronger oxidizing conditions (such as ·OH radicals) for effective degradation. Fluctuations in water quality directly alter the reaction pathways and competitive relationships. Using a single process parameter cannot simultaneously and efficiently address these two pollutants with vastly different oxidizing characteristics, leading to significant variations in COD removal rates with drastic fluctuations in influent water quality during actual operation, resulting in poor process adaptability and stability. To ensure effectiveness, excessive dosage of reagents is often used. However, residual H₂O₂ in the effluent acts as a reducing agent during COD measurement and is oxidized by potassium dichromate, leading to inflated COD readings. Simultaneously, excessive H₂O₂ / Fe₂ ratios... 2+This will increase treatment costs; ultimately, the overall treatment effect and economic efficiency will still be difficult to guarantee, and the effluent COD will still not be able to consistently meet the discharge standards. Therefore, there is an urgent need to develop a differentiated, efficient, and stable treatment process based on the characteristics of acidic wastewater, in order to achieve the industrial treatment goal of high COD removal rate, suppression of COD rebound, and stable effluent compliance. Summary of the Invention

[0004] To address the problems of existing technologies (such as ordinary Fenton oxidation or H2O2 oxidation) in treating acidic wastewater from molybdenum smelting, which suffer from poor adaptability due to drastic fluctuations in wastewater composition, high reagent consumption, incomplete oxidation, and unstable and easily rebounding COD in the effluent, this invention proposes an ultrasonic-enhanced H2O2 treatment method and system for acidic wastewater based on pollutant classification. By pre-classifying the pollutants in the complex and variable acidic wastewater from molybdenum smelting, differentiated ultrasonic-enhanced oxidation or ultrasonic-catalytic oxidation-flocculation core processes are matched for two types of wastewater: high sulfite type and high organic matter-high sulfite mixed type. By precisely controlling ultrasonic parameters, H2O2 dosage, and reaction conditions, efficient and stable COD removal is achieved, effectively suppressing problems such as rebound.

[0005] An ultrasonic-enhanced H2O2 treatment method for acidic wastewater based on pollutant typing, the specific steps of which are as follows: S1. Pollutant classification: Analyze the sulfite content and COD composition of the acidic wastewater from molybdenum smelting to be treated. Based on the TOC value, determine whether the acidic wastewater from molybdenum smelting to be treated is high-sulfite type acidic wastewater or high-organic-high-sulfite mixed wastewater. S2. Pretreatment: Pump high-sulfite acidic wastewater or high-organic-high-sulfite mixed wastewater into the equalization tank, and add alkali agent under stirring to adjust the pH value of the wastewater to 3.0~4.0 to obtain pretreated high-sulfite acidic wastewater or pretreated high-organic-high-sulfite mixed wastewater; S3. Type-specific oxidation treatment: The pretreated high-sulfite acidic wastewater is pumped into an ultrasonic-enhanced oxidation tank, and H2O2 solution is slowly added dropwise under ultrasonic conditions to carry out the oxidation reaction, thereby obtaining oxidized wastewater; Pretreated high-organic-high-sulfite mixed wastewater is pumped into an ultrasonic-enhanced oxidation tank. Under ultrasonic conditions, ferrous sulfate is added and dispersed evenly. Then, H2O2 solution is slowly added dropwise to carry out 2-3 stages of ultrasonic-enhanced catalytic oxidation reaction to obtain oxidized wastewater. S4. Flocculation and Neutralization Treatment: The oxidation wastewater is pumped into a flocculation sedimentation tank. The pH of the system is adjusted to 7.0-8.5 using an alkali agent. After static flocculation and sedimentation separation, supernatant and bottom sludge are obtained. The supernatant is the compliant effluent, and the bottom sludge will undergo dewatering treatment. Specifically, for mixed acidic wastewater with high organic matter and high sulfite content, the Fe generated during oxidation...3+ Under alkaline conditions, it forms ferric hydroxide colloids with flocculation effect, which enhances flocculation and effectively adsorbs and precipitates residual organic matter and suspended solids; for high sulfite wastewater, it mainly adjusts the pH value of the water to meet the discharge requirements and removes trace suspended solids.

[0006] Preferably, in step S1, the pH value of the acidic wastewater from molybdenum smelting to be treated is not greater than 1, and the sulfite concentration is >300 mg / L.

[0007] More preferably, the method for determining the type of acidic wastewater from molybdenum smelting in step S1 is as follows: If the TOC value is ≤100 mg / L, then the type of acidic wastewater from molybdenum smelting to be treated is high-sulfite type acidic wastewater; If the TOC value is greater than 100 mg / L, then the type of acidic wastewater from molybdenum smelting to be treated is a mixed acidic wastewater with high organic matter and high sulfite content.

[0008] Preferably, in step S3, when treating high-sulfite acidic wastewater by type-specific oxidation, the ultrasonic power density is 1~10 W / L, the frequency is 20~40 kHz, the total volume of H2O2 added to the mass ratio of COD mL:g is 13~29:1, the type-specific oxidation treatment temperature is 20~50℃, and the time is 40~80 min. When performing type-specific oxidation treatment on mixed acidic wastewater with high organic matter and high sulfite content, the ultrasonic power density is 10~50 W / L, the frequency is 20~40 kHz, the ferrous sulfate mixing and dispersion time is 10~20 min, the molar ratio of H2O2 to ferrous sulfate is 1:1.5~2.5, and the total H2O2 dosage to COD mass ratio (mL:g) is 22~48:1. The type-specific oxidation treatment temperature is room temperature, and the time is 50~120 min.

[0009] Preferably, the alkali agent is lime slurry or lime powder.

[0010] A system for treating acidic wastewater with ultrasound-enhanced H2O2 based on pollutant typing, comprising: The system includes: A equalization tank, B ultrasonic enhanced oxidation tank, C flocculation-sedimentation tank, D plate and frame filter press, and reagent storage tank; 1-1 first agitator, 1-2 second agitator, 1-3 third agitator, 2 ultrasonic rod, 3-1 first circulation pump, 3-2 second circulation pump, 4-1 first peristaltic pump, 4-2 second peristaltic pump, 4-3 third peristaltic pump, 4-4 fourth peristaltic pump, 4-5 fifth peristaltic pump, 5-1 first outlet pipe, and 5-2 second outlet pipe. The reagent storage tank includes an alkali tank a, a ferrous sulfate tank b, and a hydrogen peroxide tank c; The equalization tank A is connected to the ultrasonic enhanced oxidation tank B through the first circulation pump 3-1. The ultrasonic enhanced oxidation tank B is connected to the flocculation-sedimentation tank C through the second circulation pump 3-2. The flocculation-sedimentation tank C is connected to the plate and frame filter press D through the first outlet pipe 5-1. The drain end of the plate and frame filter press D is connected to the second outlet pipe 5-2. The first agitator 1-1 is installed in the equalization tank A, the second agitator 1-2 is installed in the ultrasonic enhanced oxidation tank B, and the third agitator 1-3 is installed in the flocculation-sedimentation tank C; the ultrasonic rod 2 is installed on the inner side wall of the ultrasonic enhanced oxidation tank B. The alkali tank a of the reagent storage tank is connected to the equalization tank A, the ultrasonic enhanced oxidation tank B and the flocculation-sedimentation tank C through the first peristaltic pump 4-1, the third peristaltic pump 4-3 and the fifth peristaltic pump 4-5 respectively. The ferrous sulfate tank b is connected to the ultrasonic enhanced oxidation tank B through the second peristaltic pump 4-2. The hydrogen peroxide tank c is connected to the ultrasonic enhanced oxidation tank B through the fourth peristaltic pump 4-4.

[0011] The beneficial effects of this invention are: (1) This invention proposes for the first time a pollutant classification method for acidic wastewater from molybdenum smelting based on COD composition, and matches it with differentiated processes to achieve precise treatment; for mixed types of high organic matter and high sulfite, ultrasonic + Fe is used. 2+ The process involves catalysis, H2O2 oxidation, and iron salt flocculation, utilizing ultrasound and Fe... 2+ Co-catalyzing the production of ·OH from H2O2 to enhance the oxidation of organic matter, and utilizing Fe 3+ The hydrolysis and flocculation effect; for the high sulfite type, a simplified process of ultrasound + H2O2 oxidation is adopted, which mainly relies on ultrasound cavitation to directly crack and H2O2 to oxidize sulfite, avoiding unnecessary iron salt addition. (2) This invention precisely controls the ultrasonic parameters and H2O2 addition. For different pollutant types, this invention optimizes the ultrasonic parameters and H2O2 addition: For acidic wastewater with high COD (COD 500~800 mg / L) and high levels of recalcitrant organic matter, a medium power density (10~50 W / L) and a high H2O2 addition (total H2O2 dosage to COD mass ratio of 22~48:1 mL / g) are used, utilizing ultrasound combined with Fe... 2+ This method promotes the decomposition of H2O2 into ·OH while avoiding the problem of residual H2O2 causing a rebound in COD. For acidic wastewater with a COD value of 300~600 mg / L and high concentration of sulfite, a low power density (1~10 W / L) and low H2O2 addition (total H2O2 dosage to COD mass ratio of 13-29:1 mL / g) are used. The strong mechanical effect of H2O2 combined with temperature (20~50 ℃) promotes the decomposition of H2O2 into ·OH while avoiding the problem of residual H2O2 causing a rebound in COD. (3) This invention introduces Fe into acidic wastewater with high COD value and high content of recalcitrant organic matter. 2+ Catalysis and Fe 3+ Flocculation, through precise control of H2O2 / Fe 2+ Molar ratio (this invention uses low H2O2 and high Fe) 2+ (using non-traditional ratios) to enhance catalytic and flocculation effects; (4) After treatment by the method of the present invention, the total COD removal rate of both types of wastewater is stable at 92%~98%, and the COD concentration of the effluent can be stably reduced to below 50 mg / L, meeting the most stringent discharge requirements; (5) By precisely controlling the oxidation endpoint and reagent ratio, the present invention effectively avoids the problem of COD value increase caused by residual H2O2 or intermediate products in the effluent. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the system structure for ultrasonic-enhanced H2O2 treatment of acidic wastewater based on pollutant classification. In the diagram, A is the equalization tank, B is the ultrasonic enhanced oxidation tank, C is the flocculation-sedimentation tank, D is the plate and frame filter press, a is the alkali tank, b is the ferrous sulfate tank, c is the hydrogen peroxide tank, 1-1 is the first stirrer, 1-2 is the second stirrer, 1-3 is the third stirrer, 2 is the ultrasonic rod, 3-1 is the first circulation pump, 3-2 is the second circulation pump, 4-1 is the first peristaltic pump, 4-2 is the second peristaltic pump, 4-3 is the third peristaltic pump, 4-4 is the fourth peristaltic pump, 4-5 is the fifth peristaltic pump, 5-1 is the first outlet pipe, and 5-2 is the second outlet pipe. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0014] The following embodiments of the present invention all employ a system for treating acidic wastewater using ultrasound-enhanced H2O2 based on pollutant typing (see...). Figure 1 A method for implementing ultrasonic-enhanced H2O2 treatment of acidic wastewater based on pollutant typing, wherein the system for ultrasonic-enhanced H2O2 treatment of acidic wastewater based on pollutant typing comprises: The system includes: A equalization tank, B ultrasonic enhanced oxidation tank, C flocculation-sedimentation tank, D plate and frame filter press, and reagent storage tank; 1-1 first agitator, 1-2 second agitator, 1-3 third agitator, 2 ultrasonic rod, 3-1 first circulation pump, 3-2 second circulation pump, 4-1 first peristaltic pump, 4-2 second peristaltic pump, 4-3 third peristaltic pump, 4-4 fourth peristaltic pump, 4-5 fifth peristaltic pump, 5-1 first outlet pipe, and 5-2 second outlet pipe. The reagent storage tank includes an alkali tank a, a ferrous sulfate tank b, and a hydrogen peroxide tank c; The equalization tank A is connected to the ultrasonic enhanced oxidation tank B through the first circulation pump 3-1. The ultrasonic enhanced oxidation tank B is connected to the flocculation-sedimentation tank C through the second circulation pump 3-2. The flocculation-sedimentation tank C is connected to the plate and frame filter press D through the first outlet pipe 5-1. The drain end of the plate and frame filter press D is connected to the second outlet pipe 5-2. The first agitator 1-1 is installed in the equalization tank A, the second agitator 1-2 is installed in the ultrasonic enhanced oxidation tank B, and the third agitator 1-3 is installed in the flocculation-sedimentation tank C; the ultrasonic rod 2 is installed on the inner side wall of the ultrasonic enhanced oxidation tank B. The alkali tank a of the reagent storage tank is connected to the equalization tank A, the ultrasonic enhanced oxidation tank B and the flocculation-sedimentation tank C through the first peristaltic pump 4-1, the third peristaltic pump 4-3 and the fifth peristaltic pump 4-5 respectively. The ferrous sulfate tank b is connected to the ultrasonic enhanced oxidation tank B through the second peristaltic pump 4-2. The hydrogen peroxide tank c is connected to the ultrasonic enhanced oxidation tank B through the fourth peristaltic pump 4-4.

[0015] Example 1: A method for treating acidic wastewater with ultrasound-enhanced H2O2 based on pollutant typing, the specific steps of which are as follows: S1. Pollutant Classification: The sulfite content and COD composition of the acidic wastewater from molybdenum smelting to be treated were analyzed. Based on the TOC value, the type of acidic wastewater from molybdenum smelting to be treated was determined to be either high-sulfite type acidic wastewater or high-organic-high-sulfite mixed wastewater. In this embodiment, the pH value of the acidic wastewater from molybdenum smelting to be treated was 0.8, the COD was 737.5 mg / L, the sulfite content was 492 mg / L, and the TOC was 235 mg / L. Therefore, the acidic wastewater from molybdenum smelting to be treated in this embodiment is a high-organic-high-sulfite mixed wastewater. S2. Pretreatment: Pump the mixed wastewater with high organic matter and high sulfite into the equalization tank, and add an alkaline agent (lime slurry) under stirring to adjust the pH value of the wastewater to 3.0~4.0 to obtain pretreated mixed wastewater with high organic matter and high sulfite. S3. Differentiated Oxidation Treatment: The pretreated mixed wastewater with high organic matter and high sulfite content is pumped into an ultrasonic-enhanced oxidation tank. Under ultrasonic conditions (ultrasonic power density of 12W / L, frequency of 25kHz), ferrous sulfate is added and mixed and dispersed evenly (15min). Then, H2O2 solution is slowly added dropwise, and a two-stage ultrasonic-enhanced catalytic oxidation reaction is carried out at room temperature for 1.5h to obtain oxidized wastewater. The molar ratio of H2O2 to ferrous sulfate is 1:2, and the total volume of H2O2 added to COD mass ratio (mL:g) is 46:1. S4. Flocculation and Neutralization Treatment: The oxidation wastewater is pumped into a flocculation sedimentation tank. The pH of the system is adjusted to 8 using an alkaline agent (lime slurry). After static flocculation and sedimentation separation, supernatant and bottom sludge are obtained. The supernatant is the compliant discharge water, and the bottom sludge will undergo dewatering treatment. Specifically, in this embodiment, the high organic matter-high sulfurous acid mixed acidic wastewater undergoes oxidation to generate Fe... 3+ Under alkaline conditions, it forms ferric hydroxide colloids with flocculation effect, which enhances flocculation and effectively adsorbs and precipitates residual organic matter and suspended matter. In this embodiment, the COD value of the supernatant was 32.45 mg / L (removal rate 95.6%), which met the emission standards and showed no increase in COD.

[0016] Example 2: A method for treating acidic wastewater with ultrasound-enhanced H2O2 based on pollutant typing, the specific steps of which are as follows: S1. Pollutant Classification: The sulfite content and COD composition of the acidic wastewater from molybdenum smelting to be treated were analyzed. Based on the TOC value, the type of acidic wastewater from molybdenum smelting to be treated was determined to be either high-sulfite type acidic wastewater or high-organic-high-sulfite mixed wastewater. In this embodiment, the pH value of the acidic wastewater from molybdenum smelting to be treated was 0.3, the COD was 698 mg / L, the sulfite content was 483 mg / L, and the TOC was 254 mg / L. Therefore, the acidic wastewater from molybdenum smelting to be treated in this embodiment is a high-organic-high-sulfite mixed wastewater. S2. Pretreatment: Pump the mixed wastewater with high organic matter and high sulfite into the equalization tank, and add alkali (lime powder) under stirring to adjust the pH value of the wastewater to 3.0~4.0 to obtain pretreated mixed wastewater with high organic matter and high sulfite. S3. Differentiated Oxidation Treatment: The pretreated mixed wastewater with high organic matter and high sulfite content is pumped into an ultrasonic-enhanced oxidation tank. Under ultrasonic conditions (ultrasonic power density of 40 W / L, frequency of 20 kHz), ferrous sulfate is added and mixed and dispersed evenly (18 min). Then, H2O2 solution is slowly added dropwise, and a two-stage ultrasonic-enhanced catalytic oxidation reaction is carried out at room temperature for 1 h to obtain oxidized wastewater. The molar ratio of H2O2 to ferrous sulfate is 1:1.8, and the total volume of H2O2 added to the COD mass ratio (mL:g) is 31:1. S4. Flocculation and Neutralization Treatment: The oxidation wastewater is pumped into a flocculation sedimentation tank. The pH of the system is adjusted to 7.5 using an alkaline agent (lime powder). After static flocculation and sedimentation separation, supernatant and bottom sludge are obtained. The supernatant is the compliant discharge water, and the bottom sludge will undergo dewatering treatment. Specifically, in this embodiment, the high organic matter-high sulfurous acid mixed acidic wastewater undergoes oxidation to generate Fe... 3+ Under alkaline conditions, it forms ferric hydroxide colloids with flocculation effect, which enhances flocculation and effectively adsorbs and precipitates residual organic matter and suspended matter. In this embodiment, the COD value of the supernatant was 42.1 mg / L (removal rate 93.8%), which meets the emission standards and there is no increase in COD.

[0017] Example 3: A method for treating acidic wastewater with ultrasound-enhanced H2O2 based on pollutant typing, the specific steps of which are as follows: S1. Pollutant Classification: The sulfite content and COD composition of the acidic wastewater from molybdenum smelting to be treated were analyzed. Based on the TOC value, the type of acidic wastewater from molybdenum smelting to be treated was determined to be either high-sulfite type acidic wastewater or high-organic-high-sulfite mixed wastewater. In this embodiment, the pH value of the acidic wastewater from molybdenum smelting to be treated was 0.5, the COD was 596 mg / L, the sulfite content was 552 mg / L, and the TOC was 41 mg / L. Therefore, the acidic wastewater from molybdenum smelting to be treated in this embodiment is high-sulfite type acidic wastewater. S2. Pretreatment: Pump the high-sulfite acidic wastewater into the equalization tank, and add an alkaline agent (lime slurry) under stirring to adjust the pH value of the wastewater to 3.0~4.0 to obtain pretreated high-sulfite acidic wastewater; S3. Type-specific oxidation treatment: The pretreated high-sulfite acidic wastewater is pumped into an ultrasonic-enhanced oxidation tank. Under ultrasonic conditions (ultrasonic power density of 3W / L and frequency of 40kHz), H2O2 solution is slowly added dropwise and the oxidation reaction is carried out at 40℃ for 80 minutes to obtain oxidized wastewater. The total volume of H2O2 added to COD mass ratio (mL:g) is 28:1. S4. Flocculation and Neutralization Treatment: The oxidation wastewater is pumped into a flocculation sedimentation tank. The pH value of the system is adjusted to 7.2 using an alkaline agent (lime slurry). After static flocculation and sedimentation separation, the supernatant and bottom sludge are obtained. The supernatant is the compliant discharge water, and the bottom sludge will be dewatered. Specifically, in this embodiment, for high sulfite wastewater, the main treatment is to adjust the pH value of the water to meet the discharge requirements and remove trace suspended solids. In this embodiment, the COD value of the supernatant was 29.2 mg / L (removal rate 95%), which meets the emission standards and there was no increase in COD.

[0018] Example 4: A method for treating acidic wastewater with ultrasound-enhanced H2O2 based on pollutant typing, the specific steps of which are as follows: S1. Pollutant Classification: The sulfite content and COD composition of the acidic wastewater from molybdenum smelting to be treated were analyzed. Based on the TOC value, the type of acidic wastewater from molybdenum smelting to be treated was determined to be either high-sulfite type acidic wastewater or high-organic-high-sulfite mixed wastewater. In this embodiment, the pH value of the acidic wastewater from molybdenum smelting to be treated was 0.5, the COD was 485 mg / L, the sulfite content was 440 mg / L, and the TOC was 37 mg / L. Therefore, the acidic wastewater from molybdenum smelting to be treated in this embodiment is high-sulfite type acidic wastewater. S2. Pretreatment: Pump the high-sulfite acidic wastewater into the equalization tank, and add an alkaline agent (lime powder) under stirring to adjust the pH value of the wastewater to 3.0~4.0 to obtain pretreated high-sulfite acidic wastewater; S3. Type-specific oxidation treatment: The pretreated high-sulfite acidic wastewater is pumped into an ultrasonic-enhanced oxidation tank. Under ultrasonic conditions (ultrasonic power density of 5W / L and frequency of 30kHz), H2O2 solution is slowly added dropwise and the oxidation reaction is carried out at 25℃ for 70 minutes to obtain oxidized wastewater. The total volume of H2O2 added to COD mass ratio (mL:g) is 15:1. S4. Flocculation and Neutralization Treatment: The oxidation wastewater is pumped into a flocculation sedimentation tank. The pH value of the system is adjusted to 8 using an alkaline agent (lime slurry). After static flocculation and sedimentation separation, the supernatant and bottom sludge are obtained. The supernatant is the compliant discharge water, and the bottom sludge will be dewatered. Specifically, in this embodiment, for high sulfite wastewater, the main treatment is to adjust the pH value of the water to meet the discharge requirements and remove trace suspended solids. In this embodiment, the COD value of the supernatant was 26.9 mg / L (removal rate 93%), which meets the emission standards and there was no increase in COD.

[0019] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for the treatment of acidic wastewater by ultrasound enhanced H2O2 based on the classification of pollutants, characterized by, The specific steps are as follows: S1. Contaminant typing: analyze the sulfite content and COD composition of the molybdenum smelting acidic wastewater to be treated, and determine the type of the molybdenum smelting acidic wastewater to be treated according to the TOC value, which is high sulfite type acidic wastewater or high organic matter-high sulfite mixed type wastewater; S2. Pretreatment: pump the high sulfite type acidic wastewater or the high organic matter-high sulfite mixed type wastewater into a conditioning tank, and add an alkali agent under stirring to adjust the pH value of the wastewater to 3.0-4.0, to obtain pretreated high sulfite type acidic wastewater or pretreated high organic matter-high sulfite mixed type wastewater; S3. Type oxidation treatment: pump the pretreated high sulfite type acidic wastewater into an ultrasonic enhanced oxidation tank, and slowly add H2O2 solution under ultrasonic conditions to carry out oxidation reaction, to obtain oxidation treated wastewater; Pump the pretreated high organic matter-high sulfite mixed type wastewater into an ultrasonic enhanced oxidation tank, add ferrous sulfate under ultrasonic conditions and disperse it uniformly, and then slowly add H2O2 solution to carry out 2-3 stage ultrasonic enhanced catalytic oxidation reaction, to obtain oxidation treated wastewater; S4. Flocculation and neutralization treatment: pump the oxidation treated wastewater into a flocculation and sedimentation tank, adjust the pH value of the system to 7.0-8.5 using an alkali agent, and carry out flocculation and sedimentation separation by standing, to obtain supernatant and bottom sludge, wherein the supernatant is the wastewater meeting the discharge standard, and the bottom sludge will be subjected to dewatering treatment.

2. The method for treating acidic wastewater by ultrasonic enhanced H2O2 based on the classification of pollutants according to claim 1, characterized in that: The pH value of the molybdenum smelting acidic wastewater to be treated in step S1 is not more than 1, and the sulfite concentration is >300 mg / L.

3. The method for treating acidic wastewater by ultrasound enhanced H2O2 based on the classification of pollutants according to claim 2, characterized in that: The method for determining the type of the molybdenum smelting acidic wastewater to be treated in step S1 is as follows: If the TOC value is ≤100 mg / L, the molybdenum smelting acidic wastewater to be treated is high sulfite type acidic wastewater; If the TOC value is >100 mg / L, the molybdenum smelting acidic wastewater to be treated is high organic matter-high sulfite mixed type acidic wastewater.

4. The method for treating acidic wastewater by ultrasound enhanced H2O2 based on the classification of pollutants according to claim 1, characterized in that: In the type oxidation treatment of the high sulfite type acidic wastewater, the ultrasonic power density is 1-10 W / L, the frequency is 20-40 kHz, the mass ratio of the total volume of H2O2 added to COD is 13-29:1, the type oxidation treatment temperature is 20-50℃, and the time is 40-80 min; In the type oxidation treatment of the high organic matter-high sulfite mixed type acidic wastewater, the ultrasonic power density is 10-50 W / L, the frequency is 20-40 kHz, the ferrous sulfate mixing and dispersing time is 10-20 min, the molar ratio of H2O2 to ferrous sulfate is 1:1.5-2.5, the mass ratio of the total volume of H2O2 added to COD is 22-48:1, and the type oxidation treatment temperature is room temperature, and the time is 50-120 min.

5. The method for treating acidic wastewater by ultrasound enhanced H2O2 based on the classification of pollutants according to claim 1, characterized in that: The alkali agent is lime milk slurry or lime powder.

6. A system for ultrasonically enhanced H202 treatment of acidic wastewater based on the classification of pollutants, characterized by, The method for implementing any one of claims 1-5 comprises: The adjusting tank (A), the ultrasonic enhanced oxidation tank (B), the flocculation-sedimentation tank (C), the plate and frame filter (D), the medicament storage tank, the first agitator (1-1), the second agitator (1-2), the third agitator (1-3), the ultrasonic rod (2), the first circulating pump (3-1), the second circulating pump (3-2), the first peristaltic pump (4-1), the second peristaltic pump (4-2), the third peristaltic pump (4-3), the fourth peristaltic pump (4-4), the fifth peristaltic pump (4-5), the first water outlet pipe (5-1), the second water outlet pipe (5-2), The medicament storage tank comprises a base agent tank (a), a ferrous sulfate tank (b) and a hydrogen peroxide tank (c); The adjusting tank (A) is communicated with the ultrasonic enhanced oxidation tank (B) through the first circulating pump (3-1), the ultrasonic enhanced oxidation tank (B) is communicated with the flocculation-sedimentation tank (C) through the second circulating pump (3-2), the flocculation-sedimentation tank (C) is communicated with the plate and frame filter (D) through the first water outlet pipe (5-1), and the plate and frame filter (D) is externally connected with the second water outlet pipe (5-2) at a water discharge end; The first agitator (1-1) is arranged in the adjusting tank (A), the second agitator (1-2) is arranged in the ultrasonic enhanced oxidation tank (B), and the third agitator (1-3) is arranged in the flocculation-sedimentation tank (C); and the ultrasonic rod (2) is arranged on an inner side wall of the ultrasonic enhanced oxidation tank (B); The base agent tank (a) of the medicament storage tank is communicated with the adjusting tank (A), the ultrasonic enhanced oxidation tank (B) and the flocculation-sedimentation tank (C) through the first peristaltic pump (4-1), the third peristaltic pump (4-3) and the fifth peristaltic pump (4-5) respectively, the ferrous sulfate tank (b) is communicated with the ultrasonic enhanced oxidation tank (B) through the second peristaltic pump (4-2), and the hydrogen peroxide tank (c) is communicated with the ultrasonic enhanced oxidation tank (B) through the fourth peristaltic pump (4-4).

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