Activated carbon desulfurization and denitrification acid production process wastewater treatment system and treatment method

Abstract

The present application relates to a kind of activated carbon desulfurization and denitrification acid process wastewater treatment system and processing method, the system includes sequentially through pipeline connection's wastewater pool, neutralization tank, reaction pool, flocculation tank, clarifier, deamination deployment pool, ammonia nitrogen stripping tower, multi-medium filter, activated carbon filter, MVR evaporator;Wastewater is carried out coagulation sedimentation after homogeneous equal amount, and the sludge after sedimentation is carried out filter pressing, and the filter water after filter pressing is removed ammonia nitrogen and double filtration by stripping, and after removing metal ions, ammonia nitrogen, COD, wastewater is discharged or reused after concentrating crystallization again;The process of wastewater treatment method is simple, easy to operate, and the wastewater treatment effect is good, energy consumption is lower, and has good market application and popularization value.

Description

Technical Field

[0001] This invention relates to the field of acid production process wastewater treatment technology, and in particular to an activated carbon desulfurization and denitrification acid production process wastewater treatment system and treatment method. Background Technology

[0002] Activated carbon desulfurization and denitrification purification processes utilize the adsorption principle of activated carbon to recover SO2 from flue gas and use it to produce sulfuric acid. During the production of industrial sulfuric acid from SO2, acidic wastewater is generated. The wastewater from the activated carbon desulfurization and denitrification sulfuric acid production process described in this invention originates from the acidic wastewater discharged from the purification section of the sulfuric acid production unit. This wastewater not only has high ammonia nitrogen content but also high organic nitrogen content, and contains toxic and harmful substances that inhibit nitrifying and nitrite-oxidizing bacteria, requiring purification treatment.

[0003] To date, numerous attempts have been made to treat wastewater from activated carbon desulfurization, denitrification, and acid production processes, as documented in the following literature:

[0004] Chinese utility model patent CN212403835U discloses a "treatment system for purifying acid production wastewater from activated coke flue gas", which includes a stirring and sealed device, a defluorination subsystem, a hardness and heavy metal removal subsystem, and an ammonia nitrogen removal and evaporation crystallization subsystem. In operation, the system first introduces the acid production wastewater into the stirring and sealed device for acid-base neutralization. Then, it introduces the defluorination subsystem to remove fluoride ions. Next, it introduces the hardness and heavy metal removal subsystem to reduce the hardness of the acid production wastewater and remove heavy metal ions. Finally, it introduces the ammonia nitrogen removal and evaporation crystallization subsystem to remove ammonia nitrogen and perform evaporation crystallization, ultimately obtaining crystalline salt and fresh industrial water.

[0005] Chinese utility model patent CN214735046U discloses a "sour wastewater treatment and recovery system applied to activated carbon dry flue gas treatment device", which includes an equalization tank, a reaction tank, and a recycled water tank. The equalization tank is connected to a wastewater inlet pipe and is used to collect and store acidic and ammonia-containing wastewater. It is connected to the reaction tank through a pipeline. The reaction tank is connected to the recycled water tank, an automatic lime powder feeder, a deammoniation agent dosing device, a blower, and an induced draft fan through pipelines. This allows the acid wastewater in the flue gas desulfurization and denitrification device to be properly treated with a simple treatment process and low treatment cost, and to achieve the reuse of wastewater and waste ammonia.

[0006] Chinese utility model patent CN203922919U discloses a "Wastewater Treatment System for Activated Carbon Desulfurization, Denitrification, and Acid Production Processes," comprising: a wastewater inlet, a first alkali-adjusting tank, a magnetic coagulation tank, a clarifier, a second alkali-adjusting tank, a filter, and a membrane absorption device connected sequentially by pipelines. The membrane absorption device is connected to an outlet, an acid replenishment outlet, and an absorbent discharge outlet. The first alkali-adjusting tank is connected to a lime slurry dosing device, the magnetic coagulation tank is connected to a flocculant dosing device, and the second alkali-adjusting tank is connected to a sodium hydroxide dosing device. The lime slurry dosing device, flocculant dosing device, and sodium hydroxide dosing device are all connected to the production water inlet. This utility model treats wastewater to a dischargeable state by employing a "magnetic coagulation sedimentation + filtration + membrane absorption" treatment method. The membrane absorption device recovers ammonia from the wastewater, reducing wastewater treatment costs. The multi-stage membrane absorption device further improves the ammonia recovery rate. Summary of the Invention

[0007] This invention provides a wastewater treatment system and method for activated carbon desulfurization, denitrification, and acid production processes. The wastewater is homogenized and then subjected to coagulation and sedimentation. The sedimented bottom sludge is then filtered by pressure. The effluent from the pressure filter is subjected to stripping to remove ammonia nitrogen and double filtration to remove metal ions, ammonia nitrogen, and COD. The wastewater is then concentrated and crystallized to meet discharge standards or be reused. The wastewater treatment method is simple, easy to operate, has good wastewater treatment effect, and low energy consumption, making it valuable for market application and promotion.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A wastewater treatment system for activated carbon desulfurization, denitrification, and acid production processes includes, in sequence, a wastewater tank, a neutralization tank, a reaction tank, a flocculation tank, a clarification tank, an ammonia removal and blending tank, an ammonia nitrogen stripping tower, a multi-media filter, an activated carbon filter, and an MVR evaporator connected by pipelines. The neutralization tank and the ammonia removal and blending tank are equipped with alkali dissolving tanks; the reaction tank is equipped with a high-molecular-weight iron salt dissolving tank; the flocculation tank is equipped with a coagulant dissolving tank; the clarification tank is connected to the neutralization tank via a sludge return pipeline, on which a sludge return pump is installed, and upstream of the sludge return pump, a sludge return pipeline is connected to a flocculant dosing tank; the ammonia removal and blending tank is further equipped with an ammonia removal agent dissolving tank and a steam inlet; the clarification tank is connected to the neutralization tank via a sludge conveying pipeline. The system connects to a sludge thickening tank, a single screw pump, and a plate and frame filter press. The clarified liquid outlet of the plate and frame filter press is connected to a wastewater tank via a pipeline. The sludge thickening tank is connected to the wastewater tank via a supernatant pipeline. A circulating pump is installed on the pipeline between the ammonia stripping tank and the ammonia nitrogen stripping tower. An intermediate water tank and a filter water pump are installed on the pipeline between the ammonia nitrogen stripping tower and the multi-media filter. The intermediate water tank is connected to the HCl metering tank via a dosing metering pump. The acid gas outlet of the HCl metering tank is connected to an acid mist absorber, and the outlet of the acid mist absorber is connected to the wastewater tank. The activated carbon filter is connected to the external discharge network via a clear water tank and a water supply booster pump. The tail gas outlet of the ammonia nitrogen stripping tower is connected in sequence to an absorption tower and a high-altitude emission device.

[0010] Furthermore, aeration devices are respectively installed at the bottom of the wastewater pool and the bottom of the sludge thickening pool, and the air inlet of the aeration device is connected to a compressed air pipeline.

[0011] Furthermore, a dosing metering pump is installed on the pipeline connecting the neutralization tank and the deammoniation mixing tank to the alkali dissolving tank; a dosing metering pump is installed on the pipeline connecting the reaction tank to the polymer iron salt dissolving tank; a dosing metering pump is installed on the pipeline connecting the flocculation tank to the coagulant dissolving tank; a dosing metering pump is installed on the pipeline connecting the flocculant dissolving tank to the sludge return pipeline; and a dosing metering pump is installed on the pipeline connecting the deammoniation mixing tank to the deammoniation agent dissolving tank.

[0012] A method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes, comprising the following steps: conditioning and neutralization, coagulation and sedimentation, ammonia nitrogen removal, filtration, concentration and crystallization, and sludge-water separation; wherein:

[0013] 1) Neutralization and coagulation sedimentation: Wastewater from the wastewater pond first enters the neutralization tank, where NaOH is added to adjust the pH to 8.5–9.5. After the effluent from the neutralization tank enters the reaction tank, 40% FeCl₂SO₄ is added to cause lead ions, mercury ions, and other ions to form heavy metal sulfide precipitates. After the effluent from the reaction tank enters the flocculation tank, coagulant is added, and then the effluent from the reaction tank enters the clarification tank. A portion of the sludge from the clarification tank is returned to the neutralization tank, and flocculant is added to the return pipe to remove suspended solids from the wastewater.

[0014] 2) Ammonia nitrogen removal: The effluent from the clarifier enters the ammonia removal and blending tank. A deammoniation agent containing a compound acid is added to the tank, and mechanical stirring promotes the agglomeration and sedimentation of the generated flocs, removing some metal ions, ammonia nitrogen, and COD from the wastewater. The wastewater in the clarifier is adjusted to pH 10.5–11.5 by adding alkali and heated to 30–50°C with steam. The effluent from the ammonia removal and blending tank enters the ammonia nitrogen stripping tower, where ammonia nitrogen is removed by "low-pressure stripping + catalytic oxidation". During the ammonia nitrogen stripping process, the pH of the wastewater is maintained at 10.5–11.5 by adding alkali intermittently, and a chlorine-containing strong oxidizing ammonia nitrogen removal agent is added. Stripping is carried out continuously for 2–3 hours to ensure that the ammonia nitrogen concentration in the wastewater is <15 mg / L.

[0015] 3) Filtration; After removing ammonia nitrogen, the wastewater is adjusted to pH 6-9, and then subjected to two-stage filtration through a multi-media filter and an activated carbon filter to remove COD from the wastewater and reduce its turbidity and color.

[0016] 4) Concentration and crystallization; the filtered wastewater is concentrated and crystallized in an MVR evaporator; the concentrated and crystallized wastewater is separated by centrifugation, and the separated wastewater is discharged to the test discharge pool. If it passes the test, it is discharged into the sewage pipe network; if it fails the test, it is returned to the concentration and crystallization section.

[0017] 5) Sludge-water separation: The sludge at the bottom of the sludge thickening tank is discharged regularly, and the sludge is lifted into the sludge conditioning tank for conditioning. After conditioning, it is periodically pumped to the plate and frame filter press for dewatering by a single screw pump. The dewatered sludge is transported off-site regularly, and the filtrate from the plate and frame filter press is returned to the wastewater tank.

[0018] Furthermore, the influent water quality index range for the wastewater is: CL - ≤13000mg / L,F - ≤16mg / L, SO4 2- ≤640mg / L, COD≤360mg / L, total iron≤0.27mg / L, Pb≤0.14mg / L, ammonia nitrogen≤450mg / L, SS≤850mg / L, conductivity≤450us / cm, pH<1.

[0019] Furthermore, the sludge formed by sedimentation in the clarification tank enters the sludge thickening tank for thickening, and is then pumped by a single screw pump into a plate and frame filter press for dewatering. The dewatered clarified liquid and the supernatant from the sludge thickening tank are returned to the wastewater tank.

[0020] Furthermore, the tail gas from the ammonia nitrogen stripping tower is introduced into an absorption tower for treatment, using water and acid as the absorbent.

[0021] Furthermore, the wastewater after ammonia nitrogen removal enters the intermediate water tank, where the pH value is adjusted by the HCl metering tank. The exhaust gas from the HCl metering tank enters the acid mist absorber for treatment, and the liquid from the acid mist absorber is discharged into the wastewater pool.

[0022] Furthermore, the flocculant is PAC or PAM.

[0023] Furthermore, the treated wastewater effluent meets the indirect discharge requirements of GB13456—2012 "Water Pollutant Discharge Standard for Iron and Steel Industry".

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1) Applicable to the treatment of wastewater from activated carbon desulfurization, denitrification and acid production processes. It organically combines chemical oxidation and MVR evaporation technology, making full use of the advantages of both, so that the treated wastewater meets the discharge standards.

[0026] 2) The treatment method described in this invention is effective for reducing ammonia nitrogen, COD, various metal ions, and Cl in wastewater. - F - SO4 2- The removal of pollutants such as iron and steel has a good effect and can meet the requirements of the indirect emission concentration limit of water pollutants for newly built enterprises in the "Emission Standard of Water Pollutants for Iron and Steel Industry GB13456-2012";

[0027] 3) The treatment method described in this invention is simple in process, easy to operate, has good wastewater treatment effect, low energy consumption, and can be automated. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a wastewater treatment system for activated carbon desulfurization, denitrification and acid production process according to the present invention. Detailed Implementation

[0029] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0030] like Figure 1As shown, the wastewater treatment system for activated carbon desulfurization, denitrification, and acid production processes of this invention includes, in sequence, a wastewater tank, a neutralization tank, a reaction tank, a flocculation tank, a clarification tank, an ammonia removal and blending tank, an ammonia nitrogen stripping tower, a multi-media filter, an activated carbon filter, and an MVR evaporator connected by pipelines. The neutralization tank and the ammonia removal and blending tank are equipped with alkali dissolving tanks; the reaction tank is equipped with a high-molecular-weight iron salt dissolving tank; the flocculation tank is equipped with a coagulant dissolving tank; the clarification tank is connected to the neutralization tank via a sludge return pipeline, and a sludge return pump is installed on the sludge return pipeline, with an upstream sludge return pipeline connected to a flocculant dosing tank; the ammonia removal and blending tank is further equipped with an ammonia removal agent dissolving tank and a steam inlet; the clarification tank is connected to the neutralization tank via a sludge conveyor... The pipeline connects sequentially to the sludge thickening tank, a single screw pump, and a plate and frame filter press. The clarified liquid outlet of the plate and frame filter press is connected to the wastewater tank via a pipeline. The sludge thickening tank is connected to the wastewater tank via a supernatant pipeline. A circulation pump is installed on the pipeline between the ammonia stripping tank and the ammonia nitrogen stripping tower. An intermediate water tank and a filter water pump are installed on the pipeline between the ammonia nitrogen stripping tower and the multi-media filter. The intermediate water tank is connected to the HCl metering tank via a dosing metering pump. The acid gas outlet of the HCl metering tank is connected to the acid mist absorber, and the outlet of the acid mist absorber is connected to the wastewater tank. The activated carbon filter is connected to the external discharge network via a clear water tank and a water supply booster pump. The tail gas outlet of the ammonia nitrogen stripping tower is sequentially connected to the absorption tower and the high-altitude emission device.

[0031] Furthermore, aeration devices are respectively installed at the bottom of the wastewater pool and the bottom of the sludge thickening pool, and the air inlet of the aeration device is connected to a compressed air pipeline.

[0032] Furthermore, a dosing metering pump is installed on the pipeline connecting the neutralization tank and the deammoniation mixing tank to the alkali dissolving tank; a dosing metering pump is installed on the pipeline connecting the reaction tank to the polymer iron salt dissolving tank; a dosing metering pump is installed on the pipeline connecting the flocculation tank to the coagulant dissolving tank; a dosing metering pump is installed on the pipeline connecting the flocculant dissolving tank to the sludge return pipeline; and a dosing metering pump is installed on the pipeline connecting the deammoniation mixing tank to the deammoniation agent dissolving tank.

[0033] The present invention discloses a wastewater treatment method for activated carbon desulfurization, denitrification, and acid production processes. The process route includes adjustment and neutralization, coagulation and sedimentation, ammonia nitrogen removal, filtration, concentration and crystallization, and sludge-water separation; wherein:

[0034] 1) Neutralization and coagulation sedimentation: Wastewater from the wastewater pond first enters the neutralization tank, where NaOH is added to adjust the pH to 8.5–9.5. After the effluent from the neutralization tank enters the reaction tank, 40% FeCl₂SO₄ is added to cause lead ions, mercury ions, and other ions to form heavy metal sulfide precipitates. After the effluent from the reaction tank enters the flocculation tank, coagulant is added, and then the effluent from the reaction tank enters the clarification tank. A portion of the sludge from the clarification tank is returned to the neutralization tank, and flocculant is added to the return pipe to remove suspended solids from the wastewater.

[0035] 2) Ammonia nitrogen removal: The effluent from the clarifier enters the ammonia removal and blending tank. A deammoniation agent containing a compound acid is added to the tank, and mechanical stirring promotes the agglomeration and sedimentation of the generated flocs, removing some metal ions, ammonia nitrogen, and COD from the wastewater. The wastewater in the clarifier is adjusted to pH 10.5–11.5 by adding alkali and heated to 30–50°C with steam. The effluent from the ammonia removal and blending tank enters the ammonia nitrogen stripping tower, where ammonia nitrogen is removed by "low-pressure stripping + catalytic oxidation". During the ammonia nitrogen stripping process, the pH of the wastewater is maintained at 10.5–11.5 by adding alkali intermittently, and a chlorine-containing strong oxidizing ammonia nitrogen removal agent is added. Stripping is carried out continuously for 2–3 hours to ensure that the ammonia nitrogen concentration in the wastewater is <15 mg / L.

[0036] 3) Filtration; After removing ammonia nitrogen, the wastewater is adjusted to pH 6-9, and then subjected to two-stage filtration through a multi-media filter and an activated carbon filter to remove COD from the wastewater and reduce its turbidity and color.

[0037] 4) Concentration and crystallization; the filtered wastewater is concentrated and crystallized in an MVR evaporator; the concentrated and crystallized wastewater is separated by centrifugation, and the separated wastewater is discharged to the test discharge pool. If it passes the test, it is discharged into the sewage pipe network; if it fails the test, it is returned to the concentration and crystallization section.

[0038] 5) Sludge-water separation: The sludge at the bottom of the sludge thickening tank is discharged regularly, and the sludge is lifted into the sludge conditioning tank for conditioning. After conditioning, it is periodically pumped to the plate and frame filter press for dewatering by a single screw pump. The dewatered sludge is transported off-site regularly, and the filtrate from the plate and frame filter press is returned to the wastewater tank.

[0039] Furthermore, the influent water quality index range for the wastewater is: CL - ≤13000mg / L,F - ≤16mg / L, SO4 2- ≤640mg / L, COD≤360mg / L, total iron≤0.27mg / L, Pb≤0.14mg / L, ammonia nitrogen≤450mg / L, SS≤850mg / L, conductivity≤450us / cm, pH<1.

[0040] Furthermore, the sludge formed by sedimentation in the clarification tank enters the sludge thickening tank for thickening, and is then pumped by a single screw pump into a plate and frame filter press for dewatering. The dewatered clarified liquid and the supernatant from the sludge thickening tank are returned to the wastewater tank.

[0041] Furthermore, the tail gas from the ammonia nitrogen stripping tower is introduced into an absorption tower for treatment, using water and acid as the absorbent.

[0042] Furthermore, the wastewater after ammonia nitrogen removal enters the intermediate water tank, where the pH value is adjusted by the HCl metering tank. The exhaust gas from the HCl metering tank enters the acid mist absorber for treatment, and the liquid from the acid mist absorber is discharged into the wastewater pool.

[0043] Furthermore, the flocculant is PAC or PAM.

[0044] Furthermore, the treated wastewater effluent meets the indirect discharge requirements of GB13456—2012 "Water Pollutant Discharge Standard for Iron and Steel Industry".

[0045] The influent indicators of the activated carbon desulfurization, denitrification and acid production process wastewater (hereinafter referred to as wastewater) described in this invention should not fluctuate drastically, provided that the requirements are met.

[0046] The wastewater from the wastewater pond has a low pH value. The acidity and alkalinity of the wastewater are adjusted in the neutralization tank. NaOH is preferred as the alkaline neutralizing agent. The pH value of the wastewater is adjusted to between 8.5 and 9.5 by an online pH meter.

[0047] After the wastewater enters the reaction tank, FeClSO4 (concentration 40%) is added to cause lead ions and mercury ions to form heavy metal sulfide precipitates.

[0048] After the wastewater enters the flocculation tank, a coagulant is added, and the dosage of the agent is controlled according to the coagulation effect during the treatment process.

[0049] The wastewater is high in both ammonia nitrogen and organic nitrogen, and contains toxic and harmful substances that inhibit nitrifying and nitrite-oxidizing bacteria. Based on the incoming water quality, selective removal of metal ions and flocculation sedimentation are performed. After the wastewater enters the clarifier, flocculants, including ferric salt flocculants and polymeric flocculants, are added to the sludge return pipe. PAC / PAM polymeric flocculants are preferred. Mechanical stirring promotes the agglomeration and sedimentation of the generated flocs. The dosage is determined based on the ammonia nitrogen value of the influent wastewater, aiming to reduce metal ions, ammonia nitrogen, and COD in the wastewater. Coagulation and sedimentation mainly use ferric salt flocculants and polymeric flocculants to reduce the SS (suspended solids) concentration in the wastewater.

[0050] Based on the separation effect of suspended solids in the clarifier, sludge is periodically discharged from the bottom of the clarifier and sent to the sludge thickening tank for treatment. The sludge is then periodically pumped by a single screw pump to a plate and frame filter press for dewatering. After dewatering, the sludge is periodically transported off-site for disposal, and the filtrate from the plate and frame filter press is returned to the wastewater tank.

[0051] To ensure the stripping efficiency of the ammonia nitrogen stripping tower, wastewater is pretreated in an ammonia stripping mixing tank before entering the tower. Alkali is added to adjust the pH to 10.5–11.5, and the water is heated to 30–50°C. A small amount of ammonia stripping agent containing a compound acid (such as the ammonia stripping agent produced by Zhengzhou Tianhe Water Purification Materials Co., Ltd.) is added. The effluent from the mixing tank enters the ammonia stripping tower, where ammonia nitrogen is stripped at a constant temperature. Alkali is added intermittently during the treatment to maintain the wastewater pH at around 11. After 2–3 hours of continuous stripping, the ammonia nitrogen concentration in the wastewater can be reduced to below the national Class I discharge standard (15 mg / L). The ammonia stripping tower uses a "low-pressure stripping + catalytic oxidation" method, and an appropriate amount of chlorine-containing strong oxidizing ammonia nitrogen removal agent (such as the ammonia nitrogen removal agent produced by Zhengzhou Tianhe Water Purification Materials Co., Ltd.) is added.

[0052] The stripping method for removing ammonia nitrogen utilizes the difference between the actual concentration and equilibrium concentration of volatile substances such as ammonia nitrogen in wastewater. Under alkaline conditions, air is used for stripping. As gas is continuously discharged during the stripping process, the concentration of ammonia in the gas phase is changed, so that its actual concentration is always lower than the equilibrium concentration under the conditions. Ultimately, dissolved ammonia in the wastewater continuously crosses the gas-liquid interface, and NH3-N in the wastewater is removed. The desorption rate is related to temperature and gas-liquid ratio.

[0053] The indirect discharge requirements of GB13456—2012 "Emission Standard of Water Pollutants for Iron and Steel Industry" are shown in Table 1:

[0054] Table 1

[0055] project unit Emission standards Color intensity (dilution factor) mg / L 100 Suspended solids (SS) mg / L 100 <![CDATA[Chemical Oxygen Demand (COD Cr )]]> mg / L 200 Total nitrogen mg / L 35 ammonia nitrogen mg / L 15 Phosphate (as P) mg / L 2 Petroleum mg / L 10 volatile phenols mg / L 1 sulfides mg / L 1 <![CDATA[Total cyanide (calculated as CN - count)]]> mg / L 0.5 Chloride (as chloride ions) mg / L 1000 boron mg / L 10 Total molybdenum (as Mo) mg / L 2 Total cobalt mg / L 1 Total vanadium mg / L 2 pH -- 6～9 Fluorides mg / L 20 Total Railway mg / L 10 Total Zinc mg / L 4 Total copper mg / L 1 Total arsenic mg / L 0.5 Total Chromium mg / L 1.5 Hexamethylene Chromium mg / L 0.5 Total lead mg / L 1 Total Nickel mg / L 1 Total cadmium mg / L 0.1 Total Mercury mg / L 0.05

[0056] The effluent from the ammonia nitrogen stripping tower enters the intermediate water tank, where the pH is adjusted to neutral by adding HCl. After being pressurized by a filtration pump, it undergoes two stages of filtration: a multi-media filter and an activated carbon filter. Finally, it flows into the clear water tank. The backwash water from both filters is returned to the sludge thickening tank. The multi-media filter and activated carbon filter serve as backup measures, effectively removing COD and reducing turbidity and color, ensuring that the final effluent fully meets standards.

[0057] Water effluent from the clean water tank is pumped into the MVR evaporator for concentration and crystallization via a water supply booster pump. In the MVR evaporator, when the wastewater concentration reaches the target value, it is pressurized by the discharge pump and sent to the circulation system for centrifugal separation. The solids proceed to the next process for drying and packaging. If impurities in the wastewater exceed a certain value, it is periodically discharged to a testing and discharge pool. Wastewater that passes the testing and discharge pool test is discharged into the sewage network; wastewater that fails the test enters the concentrate tank for further evaporation and crystallization. The MVR evaporator utilizes the principle that the boiling point of the liquid phase is greatly reduced under negative pressure, resulting in a lower temperature throughout the evaporation process. This allows the entire system to achieve efficient evaporation at relatively low temperatures, significantly reducing process energy consumption. The low steam consumption also reduces overall system energy consumption.

[0058] The exhaust gas from the above process is introduced into an acid mist absorber or absorption tower through an intake pipe. The absorbent used is water or alkaline solution. If there is a trace amount of ammonia, it is directly discharged into the atmosphere through a high-altitude extraction method.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes, implemented based on an activated carbon desulfurization, denitrification, and acid production wastewater treatment system, characterized in that... The activated carbon desulfurization, denitrification, and acid production wastewater treatment system includes, in sequence, a wastewater tank, a neutralization tank, a reaction tank, a flocculation tank, a clarification tank, an ammonia removal and blending tank, an ammonia stripping tower, a multi-media filter, an activated carbon filter, and an MVR evaporator, all connected by pipelines. The neutralization tank and the ammonia removal and blending tank are equipped with alkali dissolving tanks; the reaction tank is equipped with a high-molecular-weight iron salt dissolving tank; the flocculation tank is equipped with a coagulant dissolving tank; the clarification tank is connected to the neutralization tank via a sludge return pipeline, on which a sludge return pump is installed, and upstream of the sludge return pump, a sludge return pipeline is connected to a flocculant dosing tank; the ammonia removal and blending tank is additionally equipped with an ammonia removal agent dissolving tank and a steam inlet; the clarification tank is connected sequentially via a sludge conveying pipeline. The system connects a sludge thickening tank, a single screw pump, and a plate and frame filter press. The clarified liquid outlet of the plate and frame filter press is connected to a wastewater tank via a pipeline. The sludge thickening tank is connected to the wastewater tank via a supernatant pipeline. A circulating pump is installed on the pipeline between the ammonia stripping tank and the ammonia nitrogen stripping tower. An intermediate water tank and a filter water pump are installed on the pipeline between the ammonia nitrogen stripping tower and the multi-media filter. The intermediate water tank is connected to the HCl metering tank via a dosing metering pump. The acid gas outlet of the HCl metering tank is connected to an acid mist absorber, and the outlet of the acid mist absorber is connected to the wastewater tank. The activated carbon filter is connected to the external discharge network via a clear water tank and a water supply booster pump. The tail gas outlet of the ammonia nitrogen stripping tower is connected in sequence to an absorption tower and a high-altitude emission device. The process route includes conditioning and neutralization, coagulation and sedimentation, ammonia nitrogen removal, filtration, concentration and crystallization, and mud-water separation; among which: 1) Adjustment, neutralization, coagulation, and sedimentation: Wastewater from the wastewater pond first enters the neutralization tank, where NaOH is added to adjust the pH value to 8.5–9.5; after the effluent from the neutralization tank enters the reaction tank, 40% FeClSO4 is added; after the effluent from the reaction tank enters the flocculation tank, coagulant is added, and the effluent from the flocculation tank enters the clarification tank; a portion of the sludge from the clarification tank is returned to the neutralization tank, and flocculant is added to the return pipe; 2) Ammonia nitrogen removal: The effluent from the clarifier enters the ammonia removal and blending tank. An ammonia removal agent containing a compound acid is added to the tank, and mechanical stirring promotes the agglomeration and sedimentation of the flocculent material generated by the reaction, removing some metal ions, ammonia nitrogen, and COD from the wastewater. The wastewater in the ammonia removal and blending tank is adjusted to pH 10.5–11.5 by adding alkali and heated to 30–50°C with steam. The effluent from the ammonia removal and blending tank enters the ammonia nitrogen stripping tower, where ammonia nitrogen is removed by "low-pressure stripping + catalytic oxidation". During the ammonia nitrogen removal process, the pH of the wastewater is maintained at 10.5–11.5 by adding alkali intermittently, and a chlorine-containing strong oxidizing ammonia nitrogen removal agent is added. Stripping is carried out continuously for 2–3 hours to make the ammonia nitrogen concentration in the wastewater <15 mg / L. 3) Filtration; After removing ammonia nitrogen, the wastewater is adjusted to pH 6-9, and then subjected to two-stage filtration through a multi-media filter and an activated carbon filter to remove COD from the wastewater and reduce its turbidity and color. 4) Concentration and crystallization; the filtered wastewater is concentrated and crystallized in an MVR evaporator; the concentrated and crystallized wastewater is separated by centrifugation, and the separated wastewater is discharged to the test discharge pool. If it passes the test, it is discharged into the sewage pipe network; if it fails the test, it is returned to the concentration and crystallization section. 5) Sludge-water separation: The sludge at the bottom of the sludge thickening tank is discharged regularly, and the sludge is lifted into the sludge conditioning tank for conditioning. After conditioning, it is periodically pumped to the plate and frame filter press for dewatering by a single screw pump. The dewatered sludge is transported off-site regularly, and the filtrate from the plate and frame filter press is returned to the wastewater tank. The influent water quality index range for the wastewater is: Cl - ≤13000mg / L, F - ≤16mg / L, SO4 2- The wastewater concentrations are as follows: ≤640mg / L, COD≤360mg / L, total iron≤0.27mg / L, Pb≤0.14mg / L, ammonia nitrogen≤450mg / L, SS≤850mg / L, conductivity≤450μs / cm, pH<1; the treated wastewater effluent meets the indirect discharge requirements of GB 13456—2012 "Water Pollutant Discharge Standard for Iron and Steel Industry".

2. The method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes according to claim 1, characterized in that, Aeration devices are installed at the bottom of the wastewater tank and the bottom of the sludge thickening tank, respectively, and the air inlet of the aeration device is connected to a compressed air pipeline.

3. The method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes according to claim 1, characterized in that, A metering pump is installed on the pipeline connecting the neutralization tank and the deammoniation mixing tank to the alkali dissolving tank; a metering pump is installed on the pipeline connecting the reaction tank to the polymer iron salt dissolving tank; a metering pump is installed on the pipeline connecting the flocculation tank to the coagulant dissolving tank; a metering pump is installed on the pipeline connecting the flocculant dosing tank to the sludge return pipeline; and a metering pump is installed on the pipeline connecting the deammoniation mixing tank to the deammoniation agent dissolving tank.

4. The method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes according to claim 1, characterized in that, The sludge formed by sedimentation in the clarification tank enters the sludge thickening tank for thickening, and is then pumped by a single screw pump into a plate and frame filter press for dewatering. The dewatered clarified liquid and the supernatant from the sludge thickening tank are returned to the wastewater tank.

5. The method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes according to claim 1, characterized in that, The tail gas from the ammonia stripping tower is introduced into an absorption tower for treatment, using water and acid as the absorbent.

6. The method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes according to claim 1, characterized in that, The wastewater after ammonia nitrogen removal enters the intermediate water tank, where the pH value is adjusted by the HCl metering tank. The exhaust gas from the HCl metering tank enters the acid mist absorber for treatment, and the liquid from the acid mist absorber is discharged into the wastewater pool.

7. The method for treating wastewater from activated carbon desulfurization, denitrification, and acid production processes according to claim 1, characterized in that, The flocculant is PAC or PAM.

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