A treatment process for barium slag leachate

Abstract

The present invention relates to a treatment process for barium slag leachate, comprising a leachate collection and regulating tank which is sequentially arranged and sequentially treats the leachate, a chemical pre-precipitation tank for synchronously removing sulfur and barium, an oxidation flocculation reaction tank for oxidizing sulfide into sulfur element and flocculating and precipitating, a first sedimentation tank for solid-liquid separation, a deep oxidation tank for deep oxidation to remove organic pollutants and ammonia nitrogen, a second sedimentation tank for solid-liquid separation, a laminated filter and a clean water temporary storage tank for treating suspended matter in leachate wastewater, and also comprising a sludge treatment system for treating sludge separated from each sedimentation tank. The present invention has reasonable sequential connection between each process section, has the advantages of high efficiency, low energy consumption and easy operation and management, can realize effective joint removal of pollutants such as sulfide, barium ion, CODcr, ammonia nitrogen, TP and SS in barium slag leachate, and the effluent meets the direct emission standard requirements in the water pollutant emission limit in the "Inorganic Chemical Industry Pollutant Emission Standard".

Description

Technical Field

[0001] The invention belongs to the field of slag field leachate treatment, and in particular, relates to a slag field leachate treatment process whose pollution indicators can reach direct discharge standards. Background Art

[0002] In the national hazardous waste list, barium slag produced by the barium salt industry is classified as hazardous solid waste, waste category HW47, waste code 261-088-47. A large amount of barium slag is temporarily stored and piled in the slag yard. After rainwater leaching, a large amount of soluble barium salts such as barium sulfide are dissolved, thus producing leachate wastewater containing a large amount of barium ions and sulfides. If it is not effectively collected and treated, it will pose a certain degree of pollution threat to the surface and groundwater environment.

[0003] The composition of barium slag leachate is complex, and the main pollutants are usually high concentrations of barium ions and sulfides, accompanied by a certain concentration of CODcr and ammonia nitrogen. The main treatment methods for leachate wastewater are flocculation precipitation, adsorption, advanced oxidation, membrane filtration and biochemical methods. However, barium slag leachate contains many types of pollutants. The single use of the above processes for treatment often cannot simultaneously treat multiple pollutants in the barium slag leachate, and the treatment effect is poor and the investment cost is high.

[0004] At present, the process for treating leachate wastewater often adopts the mode of pretreatment + biochemical + deep treatment, in which the pretreatment process is required to have a higher sulfur removal capacity, because the barium slag leachate wastewater contains higher sulfides and total salts, which exceed the concentration that biological treatment can withstand, and the use of biochemical processes requires more labor costs and a larger area; in addition, for the relevant direct discharge standards, the emission indicators of total barium and sulfides are relatively high, and simple physical and chemical pretreatment or deep treatment often cannot achieve the standard treatment.

[0005] Regarding the treatment of waste residue leachate, there are also many patent documents reporting, for example: CN114684950A discloses an integrated treatment device and method for slag field leachate, and proposes a single-stage synchronous oxidation + chemical precipitation method for treating slag field leachate, firstly, alkaline oxidant and ferrous sulfate are added to the slag field leachate at the same time, the slag field leachate is pretreated at room temperature to obtain a pretreated liquid, and then a flocculant is added to the pretreated liquid to obtain a mixed liquid, and finally the mixed liquid is precipitated to obtain sludge and treated effluent located on the upper layer of the sludge. The treatment device is as follows: Figure 1As shown; the device and process are intended to solve the cumbersome steps of the traditional chemical oxidation method for treating the slag field leachate, and therefore adopt the method of simultaneous oxidation + chemical precipitation to achieve the purposes of simultaneous decarbonization, nitrogen removal, sulfur removal, and barium removal; however, it has a large defect in the actual application of treating the barium slag field leachate, because: the method only sets up a single-stage reactor, and all the dosing steps such as the oxidant, ferrous sulfate, and coagulant are carried out simultaneously, which makes the ferrous ions firstly oxidized by the oxidant to trivalent iron ions, greatly reducing the sulfur ion removal capacity, and consuming a large amount of oxidant, so that the method is far from achieving the good effects of decarbonization, nitrogen removal, sulfur removal, and barium removal in the actual treatment of the barium slag field leachate, and at the same time increases the cost of the reagents. Furthermore, there is a large gap and shortcoming in meeting the direct emission standard requirements in the water pollutant emission limit in the "Inorganic Chemical Industry Pollutant Emission Standard" (GB31573-2015).

[0006] CN112551756A discloses a method and system for removing sulfide from landfill leachate, and proposes a pretreatment process for sulfur-containing landfill leachate, wherein the landfill leachate is mixed with a desulfurization agent and then enters a desulfurization reaction tower for reaction, and the sulfide in the landfill leachate is converted into an insoluble sulfur-containing salt precipitate, and at the same time, a flocculant is added to the desulfurization reaction tower to accelerate the flocculation of the sulfur-containing salt precipitate, and after being stirred and mixed evenly by a stirring device, the overflow enters a sedimentation tank for sedimentation separation, and the desulfurized clear liquid obtained after sedimentation separation can be subsequently treated, and the bottom precipitated sludge enters a mud-water separation device for treatment through mud discharge, and finally the desulfurization purpose is achieved. The treatment system is as follows: Figure 2 As shown; however, it does not propose a complete solution for the direct discharge requirements of various pollutant indicators applicable to landfill leachate, and the sulfide pretreatment therein is designed to meet the needs of biochemical treatment. Therefore, the proposal of this technology still requires supporting biochemical processes for combined treatment. For the actual leachate treatment needs of the barium slag site, the implementation of biochemical processes means that more manpower is required for operation and maintenance, which increases the investment in labor costs. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a treatment process for barium slag leachate. The present invention occupies a small area, is highly efficient, is easy to operate and manage, and can effectively remove pollutants such as sulfide, barium ions, CODcr, ammonia nitrogen, total phosphorus and SS in the leachate.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] A treatment process for barium slag leachate, comprising a leachate collection and regulating tank which is arranged in sequence and sequentially treats the leachate, a chemical pre-precipitation tank for simultaneous desulfurization and barium removal, an oxidation flocculation reaction tank for oxidizing sulfide into sulfur element and flocculating and precipitating, a first sedimentation tank for solid-liquid separation, a deep oxidation tank for deep oxidation to remove organic pollutants and ammonia nitrogen, a second sedimentation tank for solid-liquid separation, a laminated filter for treating suspended matter in leachate wastewater and a clear water temporary storage tank, and also comprising a sludge treatment system for treating sludge separated from each sedimentation tank.

[0010] According to the present invention, preferably, the leachate collection tank collects barium slag leachate wastewater with a certain residence time, wherein a stirring device is arranged to stir and mix the sewage in the tank to achieve the purpose of homogenization and equalization, and then the wastewater in the tank is lifted to the chemical pre-sedimentation tank by a lifting water pump; further preferably, the stirring equipment uses a QJB submersible mixer.

[0011] According to the present invention, preferably, the chemical pre-sedimentation tank for simultaneous sulfur removal and barium removal includes a sulfur removal and barium removal zone where ferrous sulfate can be added to fully mix and react with sulfide and barium ions in the leachate, a flocculation zone where polyaluminium sulfate can be added to play a coagulant effect and supplement the effect of removing barium ions, and a sedimentation zone for solid-liquid separation, and the sludge separated in the sedimentation zone is discharged into the sludge treatment system;

[0012] Further preferably, the ratio of the dosage of the ferrous sulfate to the mass content of the sulfide is 5 to 7.5:1, the ferrous sulfate agent is calculated as ferrous sulfate heptahydrate, and the dosage of the polyaluminium sulfate is 0.1 to 2 mg / L;

[0013] Most preferably, the chemical pre-sedimentation tank includes a chemical reaction zone and a sedimentation zone. The chemical reaction zone is divided into two compartments. Ferrous sulfate is added to the first compartment, and a high molecular flocculant, polyaluminum sulfate, is added to the second compartment. A stirring device is respectively provided in the two compartments for mixing the reagent with the wastewater. The sulfide, barium ions and sulfate ions react to form ferrous sulfide and barium sulfate precipitates respectively. At the same time, the fine precipitated substances, under the action of polyaluminum sulfate, form larger flocs and precipitate in the sedimentation zone. A mud level meter is provided in the sedimentation zone to control automatic mud discharge. Preferably, the stirring device provided in the first reaction zone is a vertical paddle mixer, and the matching reducer is a helical gear reducer; the stirring device provided in the second reaction zone is a vertical frame mixer, and the matching reducer is a helical gear reducer.

[0014] According to the present invention, preferably, the sulfide concentration in the barium slag leachate is 20-1000 mg / L, the barium ion concentration is 20-1000 mg / L, the CODcr concentration is 50-1800 mg / L, the ammonia nitrogen concentration is 10-200 mg / L, the total phosphorus concentration is 0.1-200 mg / L, and the SS concentration is 50-1000 mg / L.

[0015] According to the present invention, preferably, the oxidation flocculation reaction tank for oxidizing sulfide into sulfur element and flocculating and precipitating includes a decarbonization and desulfurization reaction zone and a flocculation reaction zone, wherein the decarbonization and desulfurization reaction zone is divided into two compartments, and hydrogen peroxide is added to fully mix with sulfide and organic pollutants in the leachate for oxidation reaction; the flocculation reaction zone is added with alkali solution and polyacrylamide to adjust the pH and perform flocculation reaction on the sulfur element and a small amount of ferric hydroxide produced in the former zone;

[0016] Further preferably, the ratio of the dosage of hydrogen peroxide to the mass content of organic pollutants is 0.3-4:1, the alkali solution is sodium hydroxide solution, the pH value is adjusted to 8-11, the dosage of polyacrylamide is 0.001-0.01 mg / L; and the hydrogen peroxide is a hydrogen peroxide solution with a mass concentration of 10-30%.

[0017] Most preferably, the oxidation flocculation reaction tank is divided into three compartments, and stirring equipment is respectively provided. Hydrogen peroxide is added to the first compartment and the second compartment, and the hydrogen peroxide oxidizes the sulfide in the sewage into elemental sulfur. Alkali solution and polyacrylamide are added to the third compartment, and the formed fine flocs are transformed into larger flocs under the action of polyacrylamide; the addition amount of hydrogen peroxide and alkali solution is controlled by an online ORP meter and a pH meter; preferably, the stirring equipment provided in the first compartment and the second compartment reaction zone is a vertical paddle stirrer, and the matching reducer is a helical gear reducer; the stirring equipment provided in the third compartment is a vertical frame stirrer, and the matching reducer is a helical gear reducer.

[0018] According to the present invention, preferably, the first sedimentation tank is an upflow inclined plate sedimentation tank for settling the flocs produced in the oxidation flocculation sedimentation tank.

[0019] According to the present invention, preferably, the deep oxidation tank for deep oxidation removal of organic pollutants and ammonia nitrogen comprises an oxidation zone where sodium hypochlorite can be added for decarbonization and nitrogen removal, and a flocculation reaction zone where polyaluminium sulfate and polyacrylamide can be added;

[0020] Further preferably, the mass ratio of the dosage of the sodium hypochlorite to the ammonia nitrogen content in the leachate is 80-120:1, preferably, the sodium hypochlorite is a sodium hypochlorite solution with a mass concentration of 10%; the dosage of polyaluminium sulfate is 0.1-2 mg / L, and the dosage of polyacrylamide is 0.001-0.1 mg / L;

[0021] Most preferably, the deep oxidation tank is divided into three compartments and stirring equipment is respectively provided in each compartment, sodium hypochlorite is added in the first compartment, sodium hypochlorite and polyaluminium sulfate are added in the second compartment, and polyacrylamide is added in the third compartment. Sodium hypochlorite is used to remove ammonia nitrogen in sewage and oxidize organic pollutants, and polyaluminium sulfate and polyacrylamide work together to remove suspended matter in sewage, while ensuring that barium ions can reliably meet the standards; preferably, ORP and pH meters are provided in the deep oxidation tank to control the amount of sodium hypochlorite added online; preferably, vertical paddle stirrers are used for the stirring equipment in the first and second compartments, and helical gear reducers are used as the matching reducers; vertical frame stirrers are used for the stirring equipment in the third compartment, and helical gear reducers are used as the matching reducers.

[0022] According to the present invention, preferably, the second sedimentation tank is an upflow inclined plate sedimentation tank for settling the flocs of alum produced in the deep oxidation tank.

[0023] According to the present invention, preferably, the laminated filter adopts existing equipment, including a turbine guide plate and laminated plates; the sewage passes through the turbine guide plate to form a centrifugal effect, and then the raw water passes through the compressed laminated plates for surface and deep filtration. Suspended pollutants are trapped on the surface and deep areas of the laminated plates, and the filtered water flows out through the outlet pipe;

[0024] Preferably, the laminated filter is further provided with a plurality of laminated filter units for processing. When the backwashing operation is in progress, the water inlet is closed by controlling the two-position three-way valve, and the water outlet pipe and the sewage pipe are connected. After the flow direction is changed, the produced water of other laminated filter units is used for cleaning, and the backwashing effluent is connected to the sludge treatment system through the sludge discharge pipe.

[0025] According to the present invention, preferably, the effluent from the laminated filter enters a clean water temporary storage tank, in which an online water quality monitoring device is arranged. If the effluent water quality is qualified, it is directly discharged. If it is unqualified, it is refluxed and lifted to a sewage collection tank for secondary treatment.

[0026] According to the present invention, preferably, the sludge treatment system comprises a sludge concentration tank for receiving backwash water from each sedimentation tank and the laminated filter, a sludge conditioning tank for coagulating and dehydrating the concentrated sludge, and a plate-frame filter press for filtering and dehydrating the conditioned sludge;

[0027] Further preferably, the sludge conditioning tank is equipped with a stirring device for conditioning and stirring and a dosing device for adding polyaluminium chloride and polyacrylamide; preferably, the conditioning stirring device is a vertical frame mixer, and the matching reducer is a helical gear reducer; preferably, the conditioned sludge is transported to the plate and frame filter press using a screw pump;

[0028] Preferably, the dosage of polyaluminium chloride in the sludge conditioning tank is 0.05-1 mg / L, and the dosage of polyacrylamide is 0.001-0.1 mg / L.

[0029] According to the present invention, preferably, the treatment process of the barium slag leachate, a preferred embodiment, comprises the following steps:

[0030] A1: The leachate from the slag yard first enters the collection and regulation tank for homogenization and equalization to ensure stable water inflow for subsequent processes;

[0031] A2: Add ferrous sulfate to the leachate from the slag yard to remove sulfur and barium through chemical precipitation reaction, then add polyaluminium sulfate for flocculation precipitation to separate the flocculated sludge of ferrous sulfide and barium sulfate;

[0032] A3: Add hydrogen peroxide to the leachate from the slag yard to remove sulfur and degrade organic pollutants through chemical oxidation reaction, then add alkali solution and polyacrylamide for flocculation and precipitation to separate the flocculated sludge of sulfur element and iron oxyhydroxide;

[0033] A4: Sodium hypochlorite is added to the leachate from the slag dump for deep oxidation reaction to further degrade organic pollutants and ammonia nitrogen, followed by addition of polyaluminium sulfate and polyacrylamide for flocculation and precipitation to separate the flocculated sludge containing a small amount of barium sulfate and elemental sulfur;

[0034] A5: Filtration, discharge;

[0035] A6: Treat the sludge separated in steps A2, A3 and A4.

[0036] According to the present invention, preferably, step A6 comprises:

[0037] B1: In the sludge concentration tank, the sludge separated from A2, A3 and A4 is concentrated to reduce the water content, and the supernatant is returned to the collection and adjustment tank;

[0038] B2: After sludge concentration, the sludge enters the sludge conditioning tank for stirring and conditioning, and polyacrylamide is added to the sludge to improve the sludge dewatering properties;

[0039] B3: Pump the conditioned sludge to the plate and frame filter press to complete sludge dewatering.

[0040] Anything not described in detail in the present invention is based on the prior art in the art.

[0041] The beneficial effects of the present invention are as follows:

[0042] 1. The present invention has a small footprint, high efficiency, easy operation and management, and can effectively remove pollutants such as sulfide, barium ion, CODcr, ammonia nitrogen, total phosphorus and SS in the leachate.

[0043] 2. In the present invention, two-stage oxidation is adopted for the removal of CODcr, and the removal of ammonia nitrogen is carried out by chlorination at the breakpoint. There is no need to set up a biochemical process for biological decarbonization and nitrogen removal, which reduces the operational difficulty and labor cost of operation and maintenance, and provides greater operability for process debugging.

[0044] 3. The design of process connection in the present invention can make full use of the added reagents. The addition of ferrous sulfate reagent in the chemical pre-precipitation tank is not only used to remove barium ions and sulfur ions, but the remaining ferrous ions can be used to catalyze the oxidation of hydrogen peroxide added in the flocculation reaction tank to form Fenton's advanced oxidation reaction, further improve the oxidation efficiency, and achieve efficient treatment of pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of an integrated treatment device for slag field leachate in CN114684950A.

[0046] Figure 2 Schematic diagram of the desulfurization pretreatment device for landfill leachate in CN112551756A.

[0047] Figure 3 It is a process flow chart of the barium slag leachate of the present invention. DETAILED DESCRIPTION

[0048] The present invention is further described in detail with reference to the following specific embodiments and accompanying drawings, but is not limited thereto.

[0049] Example 1

[0050] This example uses the leachate from a barium slag field in Tianzhu, Guizhou. The COD Cr The concentration is 1500mg / L, the ammonia nitrogen concentration is 85mg / L, the total phosphorus concentration is 0.05mg / L, the total barium concentration is 100mg / l, and the sulfide concentration is 600mg / L.

[0051] A treatment process for barium slag leachate, comprising a leachate collection and regulating tank which is sequentially arranged and sequentially treats the leachate, a chemical pre-precipitation tank for simultaneous sulfur removal and barium removal, an oxidation flocculation reaction tank for oxidizing sulfide into sulfur element and flocculating and precipitating, a first sedimentation tank for solid-liquid separation, a deep oxidation tank for deep oxidation to remove organic pollutants and ammonia nitrogen, a second sedimentation tank for solid-liquid separation, a laminated filter for treating suspended matter in leachate wastewater and a clear water temporary storage tank, and also comprising a sludge treatment system for treating sludge separated from each sedimentation tank;

[0052] The leachate collection tank collects barium slag leachate wastewater with a certain residence time, wherein a stirring device is provided to stir and mix the sewage in the leachate collection tank to achieve the purpose of homogenization and equalization, and then the wastewater in the tank is lifted to the chemical pre-sedimentation tank by a lifting water pump, and the stirring device uses a QJB submersible mixer;

[0053] The chemical pre-sedimentation tank includes a chemical reaction zone and a sedimentation zone. The chemical reaction zone is divided into two compartments. Ferrous sulfate is added to the first compartment, and a high molecular flocculant, polyaluminum sulfate, is added to the second compartment. Stirring equipment is respectively provided in the two compartments for mixing the reagents with the wastewater. Sulfide, barium ions react with sulfate ions to form ferrous sulfide and barium sulfate precipitations respectively. At the same time, fine precipitation substances form larger flocs under the action of polyaluminum sulfate and precipitate in the sedimentation zone. A mud level meter is provided in the sedimentation zone to control automatic mud discharge. The stirring equipment provided in the first reaction zone is a vertical paddle mixer, and the matching reducer is a helical gear reducer; the stirring equipment provided in the second reaction zone is a vertical frame mixer, and the matching reducer is a helical gear reducer; the ratio of the amount of ferrous sulfate added to the mass content of sulfide is 5 to 7.5:1, the ferrous sulfate reagent is calculated as ferrous sulfate heptahydrate, and the amount of polyaluminum sulfate added is 1 to 20 mg / L;

[0054] The oxidation flocculation reaction tank is divided into three compartments, and stirring equipment is respectively provided. Hydrogen peroxide is added into the first compartment and the second compartment, and the hydrogen peroxide oxidizes the sulfide in the sewage into sulfur element. Alkali solution and polyacrylamide are added into the third compartment, and the formed fine flocs are formed into larger flocs under the action of polyacrylamide; the dosage of hydrogen peroxide and alkali solution is controlled by an online ORP meter and a pH meter; the stirring equipment provided in the first compartment and the second compartment reaction zone is a vertical paddle stirrer, and the matching reducer is a helical gear reducer; the stirring equipment provided in the third compartment is a vertical frame stirrer, and the matching reducer is a helical gear reducer; the hydrogen peroxide is a hydrogen peroxide solution with a mass concentration of 27.5%, and the ratio of the dosage of hydrogen peroxide to the mass content of organic pollutants is 0.3-4:1, the alkali solution is a sodium hydroxide solution, and the pH value is adjusted to 8-11, and the dosage of polyacrylamide is 0.001-0.01 mg / L;

[0055] The first sedimentation tank is an upflow inclined plate sedimentation tank, which is used to settle the floccules produced in the oxidation flocculation sedimentation tank;

[0056] The deep oxidation tank is divided into three compartments and each is provided with a stirring device. Sodium hypochlorite is added to the first compartment, sodium hypochlorite and polyaluminium sulfate are added to the second compartment, and polyacrylamide is added to the third compartment. Sodium hypochlorite is used to remove ammonia nitrogen in sewage and oxidize organic pollutants. Polyaluminium sulfate and polyacrylamide work together to remove suspended matter in sewage, and at the same time ensure that barium ions meet the standard reliably. ORP and pH meters are set in the deep oxidation tank to control the amount of sodium hypochlorite added online. The stirring equipment in the first and second compartments uses a vertical paddle mixer, and the matching reducer uses a helical gear reducer. The stirring equipment in the third compartment uses a vertical frame mixer, and the matching reducer uses a helical gear reducer. The mass ratio of the amount of sodium hypochlorite added to the ammonia nitrogen content in the leachate is 80-120:1. The sodium hypochlorite is a sodium hypochlorite solution with a mass concentration of 10%. The amount of polyaluminium sulfate added is 0.1-2mg / L, and the amount of polyacrylamide added is 0.001-0.1mg / L.

[0057] The second sedimentation tank is an upflow inclined plate sedimentation tank, which is used to settle the flocs produced in the deep oxidation tank;

[0058] The laminated filter comprises a turbine guide plate and laminated plates; the sewage passes through the turbine guide plate to form a centrifugal effect, and then the raw water passes through the compressed laminated plates for surface and deep filtration; the suspended pollutants are trapped on the surface and deep area of ​​the laminated plates, and the filtered water flows out through the outlet pipe; the laminated filter is also provided with a plurality of processing laminated filter units. When the backwashing operation is in progress, the water inlet is closed by controlling the two-position three-way valve, and the outlet pipe and the sewage pipe are connected. After the flow direction is changed, the produced water of other laminated filter units is used for cleaning, and the backwashing effluent is connected to the sludge treatment system through the sludge discharge pipe;

[0059] The water outlet from the laminated filter enters the clean water temporary storage tank, in which an online water quality monitoring device is installed. If the water quality monitoring is qualified, it will be directly discharged. If it is unqualified, it will be returned and lifted to the sewage collection tank for secondary treatment.

[0060] The sludge treatment system comprises a sludge concentration tank for receiving backwash water from each sedimentation tank and the laminated filter, a sludge conditioning tank for coagulating and dehydrating the concentrated sludge, and a plate-frame filter press for filtering and dehydrating the conditioned sludge; the sludge conditioning tank is equipped with a stirring device for conditioning and stirring and a dosing device for adding polyaluminium chloride and polyacrylamide; the conditioning stirring device uses a vertical frame mixer, and the matching reducer uses a helical gear reducer; the conditioned sludge is transported to the plate-frame filter press by a screw pump; the dosage of polyaluminium chloride in the sludge conditioning tank is 0.05-1mg / L, and the dosage of polyacrylamide is 0.001-0.1mg / L.

[0061] See also Figure 3The barium slag leachate first enters the collection and regulation tank, where it is homogenized and regulated by the submersible mixer to ensure stable water inflow in subsequent processes.

[0062] The leachate is then pumped into a chemical pre-sedimentation tank through a lifting water pump, and ferrous sulfate is added to the sulfur removal and barium removal area for chemical precipitation reaction. Through mechanical stirring, the sulfide in the leachate reacts with ferrous ions to form ferrous sulfide precipitation, and the barium ions react with sulfate ions to form barium sulfate precipitation. Subsequently, a coagulant aid, polyaluminum sulfate, is added to the flocculation area to form a larger floc for easy sedimentation. The resulting precipitated sludge is separated in the sedimentation area and regularly discharged to the sludge thickening tank. The supernatant in the sedimentation area flows by gravity into the oxidation flocculation sedimentation tank.

[0063] The pH of the leachate wastewater in the oxidation flocculation reaction tank is in the range of 4 to 5.5 due to the addition of reagents in the previous process stage. At this time, hydrogen peroxide is added in the oxidation zone, and the remaining sulfide in the oxidized sewage is sulfur. At the same time, the remaining ferrous ions from the previous process stage react with hydrogen peroxide to produce a Fenton reaction, further enhancing the oxidation reaction of sulfide. Subsequently, alkali solution is added in the flocculation zone to adjust the pH, and polyacrylamide is added as a coagulant aid. The oxidation product sulfur and a small amount of Fenton sludge are flocculated into larger flocs.

[0064] The leachate after the flocculation reaction enters the first sedimentation tank, where the sulfur and Fenton sludge are separated and regularly discharged to the sludge concentration tank. The supernatant of the first sedimentation tank flows by gravity into the deep oxidation tank.

[0065] In the oxidation zone of the deep oxidation tank, the leachate fully reacts with the added sodium hypochlorite to remove ammonia nitrogen and complete the treatment of the remaining COD Cr The degradation of the flocculation zone is followed by adding polyaluminium sulfate and polyacrylamide to carry out flocculation reaction;

[0066] The leachate from the deep oxidation tank enters the second sedimentation tank to separate the sludge containing a small amount of barium sulfate and sulfur, and is regularly discharged into the sludge thickening tank;

[0067] The supernatant from the second sedimentation tank is pumped into the laminated filter by a pressure pump after the outlet tank to remove suspended solids in depth. The filter is backwashed regularly and the backwash water is discharged into the sludge concentration tank.

[0068] The wastewater filtered by the laminated filter is discharged into the clean water temporary storage tank. The wastewater is discharged in compliance with the standards. If the process effluent fails to meet the standards due to the impact of the influent quality, the clean water temporary storage tank is equipped with a spare lifting water pump to pump the wastewater back to the collection and regulating tank.

[0069] The sludge mentioned above in the sludge thickening tank is designed to be concentrated for ≥15h to reduce the moisture content of the sludge. It then enters the sludge conditioning tank and is added with polyacrylamide to improve the sludge dewatering performance. Finally, the sludge is dehydrated by a plate and frame filter press and the dry sludge is transported out for disposal.

[0070] In this embodiment, the treatment process effluent indicators of barium slag leachate are as follows:

[0071] COD Cr The concentration is below 50mg / L, the ammonia nitrogen concentration is below 10mg / L, the total phosphorus concentration is below 0.5mg / L, the total barium concentration is below 2mg / L, and the sulfide concentration is below 0.5mg / L. It meets the direct emission standard of the water pollutant emission limit in the "Inorganic Chemical Industry Pollutant Emission Standard" (GB31573-2015).

[0072] The above embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A process for treating barium slag leachate, characterized in that: The process comprises a leachate collection and regulating tank which is sequentially arranged and sequentially treats the leachate, a chemical pre-precipitation tank for simultaneous sulfur removal and barium removal, an oxidation flocculation reaction tank for oxidizing sulfide into sulfur element and flocculating and precipitating, a first sedimentation tank for solid-liquid separation, a deep oxidation tank for deep oxidation to remove organic pollutants and ammonia nitrogen, a second sedimentation tank for solid-liquid separation, a laminated filter and a clear water temporary storage tank for treating suspended matter in the leachate wastewater, and also includes a sludge treatment system for treating the sludge separated from each sedimentation tank; The chemical pre-sedimentation tank used for simultaneous sulfur removal and barium removal includes a sulfur removal and barium removal zone where ferrous sulfate is added to fully mix and react with sulfide and barium ions in the leachate, a flocculation zone where polyaluminium sulfate is added to play a coagulant role and supplement the effect of removing barium ions, and a sedimentation zone for solid-liquid separation. The sludge separated in the sedimentation zone is discharged into the sludge treatment system.

2. The process for treating barium slag leachate according to claim 1, characterized in that: The leachate collection pool collects barium slag leachate wastewater with a certain residence time, wherein a stirring device is arranged to stir and mix the sewage in the pool to achieve the purpose of homogenization and equalization, and then the wastewater in the pool is lifted to the chemical pre-sedimentation tank by a lifting water pump.

3. The process for treating barium slag leachate according to claim 2, characterized in that: The mixing equipment is QJB submersible mixer.

4. The process for treating barium slag leachate according to claim 1, characterized in that: The ratio of the dosage of the ferrous sulfate to the mass content of the sulfide is 5-7.5:1, the ferrous sulfate agent is calculated as ferrous sulfate heptahydrate, and the dosage of the polyaluminium sulfate is 0.1-2 mg / L.

5. The process for treating barium slag leachate according to claim 1, characterized in that: The chemical pre-sedimentation tank includes a chemical reaction zone and a sedimentation zone. The chemical reaction zone is divided into two compartments. Ferrous sulfate is added to the first compartment and a high molecular flocculant, polyaluminum sulfate, is added to the second compartment. Stirring equipment is respectively provided in the two compartments for mixing the reagents with the wastewater. Sulfide, barium ions and sulfate radicals react to form ferrous sulfide and barium sulfate precipitates respectively. At the same time, the fine precipitated substances, under the action of polyaluminum sulfate, form larger flocs and settle in the sedimentation zone. A mud level meter is provided in the sedimentation zone to control automatic mud discharge.

6. The process for treating barium slag leachate according to claim 1, characterized in that: The barium slag leachate has a sulfide concentration of 20-1000 mg / L, a barium ion concentration of 20-1000 mg / L, a CODcr concentration of 50-1800 mg / L, an ammonia nitrogen concentration of 10-200 mg / L, a total phosphorus concentration of 0.1-200 mg / L, and a SS concentration of 50-1000 mg / L.

7. The process for treating barium slag leachate according to claim 1, characterized in that: The oxidation flocculation reaction tank used to oxidize sulfide into sulfur element and flocculate and precipitate includes a decarbonization and desulfurization reaction zone and a flocculation reaction zone. The decarbonization and desulfurization reaction zone is divided into two compartments. Hydrogen peroxide is added to fully mix with sulfide and organic pollutants in the leachate for oxidation reaction; alkali solution and polyacrylamide are added to the flocculation reaction zone to adjust the pH and flocculate the sulfur element produced in the previous area and a small amount of ferric hydroxide.

8. The process for treating barium slag leachate according to claim 7, characterized in that: The ratio of the amount of hydrogen peroxide added to the mass content of organic pollutants is 0.3-4:1, the alkali solution is a sodium hydroxide solution, the pH value is adjusted to 8-11, the amount of polyacrylamide added is 0.001-0.01 mg / L; the hydrogen peroxide is a hydrogen peroxide solution with a mass concentration of 10-30%.

9. The process for treating barium slag leachate according to claim 7, characterized in that: The oxidation flocculation reaction tank is divided into three compartments, and stirring equipment is respectively provided. Hydrogen peroxide is added into the first compartment and the second compartment, and the hydrogen peroxide oxidizes the sulfide in the sewage into elemental sulfur. Alkali solution and polyacrylamide are added into the third compartment, and the formed fine flocs are transformed into larger flocs under the action of polyacrylamide. The addition amount of hydrogen peroxide and alkali solution is controlled by an online ORP meter and a pH meter.

10. The process for treating barium slag leachate according to claim 1, characterized in that: The first sedimentation tank is an upflow inclined plate sedimentation tank, which is used to settle the floccules produced in the oxidation flocculation sedimentation tank.

11. The process for treating barium slag leachate according to claim 1, characterized in that: The deep oxidation pool for deep oxidation removal of organic pollutants and ammonia nitrogen comprises an oxidation zone for adding sodium hypochlorite for decarbonization and nitrogen removal, and a flocculation reaction zone for adding polyaluminium sulfate and polyacrylamide.

12. The process for treating barium slag leachate according to claim 11, characterized in that: The mass ratio of the dosage of sodium hypochlorite to the ammonia nitrogen content in the leachate is 80-120:1, the dosage of polyaluminium sulfate is 0.1-2 mg / L, and the dosage of polyacrylamide is 0.001-0.1 mg / L.

13. The process for treating barium slag leachate according to claim 11, characterized in that: The deep oxidation tank is divided into three compartments and each of them is provided with a stirring device. Sodium hypochlorite is added into the first compartment, sodium hypochlorite and polyaluminium sulfate are added into the second compartment, and polyacrylamide is added into the third compartment. Sodium hypochlorite is used to remove ammonia nitrogen in sewage and oxidise organic pollutants. Polyaluminium sulfate and polyacrylamide work together to remove suspended matter in sewage and can also ensure that barium ions reliably meet the standards. ORP and pH meters are arranged in the deep oxidation tank to control the amount of sodium hypochlorite added online.

14. The process for treating barium slag leachate according to claim 1, characterized in that: The second sedimentation tank is an upflow inclined plate sedimentation tank, which is used to settle the flocs of alum produced in the deep oxidation tank.

15. The process for treating barium slag leachate according to claim 1, characterized in that: The laminated filter comprises a turbine guide plate and laminated plates; the sewage passes through the turbine guide plate to form a centrifugal effect, and then the raw water passes through the compressed laminated plates for surface and deep filtration, and the suspended pollutants are trapped on the surface and deep areas of the laminated plates, and the filtered water flows out through the outlet pipe.

16. The process for treating barium slag leachate according to claim 15, characterized in that: The laminated filter is also provided with a plurality of processing laminated filter units. When the backwash operation is in progress, the water inlet is closed by controlling the two-position three-way valve, and the water outlet pipe and the sewage pipe are connected. After the flow direction is changed, the produced water of other laminated filter units is used for cleaning, and the backwashing water is connected to the sludge treatment system through the sludge discharge pipe.

17. The process for treating barium slag leachate according to claim 15, characterized in that: The water outlet from the laminated filter enters the clean water temporary storage tank, in which an online water quality monitoring device is installed. If the water quality monitoring is qualified, it will be directly discharged. If it is unqualified, it will be returned and lifted to the sewage collection tank for secondary treatment.

18. The process for treating barium slag leachate according to claim 1, characterized in that: The sludge treatment system comprises a sludge concentration tank for receiving backwash water from each sedimentation tank and the laminated filter, a sludge conditioning tank for coagulating and dehydrating the concentrated sludge, and a plate-frame filter press for filtering and dehydrating the conditioned sludge.

19. The process for treating barium slag leachate according to claim 18, characterized in that: The sludge conditioning tank is equipped with a stirring device for conditioning and stirring and a dosing device for adding polyaluminium chloride and polyacrylamide; The conditioning stirring equipment is a vertical frame mixer, and the matching reducer is a helical gear reducer. The conditioned sludge is transported to the plate and frame filter press using a screw pump.

20. The process for treating barium slag leachate according to claim 19, characterized in that: The dosage of polyaluminium chloride in the sludge conditioning tank is 0.05~1mg / L, and the dosage of polyacrylamide is 0.001~0.1mg / L.

21. The process for treating barium slag leachate according to claim 1, characterized in that: The treatment process of the barium slag leachate comprises the following steps: A1: The leachate from the slag yard first enters the collection and regulation tank for homogenization and equalization to ensure stable water inflow for subsequent processes; A2: Add ferrous sulfate to the leachate from the slag yard to remove sulfur and barium through chemical precipitation reaction, then add polyaluminium sulfate for flocculation precipitation to separate the flocculated sludge of ferrous sulfide and barium sulfate; A3: Add hydrogen peroxide to the leachate from the slag yard to remove sulfur and degrade organic pollutants through chemical oxidation reaction, then add alkali solution and polyacrylamide for flocculation and precipitation to separate the flocculated sludge of sulfur element and iron oxyhydroxide; A4: Sodium hypochlorite is added to the leachate from the slag dump for deep oxidation reaction to further degrade organic pollutants and ammonia nitrogen, followed by addition of polyaluminium sulfate and polyacrylamide for flocculation and precipitation to separate the flocculated sludge containing a small amount of barium sulfate and elemental sulfur; A5: Filtration, discharge; A6: Treat the sludge separated in steps A2, A3 and A4.

22. The process for treating barium slag leachate according to claim 21, characterized in that: Step A6 includes: B1: In the sludge concentration tank, the sludge separated from A2, A3 and A4 is concentrated to reduce the water content, and the supernatant is returned to the collection and adjustment tank; B2: After sludge concentration, the sludge enters the sludge conditioning tank for stirring and conditioning, and polyacrylamide is added to the sludge to improve the sludge dewatering properties; B3: Pump the conditioned sludge to the plate and frame filter press to complete sludge dewatering.

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