Process and system for removing total phosphorus in leachate

Abstract

The invention discloses a leachate total phosphorus removal process and system. The percolate total phosphorus removal process comprises the following steps: S01, adjusting the pH value of percolate to 3-5, adding an oxidizing agent into the percolate, and oxidizing organic phosphorus in the percolate to form inorganic phosphorus; s02, adding a dephosphorization agent into the leachate in the step SO1, stirring and filtering to obtain first filtrate; s03, adjusting the pH value of the filtrate to be neutral, adding lime emulsion into the filtrate, stirring and filtering to obtain second filtrate; s04, adding activated carbon powder into the second filtrate, stirring and filtering to obtain third filtrate; and S05, sequentially adding a PAM solution and a coagulant aid into the third filtrate, uniformly stirring, and standing for a period of time to finally obtain effluent. Through cooperation of the steps, the removal effect of total phosphorus in the leachate is effectively improved, the treatment efficiency and stability of the leachate are improved, and the treatment cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of leachate treatment, and in particular relates to a leachate total phosphorus removal process and a system thereof. Background Art

[0002] Leachate refers to a special type of waste liquid that usually contains hazardous and toxic substances and may pose a serious threat to the environment and human health. It usually comes from facilities that treat hazardous waste, such as hazardous waste landfills. When these facilities treat waste, the water in the waste will seep into the soil and groundwater to form leachate. This leachate may contain harmful chemicals such as heavy metals, organic matter, total phosphorus and toxic chemicals, which will cause serious harm to the environment and human health if it is not properly treated and discharged.

[0003] At present, the commonly used method for treating total phosphorus in leachate is evaporation. The heat source of this method usually comes from the steam generated by the incineration line. However, this treatment method cannot effectively remove organic phosphorus in total phosphorus, and the treatment effect is not obvious. In addition, the mother liquor after evaporation treatment is difficult to treat, and the impure salt cannot be effectively utilized for the time being, and can only be landfilled in a rigid landfill, which has a high disposal cost. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a leachate total phosphorus removal process and system thereof, aiming to solve the technical problem that the existing total phosphorus removal effect in leachate is poor.

[0005] To achieve the above object, the present invention provides the following technical solution: a leachate total phosphorus removal process, comprising:

[0006] S01: After adjusting the pH value of the leachate to 3-5, an oxidant is added to the leachate to oxidize the organic phosphorus in the leachate to form inorganic orthophosphorus;

[0007] S02: adding a dephosphorizing agent to the leachate in step S01, stirring and filtering to obtain a first filtrate;

[0008] S03: adjusting the pH value in the filtrate to neutral, adding lime emulsion to the filtrate, stirring and filtering to obtain a second filtrate;

[0009] S04: adding activated carbon powder to the second filtrate, stirring and filtering to obtain a third filtrate;

[0010] S05: Add PAM solution and coagulant aid to the third filtrate in sequence, stir evenly, let stand for a period of time, and finally obtain effluent.

[0011] Furthermore, the step S01 includes:

[0012] Add a certain amount of clean water and sulfuric acid to the dosing tank and stir evenly to form a sulfuric acid solution with a mass concentration of 10%;

[0013] Add the prepared sulfuric acid solution into the leachate and stir evenly to adjust the pH value of the leachate to 3-5;

[0014] Wherein, the volume ratio of the clean water to the sulfuric acid is 9:1.

[0015] Furthermore, the oxidant is SN-4, and the mass concentration of the oxidant is 3%-8%.

[0016] Furthermore, the dephosphorization agent is a hypophosphorous remover, and the mass concentration of the dephosphorization agent is 3%-8%.

[0017] Furthermore, the mass concentration of the lime emulsion is 8%-15%.

[0018] Furthermore, the mass concentration of the PAM solution is 0.05%-0.15%.

[0019] Furthermore, the standing time in step SO4 is 7-8 hours.

[0020] A leachate total phosphorus removal system comprises a first reaction tank, a second reaction tank, a third reaction tank, a fourth reaction tank, a fifth reaction tank, a sixth reaction tank, and a sedimentation tank, wherein the first reaction tank is connected to an acid tank through a first metering pump; the second reaction tank is connected to an oxidant tank through a second metering pump; the third reaction tank is connected to a dephosphorization agent tank through a third metering pump; the fourth reaction tank is connected to a lime emulsion tank through a fourth metering pump; the fifth reaction tank is connected to an activated carbon tank through a fifth metering pump; the sixth reaction tank is connected to a PAM solution tank through a sixth metering pump; and each reaction tank is connected to the sedimentation tank in sequence through a pipeline.

[0021] Furthermore, the speed ratio of the stirring devices in the second reaction tank, the third reaction tank, the fourth reaction tank, the fifth reaction tank, and the sixth reaction tank is 5:5:6:6:3.

[0022] Furthermore, it also includes a water outlet pool, and the sedimentation tank is connected to the water outlet pool through a pipeline.

[0023] The invention has the following beneficial effects: compared with the prior art, a leachate total phosphorus removal process of the invention can oxidize organic phosphorus in the leachate to form inorganic orthophosphorus by adding an oxidant to the leachate; by adding a dephosphorizing agent to the oxidized leachate, the dephosphorizing agent can react chemically with the inorganic orthophosphorus to form an insoluble phosphate precipitate, thereby achieving phosphorus removal in the leachate; by adding lime emulsion to the leachate, on the one hand, acidic substances in the wastewater can be neutralized, and the pH value of the wastewater can be adjusted to reach a suitable neutral or slightly alkaline range to meet the requirements of subsequent treatment or emission standards; on the other hand, calcium ions in the lime emulsion react with phosphate ions to form calcium phosphate precipitates, thereby further reducing the phosphorus content in the wastewater; by adding activated carbon powder to the leachate, organic matter, odor, pigment and other impurities in the water can be effectively removed by the activated carbon powder; by adding a PAM solution and a coagulant, suspended particles in the leachate can be aggregated into larger floccules, sedimentation is accelerated, and solid-liquid separation efficiency is improved. Through the coordinated cooperation of the various steps in this application, the removal effect of total phosphorus in the leachate is effectively improved, the efficiency and stability of leachate treatment are improved, and the disposal cost is reduced.

[0024] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0026] Figure 1 The present invention is a flowchart of a leachate total phosphorus removal process according to an embodiment of the present invention.

[0027] Figure 2 A structural diagram of a leachate total phosphorus removal system is provided for one embodiment of the present invention;

[0028] Figure 3 A comparison chart before and after phosphorus removal of a leachate total phosphorus removal system provided in an embodiment of the invention.

[0029] Figure Number:

[0030] 1- first reaction tank;

[0031] 2-second reaction tank;

[0032] 3- the third reaction tank;

[0033] 4- the fourth reaction tank;

[0034] 5-fifth reaction tank;

[0035] 6-sixth reaction tank;

[0036] 7- Sedimentation tank;

[0037] 8-Exit the pool. DETAILED DESCRIPTION

[0038] like Figure 1 As shown, this embodiment proposes a leachate total phosphorus removal process, comprising the following steps:

[0039] S01: After adjusting the pH value of the leachate to 3-5, an oxidant is added to the leachate to oxidize the organic phosphorus in the leachate to form inorganic orthophosphorus;

[0040] S02: adding a dephosphorizing agent to the leachate in step S01, stirring and filtering to obtain a first filtrate;

[0041] S03: adjusting the pH value in the filtrate to neutral, adding lime emulsion to the filtrate, stirring and filtering to obtain a second filtrate;

[0042] S04: adding activated carbon powder to the second filtrate, stirring and filtering to obtain a third filtrate;

[0043] S05: Add PAM solution and coagulant aid to the third filtrate in sequence, stir evenly, let stand for a period of time, and finally obtain effluent.

[0044] In the present application, by adding an oxidant to the leachate, the organic phosphorus in the leachate can be oxidized to form inorganic orthophosphorus; by adding a dephosphorizing agent to the oxidized leachate, the dephosphorizing agent can react chemically with the inorganic orthophosphorus to form an insoluble phosphate precipitate, thereby achieving the removal of phosphorus in the leachate; by adding lime emulsion to the leachate, on the one hand, the acidic substances in the wastewater can be neutralized and the pH value of the wastewater can be adjusted to a suitable neutral or slightly alkaline range to meet the requirements of subsequent treatment or emission standards; on the other hand, calcium ions in the lime emulsion react with phosphate ions to form calcium phosphate precipitates, thereby further reducing the phosphorus content in the wastewater; by adding activated carbon powder to the leachate, organic matter, odor, pigment and other impurities in the water can be effectively removed by the activated carbon powder; by adding PAM solution and coagulant aid, the suspended particles in the leachate are aggregated into larger flocs, sedimentation is accelerated, and the solid-liquid separation efficiency is improved. Through the coordinated cooperation of the various steps in this application, the removal effect of total phosphorus in the leachate is effectively improved, the efficiency and stability of leachate treatment are improved, and the disposal cost is reduced.

[0045] Preferably, step S01 includes:

[0046] Add a certain amount of clean water and sulfuric acid to the dosing tank and stir evenly to form a sulfuric acid solution with a mass concentration of 10%;

[0047] Add the prepared sulfuric acid solution into the leachate and stir evenly to adjust the pH value of the leachate to 3-5;

[0048] Wherein, the volume ratio of the clean water to the sulfuric acid is 9:1.

[0049] Specifically, 180L of clean water is added to the dosing tank, and then 20L of sulfuric acid is added, and stirred for 3-5h to form a sulfuric acid solution with a mass concentration of 10%, and then the sulfuric acid solution is added to the leachate through a metering pump. After the pH value in the leachate is adjusted to 3-5, on the one hand, the oxidizing property of the subsequent oxidant is enhanced, and on the other hand, the reaction rate of the oxidant is increased, which provides a guarantee for the subsequent oxidant to oxidize the organic phosphorus in the leachate into inorganic orthophosphorus. Of course, according to actual conditions and specific needs, 270L of water and 30L of sulfuric acid can also be added to the dosing tank for proportioning, or other methods, which are not limited here.

[0050] Preferably, the oxidant is SN-4, and the mass concentration of the oxidant is 3%-8%. Specifically, SN-4 is an ammonia nitrogen remover, and the organic phosphorus in the leachate is oxidized by the oxidizing property of the ammonia nitrogen remover.

[0051] Preferably, the oxidant is configured by pre-adding 100L of clean water into the dosing tank, then adding 10kg of the oxidant and stirring, then adding clean water to dilute to 200L, stirring continuously, and configuring the oxidant mass concentration to 5%. Subsequently, the configured oxidant is added to the leachate to oxidize the organic phosphorus in the leachate to inorganic orthophosphorus. Of course, according to actual conditions and specific needs, the mass concentration of the oxidant in the leachate can also be 4%, 6%, 7%, 8%, etc., which is not limited here.

[0052] Preferably, the dephosphorizing agent is a hypophosphorous remover, and the mass concentration of the dephosphorizing agent is 3%-8%. Specifically, the mass concentration of the dephosphorizing agent is 3%, 4%, 5%, 6%, 7%, 8%, etc. Of course, the corresponding concentration can be matched according to the actual volume of the leachate, and the mass concentration is not limited here.

[0053] In this embodiment, the preparation method of the dephosphorization agent comprises:

[0054] 200L of tap water and 6Kg of dephosphorization agent were added to the dosing tank, and the mixture was stirred at a stirring speed of 30r / min by a stirrer to obtain the required mass concentration of the dephosphorization agent. Of course, in this application, according to the actual situation and specific needs, the mass concentration of the dephosphorization agent can also be determined according to the volume of leachate that needs to be treated.

[0055] Preferably, the mass concentration of the lime emulsion is 8%-15%. The specific mass concentration ratio is determined according to the actual volume of leachate to be treated.

[0056] Specifically, the preparation method of the lime emulsion comprises:

[0057] Add 200L of tap water into the dosing tank, and then add 10Kg of lime, and stir for 3-5 hours to prepare a lime emulsion with a mass concentration of 10%.

[0058] Preferably, the mass concentration of the PAM solution is 0.05%-0.15%. Specifically, the mass concentration of the PAM is 0.05%, 0.10%, 0.12%, 0.14%, 0.15%, etc. Of course, the specific mass concentration of the PAM can also be determined according to the actual volume of leachate to be treated, which is not limited here.

[0059] Preferably, the standing time in step S04 is 7-8 hours. The standing time provides the PAM solution and the coagulant aid with a longer reaction time, so that the suspended particles aggregate into larger flocs and have sufficient time to settle.

[0060] The present application also provides a leachate total phosphorus removal system, such as Figure 2 As shown, it includes a first reaction tank 1, a second reaction tank 2, a third reaction tank 3, a fourth reaction tank 4, a fifth reaction tank 5, a sixth reaction tank 6, and a sedimentation tank 7. The first reaction tank 1 is connected to the acid tank through a first metering pump; the second reaction tank 2 is connected to the oxidant tank through a second metering pump; the third reaction tank 3 is connected to the dephosphorization agent tank through a third metering pump; the fourth reaction tank 4 is connected to the lime emulsion tank through a fourth metering pump; the fifth reaction tank 5 is connected to the activated carbon tank through a fifth metering pump; the sixth reaction tank 6 is connected to the PAM solution tank through a sixth metering pump; each reaction tank is connected to the sedimentation tank 7 in sequence through a pipeline.

[0061] In the present application, the volume of the first reaction pool 1, the second reaction pool 2, the third reaction pool 3, the fourth reaction pool 4, the fifth reaction pool 5, and the sixth reaction pool 6 is 10m 3 The volume of the sedimentation tank 7 is 40m 3 Of course, according to the actual situation and specific needs, the volumes of the above-mentioned reaction tanks and sedimentation tank 7 can also be set to other values, which are not limited here.

[0062] In the present application, by adding leachate to the first reaction tank 1, sulfuric acid is then added to the first reaction tank 1 through a first metering pump to adjust the pH value in the first reaction tank 1 to make it acidic; wherein the inlet of the first reaction tank 1 is arranged at the middle position of the first reaction tank 1, and the outlet of the first reaction tank 1 is arranged at the top position of the first reaction tank 1, and the position difference between the inlet and the outlet increases the time for adjusting the acidity of the leachate; when the pH value of the leachate reaches a suitable value, the leachate in the first reaction tank 1 flows to the second reaction tank 2 through a pipeline;

[0063] When the leachate enters the second reaction tank 2, the prepared oxidant is added to the second reaction tank 2 by the second metering pump to oxidize the leachate; wherein the inlet of the second reaction tank 2 is arranged at the top position of the second reaction tank 2, and the outlet of the second reaction tank 2 is arranged at the lower position of the second reaction tank 2. The inlet of the second reaction tank 2 is arranged at the top, and the shortest pipeline can be used to achieve connection with the outlet of the first reaction tank 1, thereby reducing material costs;

[0064] When the leachate enters the third reaction tank 3 through the pipeline, the prepared dephosphorization agent is added to the leachate through the third metering pump for dephosphorization treatment; wherein, the inlet of the third reaction tank 3 is arranged at the bottom position of the third reaction tank 3, and the outlet of the third reaction tank 3 is arranged at the top position of the third reaction tank 3. The inlet of the third reaction tank 3 is arranged at the bottom, which can be used for the shortest pipeline to achieve connection with the outlet of the second reaction tank 2, reducing the material cost; on the other hand, the reaction time of the dephosphorization treatment of the leachate can be increased through the difference in the position of the inlet and outlet, so that the dephosphorization treatment is more sufficient, and at the same time, it also effectively avoids the turbulence phenomenon when the leachate flows to the third reaction tank 3;

[0065] When the leachate enters the fourth reaction tank 4 through the pipeline, the prepared lime emulsion is added to the leachate through the third metering pump for further dephosphorization treatment, which greatly reduces the total phosphorus content in the leachate; wherein, the inlet of the fourth reaction tank 4 is arranged at the top position of the fourth reaction tank 4, and the outlet of the fourth reaction tank 4 is arranged at the bottom position of the fourth reaction tank 4; such distribution can shorten the length of the pipeline connecting two adjacent reaction tanks;

[0066] When the leachate enters the fifth reaction tank 5 through the pipeline, the prepared activated carbon is added to the leachate through the fourth metering pump to remove organic matter in the leachate; wherein the inlet of the fifth reaction tank 5 is set at the bottom and the outlet is set at the top; thus, the retention time of the leachate is increased and the reaction time is increased;

[0067] When the leachate enters the sixth reaction tank from the fifth reaction tank 5 through the pipeline, the prepared PAM solvent is added to the leachate through the fifth metering pump to remove suspended particles in the leachate; wherein the inlet of the sixth reaction tank 6 is set at the top, and the outlet is set at the top; in this way, the retention time of the leachate is increased, and the reaction time is increased.

[0068] In this application, if Figure 3 As shown, through the coordinated cooperation of the reaction tanks in the above system, the removal effect of total phosphorus in the leachate is effectively improved, the efficiency and stability of leachate treatment are improved, and the disposal cost is reduced, so that the treated leachate meets the emission limit requirements of GB18598-2019 "Hazardous Waste Landfill Pollution Control Standards".

[0069] Preferably, the speed ratio of the stirring device in the second reaction pool 2, the third reaction pool 3, the fourth reaction pool 4, the fifth reaction pool 5, and the sixth reaction pool 6 is 5:5:6:6:3. Specifically, the speed of the stirring device in the second reaction pool 2 is 50r / min; correspondingly, the speeds of the stirring devices in the third reaction pool 3, the fourth reaction pool 4, the fifth reaction pool 5, and the sixth reaction pool 6 are 50r / min, 60r / min, 60r / min, and 30r / min, respectively. Of course, the above stirring speed can also be adjusted to other values ​​according to the actual volume of the leachate to ensure uniform stirring in each reaction pool, which is not the only limitation here.

[0070] Preferably, the removal system further comprises a water outlet pool 8, and the sedimentation pool 7 is connected to the water outlet pool 8 through a pipeline. In this way, the water in the sedimentation pool 7 can be stored through the water outlet pool 8 to achieve recycling.

[0071] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A leachate total phosphorus removal process, characterized in that: The steps include: S01: After adjusting the pH value of the leachate to 3-5, an oxidant is added to the leachate to oxidize the organic phosphorus in the leachate to form inorganic orthophosphorus; S02: adding a dephosphorizing agent to the leachate in step S01, stirring and filtering to obtain a first filtrate; S03: adjusting the pH value in the filtrate to neutral, adding lime emulsion to the filtrate, stirring and filtering to obtain a second filtrate; S04: adding activated carbon powder to the second filtrate, stirring and filtering to obtain a third filtrate; S05: Add PAM solution and coagulant aid to the third filtrate in sequence, stir evenly, let stand for a period of time, and finally obtain effluent.

2. A leachate total phosphorus removal process according to claim 1, characterized in that: The step S01 comprises: Add a certain amount of clean water and sulfuric acid to the dosing tank and stir evenly to form a sulfuric acid solution with a mass concentration of 10%; Add the prepared sulfuric acid solution into the leachate and stir evenly to adjust the pH value of the leachate to 3-5; Wherein, the volume ratio of the clean water to the sulfuric acid is 9:

1.

3. A leachate total phosphorus removal process according to claim 1, characterized in that: The oxidant is SN-4, and the mass concentration of the oxidant is 3%-8%.

4. A leachate total phosphorus removal process according to claim 1, characterized in that: The dephosphorization agent is a hypophosphorous remover, and the mass concentration of the dephosphorization agent is 3%-8%.

5. A leachate total phosphorus removal process according to claim 1, characterized in that: The mass concentration of the lime emulsion is 8%-15%.

6. A leachate total phosphorus removal process according to claim 1, characterized in that: The mass concentration of the PAM solution is 0.05%-0.15%.

7. A leachate total phosphorus removal process according to claim 1, characterized in that: The standing time in step SO4 is 7-8h.

8. A leachate total phosphorus removal system, characterized in that: It includes a first reaction tank, a second reaction tank, a third reaction tank, a fourth reaction tank, a fifth reaction tank, a sixth reaction tank, and a sedimentation tank. The first reaction tank is connected to an acid tank through a first metering pump; the second reaction tank is connected to an oxidant tank through a second metering pump; the third reaction tank is connected to a dephosphorization agent tank through a third metering pump; the fourth reaction tank is connected to a lime emulsion tank through a fourth metering pump; the fifth reaction tank is connected to an activated carbon tank through a fifth metering pump; the sixth reaction tank is connected to a PAM solution tank through a sixth metering pump; each reaction tank is connected to the sedimentation tank in sequence through a pipeline.

9. A leachate total phosphorus removal system according to claim 8, characterized in that: The speed ratio of the stirring devices in the second reaction tank, the third reaction tank, the fourth reaction tank, the fifth reaction tank, and the sixth reaction tank is 5:5:6:6:

3.

10. A leachate total phosphorus removal system according to claim 8, characterized in that: It also includes a water outlet pool, and the sedimentation tank is connected to the water outlet pool through a pipeline.

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