Membrane concentrated solution pretreatment system and method

Abstract

The invention discloses a membrane concentrated solution pretreatment system and method, and belongs to the technical field of water treatment.The system comprises a first-stage oxidation pond set, a first-stage flocculation pond set, a first-stage sedimentation pond, a second-stage oxidation pond set, a second-stage flocculation pond set, a second-stage sedimentation pond, a transition pond and a filter which are sequentially connected, and the method comprises the steps that S1, sewage drainage is conducted; s2, adding a medicament; and S3, aeration. The advanced oxidation, coagulating sedimentation and filtration integrated device is adopted for pretreatment to remove a surfactant in the landfill leachate membrane concentrated solution and reduce the COD content and the calcium and magnesium content in the landfill leachate membrane concentrated solution, so that the treated landfill leachate membrane concentrated solution meets the requirements of subsequent advanced treatment, especially evaporation treatment; compared with a traditional sewage treatment system, the system is more energy-saving, saves a large amount of cost, and can meet the requirement of evaporation treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a membrane concentrate pretreatment system and method. Background Art

[0002] Landfill leachate membrane concentrate is a by-product of membrane process treatment of landfill leachate. Compared with general landfill leachate, it contains higher concentrations of organic pollutants, inorganic salts and metal ions, and has poor biodegradability. If improperly handled, it will cause more serious secondary pollution.

[0003] In recent years, research on the treatment of landfill leachate membrane concentrate has been extensive both domestically and internationally. The most typical is the combined treatment process of "pretreatment + advanced oxidation + deep treatment". However, this process has very high requirements for the initial pretreatment + advanced oxidation. If not handled properly, it may cause the difficult-to-degrade surfactant-type macromolecular pollutants and inorganic salts in the wastewater to produce a large amount of foam during the subsequent evaporation treatment process, making the evaporation process unable to proceed smoothly.

[0004] According to our research results, the safe treatment of membrane concentrate in my country is still in its infancy, and engineering application technologies such as advanced oxidation, submerged combustion evaporation (SCE) and mechanical vapor recompression (MVC / MVR) are only on a small or pilot scale. In order to effectively ensure the safe disposal of membrane concentrate in my country, it is recommended to reduce the output of membrane concentrate from the source, improve and perfect the existing membrane concentrate treatment technology, develop membrane concentrate resource utilization technology, and properly handle secondary pollutants in membrane concentrate. Summary of the Invention

[0005] In response to the above-mentioned problems, the present invention provides a membrane concentrate pretreatment system and method.

[0006] The technical solution of the present invention is:

[0007] A membrane concentrate pretreatment system comprises a primary oxidation tank group, a primary flocculation tank group, a primary sedimentation tank group, a secondary oxidation tank group, a secondary flocculation tank group, a secondary sedimentation tank, a transition tank and a filter connected in sequence;

[0008] The primary oxidation tank group includes a primary acid oxidation tank, a primary hydrogen peroxide dosing tank, a primary enhanced aeration tank and a primary alkaline oxidation tank connected in sequence, and the primary flocculation tank group includes a primary mixing tank and a primary flocculation tank connected in sequence;

[0009] The secondary oxidation tank group includes a secondary acid oxidation tank, a secondary hydrogen peroxide dosing tank, a secondary enhanced aeration tank and a secondary alkaline oxidation tank connected in sequence, and the secondary flocculation tank group includes a secondary mixing tank and a secondary flocculation tank connected in sequence;

[0010] The primary oxidation tank group and the secondary oxidation tank group are placed in two L-shaped arrangements, and the primary sedimentation tank and the secondary sedimentation tank are placed side by side;

[0011] Aeration components are provided outside the primary oxidation tank group and the secondary oxidation tank group.

[0012] Furthermore, the aeration assembly includes a main aeration pipe surrounding the outside of the primary oxidation tank group, and the main aeration pipe is connected to the primary acidic oxidation tank, the primary hydrogen peroxide dosing tank, the primary enhanced aeration tank and the primary alkaline oxidation tank respectively through an aeration valve. The main aeration pipe is also provided with three branch aeration pipes, one of the branch aeration pipes located on one side is connected to the secondary acidic oxidation tank, the branch aeration pipe located in the middle is connected to the secondary hydrogen peroxide dosing tank, and the branch aeration pipe located on the other side is connected to both the secondary enhanced aeration tank and the secondary alkaline oxidation tank, and the filter is a bag filter.

[0013] Description: The aeration components are set up to stir the sewage in each oxidation tank, causing it to tumble and promote the full fusion reaction between the sewage and the reagents, while also reducing the sedimentation of floating sludge to the bottom of the tank.

[0014] Furthermore, the first-level mixing tank and the first-level flocculation tank are placed side by side with the first-level sedimentation tank, one side of the second-level sedimentation tank is placed side by side with the second-level enhanced aeration tank and the second-level flocculation tank, and the other side of the second-level sedimentation tank is placed side by side with the transition tank. The bottom of the first-level sedimentation tank is connected to the first mud discharge pump located outside the second-level sedimentation tank through a first mud discharge pipe, and the bottom of the second-level sedimentation tank is connected to the second mud discharge pump located on one side of the first mud discharge pump through a second mud discharge pipe.

[0015] Note: The sludge at the bottom of the sedimentation tank can be discharged in time through the setting of the sludge pump.

[0016] A membrane concentrate pretreatment method, based on any one of the membrane concentrate pretreatment systems described above, comprises the following steps:

[0017] S1. Sewage drainage: The landfill leachate membrane concentrate is injected into the primary acid oxidation tank and sequentially passes through the primary hydrogen peroxide dosing tank, the primary enhanced aeration tank, the primary alkaline oxidation tank, the primary mixing tank, the primary flocculation tank, the primary sedimentation tank, the secondary acid oxidation tank, the secondary hydrogen peroxide dosing tank, the secondary enhanced aeration tank, the secondary alkaline oxidation tank, the secondary mixing tank, the secondary flocculation tank, the secondary sedimentation tank, the transition tank and the filter before being discharged;

[0018] S2. Adding reagents: adding dilute sulfuric acid and ferrous sulfate to the primary acid oxidation tank and the secondary acid oxidation tank, adding hydrogen peroxide to the primary hydrogen peroxide dosing tank and the secondary hydrogen peroxide dosing tank, adding sodium hydroxide and sodium carbonate to the primary alkaline oxidation tank and the secondary alkaline oxidation tank, adding polyaluminum chloride to the primary mixing tank and the secondary mixing tank, adding polyacrylamide to the primary flocculation tank and the secondary flocculation tank, and adding ammonium chloride to the transition tank;

[0019] S3. Aeration: Aeration is carried out in the primary oxidation pond group and the secondary oxidation pond group.

[0020] Furthermore, the flow rate of the landfill leachate membrane concentrate in step S1 is 3 to 5 m 3 / h.

[0021] Furthermore, in step S2, the amount of dilute sulfuric acid added to the primary acid oxidation tank and the secondary acid oxidation tank is 0.4-0.5 kg / t membrane concentrate, the adding speed is 1.6-1.8 kg / h, the mass concentration of dilute sulfuric acid is 20%, the amount of ferrous sulfate added to the primary acid oxidation tank and the secondary acid oxidation tank is 15-20 kg / t membrane concentrate, the adding speed is 70-80 kg / h, the ferrous sulfate is a ferrous sulfate solution with a mass concentration of 20%, the amount of hydrogen peroxide added to the primary hydrogen peroxide dosing tank is 3-4 kg / t membrane concentrate, the adding speed is 10-12 kg / h, and the secondary hydrogen peroxide dosing tank is 10-12 kg / h. The hydrogen peroxide dosing amount of the first-level hydrogen peroxide dosing tank is 1-2 kg / t membrane concentrate, the dosing rate is 3-4 kg / h, and the mass concentration of hydrogen peroxide is 30%. The sodium hydroxide dosing amount of the first-level alkaline oxidation tank and the second-level alkaline oxidation tank is 0.3-0.32 kg / t membrane concentrate, the dosing rate is 1.2-1.3 kg / h, and the sodium hydroxide is a sodium hydroxide solution with a mass concentration of 20%. The sodium carbonate dosing amount of the first-level alkaline oxidation tank and the second-level alkaline oxidation tank is 4-5 kg / t membrane concentrate, the dosing rate is 18-20 kg / h, and the sodium carbonate is a sodium carbonate solution with a mass concentration of 20%.

[0022] Furthermore, in step S2, the amount of polyaluminum chloride added to the primary mixing tank and the secondary mixing tank is 2-3 kg / t membrane concentrate, the adding rate is 6-8 kg / h, the polyaluminum chloride is a polyaluminum chloride solution with a mass concentration of 3-5%, the amount of polyacrylamide added to the primary flocculation tank and the secondary flocculation tank is 2-3 kg / t membrane concentrate, the adding rate is 6-8 kg / h, ammonium chloride solution with a mass concentration of 5% is continuously added to the transition tank, the adding rate is 6-8 L / h, and the polyacrylamide is a polyacrylamide solution with a mass concentration of 1%.

[0023] Description: By optimizing and adjusting the dosage of chemicals and sewage flow in each reaction tank, the optimal reaction parameter configuration is obtained. The investment of chemicals and operation and maintenance costs are lower than other concentrated liquid treatment devices, and it can be more widely used in production. At the same time, the evaporation capacity is increased by at least 30% in the subsequent evaporation treatment.

[0024] Furthermore, during aeration in step S3, the first-level acidic oxidation pool is injected, and the aeration volume of the first-level hydrogen peroxide dosing pool, the first-level alkaline oxidation pool, the second-level acidic oxidation pool, the second-level hydrogen peroxide dosing pool, and the second-level alkaline oxidation pool is 2.3-2.5m 3 / min, the aeration depth is 3.2-3.5m, and the aeration volume of the first-level enhanced aeration tank and the second-level enhanced aeration tank is 2.6-3m 3 / min, aeration depth is 3.5~4m.

[0025] Note: By setting up two enhanced aeration tanks in the two oxidation tank groups and adjusting the aeration parameters, the aeration efficiency can be improved.

[0026] The beneficial effects of the present invention are:

[0027] (1) The membrane concentrate pretreatment system of the present invention adopts an integrated device of advanced oxidation, coagulation precipitation and filtration to pretreatment and remove surfactants in landfill leachate membrane concentrate, reduce the COD content and calcium and magnesium content in the landfill leachate membrane concentrate, so that the treated landfill leachate membrane concentrate meets the needs of subsequent deep treatment, especially evaporation treatment, eliminates the foaming phenomenon in the subsequent evaporation treatment process, and ensures stable and reliable operation of evaporation. It is a pretreatment system specifically for deep evaporation treatment of landfill leachate membrane concentrate, which is more energy-efficient than traditional sewage treatment systems, saves a lot of costs, and can meet the requirements of evaporation treatment.

[0028] (2) The membrane concentrate pretreatment method of the present invention strictly controls the timing, speed and amount of adding different reagents in each reaction tank, thereby ensuring that the entire landfill leachate membrane concentrate pretreatment process has a relatively good pretreatment effect under the premise of using the least amount of reagents. The addition of aeration and enhanced aeration further improves the treatment effect and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of a membrane concentrated liquid pretreatment system of the present invention.

[0030] Among them, 1-first-level oxidation pond group, 11-first-level acidic oxidation pond, 12-first-level hydrogen peroxide dosing pond, 13-first-level enhanced aeration pond, 14-first-level alkaline oxidation pond, 2-first-level flocculation pond group, 21-first-level mixing pond, 22-first-level flocculation pond, 3-first-level sedimentation pond, 31-first-level sludge discharge pipe, 32-first-row sludge pump, 4-second-level oxidation pond group, 41-second-level acidic oxidation pond, 42-second-level hydrogen peroxide dosing pond, 43-second-level enhanced aeration pond, 44-second-level alkaline oxidation pond, 5-second-level flocculation pond group, 51-second-level mixing pond, 52-second-level flocculation pond, 6-second-level sedimentation pond, 61-second-level sludge discharge pipe, 62-second-row sludge pump, 7-transition pond, 8-filter, 9-aeration component, 91-main aeration pipe, 92-aeration valve, 93-branch aeration pipe. DETAILED DESCRIPTION

[0031] Example 1

[0032] A membrane concentrate pretreatment system comprises a primary oxidation tank group 1, a primary flocculation tank group 2, a primary sedimentation tank 3, a secondary oxidation tank group 4, a secondary flocculation tank group 5, a secondary sedimentation tank 6, a transition tank 7 and a filter 8 connected in sequence, wherein the filter 8 is a bag filter;

[0033] The primary oxidation tank group 1 includes a primary acidic oxidation tank 11, a primary hydrogen peroxide dosing tank 12, a primary enhanced aeration tank 13, and a primary alkaline oxidation tank 14 connected in sequence; the primary flocculation tank group 2 includes a primary mixing tank 21 and a primary flocculation tank 22 connected in sequence; the secondary oxidation tank group 4 includes a secondary acidic oxidation tank 41, a secondary hydrogen peroxide dosing tank 42, a secondary enhanced aeration tank 43, and a secondary alkaline oxidation tank 44 connected in sequence; the secondary flocculation tank group 5 includes a secondary mixing tank 51 and a secondary flocculation tank 52 connected in sequence;

[0034] The primary oxidation tank group 1 and the secondary oxidation tank group 4 are placed in two L-shaped arrangements, the primary sedimentation tank 3 and the secondary sedimentation tank 6 are placed side by side, the primary mixing tank 21 and the primary flocculation tank 22 are both placed side by side with the primary sedimentation tank 3, one side of the secondary sedimentation tank 6 is placed side by side with the secondary enhanced aeration tank 43 and the secondary flocculation tank 52, and the other side of the secondary sedimentation tank 6 is placed side by side with the transition tank 7. The bottom of the primary sedimentation tank 3 is connected to the first sludge pump 32 located outside the secondary sedimentation tank 6 through the primary sludge discharge pipe 31, and the bottom of the secondary sedimentation tank 6 is connected to the second sludge pump 62 located on one side of the first sludge discharge pipe 61;

[0035] An aeration assembly 9 is provided outside the primary oxidation tank group 1 and the secondary oxidation tank group 4. The aeration assembly 9 includes a main aeration pipe 91 surrounding the outside of the primary oxidation tank group 1. The main aeration pipe 91 is connected to the primary acidic oxidation tank 11, the primary hydrogen peroxide dosing tank 12, the primary enhanced aeration tank 13 and the primary alkaline oxidation tank 14 respectively through an aeration valve 92. The main aeration pipe 91 is also provided with three branch aeration pipes 93. One branch aeration pipe 93 located on one side is connected to the secondary acidic oxidation tank 41, one branch aeration pipe 93 located in the middle is connected to the secondary hydrogen peroxide dosing tank 42, and one branch aeration pipe 93 located on the other side is connected to both the secondary enhanced aeration tank 43 and the secondary alkaline oxidation tank 44.

[0036] Example 2

[0037] A membrane concentrate pretreatment method, based on the membrane concentrate pretreatment system in Example 1, comprises the following steps:

[0038] S1. Sewage drainage: The landfill leachate membrane concentrate is injected from the primary acid oxidation tank 11, and is discharged after passing through the primary hydrogen peroxide dosing tank 12, the primary enhanced aeration tank 13, the primary alkaline oxidation tank 14, the primary mixing tank 21, the primary flocculation tank 22, the primary sedimentation tank 3, the secondary acid oxidation tank 41, the secondary hydrogen peroxide dosing tank 42, the secondary enhanced aeration tank 43, the secondary alkaline oxidation tank 44, the secondary mixing tank 51, the secondary flocculation tank 52, the secondary sedimentation tank 6, the transition tank 7 and the filter 8. The flow rate of the landfill leachate membrane concentrate is 4m 3 / h;

[0039] S2, adding reagents: adding dilute sulfuric acid and ferrous sulfate to the primary acidic oxidation tank 11 and the secondary acidic oxidation tank 41, adding hydrogen peroxide to the primary hydrogen peroxide dosing tank 12 and the secondary hydrogen peroxide dosing tank 42, adding sodium hydroxide and sodium carbonate to the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44, adding polyaluminum chloride to the primary mixing tank 21 and the secondary mixing tank 51, adding polyacrylamide to the primary flocculation tank 22 and the secondary flocculation tank 52, and adding ammonium chloride to the transition tank 7;

[0040] The dosage of dilute sulfuric acid in the primary acid oxidation tank 11 and the secondary acid oxidation tank 41 is 0.45 kg / t membrane concentrate, the dosage rate is 1.7 kg / h, and the mass concentration of dilute sulfuric acid is 20%. The dosage of ferrous sulfate in the primary acid oxidation tank 11 and the secondary acid oxidation tank 41 is 18 kg / t membrane concentrate, the dosage rate is 75 kg / h, and the ferrous sulfate is a ferrous sulfate solution with a mass concentration of 20%. The dosage of hydrogen peroxide in the primary hydrogen peroxide dosing tank 12 is 3.5 kg / t membrane concentrate, the dosage rate is 11 kg / h, and the secondary hydrogen peroxide dosing tank 42 is 18 kg / t membrane concentrate. The hydrogen peroxide dosage is 1.5 kg / t membrane concentrate, the dosage rate is 3.5 kg / h, the mass concentration of hydrogen peroxide is 30%, the sodium hydroxide dosage of the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 0.31 kg / t membrane concentrate, the dosage rate is 1.2 kg / h, and the sodium hydroxide is a sodium hydroxide solution with a mass concentration of 20%. The sodium carbonate dosage of the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 4.5 kg / t membrane concentrate, the dosage rate is 19 kg / h, and the sodium carbonate is a sodium carbonate solution with a mass concentration of 20%;

[0041] The amount of polyaluminium chloride added to the primary mixing tank 21 and the secondary mixing tank 51 is 2.5kg / t membrane concentrate, the adding rate is 7kg / h, and the polyaluminium chloride is a polyaluminium chloride solution with a mass concentration of 4%. The amount of polyacrylamide added to the primary flocculation tank 22 and the secondary flocculation tank 52 is 2.5kg / t membrane concentrate, the adding rate is 7kg / h, and the ammonium chloride solution with a mass concentration of 5% is continuously added to the transition tank 7 at a adding rate of 7L / h. The polyacrylamide is a polyacrylamide solution with a mass concentration of 1%;

[0042] S3, aeration: aeration is carried out in the primary oxidation pond group 1 and the secondary oxidation pond group 4. During aeration, the primary acidic oxidation pond 11 is injected, and the aeration volume is 2.4m3 in sequence through the primary hydrogen peroxide dosing pond 12, the primary alkaline oxidation pond 14, the secondary acidic oxidation pond 41, the secondary hydrogen peroxide dosing pond 42, and the secondary alkaline oxidation pond 44. 3 / min, the aeration depth is 3.3m, and the aeration volume of the first-stage enhanced aeration tank 13 and the second-stage enhanced aeration tank 43 is 2.8m 3 / min, aeration depth is 3.8m.

[0043] Example 3

[0044] This embodiment differs from embodiment 2 in that:

[0045] The flow rate of the landfill leachate membrane concentrate in step S1 is 3m 3 / h.

[0046] Example 4

[0047] This embodiment differs from embodiment 2 in that:

[0048] The flow rate of the landfill leachate membrane concentrate in step S1 is 5m 3 / h.

[0049] Example 5

[0050] The difference between this embodiment and embodiment 2 is that the amount of the drug added in step S2 is different.

[0051] The dosage of dilute sulfuric acid in the primary acid oxidation tank 11 and the secondary acid oxidation tank 41 is 0.4 kg / t membrane concentrate, the dosage rate is 1.6 kg / h, and the mass concentration of dilute sulfuric acid is 20%. The dosage of ferrous sulfate in the primary acid oxidation tank 11 and the secondary acid oxidation tank 41 is 15 kg / t membrane concentrate, the dosage rate is 70 kg / h, and the ferrous sulfate is a ferrous sulfate solution with a mass concentration of 20%. The dosage of hydrogen peroxide in the primary hydrogen peroxide dosing tank 12 is 3 kg / t membrane concentrate, the dosage rate is 10 kg / h, and the secondary hydrogen peroxide dosing tank is 10 kg / h. The dosing amount of hydrogen peroxide in the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 1 kg / t of membrane concentrate, the dosing rate is 3 kg / h, and the mass concentration of hydrogen peroxide is 30%. The dosing amount of sodium hydroxide in the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 0.3 kg / t of membrane concentrate, the dosing rate is 1.2 kg / h, and the sodium hydroxide is a sodium hydroxide solution with a mass concentration of 20%. The dosing amount of sodium carbonate in the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 4 kg / t of membrane concentrate, the dosing rate is 18 kg / h, and the sodium carbonate is a sodium carbonate solution with a mass concentration of 20%.

[0052] The amount of polyaluminium chloride added to the primary mixing tank 21 and the secondary mixing tank 51 is 2kg / t membrane concentrate, the adding rate is 6kg / h, and the polyaluminium chloride is a polyaluminium chloride solution with a mass concentration of 3%. The amount of polyacrylamide added to the primary flocculation tank 22 and the secondary flocculation tank 52 is 2kg / t membrane concentrate, the adding rate is 6kg / h, and ammonium chloride solution with a mass concentration of 5% is continuously added to the transition tank 7 at a adding rate of 6L / h. The polyacrylamide is a polyacrylamide solution with a mass concentration of 1%.

[0053] Example 6

[0054] The difference between this embodiment and embodiment 2 is that the amount of the drug added in step S2 is different.

[0055] The dosage of dilute sulfuric acid in the primary acid oxidation tank 11 and the secondary acid oxidation tank 41 is 0.5 kg / t membrane concentrate, the dosage rate is 1.8 kg / h, and the mass concentration of dilute sulfuric acid is 20%. The dosage of ferrous sulfate in the primary acid oxidation tank 11 and the secondary acid oxidation tank 41 is 20 kg / t membrane concentrate, the dosage rate is 80 kg / h, and the ferrous sulfate is a ferrous sulfate solution with a mass concentration of 20%. The dosage of hydrogen peroxide in the primary hydrogen peroxide dosing tank 12 is 4 kg / t membrane concentrate, the dosage rate is 12 kg / h, and the secondary hydrogen peroxide dosing tank is 10 kg / t membrane concentrate. The dosing amount of hydrogen peroxide in the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 2 kg / t of membrane concentrate, the dosing rate is 4 kg / h, and the mass concentration of hydrogen peroxide is 30%. The dosing amount of sodium hydroxide in the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 0.32 kg / t of membrane concentrate, the dosing rate is 1.3 kg / h, and the sodium hydroxide is a sodium hydroxide solution with a mass concentration of 20%. The dosing amount of sodium carbonate in the primary alkaline oxidation tank 14 and the secondary alkaline oxidation tank 44 is 5 kg / t of membrane concentrate, the dosing rate is 20 kg / h, and the sodium carbonate is a sodium carbonate solution with a mass concentration of 20%.

[0056] The amount of polyaluminium chloride added to the primary mixing tank 21 and the secondary mixing tank 51 is 3kg / t membrane concentrate, the adding rate is 8kg / h, and the polyaluminium chloride is a polyaluminium chloride solution with a mass concentration of 5%. The amount of polyacrylamide added to the primary flocculation tank 22 and the secondary flocculation tank 52 is 3kg / t membrane concentrate, the adding rate is 8kg / h, and ammonium chloride solution with a mass concentration of 5% is continuously added to the transition tank 7 at a adding rate of 8L / h. The polyacrylamide is a polyacrylamide solution with a mass concentration of 1%.

[0057] Note: In Examples 2 to 5, the selected parameters are all reasonable adjustments within the reasonable parameter range of the present invention. No matter which parameter is selected in Examples 2 to 5, the same technical effect can be achieved.

[0058] Experimental example

[0059] Next, we evaluate the actual use effect of the system and method of the present invention. When the system and method of Example 1 and Example 2 are applied to the integrated treatment of landfill leachate membrane concentrate, the cost is shown in Table 1.

[0060] Table 1 Three-effect operation cost in a certain year

[0061]

[0062] The sewage treated by the system of the present invention is subjected to evaporation treatment, which increases the evaporation rate by at least 30%. Other systems on the market are not optimized for different water qualities and different requirements for subsequent evaporation treatment. Therefore, under the premise of achieving the same treatment effect, the use cost, especially the cost of reagents, is 20-30% higher than that of the present invention. If reagents of the same cost are used, the evaporation rate of the subsequent evaporation treatment will be reduced by 20-30%. It can be seen that the membrane concentrate pretreatment system and method of the present invention can be specifically used for deep evaporation treatment of landfill leachate membrane concentrate, which is more energy-efficient than traditional sewage treatment systems, saves a lot of costs, and can meet the requirements of evaporation treatment.

Claims

1. A membrane concentrate pretreatment system, characterized in that: The invention comprises a primary oxidation tank group (1), a primary flocculation tank group (2), a primary sedimentation tank (3), a secondary oxidation tank group (4), a secondary flocculation tank group (5), a secondary sedimentation tank (6), a transition tank (7) and a filter (8) connected in sequence; The primary oxidation tank group (1) comprises a primary acid oxidation tank (11), a primary hydrogen peroxide dosing tank (12), a primary enhanced aeration tank (13), and a primary alkaline oxidation tank (14) connected in sequence, and the primary flocculation tank group (2) comprises a primary mixing tank (21) and a primary flocculation tank (22) connected in sequence; The secondary oxidation tank group (4) includes a secondary acidic oxidation tank (41), a secondary hydrogen peroxide dosing tank (42), a secondary enhanced aeration tank (43), and a secondary alkaline oxidation tank (44) connected in sequence, and the secondary flocculation tank group (5) includes a secondary mixing tank (51) and a secondary flocculation tank (52) connected in sequence; The primary oxidation tank group (1) and the secondary oxidation tank group (4) are placed in two L-shaped arrangements, and the primary sedimentation tank (3) and the secondary sedimentation tank (6) are placed side by side. Aeration components (9) are provided outside the primary oxidation tank group (1) and the secondary oxidation tank group (4).

2. A membrane concentrate pretreatment system according to claim 1, characterized in that: The aeration assembly (9) includes a main aeration pipe (91) surrounding the outside of the primary oxidation tank group (1). The main aeration pipe (91) is connected to the primary acidic oxidation tank (11), the primary hydrogen peroxide dosing tank (12), the primary enhanced aeration tank (13), and the primary alkaline oxidation tank (14) respectively through an aeration valve (92). The main aeration pipe (91) is also provided with three branch aeration pipes (93). One branch aeration pipe (93) located on one side is connected to the secondary acidic oxidation tank (41), the branch aeration pipe (93) located in the middle is connected to the secondary hydrogen peroxide dosing tank (42), and the branch aeration pipe (93) located on the other side is connected to both the secondary enhanced aeration tank (43) and the secondary alkaline oxidation tank (44). The filter (8) is a bag filter.

3. A membrane concentrate pretreatment system according to claim 1, characterized in that: The first-level mixing tank (21) and the first-level flocculation tank (22) are both placed side by side with the first-level sedimentation tank (3); one side of the second-level sedimentation tank (6) is placed side by side with the second-level enhanced aeration tank (43) and the second-level flocculation tank (52); the other side of the second-level sedimentation tank (6) is placed side by side with the transition tank (7); the bottom of the first-level sedimentation tank (3) is connected to the first mud discharge pump (32) located outside the second-level sedimentation tank (6) through the first mud discharge pipe (31); the bottom of the second-level sedimentation tank (6) is connected to the second mud discharge pump (62) located on the side of the first mud discharge pump (32) through the second mud discharge pipe (61).

4. A membrane concentrate pretreatment method, based on a membrane concentrate pretreatment system according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Sewage drainage: The landfill leachate membrane concentrate is injected from the primary acid oxidation tank (11), and sequentially passes through the primary hydrogen peroxide dosing tank (12), the primary enhanced aeration tank (13), the primary alkaline oxidation tank (14), the primary mixing tank (21), the primary flocculation tank (22), the primary sedimentation tank (3), the secondary acid oxidation tank (41), the secondary hydrogen peroxide dosing tank (42), the secondary enhanced aeration tank (43), the secondary alkaline oxidation tank (44), the secondary mixing tank (51), the secondary flocculation tank (52), the secondary sedimentation tank (6), the transition tank (7) and the filter (8) before being discharged; S2, adding reagents: adding dilute sulfuric acid and ferrous sulfate to the primary acidic oxidation tank (11) and the secondary acidic oxidation tank (41), adding hydrogen peroxide to the primary hydrogen peroxide dosing tank (12) and the secondary hydrogen peroxide dosing tank (42), adding sodium hydroxide and sodium carbonate to the primary alkaline oxidation tank (14) and the secondary alkaline oxidation tank (44), adding polyaluminum chloride to the primary mixing tank (21) and the secondary mixing tank (51), adding polyacrylamide to the primary flocculation tank (22) and the secondary flocculation tank (52), and adding ammonium chloride to the transition tank (7); S3. Aeration: Aeration is performed in the primary oxidation pond group (1) and the secondary oxidation pond group (4).

5. A membrane concentrate pretreatment method according to claim 4, characterized in that: The flow rate of the landfill leachate membrane concentrate in step S1 is 3 to 5 m 3 / h.

6. A membrane concentrate pretreatment method according to claim 4, characterized in that: In the step S2, the amount of dilute sulfuric acid added to the primary acid oxidation tank (11) and the secondary acid oxidation tank (41) is 0.4-0.5 kg / t membrane concentrate, the adding speed is 1.6-1.8 kg / h, and the mass concentration of the dilute sulfuric acid is 20%. The amount of ferrous sulfate added to the primary acid oxidation tank (11) and the secondary acid oxidation tank (41) is 15-20 kg / t membrane concentrate, the adding speed is 70-80 kg / h, and the ferrous sulfate is a ferrous sulfate solution with a mass concentration of 20%. The amount of hydrogen peroxide added to the primary hydrogen peroxide dosing tank (12) is 3-4 kg / t membrane concentrate, the adding speed is 10-12 kg / h, and the secondary hydrogen peroxide dosing tank (41) is 10-12 kg / h. The amount of hydrogen peroxide added to the water dosing tank (42) is 1-2 kg / t of membrane concentrate, the dosing rate is 3-4 kg / h, and the mass concentration of hydrogen peroxide is 30%. The amount of sodium hydroxide added to the primary alkaline oxidation tank (14) and the secondary alkaline oxidation tank (44) is 0.3-0.32 kg / t of membrane concentrate, the dosing rate is 1.2-1.3 kg / h, and the sodium hydroxide is a sodium hydroxide solution with a mass concentration of 20%. The amount of sodium carbonate added to the primary alkaline oxidation tank (14) and the secondary alkaline oxidation tank (44) is 4-5 kg / t of membrane concentrate, the dosing rate is 18-20 kg / h, and the sodium carbonate is a sodium carbonate solution with a mass concentration of 20%.

7. The membrane concentrate pretreatment method according to claim 4, characterized in that: In step S2, the amount of polyaluminium chloride added to the primary mixing tank (21) and the secondary mixing tank (51) is 2-3 kg / t membrane concentrate, the adding speed is 6-8 kg / h, the polyaluminium chloride is a polyaluminium chloride solution with a mass concentration of 3-5%, the amount of polyacrylamide added to the primary flocculation tank (22) and the secondary flocculation tank (52) is 2-3 kg / t membrane concentrate, the adding speed is 6-8 kg / h, and the ammonium chloride solution with a mass concentration of 5% is continuously added to the transition tank (7) at a adding speed of 6-8 L / h. The polyacrylamide is a polyacrylamide solution with a mass concentration of 1%.

8. The membrane concentrate pretreatment method according to claim 4, characterized in that: During the aeration in step S3, the first acidic oxidation pond (11) is injected, and the aeration volume is 2.3-2.5 m3 in sequence through the first hydrogen peroxide dosing pond (12), the first alkaline oxidation pond (14), the second acidic oxidation pond (41), the second hydrogen peroxide dosing pond (42), and the second alkaline oxidation pond (44). 3 / min, the aeration depth is 3.2~3.5m, the aeration volume of the first-stage enhanced aeration tank (13) and the second-stage enhanced aeration tank (43) is 2.6~3m 3 / min, aeration depth is 3.5~4m.

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