Metal casting processing wastewater treatment system

Abstract

The utility model discloses a metal casting processing wastewater treatment system, include: passivation wastewater collecting pool, the passivation wastewater collecting pool stores low concentration cleaning wastewater in, passivation wastewater collecting pool, first automatic skimmer are connected in proper order, die casting and ultrasonic cleaning wastewater collecting pool, the die casting and ultrasonic cleaning wastewater collecting pool stores high concentration die casting wastewater in, die casting and ultrasonic cleaning wastewater collecting pool, gravity type oil separation tank, multiphase centrifugal oil removal machine, low temperature evaporation concentration device are connected in proper order, gravity type oil separation tank, multiphase centrifugal oil removal machine still respectively have second automatic skimmer, adjusting pool, the export of passivation wastewater collecting pool and the evaporation clear liquid export of low temperature evaporation concentration device are connected adjusting pool respectively, adjusting pool, anoxic tank, aerobic tank, MBR pool, phosphorus removal reaction tank, phosphorus removal sedimentation tank and drainage tank are connected in proper order. The utility model can high -efficient separation oil dirt, promote the oil removal efficacy of current.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment, and in particular to a wastewater treatment system for metal casting processing. Background Technology

[0002] Wastewater generated during die casting and passivation processes needs to be treated before it can be discharged. Existing wastewater treatment systems for metal castings have the following two problems:

[0003] First, the oil removal is done using the scraper in the oil separator. Once the scraper fails and there is no cleaning measure, a large amount of oil will directly enter the die casting wastewater regulating tank along with the die casting wastewater.

[0004] Second, the wastewater from metal casting processing contains both low-concentration and high-concentration wastewater. The low-concentration wastewater comes from the passivation line cleaning wastewater, while the high-concentration wastewater comes from die casting oily wastewater, other oily wastewater, ultrasonic cleaning wastewater, etc. The oil content of the two is different, and gravity-type oil separators (using oil scrapers to remove oil) alone cannot remove the oil efficiently. The low oil removal efficiency at the front end causes excessive load on the downstream biological and MBR processes, making it impossible to operate stably. Utility Model Content

[0005] To overcome the above-mentioned shortcomings, the purpose of this utility model is to provide a highly efficient wastewater treatment system for metal casting processing that separates oil sludge and improves the effectiveness of current oil removal facilities.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is: a wastewater treatment system for metal casting processing, comprising:

[0007] A passivation wastewater collection tank is provided, which stores low-concentration cleaning wastewater. The passivation wastewater collection tank and the first automatic oil skimmer are connected in sequence.

[0008] A wastewater collection tank for die casting and ultrasonic cleaning is provided, which stores high-concentration die casting wastewater. The wastewater collection tank, gravity oil separator, multiphase centrifugal oil separator, and low-temperature evaporation and concentration device are connected in sequence. The gravity oil separator and multiphase centrifugal oil separator are also connected to a second automatic oil skimmer.

[0009] The outlet of the passivation wastewater collection tank and the outlet of the clear liquid from the low-temperature evaporation and concentration device are respectively connected to the equalization tank;

[0010] The equalization tank, anoxic tank, aerobic tank, MBR tank, phosphorus removal reaction tank, phosphorus removal sedimentation tank, and drainage tank are connected in sequence.

[0011] The beneficial effects of this utility model are:

[0012] Firstly, by adding a first automatic oil skimmer, a second automatic oil skimmer, and a multiphase centrifugal oil separator, the oil sludge can be efficiently separated and automatically collected, thereby improving the efficiency of the current oil removal facilities.

[0013] Secondly, the low-concentration cleaning wastewater from the passivation surface treatment line is completely separated from the high-concentration die-casting wastewater containing release agents, grease, etc., as well as other oily wastewater currently connected to the passivation collection tank. High-concentration sewage and low-concentration wastewater are treated separately, which improves the sewage treatment capacity in a targeted manner.

[0014] Preferably, the system also includes a Lamella sedimentation tank and an air flotation reactor. The Lamella sedimentation tank is located between the equalization tank and the anoxic tank. Both the Lamella sedimentation tank and the air flotation reactor are equipped with a first PAM anion inlet pipe and a PAC inlet pipe. This application utilizes a combination of a Lamella sedimentation tank and an air flotation reactor, which can effectively remove pollutants of different forms, achieving a synergistic effect of "pretreatment load reduction + deep impurity removal".

[0015] Preferably, the MBR tank is connected to a clean water backwashing machine and a chemical cleaning tank. Using an independent clean water backwashing machine and a separate chemical cleaning tank, compared to using clean water backwashing pipes and chemical cleaning pipes, fundamentally eliminates the possibility of membrane fouling due to substandard backwash water quality, thus significantly improving the operational stability of the MBR membrane.

[0016] Preferably, the MBR tank uses a PVDF hollow fiber membrane. PVDF hollow fiber membranes have stable chemical properties and are resistant to fouling, which can improve the operating efficiency of the MBR tank.

[0017] Preferably, the phosphorus removal reaction tank is equipped with a second PAM anion inlet pipe and a phosphorus removal agent inlet pipe. High-efficiency phosphorus removal is achieved through the synergistic effect of "chemical precipitation + flocculation enhancement".

[0018] Preferably, the system also includes a Parshall flume connected to the outlet of the drainage tank. The Parshall flume is used to address the problem of fluctuating process efficiency caused by unstable flow rates during wastewater treatment, and also provides crucial data support for system operation monitoring, reagent dosing optimization, and achieving compliant discharge.

[0019] Preferably, the low-concentration cleaning wastewater is the cleaning wastewater from the passivation surface treatment line;

[0020] The high-concentration die-casting wastewater is die-casting wastewater containing oil and release agent.

[0021] Preferably, the system further includes a hydrolysis acidification tank, which is located between the dissolved air flotation (DAF) reactor and the anoxic tank. The hydrolysis acidification tank, positioned before the DAF reactor, improves the wastewater characteristics through hydrolysis acidification, creating better conditions for subsequent oil / suspended solids separation in the DAF reactor.

[0022] Preferably, the sludge outlets of the air flotation reactor, aerobic tank, MBR tank, and phosphorus removal sedimentation tank are all connected to a screw press thickener. The screw press thickener is connected to a dryer and is equipped with a PAM cation inlet pipe. During the operation of the screw press thickener, cationic polyacrylamide (PAM cation) is added to enhance the solid-liquid separation effect of the sludge through flocculation reaction. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of Embodiment 1;

[0024] Figure 2 This is a schematic diagram of the structure of Example 2. Detailed Implementation

[0025] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the scope of protection of the present invention.

[0026] Example 1

[0027] See Figure 1 As shown, this embodiment discloses a wastewater treatment system for metal casting processing, including:

[0028] Passivation wastewater collection tank 1 stores low-concentration cleaning wastewater, which is the cleaning wastewater from the passivation surface treatment line. Passivation wastewater collection tank 1 and first automatic skimmer 2 are connected in sequence.

[0029] The wastewater collection tank 3 for die casting and ultrasonic cleaning stores high-concentration die casting wastewater, which includes wastewater containing oil, mold release agent, and ultrasonic cleaning fluid. The wastewater collection tank 3, gravity oil separator 4, multiphase centrifugal oil separator 5, and low-temperature evaporation and concentration device 6 are connected in sequence. The gravity oil separator 4 and multiphase centrifugal oil separator 5 are also connected to a second automatic oil skimmer 7.

[0030] The outlets of the equalization tank 8, the passivation wastewater collection tank 1, and the clear liquid outlet of the low-temperature evaporation and concentration device 6 are respectively connected to the equalization tank 8.

[0031] The equalization tank 8, the anoxic tank 9, the aerobic tank 10, the MBR tank 11, the phosphorus removal reaction tank 12, the phosphorus removal sedimentation tank 13, and the drainage tank 14 are connected in sequence. The MBR tank 11 uses a PVDF hollow fiber membrane.

[0032] This embodiment also includes a Lamella sedimentation tank 15 and an air flotation reactor 16. The Lamella sedimentation tank 15 is located between the equalization tank 8 and the anoxic tank 9. Both the Lamella sedimentation tank 15 and the air flotation reactor 16 are equipped with a first PAM anion inlet pipe 17 and a PAC inlet pipe 18.

[0033] In this embodiment, the phosphorus removal reactor 12 is equipped with a second PAM anion inlet pipe 19 and a phosphorus removal agent inlet pipe 20. High-efficiency phosphorus removal is achieved through the synergistic effect of "chemical precipitation + flocculation enhancement".

[0034] This embodiment also includes a Parshall weir 21, which is connected to the outlet of the drainage tank 14. The Parshall weir 21 is used to solve the problem of process efficiency fluctuations caused by "unstable flow" during wastewater treatment, and at the same time provides key data support for system operation monitoring, reagent dosing optimization, and compliance with discharge standards.

[0035] Automatic oil skimmer Made of stainless steel, with an oil separation capacity of not less than 75L / h, a steel strip width of not less than 150mm, and an oil skimming depth of 2~3.5m; Multiphase high-efficiency oil removal Made of 304 stainless steel, with a processing capacity of not less than 1 t / h. Automatic separation of slag, water, and oil phases, with an oil content handling capacity of not less than 20%. Lamella sedimentation Carbon steel corrosion resistant structure, 5m×1.6m×3m, including reaction zone, sedimentation zone and concentration zone. Inclined plate thickness not less than 5mm, processing capacity not less than 150t / d, equipped with sludge thickening mixer. air flotation reactor The structure is constructed of corrosion-resistant carbon steel, measuring 4.5m × 1.6m × 3m, and includes a reaction zone, a contact zone, and a separation zone. It employs reflux pressurized dissolved air flotation, with a processing capacity of no less than 150t / d. Anoxic pool Replace and add elastic packing, and add reflux facilities. MBR pool A new MBR automatic cleaning system will be added, including an online chemical washing and water washing unit. The new system will use a PVDF hollow fiber membrane with a membrane area of ​​not less than 400 square meters. Phosphorus removal reactor Remove the partition and add a dedicated flocculation agitator to the flocculation reaction zone. Barthi Weir Material: 304 stainless steel, includes electromagnetic flow meter Low-temperature vacuum evaporator The dimensions are 5.25m × 2.53m × 3.62m. The heat pump compressor is an imported Danfoss brand, with an average evaporation temperature of 35°C and a maximum evaporation temperature of 45°C. The main body for liquid contact is made of 316 stainless steel, and the electrical cabinet is equipped with Siemens and Schneider. The evaporation capacity is 1t / h.

[0036] Table 1: Equipment Specifications and Parameters

[0037] The working principle of this embodiment is as follows:

[0038] Low-concentration wastewater is pumped into the passivation wastewater collection tank 1, where the first automatic oil skimmer 2 removes the oil from the low-concentration wastewater. The oil-removed low-concentration wastewater is then pumped into the equalization tank 8. Meanwhile, high-concentration wastewater is stored in the die-casting and ultrasonic cleaning wastewater collection tank 3. The high-concentration wastewater is pumped into the gravity oil separator 4 for initial oil skimming, followed by oil skimming by the second automatic oil skimmer 7. After oil skimming, it is pumped into the multiphase centrifugal oil separator 5. The core function of the multiphase centrifugal oil separator 5 is to achieve rapid three-phase stratification of oil (lowest density), water (medium density), and solid impurities (highest density) in the high-concentration wastewater through high-speed centrifugal force. However, a small amount of floating oil (incompletely separated free oil) or "oil film" may still remain in the water. The second automatic oil skimmer 7 then performs "secondary removal" of this residual floating oil. The waste oil / oil-containing sludge discharged from the second automatic oil skimmer 7 needs to be outsourced for treatment. High-concentration wastewater containing mold release agents enters the low-temperature evaporation and concentration device 6. The resulting concentrate (reduction > 90%) is outsourced for treatment. The resulting clear evaporated liquid is pumped into the regulating tank 8. Part of the clear evaporated liquid can be recycled to the die-casting workshop as mold release agent dilution or rinsing water.

[0039] The equalization tank 8 is used to agitate the wastewater, making the concentration of pollutants (such as COD, oil content, and metal ion concentration), pH value, and other indicators of the wastewater more uniform. It can also perform water volume buffering, preliminary impurity removal, and pre-conditioning. The wastewater in the equalization tank 8 is sequentially pumped into the Lamella sedimentation tank 15, the air flotation reactor 16, the anoxic tank 9, the aerobic tank 10, the MBR tank 11, the phosphorus removal reactor 12, the phosphorus removal sedimentation tank 13, and the drainage tank 14. After adding PAC and anionic PAM reagents to the Lamella sedimentation tank 15, the Lamella sedimentation tank 15 relies on "shallow sedimentation". The principle improves efficiency; large flocs can quickly settle to the sludge zone at the bottom of the tank, reducing the load of suspended solids on the subsequent anoxic and aerobic tanks (avoiding sludge clogging the biological system); after adding PAC and anionic PAM agents to the air flotation reactor 16, the flocs in the air flotation reactor 16 rely on air bubbles to carry them to the surface. Large flocs can more stably "wrap" the air bubbles and float to the surface to form scum (such as emulsified oil and light suspended solids); the anoxic tank 9 is used for denitrification and degradation of recalcitrant organic matter, "reducing the load" on the aerobic tank 10; the aerobic tank 10 is used for aerobic biological degradation of COD and nitrification; the hollow fiber membrane (pore size 0.01-0.1μm) in the MBR tank 11 replaces the traditional secondary sedimentation tank, achieving sludge-water separation and deep purification; phosphorus is present in the coolant and release agent of the die-casting wastewater, and the biological system (anoxic / aerobic / MBR can only remove "organic phosphorus" and cannot remove "inorganic phosphorus". It needs to be solved by chemical phosphorus removal. Phosphorus removal reaction tank 12 is used for chemical phosphorus removal to specifically remove total phosphorus (TP); phosphorus removal sedimentation tank 13 is used for solid-liquid separation to intercept phosphorus sludge and ensure that the phosphorus in the effluent meets the standards; drainage tank 14 is used to realize water quality monitoring and water volume buffering to ensure that the discharge meets the standards.

[0040] Example 2

[0041] like Figure 2 As shown, unlike Embodiment 1, this embodiment also includes a hydrolysis acidification tank 22, which is located between the dissolved air flotation reactor 16 and the anoxic tank 9. The hydrolysis acidification tank 22 is positioned before the dissolved air flotation reactor 16 to improve the wastewater characteristics through hydrolysis acidification, creating better conditions for the subsequent dissolved air flotation reactor 16.

[0042] In this embodiment, the sludge outlets of the flotation reactor 16, aerobic tank 10, MBR tank 11, and phosphorus removal sedimentation tank 13 are all connected to a screw press thickener 23. The screw press thickener 23 is connected to a dryer 24. A PAM cation inlet pipe 25 is installed on the screw press thickener 23. During the operation of the screw press thickener, cationic polyacrylamide is added to enhance the solid-liquid separation effect of the sludge through flocculation reaction. The flotation reactor 16, aerobic tank 10, MBR tank 11, and phosphorus removal sedimentation tank 13 all produce sludge. The screw press thickener first thickens the sludge, and then the dryer dries it. The two work together to gradually reduce the sludge moisture content and reduce the sludge volume, laying the foundation for subsequent final disposal (such as landfill, incineration, or resource recovery).

[0043] Example 3

[0044] Unlike Embodiment 1, the MBR tank 11 in this embodiment is connected to a clean water backwashing machine and a chemical cleaning tank. By using an independent clean water backwashing machine and an independent chemical cleaning tank, compared with clean water backwashing pipes and chemical cleaning pipes, the possibility of membrane fouling due to substandard backwash water quality is eliminated at the source, which can greatly improve the operational stability of the MBR membrane.

[0045] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They cannot be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.

Claims

1. A wastewater treatment system for metal casting processing, characterized in that: include: Passivation wastewater collection tank (1), which stores low-concentration cleaning wastewater, and the passivation wastewater collection tank (1) and the first automatic skimmer (2) are connected in sequence; The wastewater collection tank (3) for die casting and ultrasonic cleaning stores high-concentration die casting wastewater. The wastewater collection tank (3), gravity oil separator (4), multiphase centrifugal oil separator (5), and low-temperature evaporation and concentration device (6) are connected in sequence. The gravity oil separator (4) and multiphase centrifugal oil separator (5) are also connected to the second automatic oil skimmer (7). The outlet of the passivation wastewater collection tank (1) and the outlet of the clear liquid from the low-temperature evaporation and concentration device (6) are respectively connected to the regulating tank (8). The equalization tank (8), anoxic tank (9), aerobic tank (10), MBR tank (11), phosphorus removal reaction tank (12), phosphorus removal sedimentation tank (13) and drainage tank (14) are connected in sequence.

2. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: It also includes a Lamella sedimentation tank (15) and an air flotation reactor (16). The Lamella sedimentation tank (15) is located between the equalization tank (8) and the anoxic tank (9). Both the Lamella sedimentation tank (15) and the air flotation reactor (16) are equipped with a first PAM anion inlet pipe (17) and a PAC inlet pipe (18).

3. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: The MBR tank (11) is connected to a clean water backwashing machine and a chemical cleaning tank.

4. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: The MBR tank (11) uses a PVDF hollow fiber membrane.

5. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: The phosphorus removal reaction tank (12) is equipped with a second PAM anion inlet pipe (19) and a phosphorus removal agent inlet pipe (20).

6. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: It also includes a Barthel metering weir (21), which is connected to the outlet of the drainage pool (14).

7. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: The low-concentration cleaning wastewater is the cleaning wastewater from the passivation surface treatment line. The high-concentration die-casting wastewater is die-casting wastewater containing oil and release agent.

8. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: It also includes a hydrolysis acidification tank (22), which is located between the air flotation reaction tank (16) and the anoxic tank (9).

9. The wastewater treatment system for metal casting processing according to claim 1, characterized in that: The sludge outlets of the air flotation reactor (16), aerobic tank (10), MBR tank (11), and phosphorus removal sedimentation tank (13) are all connected to a screw press thickener (23). The screw press thickener (23) is connected to a dryer (24). A PAM anolyte inlet pipe (25) is installed on the screw press thickener (23).

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