Treatment method for recycling and reuse of automobile paint cleaning wastewater

Abstract

The present invention provides a method for regenerating and reusing automobile coating cleaning wastewater, comprising the following steps: step 1: adding polyferric sulfate to the wastewater in three steps; step 2: adding the liquid in step 1 to an improved filter, filtering it once to remove the polymerized particles, and then adding Ba(OH)2 to remove the Fe introduced in step 1; 3+ and SO4 2‑ The precipitation is complete, and the pH value of the filtrate is restored to 9-10. Finally, a secondary filtration is performed to remove the precipitate and obtain a clarified filtrate. Step three: The clarified filtrate from step two is subjected to deep fine filtration using a rotating ceramic membrane to obtain a colorless, clear, and transparent filtrate. Compared with the prior art, the present invention has the advantages of independently performing primary and secondary filtration in the filter barrel, avoiding the need to filter the feed liquid through different filters. This is convenient to operate, saves time and effort, simplifies the process flow, reduces the amount of equipment used, improves treatment efficiency, and reduces the cost of recycling and reusing automobile paint cleaning wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method for regenerating and reusing automobile paint cleaning wastewater. Background Art

[0002] In automotive paint shops, when changing the color of a car model, detergents are needed to clean residual paint from the paint booth and pipes, generating automotive paint wash wastewater. The main components of automotive paint wash wastewater are water, organic solvents (alcohols, amines, ethers, lipids), solid particulate matter (aluminum powder, fillers, polymer resins), color pastes (carbon black, red iron oxide, phthalocyanine blue, etc.), oils (emulsified oil and naphtha), and surfactants. With a solids content of 2-6% and a pH of 8.5-10, it contains a large number of toxic and harmful components, resulting in high concentrations and high chroma, causing serious environmental pollution. Therefore, it is necessary to develop a method for regenerating and reusing automotive paint wash wastewater to address these technical issues. Summary of the Invention

[0003] The purpose of the present invention is to disclose a method for regenerating and reusing automobile paint cleaning wastewater. First, by only adding polyferric sulfate, the effects of demulsification of the wastewater system and flocculation and aggregation of particles can be achieved. By controlling the amount of polyferric sulfate added, the sedimentation and separation of different solid phase particles in the wastewater system can be achieved. The operation is simple, the process flow is simplified, time and labor are saved, and the wastewater treatment efficiency is improved. Second, the primary filtration and secondary filtration can be independently carried out in the filter barrel, avoiding the filtration of the feed liquid in different filters. The operation is convenient, time and labor are saved, the process flow is simplified, and the wastewater treatment efficiency is reduced. The number of equipment used has improved the treatment efficiency and reduced the cost of recycling and reusing automobile paint cleaning wastewater; third, the rotary ceramic membrane is used for fine filtration, which has a lower filtration accuracy than the reverse osmosis membrane and will not intercept the effective components therein. Moreover, when treating wastewater, the osmotic flux changes little and the filtration is stable; fourth, it can remove solid particles, color pastes, and oils in automobile paint cleaning wastewater. After the cleaning wastewater is regenerated, the reuse rate of the clear and transparent liquid reaches more than 67%. The reused clear liquid is adjusted to the optimal cleaning pH value range of the cleaning solvent, retaining the effective components in the cleaning wastewater.

[0004] To achieve the above-mentioned object, the present invention provides a method for regenerating and reusing automobile paint cleaning wastewater, comprising the following steps:

[0005] Step 1: adding polyferric sulfate to the wastewater in three steps, with the first addition amount being 0.2-0.5 wt%, the second addition amount being increased to 0.25-0.6 wt%, and the third addition amount being increased to 0.3-0.75 wt%;

[0006] Step 2: Add the liquid in step 1 to the improved filter, filter it once to remove the aggregated particles, then add Ba(OH)2 to remove the Fe 3+ and SO4 2- The precipitation is complete and the pH value of the filtrate is restored to 9-10. Finally, a second filtration is performed to remove the precipitate and obtain a clear filtrate;

[0007] Step 3: Use a rotating ceramic membrane to perform deep fine filtration on the clarified filtrate in step 2 to obtain a colorless, clear and transparent filtrate.

[0008] In some embodiments, in step 2, the improved filter includes a filter barrel, a motor for driving the filter barrel to flip, a partition connected to the filter barrel, a first filter material attached to the top of the partition, an upper support net for pressing the first filter material, a second filter material attached to the bottom of the partition, and a lower support net for pressing the second filter material; an installation port is formed on the partition, an anti-backflow valve is provided in the installation port, a cavity is formed inside the partition, a plurality of liquid inlets connected to the cavity are formed below the partition, and a liquid outlet pipe is connected to the outside of the cavity.

[0009] In some embodiments, the filter barrel is provided with a drug adding port and a plugging head for plugging the drug adding port.

[0010] In some embodiments, a plurality of protrusions are formed above the partition.

[0011] In some embodiments, the first filter material has a filtration accuracy of 1 to 5 μm, and the second filter material has a filtration accuracy of 1 to 3 μm.

[0012] In some embodiments, the upper support mesh and the lower support mesh are stainless steel meshes.

[0013] In some embodiments, a bottom cover is sealed and screwed to the bottom of the filter barrel.

[0014] In some embodiments, in step 2, the amount of Ba(OH)2 added is 0.35-1 wt%.

[0015] In some embodiments, the colorless, clear and transparent filtrate obtained in step 3 can be directly returned to the workshop for recycling, and the ceramic membrane concentrated liquid can be returned to the original liquid tank.

[0016] In some embodiments, in step three, the filtration accuracy of the rotating ceramic membrane is 100 to 500 nm.

[0017] Compared with the prior art, the present invention has the following beneficial effects: first, by only adding polyferric sulfate, the effect of demulsification and particle flocculation in the wastewater system can be achieved; by controlling the amount of polyferric sulfate added, the sedimentation and separation of different solid phase particles in the wastewater system can be achieved; the operation is simple, the process flow is simplified, time and labor are saved, and the wastewater treatment efficiency is improved; second, the primary filtration and secondary filtration can be independently carried out in the filter barrel without interfering with each other, avoiding the need for filtration of the feed liquid in different filters; the operation is convenient, time and labor are saved, the process flow is simplified, and equipment is reduced. The number of uses has improved the treatment efficiency and reduced the cost of recycling and reusing automobile paint cleaning wastewater; third, the use of rotary ceramic membrane for fine filtration has a lower filtration accuracy than the reverse osmosis membrane, will not intercept the effective ingredients therein, and when treating wastewater, the osmotic flux changes little and the filtration is stable; fourth, it can remove solid particles, color paste and oil in automobile paint cleaning wastewater. After the cleaning wastewater is regenerated, the reuse rate of the clear and transparent clear liquid reaches more than 67%. The reused clear liquid is adjusted to the optimal cleaning pH value range of the cleaning solvent, retaining the effective ingredients in the cleaning wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing the treatment effects of each step of the automobile paint cleaning wastewater regeneration and reuse treatment method shown in the present invention;

[0019] Figure 2 This is a graph showing changes in the permeation flux of a rotating ceramic membrane according to the present invention;

[0020] Figure 3 It is a structural diagram of the improved filter shown in the present invention;

[0021] Figure 4 for Figure 3 Schematic diagram of the structure of the partition shown in. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in this field based on these embodiments are all within the scope of protection of the present invention.

[0023] The present invention discloses a method for regenerating and reusing automobile paint cleaning wastewater, comprising the following steps:

[0024] Step 1: Add polyferric sulfate to the wastewater three times in sequence.

[0025] The first addition amount is 0.2-0.5wt%, specifically 0.3wt%, Fe 3+ and OH in wastewater -A chemical reaction occurs rapidly, forming Fe(OH)3 precipitates. The surfactant in the wastewater is deactivated, the emulsified system begins to become unstable, and the oil in the wastewater (emulsified oil and naphtha) forms oligomeric particles with Fe(OH)3 as the core, which slowly settle.

[0026] The second addition amount is increased to 0.25-0.6 wt%, specifically 0.5 wt%. The solid particles (aluminum powder, filler and polymer resin) in the wastewater are rapidly cross-linked and agglomerated with the oligomeric particles as the core to form polymeric particles, which are quickly settled.

[0027] The third addition amount is increased to 0.3-0.75 wt%, specifically, 0.7 wt%. The dispersion of color pastes (such as carbon black, red iron oxide, phthalocyanine blue, etc.) in the wastewater decreases, and they quickly combine with the polymer particles and settle quickly.

[0028] In step one, by adding only one agent, the effects of demulsification of the wastewater system and flocculation and aggregation of particles can be achieved. By controlling the amount of polyferric sulfate added, the sedimentation and separation of different solid phase particles in the wastewater system can be achieved. The operation is simple, the process flow is simplified, time and labor are saved, and the wastewater treatment efficiency is improved.

[0029] Step 2: Add the liquid in step 1 to the improved filter, filter it once to remove the aggregated particles, and then add Ba(OH)2. The amount of Ba(OH)2 added is 0.35-1wt%, specifically 0.8wt%. 3+ and SO4 2- The precipitation is complete and the pH value of the filtrate is restored to 9. Finally, a second filtration is performed to remove the precipitate and obtain a clear filtrate.

[0030] like Figure 3 and 4 As shown, the improved filter comprises a filter barrel 1 and motors 7 located at both ends of the filter barrel 1. The motor 7 is connected to the filter barrel 1 through a rotating shaft 71. The filter barrel 1 can be turned 180 degrees under the drive of the motor 7. In order to maintain the stability of the filter barrel 1, when the filter barrel 1 is in a state such as Figure 1 When in the state shown or flipped 180 degrees, auxiliary fixation is performed by manpower or a bracket.

[0031] The filter barrel 7 further includes a partition plate 2 connected to the filter barrel 7. The partition plate 2 is connected to the filter barrel 7 by a weld, and the connection is firm and has good sealing. The partition plate 2 divides the filter barrel 1 into an upper area 11 and a lower area 12.

[0032] The filter also includes a first filter material 31 attached to the separator 2 and an upper support mesh 32 that presses against the first filter material 31. The first filter material 31 is squeezed and fixed by the separator 2 and the upper support mesh 32, thereby fixing the position of the first filter material 31 and maintaining its flatness. The filtration accuracy of the first filter material 31 is 1 to 5 μm, specifically 4 μm.

[0033] The system also includes a second filter material 41 attached to the underside of the partition 2 and a lower support mesh 42 that presses against the second filter material 41. The second filter material 41 is squeezed and fixed by the partition 2 and the lower support mesh 42, thereby fixing the position of the second filter material 41 and maintaining its flatness. The filtration accuracy of the second filter material 41 is 1 to 3 μm, specifically 2 μm.

[0034] The partition 2 supports both the first filter material 31 and the upper support mesh 32, as well as the second filter material 41 and the lower support mesh 42. This ingenious structure provides dual support. The support provided by the partition 2 prevents deformation of the upper and lower support meshes 32, 42 under wastewater pressure. The upper and lower support meshes 32, 42 are screwed together within the filter barrel 7, allowing for easy assembly and disassembly, facilitating replacement of the first and second filter materials 31, 41. The upper and lower support meshes 32, 42 are made of stainless steel.

[0035] An installation port 20 is formed at the center of the partition 2, and an anti-backflow valve 9 is provided in the installation port 20, so that the wastewater in the upper interval 11 can flow into the lower interval 12 through the anti-backflow valve 9 in the installation port 20, while the wastewater in the lower interval 12 will not flow into the upper interval 11, so that the primary filtration and the secondary filtration can be carried out independently without interfering with each other and without contaminating each other.

[0036] A plurality of evenly distributed protrusions 22 are formed above the partition 2 , and the first filter material 31 is attached to the protrusions 22 , which not only plays a supporting role but also facilitates the even flow of the filtrate after being filtered by the first filter material 31 to the anti-backflow valve 9 .

[0037] The partition 2 has an annular cavity 21 formed within it. Several liquid inlets 23 are evenly distributed below the partition 2 and communicate with the cavity 21. A liquid outlet pipe 6 is connected to the cavity 21, extending outside the filter barrel 1. After being filtered by the second filter material 41, the liquid in the second compartment 12 flows evenly into the liquid inlet 23, then into the cavity 21, and finally discharged through the liquid outlet pipe 6.

[0038] The filter barrel 1 is provided with a dosing port (not shown) and a plug 5 for plugging the port. The dosing port is located below the lower support mesh 42. A bottom cap 8 is threadedly and hermetically sealed to the bottom of the filter barrel 1. Specifically, a rubber layer is bonded to the external threads of the bottom cap 8, providing both a connection and a seal. The bottom cap 8 facilitates regular replacement of the second filter medium 41.

[0039] In the improved filter, the operation process of step 2 is as follows: the liquid in step 1 is added to the first compartment 11. Under the action of gravity, the liquid passes through the upper support mesh 32, is filtered once by the first filter material 31, and the aggregated particles are removed. Then, the liquid flows into the lower compartment 12 through the anti-backflow valve 9; Ba(OH)2 is added to the lower compartment 12 through the dosing port. The amount of Ba(OH)2 added is 0.8wt%, and the amount of Ba(OH)2 added is 0.8wt%. 2+ and SO4 in the filtrate 2- A chemical reaction occurs quickly to generate BaSO4 precipitate, a small amount of Fe 3+ and OH- to form Fe(OH)3 precipitate, thereby converting the Fe introduced in step 1 into 3+ and SO4 2- After the precipitation is complete and the pH value of the filtrate is restored to 9, the dosing port is blocked with the plug 5; the motor 7 drives the filter barrel 1 to flip 180 degrees, and the filtrate passes through the lower support mesh 42 under the action of gravity, and then undergoes secondary filtration through the second filter material 41 to remove the precipitate to obtain a clarified filtrate. The clarified filtrate enters the cavity 21 from the liquid inlet 23 and is finally discharged through the liquid outlet pipe 6.

[0040] All operations in step 2 can be performed in the filter barrel 1, avoiding the need to filter the slurry in different filters. The operation is convenient, time-saving and labor-saving, and the process flow is simplified. The number of equipment used is reduced, the processing efficiency is improved, and the cost of recycling and reusing automobile paint cleaning wastewater is reduced.

[0041] Step 3: The clarified filtrate from step 2 is subjected to deep fine filtration using a rotating ceramic membrane to obtain a colorless, clear, and transparent filtrate. The rotating ceramic membrane has a filtration precision of 100-500 nm, specifically 300 nm. The resulting colorless, clear, and transparent filtrate can be directly returned to the workshop for recycling, and the ceramic membrane concentrate is returned to the stock solution tank.

[0042] The rotary ceramic membrane has a large flux, is not blocked, has a low replacement frequency, and has a low cost per ton of water treatment. The selected ceramic membrane has a lower filtration accuracy than the reverse osmosis membrane and will not intercept the effective components. The rotary ceramic membrane has a low filtration pressure and low energy consumption. Figure 2 As shown in the figure, when the rotating ceramic membrane treats wastewater, the permeate flux changes little and the filtration is stable.

[0043] The automobile paint cleaning wastewater regeneration and reuse treatment method provided by the present invention can remove solid particles (polymer resin, filler, color paste, aluminum powder, etc.) in automobile paint cleaning wastewater, obtain a clear and transparent clear liquid after the cleaning wastewater is regenerated, and the reuse rate reaches more than 67%. The reused clear liquid is adjusted to the optimal cleaning pH value range of the cleaning solvent, retaining the effective components in the cleaning wastewater (organic solvents such as alcohols, amines, ethers, and lipids).

[0044] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0045] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for regenerating and reusing automobile paint cleaning wastewater, characterized in that: The steps include: Step 1: adding polyferric sulfate to the wastewater in three steps, with the first addition amount being 0.2-0.5 wt%, the second addition amount being increased to 0.25-0.6 wt%, and the third addition amount being increased to 0.3-0.75 wt%; Step 2: Add the liquid in step 1 to the improved filter, filter it once to remove the aggregated particles, then add Ba(OH)2 to remove the Fe 3+ and SO4 2- The precipitation is complete and the pH value of the filtrate is restored to 9-10. Finally, a second filtration is performed to remove the precipitate and obtain a clear filtrate; Step 3: Deeply filter the clarified filtrate in step 2 using a rotating ceramic membrane to obtain a colorless, clear, and transparent filtrate; The improved filter includes a filter barrel, a motor for driving the filter barrel to flip, a partition connected to the filter barrel, a first filter material attached to the top of the partition, an upper support net for pressing the first filter material, a second filter material attached to the bottom of the partition, and a lower support net for pressing the second filter material; an installation port is formed on the partition, an anti-backflow valve is provided in the installation port, a cavity is formed inside the partition, a plurality of liquid inlets connected to the cavity are formed below the partition, and a liquid outlet pipe is connected to the outside of the cavity.

2. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 1, characterized in that: The filter barrel is provided with a drug adding port and a plugging head for plugging the drug adding port.

3. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 1, characterized in that: A plurality of protrusions are formed above the partition.

4. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 1, characterized in that: The filtering accuracy of the first filter material is 1 to 5 μm, and the filtering accuracy of the second filter material is 1 to 3 μm.

5. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 1, characterized in that: The upper supporting net and the lower supporting net are stainless steel nets.

6. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 1, characterized in that: The bottom of the filter barrel is sealed and screwed with a bottom cover.

7. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 1, characterized in that: In step 2, the amount of Ba(OH)2 added is 0.35-1 wt%.

8. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 1, characterized in that: The colorless, clear and transparent filtrate obtained in step 3 can be directly returned to the workshop for recycling, and the ceramic membrane concentrate can be returned to the original liquid tank.

9. The method for regenerating and reusing automobile painting cleaning wastewater according to claim 8, characterized in that: In step three, the filtration accuracy of the rotating ceramic membrane is 100 to 500 nm.

Images