Multistage recycling system for polytetrafluoroethylene polymerization wastewater

Abstract

The utility model provides a multi-stage recycling system for polytetrafluoroethylene polymerization wastewater, which comprises a first-stage security filter, a second-stage security filter and an RO (reverse osmosis) device which are communicated in sequence, the second-stage security filter is used for filtering crystal salt particles with the filtering precision of nanoscale, two stages of reverse osmosis membranes are arranged in the RO device, a first outlet pipe is arranged in a cavity between the two stages of reverse osmosis membranes and communicated with a concentrated water recovery tank, and a second outlet pipe is arranged in a cavity behind the two stages of reverse osmosis membranes and communicated with a water production tank. The waste water recycling device has the beneficial effects that the waste water generated in the polytetrafluoroethylene polymerization production process is recycled, so that the environmental pollution is reduced, the recycling of resources is realized, and the production cost is greatly reduced at the same time.

Description

Technical Field

[0001] This utility model relates to the field of wastewater recycling technology, specifically to a multi-stage recycling system for polytetrafluoroethylene (PTFE) polymerization wastewater. Background Technology

[0002] The wastewater pollution problem arising from the intermittent production process of polytetrafluoroethylene (PTFE) presents a multi-dimensional challenge for treatment. In terms of pollutant characteristics, the wastewater system exhibits two significant "high" features: fluoride concentrations exceeding standards by hundreds of times, reaching 2000-5000 mg / L; and COD levels consistently remaining in the 800-1500 mg / L range. Analysis has identified persistent organic pollutants such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), as well as incompletely degraded polymeric additives like sodium dodecyl sulfate (SDS) and hydroxypropyl cellulose (HPMC). This fluoride-organic complex pollution system leads to a synergistic inhibitory effect among pollutants. In conventional treatment processes, the calcium salt precipitation reaction is significantly interfered with by the complexation of organic ligands, resulting in calcium fluoride precipitates with particle sizes concentrated in the 0.1-1 μm colloidal range and settling rates less than 30% of traditional flocs. Even with enhanced treatment using multi-stage series reactors, the effluent fluoride concentration generally remains in the 15-25 mg / L range.

[0003] At the process operation level, the existing treatment flow suffers from multiple technical contradictions. The calcium salt precipitation unit needs to maintain a strongly alkaline environment with a pH of 8.5-9.5 to improve defluorination efficiency, but this directly leads to the destruction of the colloidal stability of residual emulsified oligomers in the wastewater, generating a large amount of scum that clogs the water distributors of the subsequent biological treatment system. While acidification pretreatment can improve the separation of organic matter, it causes fluorides to exist in the form of HF, resulting in a 3-5 times increase in equipment corrosion rate. The biological treatment section also faces the problem of microbial inhibition due to the imbalance of carbon, nitrogen, and phosphorus ratios (C:N:P≈200:5:1), coupled with the inherent biotoxicity of PFAS substances, which shortens the survival period of the dominant bacteria in the activated sludge by more than 40%, significantly weakening the system's resistance to shock loads.

[0004] At the environmental regulatory level, there is a structural contradiction due to a misaligned standard system. The existing "Integrated Wastewater Discharge Standard" only sets a limit of 10 mg / L for total fluoride, but it does not differentiate between dissolved and colloidal fluoride for testing. In reality, 30-40% of fluoride in the treated effluent still exists in the colloidal form of CaF2·nH2O, and conventional fluoride ion electrode methods have a negative bias of 15%-20%. The risk of secondary pollution runs through the entire treatment chain. The calcium precipitation method produces 80-120 kg of calcium fluoride sludge with a water content of 98% for every 1 m³ of wastewater treated, and the fluoride ion concentration in its leachate still reaches 50-80 mg / L, posing a potential environmental risk. Utility Model Content

[0005] The purpose of this invention is to achieve full reuse of wastewater generated during the polymerization process.

[0006] A multi-stage recycling system for polytetrafluoroethylene (PTFE) polymerization wastewater is provided, comprising a primary security filter, a secondary security filter, and an RO reverse osmosis unit connected in sequence. The primary security filter has a filtration precision of micron-level for PTFE powder, and the secondary security filter has a filtration precision of nano-level for crystalline salt particles. The RO reverse osmosis unit is equipped with two stages of reverse osmosis membranes. The chamber between the two stages of reverse osmosis membranes is provided with a first outlet pipe connected to a concentrate recovery tank, and the chamber after the two stages of reverse osmosis membranes is provided with a second outlet pipe connected to a product water tank.

[0007] As a preferred embodiment, the inlet pipe of the RO reverse osmosis unit is equipped with a high-pressure pump, and the filter element of the RO reverse osmosis unit is a stainless steel filter element.

[0008] As a preferred embodiment, a buffer tank is provided between the primary security filter and the secondary security filter.

[0009] As a preferred embodiment, the primary security filter is connected to a drying device to dry the polytetrafluoroethylene powder.

[0010] As a preferred embodiment, the inlet pipe of the primary security filter is equipped with a raw water tank for collecting polytetrafluoroethylene polymerization wastewater.

[0011] As a preferred embodiment, the product water tank is connected to the polymerization system, and the concentrate recovery tank is connected to the washing system.

[0012] As a preferred embodiment, the inlet pipes of the primary security filter and the secondary security filter are equipped with water pumps.

[0013] The beneficial effects of this utility model are as follows:

[0014] This invention recycles and utilizes wastewater generated during the polymerization of polytetrafluoroethylene (PTFE), reducing environmental pollution while achieving resource recovery and significantly lowering production costs. Solid materials in the polymerization wastewater are dried and sold externally, while the liquid is defluorinated and recycled via an RO reverse osmosis system. This process achieves the separation of fluoride ions from the PTFE polymerization wastewater, solving the problem of PTFE polymerization wastewater waste and generating economic benefits, thus realizing complete wastewater recycling and reuse. Attached Figure Description

[0015] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0016] Figure 1This is a schematic diagram of the structure of this utility model.

[0017] The numbers in the attached diagram are:

[0018] 1. Primary security filter; 2. Secondary security filter; 3. RO reverse osmosis unit; 4. Concentrate recovery tank; 5. Product water tank; 6. High-pressure pump; 7. Buffer tank; 8. Raw water tank; 9. Feed water pump. Detailed Implementation

[0019] To illustrate the features of this utility model, the following description, in conjunction with the accompanying drawings and embodiments, will further explain this utility model.

[0020] Example:

[0021] Please see Figure 1 This utility model provides a multi-stage recycling system for polytetrafluoroethylene (PTFE) polymerization wastewater, comprising a primary security filter 1, a secondary security filter 2, and an RO reverse osmosis device 3 connected in sequence. The primary security filter 1 has a filtration accuracy of micron-level for PTFE powder, and the secondary security filter 2 has a filtration accuracy of nano-level for crystalline salt particles. The RO reverse osmosis device 3 is internally equipped with two-stage reverse osmosis membranes. The chamber between the two-stage reverse osmosis membranes is equipped with a first outlet pipe 31 connected to a concentrate recovery tank 4, and the chamber after the two-stage reverse osmosis membranes is equipped with a second outlet pipe 32 connected to a product water tank 5.

[0022] Preferably, in this embodiment, the inlet pipe of the RO reverse osmosis device 3 is equipped with a high-pressure pump 6, and the filter element of the RO reverse osmosis device 3 is a stainless steel filter element.

[0023] Preferably, in this embodiment, a buffer water tank 7 is provided between the primary security filter 1 and the secondary security filter 2.

[0024] Preferably, in this embodiment, the primary security filter 1 is connected to a drying device to dry the polytetrafluoroethylene powder.

[0025] Preferably, in this embodiment, the inlet pipe of the primary security filter 1 is equipped with a raw water tank 8 for collecting polytetrafluoroethylene polymerization wastewater.

[0026] Preferably, the multi-stage recycling system for polytetrafluoroethylene polymerization wastewater described in this embodiment is characterized in that: the product water tank 5 is connected to the polymerization system, and the concentrate recovery tank 4 is connected to the washing system.

[0027] Preferably, the multi-stage recycling system for polytetrafluoroethylene polymerization wastewater described in this embodiment is characterized in that: a water supply pump 9 is installed in the inlet pipes of the primary security filter 1 and the secondary security filter 2.

[0028] The above embodiments and accompanying drawings are only used to illustrate the technical solutions of this utility model and are not intended to limit this utility model. This utility model has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of this utility model do not depart from the spirit of this utility model and should also fall within the protection scope of the claims of this utility model. Other related technical structures not disclosed in detail in this utility model are existing technologies in the art.

Claims

1. A multi-stage recycling system for polytetrafluoroethylene polymerization wastewater, characterized in that: The device includes a primary security filter (1), a secondary security filter (2), and an RO reverse osmosis device (3) connected in sequence. The primary security filter (1) has a filtration accuracy of micron-level filtration of polytetrafluoroethylene powder, and the secondary security filter (2) has a filtration accuracy of nano-level filtration of crystalline salt particles. The RO reverse osmosis device (3) is equipped with two-stage reverse osmosis membranes. The chamber between the two-stage reverse osmosis membranes is equipped with a first outlet pipe (31) connected to the concentrate recovery tank (4), and the chamber after the two-stage reverse osmosis membranes is equipped with a second outlet pipe (32) connected to the product water tank (5).

2. The multi-stage recycling system for polytetrafluoroethylene polymerization wastewater according to claim 1, characterized in that: The inlet pipe of the RO reverse osmosis device (3) is equipped with a high-pressure pump (6), and the filter element of the RO reverse osmosis device (3) is a stainless steel filter element.

3. The multi-stage recycling system for polytetrafluoroethylene polymerization wastewater according to claim 1, characterized in that: A buffer tank (7) is provided between the primary security filter (1) and the secondary security filter (2).

4. The multi-stage recycling system for polytetrafluoroethylene polymerization wastewater according to claim 1, characterized in that: The primary security filter (1) is connected to a drying device to dry polytetrafluoroethylene powder.

5. The multi-stage recycling system for polytetrafluoroethylene polymerization wastewater according to claim 1, characterized in that: The inlet pipe of the primary security filter (1) is equipped with a raw water tank (8) for collecting polytetrafluoroethylene polymerization wastewater.

6. The multi-stage recycling system for polytetrafluoroethylene polymerization wastewater according to claim 1, characterized in that: The product water tank (5) is connected to the polymerization system, and the concentrate recovery tank (4) is connected to the washing system.

7. The multi-stage recycling system for polytetrafluoroethylene polymerization wastewater according to claim 1, characterized in that: Water pumps (9) are installed in the inlet pipes of the primary security filter (1) and the secondary security filter (2).

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