PTFE wastewater treatment process

Industrial wastewater includes production wastewater and production sewage, which refers to the wastewater and waste liquid produced in the industrial production process, which contain industrial production materials, intermediate products, by-products, and pollutants generated in the production process that are lost with the water.

There are many kinds of industrial wastewater with complex compositions.

Among them, the treatment of viscous wastewater has always been a difficult problem in wastewater treatment.

The viscous wastewater mainly comes from the printing and dyeing industry, leather industry, paper industry, coking industry, plastic industry and other fields. The conventional physical and chemical treatment processes are affected by the viscosity of wastewater, so special treatment processes are required to treat viscous wastewater.

PTFE (polytetrafluoroethylene) wastewater in viscous wastewater is also a kind of viscous wastewater, mainly caused by the viscous PTFE powder in the wastewater.

PTFE powder is extremely small, with a particle size ranging from tens of nanometers to hundreds of nanometers, and it is difficult to completely remove it by pretreatment processes such as coagulation sedimentation, and air flotation, and filtration.

The conventional double-membrane method (microfiltration/ultrafiltration + reverse osmosis) process used to treat PTFE wastewater has very serious fouling of the separation membrane, requiring frequent chemical cleaning, and without adding powdered activated carbon, the wastewater treatment system may not operate normally.

Using the large cross-flow tubular membrane + reverse osmosis membrane process with strong anti-pollution performance, it is necessary to continuously add powdered activated carbon. The powdered activated carbon that adsorbs pollutants may be defined as hazardous waste, which increases operating costs.

In the operation of a tubular membrane, it is necessary to use a large cross-flow to increase the liquid flow rate on the membrane surface and flush out the pollutants attached to the membrane surface, which leads to high power consumption and high investment.

The prior art adopts the process of large cross-flow tubular membrane + reverse osmosis membrane for the treatment of viscous wastewater; the tubular membrane in this process needs to use large cross-flow to increase the liquid flow rate on the membrane surface to wash away the pollution attached to the membrane surface. material, high power consumption.

In addition to the above treatment methods, in the prior art, the microfiltration/ultrafiltration + reverse osmosis process can also be used for the treatment of viscous wastewater.
This treatment method can cause serious fouling of the separation membrane, requiring frequent chemical cleaning. And when the above two conventional double-membrane processes are used to treat viscous wastewater.

In order to ensure the normal operation of the system, it is also necessary to continuously add powdered activated carbon. The powdered activated carbon that adsorbs pollutants is also a hazardous waste product in a strict sense, which greatly increases the operating cost.

  • Transfer the PTFE wastewater in the raw water tank to the air flotation device.
  • Flocculant is added to the reaction tank of the air flotation device so that the PTFE wastewater is fully mixed and flocculated with the flocculant in the reaction tank of the air flotation device to form suspended particles.
  • Then, the PEFE wastewater after the flocculation reaction is fed into the air flotation tank through the middle water inlet hole of the air flotation device, and a large number of micro-bubble groups are released at the bottom of the air flotation tank of the air flotation device, which will slowly rise under the carry of the micro-bubbles. The suspended matter finally floating on the water surface is scraped into the slag tank by a slag scraper for subsequent treatment.
  • Input the air flotation water into the intermediate water tank, and send the air flotation water from the intermediate water tank to the wedge wire filter pre-filtering device for filtration.
  • The effluent of the pre-filtration device is directly supplied to the vibrating membrane filtering device, and the concentrated water intercepted by the vibrating membrane filtering device is supplied to the raw water tank and the vibrating membrane water inlet.
  • The effluent filtered by the vibrating membrane filter device is supplied to the reverse osmosis water inlet tank, and then enters the reverse osmosis membrane device through the feed pump, security filter, and reverse osmosis high-pressure pump.
  • The air-floating water pump can be used to send the air-floating water from the intermediate water tank to the pre-filtering device for filtration.
  • The vibrating membrane is an ultrafiltration membrane used to filter out the viscous PTFE fine powder. The pore diameter of the ultrafiltration membrane is between 10nm and 100nm, and the molecular weight cut-off is between 1000 and 500000 Daltons. The vibrating membrane is set to vibrate over frequency during operation, the vibration frequency is 40-50 Hz, and the vibration amplitude is 5-12 mm.
  • Only the flocculant PAC (poly aluminum chloride) is added to the floating device, and the dosage of the flocculant PAC is 10mg/L to 20mg/L.
  • After the air-floating scum is collected, dewatering is carried out, and the dewatering machine is a paper bag filter.
  • In the sewage treatment equipment, the air flotation device is an air flotation machine, and the pre-filtration device is a sand filter tank.
  • The osmosis membrane device includes a reverse osmosis water inlet tank, a reverse osmosis feed pump, a security filter, a reverse osmosis high-pressure pump, and a reverse osmosis membrane assembly. The reverse osmosis water inlet tank and the reverse osmosis water inlet end of the security filter pass through The reverse osmosis feed pump is connected.
  • The outlet end of the security filter is connected with the inlet end of the reverse osmosis membrane module through the reverse osmosis high-pressure pump.
  • The reverse osmosis concentrated water end and the reverse osmosis product water end are located on the reverse osmosis membrane module.
  • High-frequency system for generating strong shear force, the high-frequency system includes a high-frequency exciter, vibrating body, and support rod.
  • A screening assembly for realizing material separation, the screening assembly includes a vibrating tray, a diaphragm, an O-ring, an O-ring retainer, and an inlet/outlet channel.
  • A water supply system for conveying wastewater to the screening assembly.
  • The water supply system includes water supply pumps, valves, meters, and filters.
  • For flushing and cleaning the flushing and cleaning system of the screening assembly, the flushing and cleaning system includes a cleaning water tank, control valves, and pipe fittings.

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