Reuse and Treatment Technology of Fluorinated Wastewater in Photovoltaic Industry

Reverse osmosis is a water treatment technology that has emerged in recent decades. It has been widely used in industrial water supply, reclaimed water reuse, wastewater treatment and residential drinking water. It has the advantages of environmental protection and high desalination rate.

In recent years, my country's photovoltaic industry has developed rapidly, and photovoltaic wastewater treatment has received increasing attention. Fluorinated wastewater is the main wastewater produced in the photovoltaic industry. Most enterprises discharge fluorinated wastewater after defluorination treatment. However, with the increasing scarcity of water resources, the reuse of fluorinated wastewater has become an inevitable trend.

Wastewater Source
The fluorine-containing wastewater of the company mainly comes from the battery workshop. The process of the battery workshop is: texturing→diffusion→wet etching→spraying anti-reflection film→printing and sintering. Among them, the two processes of silicon wafer texturing and etching generate waste water, including waste acid solution (nitric acid + hydrofluoric acid, hydrofluoric acid + hydrochloric acid or hydrofluoric acid), waste alkali solution (potassium hydroxide), acid cleaning water and alkali wash water. Among them, the amount of waste acid and waste lye is small and is intermittently discharged, while the water volume of acid cleaning water and alkali cleaning water is relatively large, and the water quality and water volume are relatively stable. Due to the small amount of waste acid liquid, large fluctuations in water quality and water volume, and strong corrosiveness, the project does not consider the reuse of this part of wastewater, and this wastewater is connected from the production equipment to an independent pipeline and flows into the original treatment of the enterprise In the defluorination treatment of the facility, acid cleaning water, alkali cleaning water and waste alkali liquor are used as raw water for reuse.

Existing Fluoride Removal Facilities
The effluent of the wastewater treated by the company's original fluorine-containing wastewater treatment facilities can meet the third-level standard of the "Comprehensive Wastewater Discharge Standard" (GB8978-1996). The defluorination treatment facility is mainly by adding lime, calcium chloride and flocculant, so that the fluoride in the wastewater and the calcium ions in the lime and calcium chloride form calcium fluoride precipitation, so as to achieve the purpose of removing fluoride in the wastewater.

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