Fluoride removing technology for wastewater discharged from polysilicon solar photovoltaic cell productions

Abstract

The invention discloses a fluoride removing technology for wastewater discharged from polysilicon solar photovoltaic cell productions. The technology comprises the steps that: step 101, high-fluorine water and low-fluorine water are both delivered to a regulating tank; calcium oxide or calcium hydrate is added to the tank, and is dissolved by stirring; and the pH value of the solution in the regulating tank is regulated to 7; step 103, treated high-fluorine water and low-fluorine water are delivered to a reaction tank; a fluoride removing flocculating agent which is a permanganic composite salt containing hydroxy is added into the tank; the solution is dissolved by stirring; the pH value of the solution in the reaction tank is regulated to a value between 6 and 7; when pink color in the reaction tank is disappeared, flocculated deposition is formed; and water in the reaction tank is then filtered and discharged. With the fluoride removing technology for wastewater discharged from polysilicon solar photovoltaic cell productions, salt content and chemical oxygen demand of the fluoride-containing wastewater can be reduced through water treatment, F- content of the fluoride-containing wastewater can also be reduced, and secondary pollution is not brought to the fluoride-containing wastewater.

Description

technical field [0001] The invention relates to a process for removing fluorine from waste water, in particular to a process for removing fluorine from waste water produced by polycrystalline silicon solar photovoltaic cells. Background technique [0002] With the global development and utilization of solar energy technology, the production industry of polycrystalline silicon solar photovoltaic cells has developed rapidly. However, in the current polysilicon solar cell industry, a large amount of fluorine-containing wastewater will be produced, which is very serious for environmental pollution. Fluoride-containing wastewater according to the F in the water - The amount is divided into high-fluorine water and low-fluorine water. Among them, the fluorine content of high-fluorine water is greater than 20000mg / L, and the general pH value is <1. Pickling from each process, mixed pickling solution; the fluorine content in low-fluorine water is 100-400mg / L, the pH is between 3...

AI Technical Summary

Problems solved by technology

[0005] The traditional defluoridation process adopts a continuous method, that is, the chemical is added as the wastewater enters. This continuous process seems to be in line with industrial production, but this process is random, and the fluorine content of the influent water quality is unstable. It is also difficult to be uniform, which will inevitably cause instability in the fluorine content of the effluent water quality

[0006] 2. The salt content of the effluent after treatment is too high

[0008] 3. The chemical oxygen demand (COD) of the effluent after treatment is high

[0014] 5. The effluent water quality after treatment causes secondary pollution

It is well known that carbide slag contains calcium carbide CaC 2 , added to the wastewater to generate C 2 h 2 and Ca(OH) 2 , although a large amount of Ca 2+ , but emits colorless and toxic acetylene gas C 2 h 2 Due to the existence of impurities, it often has an unpleasant smell, which is extremely harmful to environmental protection workers, and acetylene has a considerable solubility in water, and a volume of water at room temperature dissolves about a volume of acetylene, causing secondary damage to the treated effluent. secondary pollution

Images