High-fluoride-containing wastewater treatment technology in fluorine chemical industry

Abstract

The invention discloses a high-fluoride-containing wastewater treatment technology in the fluorine chemical industry. The treatment technology comprises the steps that precipitation is conducted, fluoride-containing wastewater is collected and fed into an adjusting pool, calcium hydroxide slurry is added into the adjusting pool and evenly mixed, the pH value of the adjusting pool is controlled to range from 4 to 6, and standing precipitation is conducted; flocculation is conducted, the wastewater which is treated through the precipitation is introduced into a first flocculation pool, a mixed solution of polyaluminium sulfate and sodium hydroxide is added, the pH value of the first flocculation pool is controlled to range from 7 to 9, solid-liquid separation is conducted after standing is conducted, separated liquid is introduced into a second flocculation pool, a combined flocculating agent of PFC and PAM is added, and standing precipitation is conducted after even mixing is conducted; microfiltration is conducted, and microfiltration is conducted on the wastewater which is treated through the flocculation through a microporous filter; absorption is conducted, the wastewater which is treated through the microfiltration is introduced into an absorption pool, the pH of the wastewater is adjusted to range from 4 to 6, a modified absorbent is added, and standing is conducted after even mixing is conducted. By means of the treatment technology, the fluorine content of the wastewater reaches the effluent standard, and the whole treatment technology is simple, mature, practical, economic and reasonable.

Description

technical field [0001] The invention relates to the technical field of wastewater treatment, in particular to a process for treating wastewater with high fluorine content in fluorine chemical industry. Background technique [0002] In recent years, my country's fluorine chemical industry has developed rapidly, and the overall fluorine chemical market is growing at a rate of 15-20%. In the future, the fluorine chemical industry will also be one of the fastest growing industries in the chemical industry. However, the environmental threat brought by the rapid development of the fluorine chemical industry has become the biggest obstacle to the sustainable development of the industry. On the one hand, due to the large amount of fluorine-containing wastewater produced in the manufacturing process of fluorine chemical products, it is easy to pollute water, soil and plants. On the other hand, because most of the fluorine element in wastewater treatment eventually enters into the sl...

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Problems solved by technology

The process is simple and convenient, and the cost is low, but the calcium fluoride precipitate generated in the commonly used lime precipitation defluorination method will be wrapped in Ca(OH) 2 The surface of the particle, so that it cannot be fully utilized, so it is necessary to add an excess of Ca 2+ , but a large amount of calcium salt is mixed into the sludge, which not only increases the sludge production, but also reduces the purity of the fluorine-containing sludge. At the same time, the fluorine content in the treated wastewater is more than 20mg / L, which is difficult to meet the national discharge standard

Flocculation-sedimentation method tends to generate very fine particles with small specific gravity and high viscosity during the process of wastewater treatment, and it is colloidal during the sedimentation process, so separation is difficult, which not only makes it difficult for wastewater to meet the standard, but also produces sludge with high moisture content, which is difficult to recycle.

[0004] According to my country's "Drinking Water Hygienic Standards", the fluorine content of drinking water is less than 1.0mg / L. It is difficult to reduce the fluorine content in wastewater treated by traditional chemical precipitation and flocculation precipitation to the above standard.

In order to further reduce the concentration of fluoride ions in fluorine-containing wastewater, the current fluoride-containing wastewater treatment processes include adsorption, ion exchange resin, liquid membrane, reverse osmosis, electrodialysis, and co-distillation in addition to the above two types. Among these methods, the adsorption method has become the most concerned method due to its advantages of simple operation, low cost, convenience and easy access, and it was found in the adsorption research that laterite, activated carbon, fly ash, alumina , hydroxycalcium phosphate, rectorite, etc. all have a certain adsorption effect on fluorine ions. These materials in the form of powder have a wide range of sources, low cost, easy regeneration, large adsorption capacity and high efficiency, but they are only suitable for fluorine-containing materials. Advanced treatment of wastewater, and the adsorbent is usually difficult to separate and regenerate, which limits the application

[0005] Therefore, considering the practical operability and economic factors, it is urgent to develop an efficient method for the treatment of high-fluorine-containing wastewater in fluorine chemical industry for the treatment of industrial wastewater whose main goal is to meet the discharge standards, so as to overcome the unhealthy quality of treated wastewater caused by traditional processes. It is of great significance for the treatment of fluorine-containing wastewater in fluorine chemical industry

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