CN-122010327-A - Multistage treatment process for fluorine-containing wastewater

CN122010327ACN 122010327 ACN122010327 ACN 122010327ACN-122010327-A

Abstract

The invention relates to the technical field of industrial wastewater treatment, in particular to a multistage treatment process of fluorine-containing wastewater. Aiming at the problems that the defluorinating agent in the prior art has low reaction efficiency, difficult micro-fine sludge sedimentation, incapability of synchronously degrading organic complex, serious membrane pollution and the like, the invention adopts a high-shear in-situ copolymerization technology to prepare the liquid phase multifunctional catalyst containing polysilicic acid skeleton, and couples a multistage gradient reaction and a tubular ceramic membrane forced separation technology, the technology utilizes Fenton-like catalytic activity of the medicament and a rigid net capturing mechanism to realize deep synergistic removal of fluorine, COD and total phosphorus, obviously reduces the membrane flux attenuation rate and the sludge water content, and has the advantages of short flow, stable yielding water reaching standards and the like.

Inventors

ZHAO HAO
ZHAO XIANGUANG
LI SHUO
Fan Bingze

Assignees

南京工业大学

Dates

Publication Date: 20260512
Application Date: 20260123

Claims (7)

1. A multistage treatment process of fluorine-containing wastewater is characterized by comprising the steps of pumping raw water of fluorine-containing organic wastewater into a first-stage oxidation reaction kettle, pumping ferrous sulfate solution, maintaining the system environment to be acidic, and performing Fenton oxidation and vein-breaking treatment to obtain first-stage oxidation treatment water; Pumping the primary oxidation treatment water into a secondary mineralization reaction kettle, regulating the system environment to be alkaline, and carrying out mineralization reaction to obtain secondary mineralization treatment water; Overflowing the secondary mineralized treatment water into a tertiary advanced treatment kettle, pumping a defluorination catalyst to obtain tertiary advanced treatment water, connecting the tertiary advanced treatment water with a tubular ceramic membrane circulation system, and performing cross-flow filtration, concentration and reflux to obtain standard water; the fluorine removal catalyst comprises the constituent elements of iron, aluminum and silicon.
2. The multistage treatment process of fluorine-containing wastewater according to claim 1, wherein the fluorine removal catalyst is prepared by injecting metal salt modified solution into polysilicic acid stock solution to obtain precursor mixed solution, adding sodium bicarbonate powder into the precursor mixed solution, adjusting the basicity of the solution, heating, stirring, curing and cooling.
3. The multistage treatment process of fluorine-containing wastewater according to claim 2, wherein the metal salt modification solution is prepared by dissolving polyaluminum chloride, ferrous sulfate heptahydrate and titanyl sulfate in deionized water, the polysilicic acid stock solution is prepared by dripping sulfuric acid solution into diluted sodium silicate solution, regulating the system to be in a strong acid environment, and stirring and reacting, wherein the pH value corresponding to the strong acid environment is 2.0-3.0.
4. The multistage treatment process of fluorine-containing wastewater according to claim 1, wherein the Fenton oxidation and vein-breaking treatment is a reaction of dropwise adding hydrogen peroxide solution, pumping the hydrogen peroxide solution while pumping the fluorine removal catalyst, and adjusting the system environment to be acidic.
5. The multistage treatment process of fluorine-containing wastewater according to claim 1, wherein the three-stage advanced treatment kettle comprises a rapid mixing zone and a slow flocculation zone, wherein the residence time of the rapid mixing zone is 1.5-2.5min, the residence time of the slow flocculation zone is 13.5-18min, the hydraulic reaction residence time of the primary oxidation reaction kettle is 42-75min, and the hydraulic reaction residence time of the secondary mineralization reaction kettle is 20-40min.
6. The multistage treatment process of fluorine-containing wastewater according to claim 1, wherein the cross-flow filtration is characterized in that part of the three-stage advanced treatment water carries trapped suspended substances as concentrated solution to flow out from an outlet and flow back to a front-end reaction system, and the rest of the three-stage advanced treatment water is discharged as penetrating solution through a tubular ceramic membrane to obtain the standard-reaching water.
7. The multistage treatment process of fluorine-containing wastewater according to claim 1, wherein the pumping flow rate of the ferrous sulfate solution is 90-110mL/h, the pumping flow rate of the hydrogen peroxide solution is 250-350mL/h, and the cross-flow rate of the membrane surface in the membrane tube is 3.5-4.5m/s.

Description

Multistage treatment process for fluorine-containing wastewater Technical Field The invention relates to the technical field of industrial wastewater treatment, in particular to a multistage treatment process of fluorine-containing wastewater. Background With the explosive growth of new photovoltaic energy sources, semiconductor integrated circuits and fluorine fine chemical industry, the discharge amount of fluorine-containing wastewater is increasing. In the working section of texturing and etching of a photovoltaic cell and the working procedure of cleaning and polishing of a semiconductor wafer, hydrofluoric acid, ammonium fluoride and fluorine-containing mixed acid are widely used as an etching agent and a cleaning agent, so that the generated wastewater is high in fluoride ion concentration and often accompanied with high-concentration organic pollutants such as a surfactant, an alcohol solvent, an organic complexing agent and the like, and the complex water quality characteristics of the formed fluoride and organic carbon coexist, so that the treatment difficulty is greatly increased. At present, the existing fluorine-containing wastewater treatment technology mainly uses a calcium salt precipitation method, namely lime or calcium chloride is added to generate calcium fluoride precipitation, and an aluminum salt coagulation method is used for carrying out deep control. However, in practical engineering applications, such conventional processes face a number of bottlenecks. Firstly, the method is limited by physical restriction of solubility product of calcium fluoride, the concentration of fluorine in effluent is difficult to stably reduce to a strict emission standard below 1mg/L by a simple calcium method, secondly, a large amount of organic complexing agents in wastewater can form stable coordination compounds with fluorine or metal ions to inhibit precipitation reaction, so that incomplete defluorination is caused, and more seriously, organic matters are wrapped on the surface of crystal nucleus to prevent crystal growth, and the generated sludge has fine particles, light specific gravity and strong hydrophilicity, is extremely difficult to settle in a traditional gravity sedimentation tank, and is extremely easy to cause excessive fluoride carried by effluent suspended matters, namely the phenomenon of so-called fluorine running. In addition, the resin adsorption or fixed bed adsorption process commonly adopted in the existing advanced treatment has the problems of frequent regeneration, high requirement on the inflow SS and easy poisoning and invalidation by organic matters, and for the membrane separation technology, the traditional coagulated flocs are loose and have viscosity, so that serious membrane hole blockage and flux attenuation are easy to cause. Therefore, development of a synergistic treatment process capable of synchronously realizing deep defluorination and organic matter degradation, remarkably improving sludge sedimentation and dehydration performance and adapting to an efficient membrane separation system is needed. For this purpose, a multistage treatment process for fluorine-containing wastewater is proposed. Disclosure of Invention The invention aims to provide a multistage treatment process of fluorine-containing wastewater. The preparation method utilizes the Fenton-like catalytic activity of the medicament and a rigid net capturing mechanism to realize the deep synergistic removal of fluorine, COD and total phosphorus, obviously reduces the membrane flux attenuation rate and the sludge water content, and has the advantages of short flow, stable yielding water reaching standards and the like. In order to achieve the above purpose, the present invention provides the following technical solutions: The invention provides a multistage treatment process of fluorine-containing wastewater, which comprises the steps of pumping raw water of fluorine-containing organic wastewater into a first-stage oxidation reaction kettle, pumping ferrous sulfate solution, maintaining the system environment as acidity, and performing Fenton oxidation and vein breaking treatment to obtain first-stage oxidation treatment water; Pumping the primary oxidation treatment water into a secondary mineralization reaction kettle, regulating the system environment to be alkaline, and carrying out mineralization reaction to obtain secondary mineralization treatment water; Overflowing the secondary mineralized treatment water into a tertiary advanced treatment kettle, pumping a defluorination catalyst to obtain tertiary advanced treatment water, connecting the tertiary advanced treatment water with a tubular ceramic membrane circulation system, and performing cross-flow filtration, concentration and reflux to obtain standard water; The fluorine removal catalyst comprises the constituent elements of iron, aluminum and silicon. Preferably, the defluorination catalyst is prepared by injecting metal salt modified