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A treatment method for denitrification and fluorine removal and reuse of silicon industry wastewater

A technology for industrial wastewater and treatment methods, applied in the field of wastewater treatment, can solve the problems of large wastewater treatment volume and large amount of acid and alkali, and achieve the effects of low operating cost, reduced floor space, and high water reuse rate

Active Publication Date: 2020-11-20
NANJING UNIV +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Aiming at the problems of large wastewater treatment process in the existing silicon industry wastewater treatment process, the need to repeatedly add acid-base reagents for adjustment, and the large amount of acid-base consumption, the present invention provides a new treatment method for denitrification, fluorine removal and reuse

Method used

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  • A treatment method for denitrification and fluorine removal and reuse of silicon industry wastewater
  • A treatment method for denitrification and fluorine removal and reuse of silicon industry wastewater
  • A treatment method for denitrification and fluorine removal and reuse of silicon industry wastewater

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Embodiment 1

[0037] A treatment system for implementing the treatment method of denitrification, fluorine removal and reuse of wastewater from silicon industries such as photovoltaics and integrated circuits, including a general wastewater tank, an ultrafiltration membrane, a reverse osmosis membrane, a reused water tank, an acidic wastewater tank, Regulating tank, primary sedimentation defluorination tank, denitrification tank, secondary sedimentation defluorination tank and discharge system, general wastewater tank, regulating tank, primary precipitation defluorination tank, denitrification tank, secondary precipitation defluorination tank and discharge The systems are connected sequentially, the acidic wastewater pool is connected to the regulating pool, the clear water effluent from the reverse osmosis system is introduced into the reuse pool and returned to the silicon industry production units such as photovoltaics and integrated circuits, and the wastewater flows in from the general w...

Embodiment 2

[0053] Such as figure 1 Shown, system and treatment method step are the same as embodiment 1, and difference is, in step (1), general waste water is separated into fluorine-containing nitrate nitrogen concentrated water of 5% volume and the clear water of 95% volume; The mixing ratio of the concentrated fluorine-containing nitrate nitrogen water and the strongly acidic high-fluorine wastewater from the acid wastewater pool is 1.2:1.5; the concentration of fluoride ions in the wastewater after the primary precipitation in step (3) is 880 mg / L, and the concentration of nitrate nitrogen 1500mg / L, the pH of the waste water supernatant is 6; the organic matter is methanol in the step (4), the pH value of the denitrification tank effluent is 8, and the total nitrogen concentration is 25mg / L; in the step (6), the secondary precipitation defluorination F in the wastewater supernatant discharged from the pool - The concentration is 4mg / L, the total nitrogen concentration is 25mg / L, an...

Embodiment 3

[0058] Such as figure 1 Shown, system and treatment method step are the same as embodiment 1, and difference is, in step (1), general waste water is separated into the fluorine-containing nitrate nitrogen concentrated water of 3% volume and the clear water of 97% volume; The mixing ratio of the fluorine-containing nitrate-nitrogen concentrated water and the strongly acidic high-fluorine wastewater from the acidic wastewater pool is 1:2, wherein the volume of the fluorine-containing nitrate-nitrogen concentrated water and the concentrated acid wastewater are 300m 3 / d and 600m 3 / d; In the step (3), the fluoride ion concentration in the waste water after the first-level precipitation is 950mg / L, and the nitrate nitrogen concentration is 1600mg / L, and the pH of the waste water supernatant is 5.5; Organic matter is acetic acid in the step (4). The pH value of the nitrification pond effluent is 9, and the total nitrogen concentration is 25mg / L; - The concentration is 5mg / L, the ...

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Abstract

The invention discloses a treatment method for removing nitrogen and fluorine and recycling waste water of the silicon industry, which belongs to the field of the industrial waste water treatment. Thetreatment method comprises the following steps: (1) guiding ordinary waste water into a hyperfiltration and reverse osmosis system, and separating, thus obtaining fluorine-containing and nitrogen-containing nitrogen concentrated water and clear water; (2) mixing the fluorine-containing and nitrogen-containing nitrogen concentrated water and strong-acidity high fluorine waste water in an adjustingpond, and then guiding into a primary precipitation fluorine removal tank; (3) controlling the pH value of supernatant of the wastewater to be faintly acid and the concentration of fluorine ions to be less than or equal to 1000 mg / L, removing calcium fluoride precipitates as mud slag, and guiding the supernatant into a denitrification pool; (4) performing biochemical nitrogen removal by using denitrifying bacteria, and guiding the treated wastewater ino a secondary precipitation fluorine removal tank; and (5) precipitating fluorine ions in the secondary precipitation fluorine removal tank, removing calcium fluoride precipitate, and enabling the final discharged water to reach the emission standard. By adopting the treatment method, the floor occupation area of a waste water pool can be reduced; and the defect of the traditional process that a great amount of alkali is needed for removing the fluorine and a great amount of acid is needed for denitrification can be overcome, the treatment cost is decreased, and the popularization of the treatment method is facilitated.

Description

technical field [0001] The invention belongs to the technical field of waste water treatment, and relates to a treatment method for waste water containing fluorine and nitrate nitrogen, in particular to a treatment method for denitrification, fluorine removal and reuse of waste water in the silicon industry. Background technique [0002] In recent years, my country's photovoltaic, integrated circuit and other silicon industries have developed rapidly, bringing huge economic benefits to the society, but also bringing new environmental problems. In the production process of polycrystalline silicon wafers, nitric acid and hydrofluoric acid are generally used for texturing and etching, and then high-purity water is used for cleaning. In this process, two types of waste water will be produced. One type of waste water is mixed with waste acid and waste lye. Because the amount of waste acid is large and the amount of waste lye is small, the mixed waste water is highly acidic and ha...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/14C02F101/16C02F101/14
CPCC02F1/441C02F1/444C02F1/583C02F3/28C02F3/34C02F9/00C02F2101/14C02F2101/163C02F2301/08
Inventor 张炜铭潘丙才吕路汪林
Owner NANJING UNIV
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