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A method for the treatment and recycling of mixed acid wastewater in the photovoltaic industry

A recycling method and recycling technology, which is applied in the field of mixed acid wastewater treatment and resource recycling in the photovoltaic industry, can solve the problem of low removal efficiency, achieve the effects of improving fluorine removal efficiency, reducing foam formation, and improving treatment efficiency

Active Publication Date: 2020-08-11
JIANGSU NJU ENVIRONMENTAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] Aiming at the defect that a large amount of chemical reagents need to be added and the removal efficiency is not high in the prior art for the removal of fluorine from the mixed acid wastewater in the photovoltaic industry, the present invention aims to propose a method for the treatment and resource recovery of the mixed acid wastewater in the photovoltaic industry. Cost-effective treatment of mixed acid wastewater in the photovoltaic industry while realizing resource recovery of nitrate nitrogen

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  • A method for the treatment and recycling of mixed acid wastewater in the photovoltaic industry
  • A method for the treatment and recycling of mixed acid wastewater in the photovoltaic industry
  • A method for the treatment and recycling of mixed acid wastewater in the photovoltaic industry

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Embodiment 1

[0037] figure 1 It is a simple process flow diagram of the present invention, combined with figure 1 , the method for the treatment and recycling of mixed acid wastewater in the photovoltaic industry of this embodiment includes the following steps:

[0038] a) In this embodiment, the molar concentration of fluoride ions in the mixed acid wastewater in the photovoltaic industry is 0.637mol / L, and the molar concentration of nitrate nitrogen is 0.04mol / L. The first fluoride removal pool and the second fluoride removal pool;

[0039] B) add calcium hydroxide emulsion in the first defluoridation pond, the molar concentration of calcium ion in the calcium hydroxide emulsion is 30% of the fluoride ion molar concentration in the first defluorination pond, i.e. the molar concentration of calcium ion is 0.191mol / L, the pH value of the first defluoridation tank is 4.0, so that fluoride ions and calcium ions form calcium fluoride precipitation, and the mud-water mixture in the first def...

Embodiment 2

[0045] The treatment and recycling method of mixed acid wastewater in the photovoltaic industry of this embodiment includes the following steps:

[0046] a) In this example, the molar concentration of fluoride ions in the mixed acid wastewater in the photovoltaic industry is 0.342 mol / L, and the molar concentration of nitrate nitrogen is 0.064 mol / L. The above wastewater is introduced into the regulating tank for water quality homogenization, and the volume ratio is 3:1. The first fluoride removal pool and the second fluoride removal pool;

[0047] B) add calcium hydroxide emulsion in the first defluoridation pond, the molar concentration of calcium ion in the calcium hydroxide emulsion is 40% of the fluoride ion molar concentration in the first defluorination pond, i.e. the molar concentration of calcium ion is 0.137mol / L, the pH value of the first defluoridation tank is 6.0, so that fluoride ions and calcium ions form calcium fluoride precipitation, and the muddy water mixtu...

Embodiment 3

[0053] The treatment and resource recycling method of mixed acid wastewater in the photovoltaic industry in this embodiment, the operation steps are as follows:

[0054] a) In this example, the molar concentration of fluoride ions in the mixed acid wastewater of the photovoltaic industry is 1.158mol / L, and the molar concentration of nitrate nitrogen is 0.086mol / L. The first fluoride removal pool and the second fluoride removal pool;

[0055] B) add calcium hydroxide emulsion in the first defluoridation pond, the molar concentration of calcium ion in the calcium hydroxide emulsion is 35% of the fluoride ion molar concentration in the first defluorination pond, i.e. the molar concentration of calcium ion is 0.405mol / L, the pH value of the first defluoridation tank is 5.2, so that fluoride ions and calcium ions form calcium fluoride precipitation, and the muddy water mixture in the first defluoridation tank is introduced into the second defluoridation tank;

[0056] c) measure t...

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Abstract

The invention relates to a treatment and resource recycling method of mixed acid wastewater in photovoltaic industry and belongs to the technical field of wastewater treatment. The method comprises the following steps: a) respectively introducing wastewater into a first defluorination pond and a second defluorination pond; b) adding a calcium hydrate emulsion into the first defluorination pond, and introducing a water-sludge mixture into the second defluorination pond; c) adding calcium carbonate into the second defluorination pond, introducing the water-sludge mixture into a first sedimentation basin for treatment, and introducing a supernatant into a softening pond; d) adding carbonate into the softening pond, recycling the formed calcium carbonate precipitate into the second defluorination pond, and introducing the water-sludge mixture into a second sedimentation basin for treatment; and e) treating a supernatant from the second sedimentation basin through an electrodialyzer to obtain a by-product. By the method, fluoride is removed while resource recycling of nitrogen element is realized. The two-step defluorination efficiency is high, operational cost of wastewater treatment can be effectively reduced, and zero emission of mixed acid wastewater in photovoltaic industry can be realized.

Description

technical field [0001] The invention belongs to the technical field of waste water treatment, and in particular relates to a treatment and recycling method of mixed acid waste water in the photovoltaic industry. Background technique [0002] As one of the important development industries of new energy, the photovoltaic industry has developed rapidly in my country in the past ten years. Its rapid development has brought huge economic benefits to modern society, but also brought new environmental problems. During the production process of polycrystalline silicon wafers, nitric acid and hydrofluoric acid are usually used for etching, and the etching waste liquid contains a large amount of fluorine ions and nitrate nitrogen. Generally speaking, the fluoride ion concentration in the mixed acid wastewater in the photovoltaic industry exceeds 3000mg / L, the nitrate nitrogen concentration exceeds 1000mg / L, and the pH value is less than 4. If not handled properly, it will seriously p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/04C02F101/14
CPCC02F1/04C02F1/4693C02F1/5236C02F1/66C02F3/00C02F5/02C02F9/00C02F2001/007C02F2101/14C02F2301/08
Inventor 汪林李丽芳唐凯马信张建春张炜铭何锐吕振华王利慧邵燕
Owner JIANGSU NJU ENVIRONMENTAL TECH