Method for treating waste liquid for decomposing organic fluorine compound

Abstract

To provide a method for decomposing waste liquid of an organic fluorine compound.SOLUTION: A waste liquid treatment method for decomposing an organic fluorine compound by means of microorganisms, wherein the organic fluorine compound is decomposed by using an aerobic reducing bacterium.

Description

[Technical Field]

[0001] The present invention relates to a waste liquid method for decomposing organic fluorine compounds. [Background technology]

[0002] Chlorofluorocarbon organic fluorine compounds have been used in various industrial fields, such as cleaners for metal processing and cleaners for semiconductor electronic components. Furthermore, organic fluorine compounds such as perfluorocarboxylic acids and perfluoroalkylsulfonic acids have been used in various industrial fields as components or intermediate raw materials for anti-reflective agents, emulsifiers, water repellents, etc. Furthermore, fluorine-based pesticides are manufactured and used in large quantities, taking advantage of the property that their activity changes dramatically upon fluorine introduction.

[0003] Furthermore, a large amount of organic fluorine compounds adsorbed on adsorbents such as activated carbon during wastewater treatment is left untreated, and there is a risk that the adsorbed organic fluorine compounds may be released from the adsorbent.

[0004] These organic fluorine compounds are extremely stable, and some of them are found to exist in the atmosphere, rivers, oceans, soil, and other natural environments, as well as in living organisms, raising concerns about their persistence in the environment. It is desirable to decompose these persistent organic fluorine compounds and make them non-polluting.

[0005] Methods for decomposing organic fluorine compounds in water include decomposition treatment using the Fenton reaction, ultrasonic treatment, decomposition treatment using supercritical water, and decomposition treatment using ultraviolet light irradiation. However, there are problems with the highly stable organic fluorine compounds, such as their high cost, the need for special equipment, and limitations on the concentration of the organic fluorine compounds in the treatment solution.

[0006] A method for decomposing organic fluorine compounds using microbubbles and microorganisms has also been disclosed, but there are problems in that the concentration of organic fluorine compounds is limited to low concentrations, and the equipment is large-scale and operation and management are cumbersome. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-131478 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-253012 Summary of the Invention [Problem to be solved by the invention]

[0008] In order to solve the above problems, the present invention aims to provide a method for efficiently decomposing waste liquids of persistent organic fluorine compounds in a simple manner while greatly improving the concentration limit of the treatment liquid. [Means for solving the problem]

[0009] The present inventors have conducted research to achieve the above object and have arrived at the present invention, which is a wastewater treatment method for decomposing organofluorine compounds using microorganisms, characterized in that the microorganisms are aerobic reducing bacteria in the presence of water.

[0010] The method for treating wastewater by decomposing organic fluorine compounds using microorganisms according to the present invention is characterized in that the microorganisms are aerobic reducing bacteria in the presence of water, and a surfactant is further used.

[0011] As a result of various investigations into wastewater treatment methods that use microorganisms to decompose organic fluorine compounds, we discovered that aerobic reducing bacteria have an extremely high ability to decompose organic fluorine compounds in the presence of water.

[0012] In the present invention, when the organic fluorine compound is dissolved in water, a surfactant may not be necessary. However, when the organic fluorine compound is insoluble in water, the addition of a surfactant can emulsify the compound and increase the decomposition rate.

[0013] The ratio of water to the organic fluorine compound of the present invention is not particularly limited, but in the case of an insoluble organic fluorine compound, a ratio of water to the organic fluorine compound that allows emulsification is selected. Furthermore, a trace amount of the aerobic reducing bacteria of the present invention is sufficient relative to the amount of water. For ease of handling, the aerobic reducing bacteria are preferably supported on silica powder or the like.

[0014] In addition, organic fluorine compounds adsorbed on adsorbents such as activated carbon during wastewater treatment can also be decomposed in the same manner. In the presence of water, the adsorbent and the aerobic reducing bacteria of the present invention can be mixed to easily decompose the compounds.

[0015] The treatment temperature of the present invention is determined by the temperature at which the aerobic reducing bacteria are used. The temperature at which the aerobic reducing bacteria are used is preferably 0°C to 80°C, and more preferably 20°C to 40°C. [Effects of the Invention]

[0016] In the treatment of wastewater containing persistent organic fluorine compounds, from high to low concentrations, the compounds can be decomposed extremely efficiently using a novel microorganism without using any special equipment. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Example]

[0018] Into a 300cc glass beaker, 40cc of 1-chloro-2,3,3-trifluoro-1-propene (CTFP), 160cc of distilled water, 20mg of surfactant, and 5mg of aerobic reducing bacteria supported on silica powder were placed.

[0019] When the mixture was stirred, it turned milky white. There was a slight odor of CTFP. The beaker containing the mixture was then left to stand. The temperature of the mixture was 27°C, and the room temperature was also 27°C.

[0020] After 3 hours, the milky white color of the reaction solution became slightly lighter. After 6 hours, the reaction solution became transparent. After 24 hours, it remained transparent and the CTFE odor was completely gone. The pH of the reaction solution was 9 using litmus paper.

[0021] After 24 hours, the reaction solution was analyzed for fluorine (JIS K0102 34.1), and the result was 0.33 mg / L. [Example]

[0022] 10 g of 1-chloro-2,3,3-trifluoro-1-propene (CTFP), 50 g of distilled water, 10 mg of surfactant, and 2.5 mg of aerobic reducing bacteria supported on silica powder were placed in a 300 cc glass beaker.

[0023] When the mixture was stirred, it turned milky white. There was a slight odor of CTFP. The beaker containing the mixture was then left to stand. The temperature of the mixture was 8°C, and the room temperature was 5°C.

[0024] After 4 days, the CTFP odor of the reaction solution had disappeared. The total weight of the solution was measured and found to have decreased by 10 g. The pH of the solution was measured using litmus paper and found to be 10.

[0025] To determine whether or not CTFP evaporated during the reaction, the total weight of the mixture was measured under the same conditions except for the absence of aerobic reducing bacteria. The results showed no change in weight between the start and end of the four-day period. [Industrial Applicability]

[0026] The present invention provides a wastewater treatment method for decomposing persistent organic fluorine compounds using aerobic reducing bacteria. According to the treatment method of the present invention, even highly concentrated wastewater can be decomposed without pretreatment such as dilution, and the treatment equipment can be made small and simple. This is a useful wastewater treatment method with low running costs.

Claims

1. A wastewater treatment method for decomposing organic fluorine compounds using microorganisms, characterized in that the microorganisms are aerobic reducing bacteria in the presence of water.

2. 2. The method for treating waste liquid according to claim 1, wherein a surfactant is used.