JPH06126288A - Method of removing biologically hardly degradable material - Google Patents

Abstract

PURPOSE:To efficiently remove by treating with ozone for an aqueous liquid containing a hardly degradable material having a specific physical and chemical property, in treatment of waste water, etc., at production of a coke. CONSTITUTION:The aqueous liquid incorporating a phenolic hydroxy group, a carboxylic group, a sulfo group, a nitro group and an ester group in the molecule whose weight average molecular weight is about 1000-1500 and being water-soluble and forming an acid and hygroscopic precipitate in acidic condition and also containing the biologically hardly degradable material, is treated with ozone. In this case, the ozone concentration, aeration speed and treatment time, etc., are selected such that the ozone quantity for one l treating water is about >=100mg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing / removing a biologically persistent substance contained in an aqueous solution. More specifically, it relates to the decomposition and removal of biologically difficult-to-decompose substances contained in the wastewater discharged in the coke manufacturing process.

[0002]

2. Description of the Related Art In the process of producing coke, coke oven gas (COG), tar, and the like that are distilled off during dry distillation of raw coal are cooled with water and used for their respective purposes. At that time, a liquid having a high ammonia content is discharged. This effluent is called ammonium hydroxide and usually contains about 6,000 ppm of ammonia.

In addition to ammonia, the ammonium hydroxide contains a large amount of various substances such as phenol, cresol and other phenols, cyanide, sulfide and the like. Usually, anhydrous water is diluted about 4 to 5 times with industrial water or seawater, and is subjected to biological treatment with activated sludge (fission bacteria, flagellates, ciliates, etc.) The contained substances such as are decomposed and removed.

[0004]

However, since the substances contained in the ammonium hydroxide discharged from the coke manufacturing process are not constant because they differ depending on the conditions such as the carbonization conditions of the raw coal, the load of the activated sludge changes and the activity of the activated sludge is changed. Have a great influence on. In addition, there is a limit to the decomposition and removal rate of the substances contained in the ammonium hydroxide by activated sludge, which is a problem in the wastewater treatment of ammonium hydroxide.

[0005]

[Means for Solving the Problems] The inventors of the present invention have made various studies to provide a method for decomposing / removing biologically difficult-to-decompose substances that cannot be decomposed and removed by activated sludge from aminated water. The components that cannot be removed were specified.
As a result, the physicochemical properties of the substances that occupy most of them were clarified. That is, as a result of examining a method for removing the biologically difficult-to-decompose substance, it is possible to efficiently decompose and remove the biologically difficult-to-decompose substance by subjecting the aqueous solution containing the substance to ozone treatment under specific conditions. The present inventors have completed the present invention by finding that they can be performed, and that the coloring substance in the aqueous solution can be efficiently decolorized and removed due to a cause different from that of the hardly decomposable substance.

That is, the gist of the present invention is at least the following physicochemical properties (a) to (e) (a) a weight average molecular weight of about 1,000 to 1,500 (b) a phenolic hydroxyl group in the molecule. , Carboxyl group,
Having a sulfonic acid group or a nitro group (c) Having an ester bond in the molecule (d) Soluble in water to form a precipitate under acidic conditions (e) The precipitate is acidic and exhibits hygroscopicity A method for removing a biologically difficult-to-decompose substance-containing aqueous solution containing the biologically difficult-to-decompose substance by treating the aqueous solution containing the biologically-hardly-decomposable substance with ozone. And a method for removing a biologically difficult-to-decompose substance, which is characterized by decomposing / removing.

The present invention will be described below. The aqueous solution treated in the present invention contains at least the biologically difficult-to-decompose substance having the physicochemical properties (a) to (e). The biologically difficult-to-decompose substance in the present invention is not decomposed by oxidation with an oxidizing agent such as hydrogen peroxide or oxygen or heating at 200 ° C., and is concentrated in the bottom of the pot by stripping treatment with steam.

Although the chemical structure of the biologically difficult-to-decompose substance in the present invention is unknown, for example, the result of elemental analysis (C = 21.6%, H = 4.9%, N = 9.8%). , Ash content = 2.7%, others = 61%), X-ray microanalyzer result (sulfur is detected), IR spectrum (KBr tableting method) result (FIG. 1), ¹ H-NMR and ¹³ C-NMR [solvent: dimethyl sulfoxide (DMS
From the results of O) (FIGS. 2 and 3)], it is presumed that the condensation product is a benzene ring having a functional group as shown below.

[0009]

Embedded image --OH --COOH --NO ₂ and / or --SO ₃ H --NOH Also, GPS (column “Asahipak GS-310H”, column temperature 40 ° C., eluent; acetonitrile / water = 40/60,
The calibration curve; polyethylene glycol) has a weight average molecular weight of about 1,000 to 1,500.

[0010] Specifically, there is an example of cold water such as COG or tar discharged in the coke manufacturing process, which is cold water. For cheap water, it is usually 6,000 to 6,50
0ppm ammonia, COD conversion approximately 4,000-
Phenols such as 5,000 ppm and cresol are contained as main components, and in addition, about 500 to 700 ppm of cyanide compound in COD conversion, about 300 to 4
The biologically degradable substance of the present invention of 00 ppm and the biologically easily degradable substance of unknown structure of about 700 to 1,000 ppm are contained as minor components.

In the case of treating ammonium hydroxide, the main components such as phenol and cresol may be decomposed and removed in advance by an activated sludge treatment according to a conventional method. As the activated sludge at this time, the above-mentioned bacteria that decompose phenol, cresol and the like are used, and usually diluted with industrial water or seawater to about 4 to 5 times and reacted at a temperature of 30 to 40 ° C. Then, sedimentation separation is performed to obtain a supernatant.

In the ozone treatment of the present invention for such an aqueous solution, the amount of ozone per liter of treated water is 100 mg or more,
Preferably 200 mg or more, particularly preferably 400
The ozone concentration, the aeration rate, the treatment time, etc. are appropriately selected so that the amount becomes about 1000 mg. The temperature of the treated water is usually about 25 to 40 ° C. By the ozone treatment as described above, usually 40 to 60% of the substance can be separated and removed. Further, in the present invention, as shown in the below-mentioned Example (FIG. 4), the coloring substance in the treatment aqueous solution is also added to 80%.
Approximately 98% can be decolorized and removed.

[0013]

EXAMPLES The present invention will be described in more detail with reference to the following examples. Example 1. The ammonium hydroxide discharged from the coke production process is diluted 4 times with seawater, treated with activated sludge under stirring at 30 to 35 ° C. for about 16 hours, sedimented and separated to obtain a supernatant (pH 8.3).
Got The obtained supernatant was subjected to high performance liquid chromatography (HPLC: column "Nucleosil 100", column temperature 4
As a result of analysis at 0 ° C., eluent: acetonitrile / water = 40/60), the peaks of phenol, cresol, and xylenol contained in the untreated water before treatment disappeared.

Ozone was aerated through the supernatant so that the amount of ozone was 0 to 1500 mg per liter of the supernatant. Then, the absorbance (460 nm) of the ozone-treated solution and the change in the proportion of the biologically difficult-to-decompose substance (COD _Mn value) were measured. The results are shown in Fig. 4. As is clear from FIG. 4, it can be seen that the biologically difficult-to-decompose substance that could not be removed by the ozone treatment can be decomposed and removed by the ozone treatment. Further, it can be seen that decolorization of the supernatant liquid colored in pale yellow can be performed at the same time.

[0015]

EFFECTS OF THE INVENTION According to the method of the present invention, a biologically difficult-to-decompose substance having the above-mentioned physicochemical properties, which accounts for most of the components that cannot be decomposed and removed by a biological method such as activated sludge treatment, is obtained. It can be removed and its content can be reduced.

[Brief description of drawings]

FIG. 1 is an IR spectrum of a biologically persistent substance according to the present invention.

FIG. 2 shows the ¹ H-NMR analysis result of the same substance.

FIG. 3 shows the ¹³ C-NMR analysis result of the same substance.

FIG. 4 shows changes in absorbance (460 nm) and residual amount of biologically difficult-to-decompose substance in ozone treatment of an activated sludge treatment liquid of ammonium hydroxide.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazutaka Akai No. 1 Kyushu Town, Sakaide City, Kagawa Prefecture Mitsubishi Chemical Co., Ltd. Sakaide Factory (72) Inventor Hideki Hidemi No. 1, No. 1 Town Town, Sakaide City, Kagawa Prefecture Mitsubishi Kasei Corporation Ceremony company Sakaide factory

Claims (2)

[Claims] 1. At least the following physicochemical properties (a) to (e): (a) a weight average molecular weight of about 1,000 to 1,500 (b) a phenolic hydroxyl group or a carboxyl group in the molecule;
Having a sulfonic acid group or a nitro group (c) Having an ester bond in the molecule (d) Soluble in water to form a precipitate under acidic conditions (e) The precipitate is acidic and exhibits hygroscopicity A method for removing a biologically difficult-to-decompose substance-containing aqueous solution containing the biologically difficult-to-decompose substance by treating the aqueous solution containing the biologically-hardly-decomposable substance with ozone. A method for removing a biologically difficult-to-decompose substance, which comprises decomposing / removing. 2. The removal method according to claim 1, wherein the aqueous solution containing a biologically difficult-to-decompose substance is ammonium hydroxide discharged from the coke manufacturing process.