JPH09327688A - Method and apparatus for treating organic matter waste solution containing inorganic salt in high concentration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat an org. matter waste soln. containing inorg. salts in high concn. by forming a combustion furnace from an inexpensive furnace material and decomposing org. matter at a low temp. to treat the same in inexpensive operation cost and recovering reutilizable inorg. salts. SOLUTION: In treatment of an org. matter waste soln. containing inorg. salts in high concn., crystals of inorg. salts. are precipitated in an anhydride precipitation region by an evaporative concn. method and, at the same time, org. matter is separated as crystals forming eutectic crystals along with inorg. salts and the separated inorg. salts and org. matter are charged in a decomposition furnace 3 held to an atmosphere having a temp. range from the melting temp. of the inorg. salts to that of the org. matter to be stagnated for a time sufficient to decompose org. matter to water-insoluble carbide. Thereafter, ash obtained by this decomposition is dissolved in water and this soln. is filtered to be separated into reutilizable inorg. salts and a small amt. of carbide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating an organic waste liquid containing a high concentration of an inorganic salt, and more particularly to a waste liquid in a purification step or an aqueous phase reaction by a salting-out method for dyes or dye intermediates. The present invention relates to a method and an apparatus for treating a waste liquid containing a high-concentration inorganic salt (sodium chloride, potassium chloride, sodium sulfate, etc.) and a water-soluble organic substance such as process waste liquid.

[0002]

2. Description of the Related Art Generally, waste liquid containing organic matter is disposed of by ocean dumping or decomposed by an activated sludge method. However, in the case of a waste liquid containing a high concentration of an inorganic salt and a water-soluble organic substance such as a waste liquid of a purification process by a salting-out method of a dye or an intermediate of a dye or a waste liquid of an aqueous phase reaction process, COD (chemical oxygen demand) Very heavy load, 1
Since the types of organic substances were not constant even within one factory and the concentration of inorganic salts was extremely high, it was difficult to perform stable activated sludge treatment even when diluted with a huge amount of water. For this reason, conventionally, a method of spraying waste liquid little by little into the incinerator within a range where the combustion temperature is maintained, and, for example, JP-B-55
The so-called submerged combustion method as disclosed in Japanese Unexamined Patent Publication No. -10803 is adopted. Here, the in-liquid combustion method is
The waste liquid is concentrated to a concentration at which crystals are not precipitated or a part of inorganic salt is precipitated, and the concentrated liquid is sprayed into a high-temperature atmosphere maintained at about 900 ° C by combustion of a combustion improver, thereby producing organic matter. Is a method of instantaneously burning and decomposing so that the combustion gas is immediately absorbed in water.

[0003]

However, in the method of spraying into the incinerator, the furnace material is corroded by a large amount of inorganic salt contained in the waste liquid, and the amount of ash is increased by the high concentration of inorganic salt in the waste liquid. There are problems such as an increase in the amount and generation of clinker (a rock-like inorganic salt and lump of carbide formed on the furnace wall or the furnace bottom) in the furnace.

On the other hand, in the submerged combustion method, a large amount of inorganic substance is present in the high temperature furnace material, and especially when the inorganic substance is chloride, the life is short even if a high-grade furnace material is used, and it is regularly used. In addition, it was necessary to repair the furnace frequently. In addition, a large amount of water is required for the waste liquid to bring in a large amount of energy to maintain a high temperature atmosphere, and the use of a large amount of the combustion improver requires a high operating cost. was there. Furthermore, in the liquid that has absorbed the combustion gas, in addition to the inorganic salts originally present in the waste liquid, various salts generated when organic substances are decomposed or sulfites and sulfates generated from the combustion improver are included. Since it exists, there is no method of reusing the inorganic salt, and the fact is that there is no method other than treating this inorganic salt with a wastewater treatment device and discharging it.

In order to solve the above problems, the present invention makes it possible to manufacture a combustion furnace with an inexpensive furnace material, and at the same time, decompose organic substances at a low temperature to process them at a low operating cost. An object of the present invention is to provide a method and an apparatus for treating an organic waste liquid containing a high concentration of an inorganic salt, which is capable of recovering a reusable inorganic salt.

[0006]

In order to achieve the above-mentioned object, the method for treating an organic waste liquid containing a high concentration of inorganic salt according to the present invention firstly includes a high concentration of inorganic salt. When treating the organic waste liquid, the crystals of the inorganic salt are precipitated in the precipitation region of the anhydride by the evaporative concentration method, and at the same time, the organic substance is separated as crystals that co-crystallize with the inorganic salt, and the separated inorganic salt and organic substance are separated. , Was placed in a decomposition furnace in an atmosphere below the melting temperature of the inorganic salt and above the decomposition temperature of the organic matter, and allowed to stay in the decomposition furnace for a sufficient time to decompose the organic matter into water-insoluble carbides. After that, the ash obtained by this decomposition is dissolved in water, and the solution is filtered to separate into reusable inorganic salts and a small amount of carbides.

Secondly, the same treatment method is a treatment method applied to the case of an organic substance which does not crystallize, and in treating an organic waste liquid containing a high concentration of an inorganic salt, it is dried by an evaporation concentration method. In the precipitation area of, precipitate the crystals of the inorganic salt,
At the same time, the organic matter concentrated to a high concentration is attached to the crystals of the inorganic salt and taken out, and the separated inorganic salt and organic matter are decomposed in the atmosphere at the melting temperature of the inorganic salt or lower and the decomposition temperature of the organic substance or higher. After being placed in a furnace and allowed to stay in the decomposition furnace for a sufficient time for the organic matter to decompose into water-insoluble carbides, the ash obtained by this decomposition is dissolved in water and the solution is filtered. It is characterized by separating into a reusable inorganic salt and a small amount of carbide.

In order to specifically realize the above-mentioned treatment method, the treatment apparatus for an organic waste liquid containing a high concentration of an inorganic salt according to the present invention comprises (a) an inorganic salt crystal in an anhydrous precipitation region by an evaporative concentration method. , (B) a centrifuge for separating crystals of the inorganic salt and organic matter deposited in the crystal can from the suspension, (c) an inorganic salt and an organic matter separated by the centrifuge A decomposition furnace for decomposing the organic matter into water-insoluble carbides by maintaining the temperature at a predetermined temperature, (d) a dissolution tank for dissolving the ash after decomposition in water in the decomposition furnace, (e) It is characterized by comprising a filter for filtering a solution dissolved in a dissolution tank and (f) a concentration crystallization device for taking out reusable inorganic salt from the solution which has passed through this filter.

According to the present invention, since the solid matter brought into the cracking furnace is in a crystalline form, the amount of attached water is extremely small, and the heat of decomposition of organic matter is also taken into consideration, so that the required temperature can be maintained with a minimum amount of the combustion improver. Can be maintained. Further, since the inorganic salt is charged in the form of anhydrous crystals, the inorganic salt does not solidify in a clinker shape and does not scatter into the furnace to corrode the furnace wall. Furthermore, in the ash after the decomposition of the inorganic salt and the organic matter, nitrogen oxides and sulfur oxides generated by the decomposition of the organic matter or the combustion of the combustion improver are hardly mixed,
Highly pure crystals can be recovered by dissolving this ash in water and separating the insoluble matter by filtration since only the insoluble charcoal in water and the inorganic salt contained in the waste liquid are left. In this way, it is possible to treat at a low operating cost, there is no corrosion of the furnace material or the generation of clinker in the furnace, and it is possible to recover and reuse the inorganic salt, and a treatment method and treatment with great practical effects. The device can be obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The operating conditions of the cracking furnace in the present invention are preferably selected as follows. First, the temperature in the furnace is generally 250 ° C
Since it is around 350 ° C, the melting temperature of the inorganic salt is 800 ° C for sodium chloride, 776 ° C for potassium chloride, and 884 ° C for sodium sulfate, but the local heat generated by decomposition of organic substances Considering the temperature rise by 600 ℃, which is about 150 ℃ lower than these temperatures
It is preferably about 700 ° C. The residence time is the time at which the organic matter is decomposed at the selected temperature until it becomes almost completely water-insoluble carbide, and the operating temperature is selected so that this time is 10 to 60 minutes. preferable.

As the decomposition furnace in the present invention, various types of furnaces used as incinerators can be used, but the distribution of organic substances contained between the inorganic salt crystals supplied to the decomposition furnace. Since the temperature is not uniform, the vicinity of the crystals of the inorganic salt with a high organic matter concentration may reach the melting temperature of the inorganic salt or higher due to the heat of decomposition of the organic matter and solidify. A mixing type incinerator capable of mechanically moving the furnace, for example, a rotary hearth type, a single stage furnace with a stirring device, or a rotary kiln type is preferable.

[0012]

EXAMPLES Next, specific examples of the method and apparatus for treating an organic waste liquid containing a high concentration of inorganic salt according to the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a flow chart schematically showing a processing flow in an apparatus for treating an organic waste liquid containing a high concentration of inorganic salt according to an embodiment of the present invention. In this example, a basic monoazo dye starting from a thiazole compound was salted out with sodium chloride, and a waste liquid after separation of the dye (sodium chloride; 21%, basic monoazo dye and its isomer; 2 %, Balance: water) 18
It is designed to be continuously processed by the processing apparatus at a flow rate of 0 kg / h.

First, the waste liquid is separated into a centrifugal separator 2 described later.
It is supplied to the vacuum evaporation crystal can 1 together with the filtrate discharged from the vacuum evaporation crystal can 1, and in this vacuum evaporation crystal can 1, the operating liquid temperature is 70 ° C. and the vacuum degree is 1 due to the steam obtained from the waste heat boiler 8.
Water is evaporated at 57 Torr to precipitate crystals. Next, the solution that has passed through the vacuum evaporation crystal can 1 is sent to the centrifuge 2, and the centrifuge 2 continuously causes an average of 46
kg / h of crystals (sodium chloride and organic crystals) are separated.

Thereafter, the crystals of sodium chloride and organic matter separated in the centrifugal separator 2 are heated in the hot air generating furnace 7 by the hot air produced by the combustion of the combustion improver to raise the temperature in the furnace to 6
It is continuously charged into the rotary hearth type decomposition furnace 3 maintained at 30 ° C. Then, in the rotary hearth-type decomposition furnace 3, the organic matter is allowed to stay for a time sufficient to decompose into water-insoluble carbide (in this embodiment, an average retention time of 20 minutes), and then ash is scraped from below. The exhaust gas from the rotary hearth decomposition furnace 3 is introduced into the waste heat boiler 8 via a reburning deodorization furnace, a heat exchanger, etc. (not shown), and then the exhaust gas treatment device 9
Is processed in

Next, the ash scraped out from the rotary hearth type decomposition furnace 3 is put into the melting tank 4 maintained at 60 ° C. In the dissolution tank 4, water is replenished so that the concentration of sodium chloride in the solution is maintained at 22%. Thus, from this dissolution tank 4, a black solution 165 in which the carbide is suspended
kg / h can be obtained.

The insoluble carbides taken out from the dissolution tank 4 are filtered by the cartridge filter 5 having a pore size of 1 μm to obtain 160 kg / h of colorless and transparent salt water. Then
This salt water is supplied to the concentration crystallization device 6, and the concentration crystallization device 6 uses the steam from the waste heat boiler 8 to generate sodium chloride crystals. When the sodium chloride crystals thus produced were used as sodium chloride for salting out a basic monoazo dye starting from a thiazole compound, no effect on product quality was observed.

Comparative Example 1 Treatment was carried out under the same conditions as in Example 1 except that the temperature inside the rotary hearth decomposition furnace 3 was 600 ° C. and the average residence time was 8 minutes. As a result, the filtrate of the cartridge filter 5 was brown and the crystals of sodium chloride obtained in the concentrated crystallization device 6 were colored, and could not be reused as crystals for salting out.

(Comparative Example 2) Except that the temperature inside the rotary hearth decomposition furnace 3 was 720 ° C. and the average residence time was 20 minutes,
The treatment was performed under the same conditions as in Example 1. As a result, it was observed that the crystals were locally melted and a lump having a width of about 10 to 20 cm was sometimes formed, and it was sometimes impossible to take out ash. Also, when the inside was inspected after the operation was stopped, clinker was found in a part of the furnace material.

(Example 2) Waste liquid after separation of an anthraquinone compound in the reaction step of an anthraquinone compound having a sulfone group and a nitro group, which is an intermediate such as an acid dye (sodium sulfate; 25%, anthraquinone compound and its isomerism) Body: 4%, balance: water) 190 kg / h
Is continuously supplied to the vacuum evaporation crystal can 1 at a flow rate of, and the operating liquid temperature is 68 ° C. by the steam obtained from the waste heat boiler 8.
Anhydrous sodium sulfate crystals were precipitated while evaporating water at a vacuum degree of 157 Torr, and were continuously separated by a centrifuge 2 so that 20% of the mother liquor adhered, and an average of 54 kg /
A solid of h was obtained.

Next, the concentrated mother liquor containing the separated anhydrous sodium sulfate, organic crystals, and high-concentration organic matter is heated in the hot-air generating furnace 7 by hot air produced by burning the combustion improver to raise the temperature in the furnace to 670. It is continuously charged into the rotary hearth decomposition furnace 3 maintained at 0 ° C., and ash is scraped out from below with an average residence time of 18 minutes. Then, the ash scraped out from the rotary hearth decomposition furnace 3 is put into the melting tank 4 maintained at 60 ° C. In the dissolution tank 4, water is replenished so that the concentration of sodium chloride in the solution is maintained at 27%. In this way, 170 kg / h of a black solution in which carbides are suspended is obtained from the dissolution tank 4.

The insoluble carbide taken out from the dissolution tank 4 is filtered by the cartridge filter 5 having a pore size of 1 μm to obtain a colorless transparent sodium sulfate solution 165 kg / h. Next, this solution is supplied to the concentration crystallization device 6, and the water vapor from the waste heat boiler 8 is used in the concentration crystallization device 6 to produce crystals of anhydrous sodium sulfate. It was confirmed that the crystals of anhydrous sodium sulfate thus produced had a quality that could be used as industrial anhydrous sodium sulfate for dyeing and the like.

(Comparative Example 3) The treatment was carried out under the same conditions as in Example 2 except that the temperature inside the rotary hearth decomposition furnace 3 was 600 ° C and the average residence time was 8 minutes. As a result, the filtrate of the cartridge filter 5 was brown and the crystals of anhydrous sodium sulfate obtained by the concentration crystallization device 6 were colored, and could not be reused as industrial crystals.

[Brief description of drawings]

FIG. 1 is a flow chart schematically showing a treatment flow in a treatment apparatus for an organic waste liquid containing a high concentration of inorganic salt according to an embodiment of the present invention.

[Explanation of symbols]

 1 Vacuum Evaporation Crystal Can 2 Centrifuge 3 Rotating Hearth Decomposition Furnace 4 Melting Tank 5 Cartridge Filter 6 Concentrating Crystallizer 7 Hot Air Generator 8 Waste Heat Boiler 9 Exhaust Gas Treatment Device

Claims (3)

[Claims] 1. When treating an organic waste liquid containing a high concentration of an inorganic salt, a crystal of an inorganic salt is precipitated in an anhydrous precipitation region by an evaporative concentration method, and at the same time, an organic substance is separated as a crystal co-crystallizing with the inorganic salt. Then, the separated inorganic salt and organic matter are charged at a melting temperature of the inorganic salt or less and into a decomposition furnace in an atmosphere of a decomposition temperature of the organic matter or higher, and the organic matter is decomposed into water-insoluble carbides. After being retained in the decomposition furnace for a sufficient time, the ash obtained by this decomposition is dissolved in water, and the solution is filtered to separate reusable inorganic salts and a small amount of carbides. A method for treating an organic waste liquid containing a high-concentration inorganic salt. 2. When treating an organic waste liquid containing a high concentration of an inorganic salt, a crystal of an inorganic salt is precipitated in an anhydrous precipitation region by an evaporative concentration method, and at the same time, an organic substance concentrated to a high concentration is converted into The crystals are adhered to the crystals and taken out, and the separated inorganic salts and organic substances are put into a decomposition furnace in an atmosphere having a melting temperature of the inorganic salts or lower and a decomposition temperature of the organic substances or higher, and the organic substances are insoluble in water. After being retained in the cracking furnace for a sufficient time to decompose into carbides, the ash obtained by this decomposition is dissolved in water, and the solution is filtered to obtain reusable inorganic salts and a small amount of carbides. A method for treating an organic waste liquid containing a high concentration of inorganic salt, characterized in that the organic waste liquid is separated. 3. A crystal can for precipitating crystals of an inorganic salt in an anhydrous precipitation region by (a) an evaporation concentration method, and (b) crystals of an inorganic salt and an organic substance precipitated in the crystal can from a suspension. A centrifuge for separating, (c) a decomposition furnace for receiving the inorganic salt and the organic matter separated by the centrifuge, and decomposing the organic matter into a water-insoluble carbide by being maintained at a predetermined temperature, (d) ) A dissolution tank for dissolving the ash after decomposition in this decomposition furnace in water, (e) a filter for filtering the solution dissolved in this dissolution tank, and (f) an inorganic material that can be reused from the solution that has passed through this filter. An apparatus for treating an organic waste liquid containing a high concentration of inorganic salt, comprising a concentration crystallization device for extracting a salt.