JP2003266087A - Treatment method for emulsion wastewater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently performing the cleaning treatment of emulsion wastewater without accompanying the scaling-up of equipment or a rise in running cost. <P>SOLUTION: Emulsion wastewater is subjected to wet oxidation treatment under temperature and pressure conditions holding the wastewater to a liquid phase. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying emulsion wastewater, specifically, wastewater containing a water-insoluble or sparingly water-soluble organic substance (hereinafter abbreviated as "poorly-soluble organic substance") (hereinafter referred to as "emulsion"). Waste water ”) is efficiently wet-oxidized.

[0002]

2. Description of the Related Art Wastewater discharged from factories has various properties. In the case of emulsion wastewater, even if the COD concentration is low, sparingly soluble organic substances are often hard to decompose. In many cases, it cannot be easily decomposed and cannot be sufficiently purified. In particular, when biological treatment is used, the treatment time is long and excess sludge is generated. Therefore, it is necessary to provide a treatment facility for the excess sludge, and there is a problem that the treatment cost increases. Further, as another treatment method, there is an activated carbon adsorption method using activated carbon, but since the adsorption speed is slow and the adsorption amount has an upper limit, a large amount of emulsion wastewater discharged from the factory cannot be efficiently treated. In addition, there is a problem that a treatment operation is required to regenerate the activated carbon having a reduced adsorption performance, resulting in an increase in treatment cost. In addition, it is necessary to treat the poorly soluble organic substance desorbed from the activated carbon during the regeneration operation.

Further, there is a combustion method in which incineration is used as a method for treating emulsion wastewater, but not only waste of resources due to burning fossil fuel as a fuel but also carbon dioxide which has recently been highlighted as a problem of global warming. It has problems such as increased emissions.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and an object thereof is to efficiently treat emulsion wastewater without enlarging equipment and increasing running cost. The purpose of the present invention is to provide a method capable of purifying treatment.

[0005]

Means for Solving the Problems The present invention, which has been able to solve the above-mentioned problems, refers to the fact that emulsion wastewater is subjected to wet oxidation treatment at a temperature and pressure at which the wastewater holds a liquid phase. It is a processing method.

In carrying out the present invention, emulsion waste water is separated into a non-permeate and a permeate using a microfiltration membrane or an ultrafiltration membrane, and the whole or a part of the non-permeate is subjected to wet oxidation treatment. Is recommended. Further, in the present invention, it is desirable that the average particle size of the organic substances contained in the waste water of the emulsion is 0.01 to 100 μm.

In the present invention, the emulsion drainage is
It is also a preferred embodiment to carry out the non-catalytic wet oxidation treatment at a temperature and pressure at which the wastewater holds the liquid phase, and then perform the catalytic wet oxidation treatment at a temperature and pressure at which the liquid phase is held.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies conducted by the present inventors in order to solve the above problems, as a result of performing wet oxidation treatment on emulsion wastewater at a temperature and pressure at which the wastewater holds a liquid phase, the efficiency is improved. The purification cost can be improved, and the treatment cost increases due to secondary treatment such as sludge treatment, regeneration operation, and treatment of desorbed substances, which has been a problem in the above biological treatment and adsorption treatment, and fuel cost and waste gas. It has been found that the problems associated with combustion processing such as pollution can be solved.

Emulsion drainage, which is the subject of the present invention, refers to drainage in a state in which poorly soluble organic substances are dispersed in water in the form of fine particles. The poorly soluble organic substance may be in a liquid form or a solid form. The particle size of the poorly soluble organic material in the case of a solid state is not particularly limited, but if the average particle size is 0.01 to 100 μm, it can be efficiently treated.

No particular limitation is imposed on the wastewater having such properties, but the sparingly soluble organic matter contained in the wastewater is, for example, a copolymer of one or more of the following polymerizable monomers. Is mentioned. Examples of the polymerizable monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. ) A (meth) acrylic acid ester-based polymerizable monomer which is an ester of acrylic acid and an alcohol having 1 to 18 carbon atoms (excluding cyclic alcohols); (meth)
Carboxyl group-containing polymerizable monomers such as acrylic acid, itaconic acid, croton powder, maleic acid, maleic anhydride; styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, chloromethylstyrene, ethylvinylbenzene, etc. Styrene-based polymerizable monomers; cyclohexyl group-containing polymerizable monomers such as cyclohexyl (meth) acrylate; unsaturated esters such as methyl crotonate, vinyl acetate, vinyl propionate; butadiene, isoprene, 2
-Methyl-1,3-butadiene, 2-chloro-1,3-
Dienes such as butadiene; (meth) allyl alcohol,
Allyls such as glycidyl (meth) allyl ether; unsaturated cyanides such as (meth) acrylonitrile and α-chloroacrylonitrile; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylic acid Hydroxyl group-containing (meth) acrylic acid esters such as monoesters of ethylene glycol and polypropylene glycol, monoesters of (meth) acrylic acid and polypropylene glycol; polyethylene glycol chain-containing polymerizable monomers such as polyethylene glycol (meth) acrylic ester Polymer; 1 to 300 mol of oxyalkylene having 2 to 4 carbon atoms is added to the alcohol or amine such as methoxypolyethylene glycol mono (meth) acrylate and methoxypolyalkylene glycol mono (meth) acrylate. Esters or amides of the selected alkyl polyalkylene glycol and the unsaturated monocarboxylic acids; allyls obtained by adding 1 to 300 mol of oxyalkylene having 2 to 4 carbon atoms to (meth) allyl alcohol; dimethylaminoethyl (meth ) Acrylamide, dimethylaminopropyl (meth) acrylamide, (meth) acrylamide, N-monomethyl (meth) acrylamide, (meth) acrylalkylamide, N-monoethyl (meth) acrylamide, N-methylol (meth)
(Meth) acrylamide and its derivatives such as acrylamide, N, N-dimethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, methylene (meth) acrylamide; unsaturated dicarboxylic acids and carbon such as dimethyl maleate and dimethyl fumarate. Diamides with amines of number 1 to 22; N-vinylpyrrolidone; (meth)
Basic polymerizable monomers such as methylaminoethyl acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, vinylpyridine and vinylimidazole; vinyl Unsaturated sulfonic acids such as sulfonic acid, (meth) allyl sulfonic acid, sulfoethyl (meth) acrylate, 2-methylpropane sulfonic acid (meth) acrylamide, styrene sulfonic acid, and their monovalent metal salts, divalent metal salts, ammonium Salt and organic amine salt; 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, 2-
Acidic phosphate ester group-containing polymerizable monomers such as (meth) acryloyloxyethyl phenyl phosphate; carboxylic acid monomers such as vinylphenol; 2-aziridinylethyl (meth) acrylate, (meth) acryloylaziridine, etc. Aziridine group-containing monomer; Oxazoline group-containing polymerizable monomers such as 2-isopropenyl-2-oxazoline and 2-vinyloxazoline; Epoxy group-containing polymerizable monomer such as glycidyl (meth) acrylate and acrylglycidyl ether Polymers; hydrolyzable silicon groups such as vinyltrimethoxysilane, vinyltriethoxysilane, γ- (meth) acryloylpropyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, and allyltriethoxysilane that are directly bonded to silicon atoms. Containing polymerizable monomer; vinyl fluoride, Kka vinylidene, vinyl chloride, a halogen-containing polymerizable monomer of vinylidene chloride, (poly)
Ethylene glycol di (meth) acrylate, (poly)
Bifunctional (meth) acrylates such as alkylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate; (meth) acrylic acid and ethylene Glycol,
Esters with polyhydric alcohols such as ethylene glycol, 1,3-butylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, polyethylene glycol, propylene glycol, polypropylene glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol. Polyfunctional (meth) acrylic acid esters having two or more polymerizable unsaturated groups in the molecule such as a compound; two or more polymerizable unsaturated groups in the molecule such as diallyl phthalate, diallyl fumarate and diallyl fumarate A polyfunctional allyl compound having; an allyl (meth) acrylate; a divinyl aromatic such as divinylbenzene; a polymerizable polyfunctional monomer such as allyl (meth) acrylate and divinylbenzene; a cyanurate such as triallyl cyanurate; Styrene, propylene, isobutylene, olefins such as diisobutylene; methyl vinyl ether, various monomers such as vinyl ethers such as butyl vinyl ether.

The discharge source of such emulsion wastewater is not particularly limited, but examples thereof include various industrial plants such as chemical plants, food processing plants, and metal processing plants.

The sparingly soluble organic matter in the waste water is subjected to wet oxidation treatment by the treatment method of the present invention. In the present invention, "oxidation" is a treatment for oxidizing and / or decomposing the sparingly soluble organic matter. It is meant to include the process of decomposing organic matter into nitrogen gas, carbon dioxide, water, and ash.

The method of the present invention will be described below with reference to the schematic explanatory views illustrated in FIGS. 1 and 2. However, the method of the present invention is not limited to the following examples, and is not particularly limited. Unless otherwise specified, appropriate changes may be added.

In the schematic explanatory view shown in FIG. 2, emulsion wastewater discharged from a factory or the like is introduced from a line 1,
It is supplied to a wet oxidation reaction tower (hereinafter referred to as reaction tower 7).

At this time, when the COD concentration of the emulsion wastewater supplied to the reaction tower 7 is low (usually COD (Cr))
(Less than 10,000 mg / L), sufficient heat cannot be recovered because the reaction heat generated when the wastewater is subjected to wet oxidation treatment is small, resulting in insufficient heat quantity in the reaction tower required for wet oxidation treatment, resulting in insufficient heat quantity. In some cases, the heating cost for compensating for this may increase. In particular, when emulsion wastewater discharged from factories is introduced into the reaction tower 7, a large amount of wastewater must be treated and the reaction tower 7 must be enlarged. Therefore, maintenance of installation space and operation of large equipment is required. Or running cost increase may be a problem.

In such a case, the emulsion waste water is used as a microfiltration membrane (hereinafter abbreviated as "MF membrane") or an ultrafiltration membrane (hereinafter abbreviated as "UF membrane") as shown in FIG. When it is supplied to the membrane treatment step 22, the hardly soluble organic matter contained in the emulsion wastewater, particularly the organic matter present in the wastewater in the form of fine particles having an average particle size of 0.01 μm to 100 μm, can be concentrated in the non-permeable liquid, and The downsizing of the tower 7 and the thermal self-sustaining operation can be achieved, and the above problems can be solved.

Here, the UF membrane means the UF film contained in the wastewater.
A filtration membrane having a removal performance for fine particulate hardly soluble organic substances in a unit of 01 μm, and an MF membrane is a filtration membrane having removal performance for fine particulate hardly soluble organic substances in a unit of 0.1 μm contained in wastewater. .

The film material of the UF film and the MF film is not particularly limited, and known UF film and MF film can be adopted. U
Examples of materials for F film and MF film include cellulose, polycarbonate, polyamide, polysulfone, polyether sulfone, polyolefin, vinylidene fluoride, ethylene tetrafluoride, polyacrylonitrile, cellulose acetate, ceramics, metal, porous glass, and carbon. For example, it may be appropriately selected according to the properties (temperature, composition, pH, etc.) of the wastewater to be treated, and which of the UF membrane and the MF membrane should be selected is the type of the wastewater, especially the particle size of the organic matter to be concentrated. It may be appropriately selected according to In the membrane treatment of the present invention, either one of the UF membrane and the MF membrane may be used alone, but any combination of these may be used for wastewater treatment, and the resulting non-permeate may be treated with different filtration membranes in sequence. May be.

The membrane module of the UF membrane and the MF membrane used in the present invention is not particularly limited, and may be, for example, a flat membrane module, a hollow fiber module, a spiral module, a cylindrical module, a pleated module, or the like. A hollow fiber type module or a spiral type module, which has a large membrane area and is suitable for making the apparatus compact, is desirable.

In order to carry out the wet oxidation treatment efficiently, the non-permeable liquid COD (Cr) is preferably 10,000.
0 mg / L or more, more preferably 15,000 mg / L
It is desirable to concentrate until the above. In particular, when the non-permeate is subjected to wet oxidation substantially without using a catalyst, if the COD (Cr) of the non-permeate is 10,000 mg / L or more, the amount of heat required for the wet oxidation treatment should be supplemented by the heat of oxidation reaction. Therefore, the running cost related to heat supply can be reduced as compared with the case of wet-oxidizing unconcentrated emulsion wastewater. Further, if COD (Cr) is too high, the treatment performance in the wet oxidation treatment step may be deteriorated. Therefore, it is preferably 70,000 mg / L or less, more preferably 50,000 mg / L or less.

By subjecting the emulsion wastewater to a membrane treatment, the organic substance to be treated can be concentrated in the impermeable liquid,
As a result, the amount of waste water subjected to the wet oxidation treatment can be reduced, and the wet oxidation treatment facility can be downsized. Moreover, as a result of concentrating the organic matter in the non-permeate, the permeate does not substantially contain the organic matter, and the COD (Cr) of the permeate is extremely low. Or
It may be reused as industrial water or the like, or may be further subjected to any purification treatment such as biological treatment, wet oxidation treatment and combustion treatment.

The effluent of the emulsion drainage as described above,
The specific method of treatment using a UF membrane is not particularly limited, but for example, as shown in FIG. 1, emulsion wastewater discharged from a factory or the like is supplied to a storage tank 22 through a line 21, and further a membrane treatment step through a line 23. 24 may be supplied. At this time, the emulsion wastewater is stored in the storage tank 2.
It may be directly supplied to the membrane treatment step 24 without passing through 2, but when the poorly soluble organic matter is not sufficiently concentrated in the non-permeate,
Since it is preferable to supply the non-permeate again to the membrane treatment step 24 for concentration, it is preferable to provide a storage tank so that the non-permeate can be circulated to the membrane treatment step. The emulsion wastewater may be continuously supplied, but a storage tank is provided to supply the emulsion wastewater to the membrane treatment process according to the membrane treatment capacity, and the emulsion wastewater storage tank is provided according to the overall wastewater treatment capacity. It is desirable to use a batch system for supplying to. Therefore, as shown, the storage tank 22
Is provided, and after supplying the emulsion wastewater according to the capacity of the tank 22 through the line 21, the supply of the wastewater is stopped and the membrane treatment step 2 is performed from the tank 22 according to the membrane treatment capacity.
It is desirable to supply the wastewater to No. 4 while adjusting the pressure and flow rate with a pump not shown. Further, the non-permeate obtained by the membrane treatment process is passed through the line 26 to the storage tank 22.
It is preferable to return the solution to the membrane and supply it to the membrane treatment step until the desired COD (Cr) concentration is reached to concentrate the hardly soluble organic matter. By performing the membrane treatment step in a batch system and circulating the non-permeate into the membrane treatment step 24,
Since the permeated liquid is discharged through the line 25, the amount of drainage can be reduced, which is desirable.

After concentrating the sparingly soluble organic substance to a desired concentration, the non-permeate is sent from the storage tank 22 to the wet oxidation treatment step 28 through the line 27, and the non-permeation liquid in the non-permeation fluid is subjected to the wet oxidation treatment step. The sparingly soluble organic matter is subjected to a wet oxidation treatment, and a cleaning liquid is obtained via the line 29.

In the present invention, the UF membrane or the MF membrane is used in the membrane treatment step as described above, but a reverse osmosis membrane (RO membrane) or a nanofilter (NF membrane) having finer membrane pores than the UF membrane. The use of) also makes it possible to concentrate the finely divided organic matter contained in the wastewater of the emulsion. However, when the RO membrane and the NF membrane are used, the membrane pores are too fine, and therefore they are unsuitable as membranes for separating hardly soluble organic substances existing in water as an emulsion.

The non-permeable liquid obtained by the membrane treatment with the UF membrane and the MF membrane is supplied to the wet oxidation treatment step. At this time, the entire amount of the non-permeable liquid obtained by the membrane treatment may be supplied to the wet oxidation treatment process, or a part of the non-permeable liquid may be wet-oxidized depending on the treatment capacity of the wet oxidation treatment process and the purpose of treatment. It may be supplied to the process and the rest may be supplied to any process, and the amount of the non-permeate liquid supplied to the wet oxidation process is not particularly limited.

By subjecting the non-permeate to a wet oxidation treatment step as described below, the hardly-soluble organic matter in the non-permeate can be wet-oxidized, and highly purified treated water containing almost no organic matter. Is obtained.

Further, a part or all of the permeate of the UF membrane or the MF membrane of the present invention and the purification liquid after the wet oxidation treatment may be supplied to an activated sludge treatment or a biological treatment such as methane fermentation for treatment. Alternatively, other processing such as combustion processing can be performed.

Wastewater pretreated as described above, or pretreatment
Untreated wastewater is introduced from line 1 as shown in Fig. 2.
Wet through the supply pump 2, heat exchanger 5 and heater 6.
It is supplied to the oxidation reaction tower (hereinafter referred to as the reaction tower 7).
The amount of wastewater supplied to the wet oxidation treatment device is not particularly limited
However, the space velocity is 0.1 hr^-1If less than, throughput is reduced
Then, excessive equipment may be required. Conversely, 10 hours
^-1If it exceeds, wet type of poorly soluble organic matter in the reaction tower
Because the oxidation process becomes insufficient, the space around the reaction tower
0.1 hr at speed^-1~ 10 hr^-1, And more preferably 0.
2 hr^-1~ 5 hr ^-1, More preferably 0.3 hr^-1~ 3
hr^-1Supply pump 2 or shown so that it is within the range of
Adjust the supply amount appropriately with a control device such as a supply amount control valve
It is desirable to do.

The heat exchanger 5 and the heater 6 are optional facilities, but in order to accelerate the time for the wastewater to reach the desired processing temperature in the reaction tower 7 and to improve the processing efficiency, the wastewater is beforehand discharged. It is preferable to heat, and from the viewpoint of reducing the heating cost, as shown in the figure, it is desirable to preliminarily heat with a heater after heat exchange with the treatment liquid treated in the reaction tower 7 as a heat source. The heating temperature by the heat exchanger 5 and the heater 6 is not particularly limited.

The preheated waste water is supplied to the reaction tower 7 and subjected to wet oxidation treatment. The wet oxidation treatment can be performed in the presence or absence of an oxygen-containing gas, but increasing the oxygen concentration in the distribution water improves the efficiency of the wet oxidation treatment in the reaction tower. It is desirable to mix the contained gas.

The specific method of supplying the oxygen-containing gas is not particularly limited, but the pump 2 is prepared by mixing the wastewater and the oxygen-containing gas sufficiently and mixing the oxygen-containing gas.
From the viewpoint of preventing cavitation from occurring in the exhaust gas, for example, as shown in the figure, an oxygen-containing gas may be introduced from the oxygen-containing gas supply line 3, pressurized by the compressor 4, and then mixed into the waste water from before the heat exchanger 5. desirable.

The oxygen-containing gas includes oxygen molecules and / or
Alternatively, it is not particularly limited as long as it is a gas containing ozone,
Pure oxygen, oxygen-enriched gas, air, or the like may be used, or hydrogen peroxide solution or oxygen-containing exhaust gas generated in another plant may be used. Among these, it is recommended to use air from the economical point of view.

The supply amount of the oxygen-containing gas is not particularly limited, and it is sufficient to supply an amount effective for enhancing the oxidizing ability with respect to the hardly soluble organic substance. The supply amount of the oxygen-containing gas may be appropriately adjusted by providing the oxygen-containing gas flow rate control valve 4a, for example. The supply amount of the oxygen-containing gas is preferably 0.5 to the theoretical oxygen demand of the hardly soluble organic substance.
It is recommended that the amount of oxygen is 5.0 times, more preferably 0.7 times to 3.0 times. The supply amount of the oxygen-containing gas is 0.
When the amount is less than 5 times, a relatively large amount of the poorly soluble organic matter may remain in the treatment liquid obtained through the wet oxidation treatment without being sufficiently oxidized and / or decomposed. Further, even if oxygen is supplied more than 5.0 times, the improvement of the processing performance corresponding to the supply amount is not recognized.

In the present invention, "theoretical oxygen demand" means that a poorly soluble organic matter is oxidized to carbon dioxide, water, and ash,
It means the amount of oxygen required for decomposition, and the theoretical oxygen demand can also be substituted by COD (Cr).

The reaction temperature of the wet oxidation reaction in the reaction tower 7 is affected by other conditions as well, but if it exceeds 370 ° C., the waste water cannot be kept in a liquid phase state, and there are problems such as enlargement of equipment and an increase in running cost. May occur. Therefore, the reaction temperature is preferably 370 ° C. or lower, more preferably 2
It is preferably 80 ° C. or lower, more preferably less than 180 ° C. On the other hand, if the temperature is lower than 80 ° C, it may be difficult to carry out the wet oxidation reaction efficiently, so that the temperature is preferably 80 ° C or higher, more preferably 100 ° C or higher, and further preferably 110 ° C or higher.

In order to efficiently perform the oxidative decomposition treatment of the poorly soluble organic matter, it is preferable to treat the wastewater at a high temperature, but the wastewater is in a gas state even if the wastewater temperature is within the above range. There is. When the wastewater becomes a gas state, hardly soluble organic substances, inorganic substances, etc. may be deposited inside the reactor, the pipe, etc., and may be clogged or pressure loss may increase. Further, when the waste water becomes a gas state, a large amount of energy is required as heat of vaporization, which causes an increase in running cost for heating, which is not preferable. Also, as will be described later, in the case of wet oxidation treatment using a catalyst, when the wastewater becomes a gas state, hardly soluble organic substances, inorganic substances, etc. adhere to the catalyst surface,
The activity of the catalyst may deteriorate. Therefore, it is recommended to apply pressure to the inside of the reaction tower so that the waste water can maintain the liquid phase even at high temperature. The specific pressurizing method is not limited, but it is desirable to provide a pressure adjusting valve at the exhaust gas discharge port of the reaction tower and appropriately adjust the pressure according to the processing temperature so that the waste water can maintain the liquid phase in the reaction tower. . For example, when the treatment temperature is 80 ° C. or higher and lower than 95 ° C., the wastewater is in a liquid phase even under atmospheric pressure, and it may be under atmospheric pressure from the economical viewpoint, but in order to improve the treatment efficiency, it is added. It is preferable to press. When the treatment temperature is 95 ° C. or higher, the waste water is often vaporized under atmospheric pressure. Therefore, when the treatment temperature is 95 ° C. or higher and lower than 170 ° C., 0.2 to 1 MPa (Gaug
e) a pressure of about 1 to 5 MPa (Gauge) when the processing temperature is 170 ° C. or higher and lower than 230 ° C., and 5 MPa (Gaug) when the processing temperature is 230 ° C. or higher.
e) It is desirable to control the pressure so that the waste water can maintain the liquid phase by applying a super pressure.

In the present invention, the number, type, shape, etc. of the reaction towers are not particularly limited, and a single or a plurality of reaction towers may be arbitrarily combined, and a single-tube reaction tower or a multi-tube reaction tower, etc. Can be used. For example, when a plurality of reaction towers are installed, the reaction towers may be arranged in series or in parallel depending on the purpose.

In the illustrated example, a gas-liquid upward cocurrent flow is used as a method of supplying wastewater to the reaction tower 7, but various forms such as a gas-liquid downward cocurrent flow and a gas-liquid countercurrent flow can be adopted. In the reaction tower, in order to improve the contact efficiency of gas-liquid and reduce the uneven flow of gas-liquid, it is possible to fill a packing material or incorporate an internal crop such as a gas-liquid dispersion plate.

The wet oxidation treatment method in the reaction tower 7 may be a wet oxidation treatment without using a solid catalyst (hereinafter referred to as non-catalytic wet oxidation treatment) or a wet oxidation treatment with a solid catalyst (hereinafter referred to as catalytic wet oxidation treatment). It may be.
However, when treating the wastewater of the emulsion by the catalytic wet oxidation treatment, the sparingly soluble organic matter adheres to the surface of the catalyst to cover the active sites, resulting in a decrease in the catalytic activity and a decrease in the processing performance. In some cases, low molecular weight organic matter remains, and sufficient purification treatment may not be possible. Therefore, it is desirable to treat the wastewater by a non-catalytic wet oxidation treatment that does not cause such problems.

Depending on the type of waste water and the treatment conditions, the poorly soluble organic matter may not be sufficiently oxidatively decomposed by the non-catalytic wet oxidation treatment and the organic matter may remain in the treatment liquid. Is a solubilized organic substance that is oxidatively decomposed and is easily decomposable, so that it can be easily oxidatively decomposed in any treatment step (preferably a catalytic wet oxidation treatment). Further, if the hardly soluble organic matter is converted into the soluble organic matter, the problem that the catalytic activity is lowered hardly occurs even if the treatment is carried out by the catalytic wet oxidation.

Therefore, in order to achieve excellent purification treatment performance while preventing reduction in catalytic activity, the sparingly soluble organic matter in the waste water is converted into soluble organic matter by non-catalytic wet oxidation treatment, and a treatment liquid containing the soluble organic matter is treated. It is desirable to carry out a catalytic wet oxidation treatment.

The packing to be filled in the reaction tower is not particularly limited in terms of material, kind, size, etc., as long as it improves gas-liquid contact efficiency, and various packings can be used. Examples of the material of the filler include metal, ceramic, glass, resin and the like. Examples of the shape of the filler include pellets, spheres, granules, rings (Raschig rings, Lessing rings, ball rings, etc.), honeycombs, nets, and nets or plates having a woven structure. The size of these fillers is also not particularly limited. For example, in the case of pellets, spheres, or rings, the diameter (outer diameter) or major axis is 3 mm to 5 mm.
Are preferred. Also, when using a gas-liquid dispersion plate, the material, type, size, etc. are not particularly limited, and various materials such as a single-hole plate, a perforated plate, a single-hole plate with a collision plate, and a perforated plate with a collision plate can be used. A gas-liquid dispersion plate can be used. Further, these fillers and the gas-liquid dispersion plate may be used together.

Of course, the solid catalyst may be filled in the reaction tower in addition to the above-mentioned packing or gas-liquid dispersion plate, or in place of the packing or gas-liquid dispersion plate. The solid catalyst may be a catalyst that is generally used for wet oxidation treatment that has both activity and durability under liquid phase oxidation conditions. Specifically, at least one selected from the group consisting of titanium, silicon, aluminum, zirconium, manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium, and iridium.
Examples are catalysts containing one or more elements and / or activated carbon. As the activated carbon, in addition to the normally used activated carbon, activated coke, graphite carbon and activated carbon fiber are also included.

The shape of the catalyst is also not particularly limited, and various shapes such as granular, spherical, pellet, ring, crushed, and honeycomb can be used. Among these, spherical and pellet formed. Those are preferable.

The treatment liquid obtained by the wet oxidation treatment as described above is supplied to the gas-liquid separator 9 through the line 1a.
Further, as shown in the figure, it is desirable to appropriately cool the heat exchanger 5 and the cooler 8 if necessary.

In the gas-liquid separator 9, the liquid level controller L
It is desirable to detect the liquid surface state by using C and control the liquid surface control valve 10 so that the liquid surface in the gas-liquid separator becomes constant. The temperature in the gas-liquid separator is not particularly limited, but since carbon dioxide is contained in the treatment liquid obtained by the wet oxidation treatment in the reaction tower, the temperature in the gas-liquid separator is increased, for example. Carbon dioxide in the liquid may be released, or the liquid after being separated by the gas-liquid separator may be bubbled with a gas such as air to release the carbon dioxide in the liquid.

The purification treatment liquid obtained through the line 11 is a highly purified treatment liquid containing substantially few hardly soluble organic substances.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples do not limit the present invention.
All changes and modifications made without departing from the spirits of the preceding and the following are included in the technical scope of the present invention.

[0049]

EXAMPLES Example 1 When treating the emulsion wastewater, a wet oxidation treatment was performed based on the flow of FIG. Wastewater used for treatment is COD (Cr) 12,000 discharged from the chemical plant.
It was an emulsion drainage of mg / L.

The emulsion wastewater was supplied to the reaction tower 7 (cylindrical shape having a diameter of 25 mm and a length of 2000 mm) through the line 1 to perform wet oxidation treatment. A gas-liquid dispersion plate (single hole plate with collision plate) at a distance of 240 mm on the lower side inside the reaction tower.
Was installed so that the layer length was 1,440 mm. A catalyst of 177 mL is installed on top of it, and the catalyst layer length is 360 mm.
So that Emulsion drainage is 177 mL / h
The pressure was fed by the pump 2 so that the flow rate was r, and the air was supplied from the line 3 to the wastewater while the pressure was increased by the compressor 4 so that the flow rate was 14 NL / hr (equivalent to twice the theoretical oxygen demand). Further, the waste water was heated by the heat exchanger 5 and the heater 6 and then supplied to the reaction tower 7 from the lower side to perform wet oxidation treatment (treatment temperature 170 ° C.). The wet oxidation treatment liquid was introduced into the gas-liquid separator 9 after being cooled by the heat exchanger 5 and the cooler 8. In the gas-liquid separator 9, the liquid level controller (LC) detects the liquid level and operates the liquid level control valve 10 to maintain a constant liquid level, and the pressure controller (PC) detects the pressure to control the pressure. The valve 12 was operated and controlled so as to maintain the pressure of 0.9 MPaG.
The treated liquid after gas-liquid separation was discharged through line 11. The COD (Cr) concentration of the obtained treated water was 96 mg / L.

Example 2 When treating the emulsion wastewater, a wet oxidation treatment was performed according to the flow charts of FIGS. 1 and 2. The wastewater used for treatment is
COD (Cr) 7000m discharged from chemical plant
It was an emulsion drainage of g / L. In the membrane treatment apparatus, a hollow fiber type ultrafiltration membrane (FUS-0382 (manufactured by Daisen Membrane Systems) (fraction molecular weight: 30000, membrane material: polyethersulfone) was used as a filtration membrane.

After 50 liters of the emulsion waste water was added to the tank, it was supplied to the membrane treatment apparatus at a pressure of about 0.2 MPa (Gauge). The impermeable liquid was returned to the tank and the membrane treatment was repeated until the COD (Cr) concentration of the impermeable liquid reached 35,000 mg / L. The permeated liquid (COD (Cr):
9 mg / L) was separately supplied to the treatment step. The amount of concentrated waste water when the non-permeated liquid reached the concentration was 10 L.
A reaction tower 8 (a cylindrical shape having a diameter of 25 mm and a length of 2000 mm) which is a wet oxidation treatment device for the concentrated waste water through a line 1.
And subjected to wet oxidation treatment. The reaction tower used at this time was an empty tower with no packing inside. In addition, the waste water is pressure-fed and fed by the pump 2 so that the flow rate is 0.5 L / hr, and the air is supplied through the line 3 to 120 N
It was supplied to the drainage while being pressurized by the compressor 4 so that the flow rate was L / hr (equivalent to twice the theoretical oxygen demand).
Further, the waste water was heated by the heat exchanger 5 and the heater 6 and then supplied to the reaction tower 7 for wet oxidation treatment (treatment temperature 230 ° C.). The wastewater treatment liquid that has been subjected to the wet oxidation treatment is the heat exchanger 5
And, after being cooled by the cooler 8, it was introduced into the gas-liquid separator 9. In the gas-liquid separator 9, the liquid level controller (LC) detects the liquid level to operate the liquid level control valve 10 to maintain a constant liquid level, and the pressure controller (PC) detects the pressure to control the pressure. Operate valve 12 to 4.0M
The pressure was controlled so that the pressure of Pa (Gauge) was maintained. The treated liquid after gas-liquid separation was discharged through line 11. The COD (Cr) concentration of the obtained treated water was 16 mg / liter.

[0053]

INDUSTRIAL APPLICABILITY In the treatment of emulsion wastewater containing a sparingly soluble organic substance, according to the method of the present invention, the sparingly soluble organic substance can be efficiently wet-oxidized, and the treated water obtained is highly purified treated water. Further, according to the method of the present invention for concentrating the poorly soluble organic matter in the waste water, a more efficient wet oxidation treatment becomes possible. In particular, by converting a poorly soluble organic matter into a solubilized organic matter by a non-catalytic wet oxidation treatment and subjecting the solubilized organic matter to a catalytic wet oxidation treatment, it is possible to obtain treated water having a higher treatment efficiency and a higher purification treatment. Therefore, according to the method of the present invention, it is possible to efficiently purify the emulsion wastewater without enlarging the equipment and increasing the running cost, as compared with the conventional treatment method.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of a treatment process of emulsion wastewater of the present invention.

FIG. 2 is a schematic explanatory view showing an example of a wet oxidation treatment process of the present invention using a wet oxidation treatment.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toru Ishii             Hyogo prefecture Himeji city             1 Within Nippon Shokubai Co., Ltd. F-term (reference) 4D006 GA06 GA07 HA01 HA61 KA72                       KB30 MA01 MC02 MC03 MC04                       MC05 MC11 MC18 MC39 MC49                       MC54 MC62 MC63 PA02 PB08                       PB15 PB70 PC11                 4D050 AA13 AB07 AB27 BB01 BC01                       BC02 BC05 BC06 BC07 BD02                       BD03 BD06 BD08 CA09

Claims (4)

[Claims] 1. A method for treating emulsion wastewater, which comprises subjecting the emulsion wastewater to a wet oxidation treatment under a temperature and pressure at which the wastewater retains a liquid phase. 2. The emulsion wastewater is separated into a non-permeate and a permeate using a microfiltration membrane or an ultrafiltration membrane, and the whole or a part of the non-permeate is subjected to wet oxidation treatment.
The processing method described in. 3. The average particle size of the emulsion is 0.0
The treatment method according to claim 1 or 2, which has a thickness of 1 to 100 µm. 4. The non-catalyst wet oxidation treatment of the emulsion wastewater at a temperature and a pressure at which the wastewater maintains a liquid phase, and then a catalytic wet oxidation treatment.
The processing method according to any one of 1.