JPH05177197A - Treatment process for waste water - Google Patents

Abstract

PURPOSE:To remove a COD component and inorganic nitrogen components efficiently and to a high degree out of waste liquid containing the COD component and inorganic nitrogen components and also an inorganic sulfur compound of high concentration without generating malodor gas such as hydrogen sulfide. CONSTITUTION:Organic waste water containing inorganic nitrogen compounds of 3000mg-N/liter or less, a COD component of 100ppm or less and inorganic sulfur compounds/of 30mg-S/liter is biologically treated by anyone of the biological filter process, the rotating disc process and the active sludge process for floating and moving freely a carrier for microbes in an aeration tank under the condition of dissolved oxygen concentration of 0.3-3mg/liter.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an inorganic nitrogen compound and CO
The present invention relates to a method for treating an organic wastewater containing a component D and containing a large amount of an inorganic sulfur compound. Specifically, the present invention relates to a biological treatment method suitable for treating waste liquids such as photographic development waste liquids, brewing and pharmaceutical wastewaters, etc., which have been pretreated by methods such as electrolytic treatment, ozone and ultraviolet light treatment, and wet oxidation treatment. ..

More specifically, when the removal of nitrogen and the removal of COD components from these pretreated waste liquor or a mixture of the pretreated waste liquor and other wastewater are carried out by biological treatment, hydrogen sulfide derived from a large amount of inorganic sulfur compounds is used. The present invention relates to a method for efficiently performing processing without occurrence of

[0003]

2. Description of the Related Art Conventionally, as a biological treatment method for removing nitrogen and COD components from wastewater, a treatment method combining aerobic treatment and anaerobic treatment has been used, and there are several treatment methods. For example, in the three-stage activated sludge method, after COD removal in the first-stage aerobic tank, ammonia is oxidized to nitrate ions in the second-stage nitrification tank, and denitrifying bacteria are removed in the third-stage anaerobic tank. It works to turn nitric acid into nitrogen gas for denitrification.

Further, for example, in the anaerobic-aerobic circulation method, the waste liquid is first introduced into the anaerobic tank. The liquid is circulated from the anaerobic tank to the aerobic tank and from the aerobic tank to the anaerobic tank. Treated water is discharged from the aerobic tank. Nitrification and COD component removal are performed in the aerobic tank, and denitrification and COD component removal are performed in the anaerobic tank.

[0005]

It is known that the wastewater treatment method for removing nitrogen described above is capable of treating organic wastewater such as sewage and human waste fairly well. The wastewater containing various complicated components is discharged as the wastewater of, for example, as a comprehensive wastewater of photographic processing wastewater, brewing and pharmaceuticals, it contains a large amount of inorganic sulfur compounds in addition to the inorganic nitrogen compounds and COD components. Since organic wastewater is discharged and contains inorganic nitrogen compounds and COD components, it is desirable to remove these components by conventional biological treatment methods.

The above-mentioned three-stage activated sludge method and anaerobic-aerobic circulation method include inorganic nitrogen compounds such as ammonia and nitrate ions and organic COD components, and a large amount of inorganic sulfur compounds such as sulfate ions and dithionic acid. When applied to wastewater containing
In these systems, since an independent anaerobic tank is used for biological denitrification, there is a problem that hydrogen sulfide is easily generated in the anaerobic tank.

[0007] The generation of hydrogen sulfide is a problem because if an anaerobic tank is not provided with any deodorizing measures such as a desulfurization device, it emits a malodorous and toxic gas. Further, in the anaerobic-aerobic circulation treatment, hydrogen sulfide generated in the anaerobic tank promotes the growth of filamentous sulfur bacteria which cause bulking in the aerobic tank, which deteriorates the treatment efficiency. A first object of the present invention is to establish an effective detoxification means without environmental pollution over both the water quality of waste liquid and the atmosphere. A second object of the present invention is to provide a means for treating organic pollutant components and inorganic nitrogen components in wastewater inexpensively and efficiently. Further, a third object of the present invention is to efficiently and organically generate a malodorous gas such as hydrogen sulfide in biological treatment of a waste liquid containing a COD component and an inorganic nitrogen component and a high concentration of an inorganic sulfur compound. It is to provide a means for removing COD components and inorganic nitrogen components.

[0008]

The present invention has achieved the above object by the following means. Regarding organic wastewater containing 3000 mg-N / liter or less of inorganic nitrogen compound, 100 ppm or less of COD component and 30 mg-S / liter or more of inorganic sulfur compound, dissolved oxygen concentration 0.3 to 3 m
A method for treating wastewater, which comprises performing any of the following biological treatments (A) to (C) under a condition of g / liter.
(A) Biological filtration method (B) Rotating disk method (C) Activated sludge method in which a carrier for microorganisms is suspended in the aeration tank so that it can be freely moved and treated. Wastewater applicable to the treatment method of the present invention As 30mg
The type of the organic waste liquid is not particularly limited as long as it is an organic waste liquid containing a high-concentration inorganic sulfur compound of -S / liter or more and an inorganic nitrogen compound of 3000 mg-N / liter or less and a COD component of 100 ppm or less. For example, a liquid obtained by subjecting a photo-developing waste liquid, a pharmaceutical waste liquid, a brewing waste liquid, a pickling factory waste liquid, or the like to some pretreatment is targeted.

As a pretreatment method, an electrolytic oxidation method (for example, JP-A-48-84462 and JP-A-49-119458) is used.
Japanese Patent Publication No. 53-43478, Japanese Patent Laid-Open No. 49-1194.
57, etc.), ion exchange method (Japanese Patent Publication No. 51-37704)
No. 5, Japanese Patent Publication No. 53-383, Japanese Patent Publication No. 53-43271, etc.), reverse osmosis method (Japanese Patent Laid-Open No. 50-22463), Fenton oxidation method (Trans, Foroday SOC.
47, 462 (1951), 47, 591 (1951)
)), Iron powder oxidation method (JP-A-58-51982, JP-A-55-35976), ozone oxidation method (Sadajiro Miyata,
Rikumasa Arai, “Ozone oxidation of organic compounds in water”,
Water treatment technology, 22, 2, 145 (1981), etc.), oxidation method using ozone and ultraviolet rays (Environ.
log. , Vol4, No. 4, p252-258,
(1985)), wet oxidation method and the like. As the wet oxidation method, the Chimmermann method (US Pat. No. 2665) is used.
No. 249), or a method of performing wet oxidation in the presence of an oxidation catalyst (JP-B-56-42992, JP-B-59-1).
9757).

That is, by carrying out these pretreatments to bring them within the regulation of the present invention, the biological treatment of the present invention is applied.
These pretreatments can effectively detoxify components that have not been detoxified. Further, a liquid obtained by mixing these pretreated liquids with some other waste liquid is also targeted. Further, a liquid obtained by subjecting these pretreatment liquids to some treatment, for example, removal of ammonia by an ammonia stripping method or the like is also applicable.

The waste liquid which is the object of the processing method of the present invention preferably includes a waste liquid obtained by pre-processing the photographic development waste liquid by some method. Generally, a photographic developing solution contains a high concentration of a COD component, an inorganic nitrogen compound, and an inorganic sulfur compound, and biological treatment is difficult as it is, and it is necessary to perform treatment in advance so as to be within a specified range. The organic wastewater to be treated in the present invention is preferably 200 to 2
000 mg-N / liter of inorganic nitrogen compound, 200-
5000 ppm (more preferably 400 to 3000 pp
m) COD component, 50 to 60,000 mg-S / liter (more preferably 100 to 4000 mg-S / liter of inorganic sulfur compound). These waste liquids use acid or alkali before biological treatment. PH
It is preferably adjusted to 6-8. Examples of the acid used include sulfuric acid, and examples of the alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide and the like.

The photographic processing waste liquid used for pretreatment for use in the processing method of the present invention is a processing liquid generated when a silver halide light-sensitive material is developed. Here, the photosensitive material includes a black and white photosensitive material in addition to a color photosensitive material. For example, color paper, color reversal paper, color negative film for photography, color reversal film,
In addition to film negatives or positive films, direct positive color light-sensitive materials, X ray films, printing light-sensitive materials, microfilms, black-and-white films for photography, and the like.

The photographic processing waste liquid will be described below. The photographic processing waste liquid is mainly composed of photographic processing liquid components. In addition, the photographic processing waste liquid contains reaction products such as oxidants of developing agents, sulfates, and halides generated in the photographic processing process, trace amounts of gelatin dissolved from the photosensitive material, and components such as surfactants. ing.

The photographic processing solution comprises a developing solution used for color processing, black-and-white processing, etc., a fixing solution, a bleaching solution, an image stabilizing solution and the like. Many color paper developers include alkylene glycols and benzyl alcohols together with color developing agents, sulfites, hydroxylamine salts, carbonates, water softeners, and the like. On the other hand, color negative developers, color positive developers, and some color paper developers are
Does not contain these alcohols.

Color developers usually contain an aromatic primary amine color developing agent. It is mainly a p-phenylenediamine derivative, a typical example of which is N, N-diethyl-
p-phenylenediamine, 2-amino-5-diethylaminotoluene, 2-methyl-4- [N-ethyl-N-
(Β-hydroxyethyl) amino] aniline and N-ethyl-N- (β-methanesulfonamidoethyl) -3-methyl-4-aminoaniline. Also, these p-
The phenylenediamine derivative is a salt such as sulfate, hydrochloride, sulfite or p-toluenesulfonate. The content of the aromatic primary amine developing agent is in the range of about 0.5 g to about 10 g per liter of the developing solution.

The color developing solution contains various hydroxylamines as preservatives. Hydroxylamines may be substituted or unsubstituted. In the case of a substituted form, hydroxylamines in which the nitrogen atom is substituted by a lower alkyl group, especially by two alkyl groups (for example, having 1 to 3 carbon atoms) Substituted hydroxylamines. The content of hydroxylamines is 0 to 5 g per liter of color developing solution.

Further, 1-phenyl-3 is contained in the black and white developer.
-Pyrazolidone, 1-phenyl-4-hydroxymethyl-4-methyl-3-pyrazolidone, N-methyl-p-aminophenol and its sulfate, hydroquinone and its sulfonate, etc. are included. Color and black and white developers usually contain sulfites such as sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, sodium metasulfite and potassium metasulfite as preservatives, and carbonyl sulfite adducts. The content of these is 0 g to 5 g / liter. As a preservative, a combination of N, N-dialkyl-substituted hydroxylamine and alkanolamine such as triethanolamine is also used in color and black and white developers. The color and black and white developers have a pH of 9-12. Various buffers are used to maintain the above pH. As a buffer,
Carbonate, phosphate, borate, tetraborate, hydroxybenzoate, glycine salt, N, N-dimethylglycine salt, leucine salt, norleucine salt, guanine salt, 3,4
-Dihydroxyphenylalanine salt, alanine salt, aminobutyric acid salt, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydrosiaminomethane salt, lysine salt and the like can be used. Particularly, carbonates, phosphates, tetraborates, and hydroxybenzoates have excellent solubility and buffering ability in a high pH range of pH 9.0 or higher, and even if added to a developing solution, they adversely affect photographic performance. These buffers are often used because they have the advantages of being free from (fogging, etc.) and being inexpensive. The amount of the buffer added to the developing solution is usually 0.1 mol / liter to 1 mol / liter.

In addition, the developing solution contains various chelating agents which are added as precipitation inhibitors for calcium and magnesium or for improving the stability of the developing solution. Typical examples thereof are nitrilotriacetic acid, diethylenetriaminepentaacetic acid, nitrilo-N, N, N-trimethylenemethylenephosphonic acid, ethylenediamine-N, N, N ', N'-tetramethylenephosphonic acid, 1,3-diamino-2. -Propanoltetraacetic acid, transcyclohexanediaminetetraacetic acid,
1,3-diaminopropane tetraacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid and the like. Two or more of these chelating agents may be used in combination as necessary.

The developing solution contains various development accelerators.
As the development accelerator, thioether compounds, p-phenylenediamine compounds, quaternary ammonium salts, p-
Aminophenols, amine compounds, polyalkylene oxides, 1-phenyl-3-pyrazolidones, hydrazines, mesoionic compounds, thione compounds, imidazoles and the like.

The developing solution often contains bromine ions for the purpose of preventing fogging, but a developing solution containing no bromine ions may be used for a light-sensitive material mainly containing silver chloride. is there. In addition, a compound that gives a chlorine ion such as NaCl or KCl may be contained as an inorganic antifoggant. If desired, various organic antifoggants may be contained. The organic antifoggant may contain, for example, adenines, benzimidazoles, benztriazoles and tetrazoles. The content of these antifoggants is 0.010 to 2 g per liter of the developing solution. These antifoggants include those which are eluted from the light-sensitive material during processing and accumulated in the developing solution.

If desired, various surfactants such as alkylphosphonic acid, arylphosphonic acid, fatty acid carboxylic acid and aromatic acid carboxylic acid may be contained. In black-and-white photographic processing, fixing processing is performed after development processing. Further, in the color photographic process, a bleaching process is usually carried out between the developing process and the fixing process, and the bleaching process may be carried out simultaneously with the fixing process by one-bath bleach-fixing (Brix). The bleaching solution contains EDTA of iron (III) or Co (III) as an oxidant, diethylenetriaminepentaacetic acid,
It contains nitrilotriacetic acid, 1,3-diamino-propanetetraacetate, phosphonocarboxylate, as well as persulfate and quinones. In addition, alkali bromide, a rehalogenating agent such as ammonium bromide, borate salts, carbonates, and nitrates may be optionally contained. The fixer or the bleach-fixer may contain thiosulfate (sodium salt, ammonium salt), acetate, borate, ammonium or potassium alum sulfite.

In the processing of the silver halide photographic light-sensitive material, after the fixing processing or the one-bath bleach-fixing processing,
It is common to carry out washing with water and / or stabilizing treatment.
The pH of the washing water in the processing of the light-sensitive material is 4-9, preferably 5-8. Further, the light-sensitive material can be directly processed with a stabilizing solution instead of the above washing with water. In such stabilization treatment, Japanese Patent Laid-Open No. 57-
8,543, 58-14, 834, 60-220,
All known methods described in No. 345 can be used.

Further, there is a case where further stabilizing treatment is carried out after the water washing treatment, and an example thereof is a stabilizing bath containing formalin and a surfactant, which is used as a final bath of a color light-sensitive material for photographing. be able to. Various chelating agents and antifungal agents can also be added to this stabilizing bath. As the photographic processing waste liquid, there are a waste liquid generated by using the above photographic processing liquid, a reducing liquid accompanying plate making work, a developing treatment tank cleaning liquid, and the like.

The waste liquid containing silver is used for biological treatment after or after the silver recovery treatment. As a method of recovering silver, a method of depositing silver using electrolysis, a method of introducing steel wool, and a method of depositing silver in a solution on steel wool by utilizing a difference in ionization tendency between iron and silver,
A method in which a sodium sulfide solution is added and silver is precipitated as silver sulfide can be used.

The biological treatment method used in the present invention is, for example, a method described in “Wastewater Treatment by Microbial Immobilization Method” edited by Ryuichi Sudo (Industrial Water Research Society). As the biological filtration method, for example, a sprinkling filter bed method, an aerobic fixed bed method, or an aerobic fluidized bed method is used. The biological filtration method and the rotating disk method are methods in which a filter bed, a fixed bed, a fluidized bed or a disk serves as a carrier for microorganisms, and waste water is treated by a biofilm formed thereon.

It is known that the biofilm formed on the carrier has an anaerobic atmosphere as the carrier approaches. When the use of the anaerobic atmosphere inside the biofilm for denitrification of the waste liquid which is the subject of the present invention was examined, hydrogen sulfide was obtained if the dissolved oxygen concentration of the liquid in the biological treatment apparatus was 0.3 to 3 mg / liter. It was found that denitrification was performed without the occurrence of.

That is, the object could be achieved by positively utilizing the anaerobic atmosphere formed in a part of the aerobic treatment tank. As the carrier used for biological filtration, one or more types of granular media such as gravel, sand, activated carbon, anthracite, and plastic materials, or plastic filter media can be used.

As described above, it is possible to create an anaerobic atmosphere in a part of the aerobic treatment tank even in the aeration tank in the activated sludge treatment. That is, in the state where a carrier for microorganisms that can freely move in the aeration tank is added to the aeration tank,
The dissolved oxygen concentration in the aeration tank is 0.3 to 3 mg / liter,
It has been found that when the amount is preferably 0.5 to 2 mg / liter, more preferably 0.5 to 1 mg / liter, the carrier becomes an anaerobic atmosphere and denitrification is performed. The COD component in the waste liquid is used as the hydrogen source for denitrification, but if the COD component alone is insufficient as the hydrogen source, an organic substance such as methanol may be added.

As the carrier for microorganisms, for example, a carrier for entrapping microorganisms as described in “Raw wastewater treatment by microorganism immobilization method” edited by Ryuichi Sudo (published by Industrial Water Research Society) is used. The carrier on which the denitrifying bacteria are entrapped and immobilized is added in an amount of 5 to 30%, preferably 10 to 15% of the volume of the aeration tank. Examples of the material for the immobilization carrier include acrylamide, polyvinyl alcohol, photocurable resin, sodium polyacrylate, sodium alginate, k-carrageenan, polyethylene glycol ester and the like. The size of the entrapping immobilization pellets is a granular material of 2 to 10 mm per piece, and the shape is a cube,
For example, a sphere or a cylinder. The preferred size is 2-5m on a side
m.

Further, as the carrier for microorganisms, for example, a porous granular material having open cells as described in JP-A-58-67395, that is, a sponge-like substance in which the outside and the inside are connected by bubbles is used. Be done. This sponge-like substance is added in an amount of 5 to 40%, preferably 10 to 15% of the volume in the aeration tank. It is not necessary to support microorganisms on the sponge-like substance in advance, and if the sponge-like substance is kept flowing in the aeration tank, the microorganisms propagate inside the pores of the sponge. Dissolved oxygen concentration in the aeration tank is 0.3 to 3
In the state of mg / liter, preferably 0.5 to 2 mg / liter, more preferably 0.5 to 1 mg / liter, the inside becomes an anaerobic atmosphere so that facultative anaerobic bacteria propagate and denitrify. Become.

As the material of the sponge-like substance, polyurethane, urea resin, polyethylene, polypropylene, silicone polymer and the like are used. The size and shape of the sponge-like substance is a cube with sides of 5 to 50 mm, diameter of 5 to 50 mm
The size of the spheres and bubbles is 0.1 to 3 mm. The preferred size is 10 to 20 mm for a cube and 1 for a sphere.
0 to 20 mm, preferably the bubble size is 0.3 to 1 m
m.

Among the inorganic nitrogen compounds contained in the waste liquid to be treated, nitrate ions and nitrite ions are denitrified in an anaerobic atmosphere and removed as nitrogen gas, but ammonium ions can be removed by biological nitrification. It needs to be converted to nitrate or nitrite once. Biological nitrification may be carried out in the same treatment tank in the biological treatment method of the present invention, or a single nitrification tank may be provided separately from the treatment tank to circulate the liquid in the treatment tank and the nitrification tank.

In the activated sludge treatment, nitrification can also be performed by adding a carrier in which nitrifying bacteria are entrapped and immobilized in the aeration tank. Nitrification and denitrification in the same tank were achieved by increasing the size of the nitrifying bacterium entrapping immobilization carrier and the size of the denitrifying bacterium carrier. In this case, the size of the carrier on which the nitrifying bacteria are entrapped and immobilized is preferably 2 to 3 mm on a side,
The size of the denitrifying bacterium carrier is preferably 6 to 10 mm in the case of the entrapping immobilization carrier, and is preferably a cube of 13 to 20 mm on a side and a sphere of 13 to 20 mm in diameter for the sponge-like substance. The nitrifying bacteria entrapping immobilization carrier has an aeration tank volume of 15 to 20.
% Carrier added for denitrification to 1% volume
0-15% added.

The biota used in the present invention may be marine microorganisms derived from seawater or microorganisms derived from fresh water. Marine microorganisms are used when the salt concentration of the wastewater is 3% or more, and freshwater-derived microorganisms are used when the salt concentration is less than 3%.

[0035]

In the treatment method of the present invention, an inorganic nitrogen compound, which is one of the causes of eutrophication of water bodies, and CO, which causes water pollution,
In the D component, and further in the denitrification process, the organic waste liquid containing a high concentration of inorganic sulfur compound which pollutes the atmosphere and adversely affects biological treatment and causes hydrogen sulfide generation is efficiently treated,
It makes it harmless.

The content of the present invention was achieved only by optimizing the treatment conditions and the size and amount of the microbial carrier and finding the most suitable conditions, and is not a simple combination of conventional techniques. That is, by optimizing the dissolved oxygen concentration in the biological treatment tanks of the biological filtration method, rotating disk method, and activated sludge method, both aerobic treatment such as COD component removal and nitrification and anaerobic treatment such as denitrification are compatible in the same tank. It was made possible.

In the case of the activated sludge method, a carrier serving as a carrier for denitrifying bacteria is suspended and flowed in an aeration tank, but denitrification in an aerobic tank becomes possible only by optimizing the size and amount of the carrier. It was

[0038]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to this embodiment. (Explanation of waste liquid used) What is the photographic development waste liquid in the text?
Silver recovery system waste liquid (color photo processing, CN-16 fixer,
CN-16Q bleaching solution, fixing solution, CP-20 bleach-fixing solution, CP-23 bleaching-fixing solution, and black-and-white photographic processing fixing solution, Fuji F , GRF1 waste solution and water 4: 1:
The mixture was mixed at a ratio of 3: 2: 7: 3: 2 and then subjected to silver recovery processing) and a developing solution waste solution (color photographic processing CN-16 ,
CN-16Q , CP-20 , CP-23 developer and black-and-white photographic processing developer RD3 , GRD1 waste solution and water mixed at a ratio of 4: 1: 3: 2: 7: 3: 2 respectively) And are mixed in a volume ratio of 1: 1.

All underlined items are trade names of the processing liquid of Fuji Photo Film Co., Ltd. Example 1 A photographic development waste liquid was processed by the Timmermann method. The processing conditions were 250 ° C., 60 kg / cm ² , and 3 hours. The components of the obtained treatment liquid were COD 2760 ppm,
NH ₃ 8600mg-N / l, T-N9700m
g-N / l, was SO ₄ ^{2- 27000mg-S} / liter.

When ammonia was removed from this solution by the ammonia stripping method, the components of the treatment solution were COD27.
00ppm, NH ₃ 350mg-N / l, T-N
1400 mg-N / L, SO ₄ ^2- 26900m
It was g-N / liter. 4N sulfuric acid was added to the solution
Was adjusted to 7, and the liquid diluted 8 times with water was treated by the aerobic fixed bed method which is one of the biological filtration methods.

The aerobic fixed bed used is shown in FIG. That is,
Wastewater used for biological treatment is introduced into the biological treatment tank 1 through the inflow pipe 4, and is passed downward through the filter medium 2 maintained in an aerobic atmosphere by blowing air from the diffuser pipe 3.
The dissolved oxygen concentration in the liquid is measured using a dissolved oxygen meter 6 inserted in the filter medium 2, and the dissolved oxygen concentration is 0.5 to 1.0.
Air blowing was adjusted so that the amount was mg / l. When the liquid passes through the filter medium 3, the microbial film attached to the surface of the filter medium undergoes biological treatment. The treated water is discharged from the drain pipe 5.

The biological filtration treatment is performed with a COD load of 2 kg / m ^3.
・ Done in a day. The quality of the resulting treated water is CO
D40ppm, NH ₃ 1~5mg-N / l, T-
N20~40mg-N / l, SO ₄ ^2-3300
It was mg-S / liter. No odor was generated by hydrogen sulfide during the treatment. The COD load of biological filtration is 1
0 kg / m ³ · day or less and it is preferably a 2-3 kg / m ³ · day. Comparative Example 1 In the biological filtration treatment in Example 1, the dissolved oxygen concentration in the biological filtration tank was set to 4 to 5 mg / l. When the biological filtration treatment was performed using the same liquid as that used for biological filtration in Example 1, the quality of the obtained treated water was COD 50 ppm,
NH ₃ 1~5mg-N / l, T-N95~100
mg-N / L, was SO ₄ ^{2- 3300mg-S} / liter. There was no bad odor due to hydrogen sulfide during the treatment. Comparative Example 2 Anaerobically using the same liquid as that used for biological filtration in Example 1.
The treatment was carried out by the aerobic circulation method. First, the liquid to be treated continuously flows into the anaerobic tank. The liquid is circulated by a pump between the anaerobic tank and the aerobic tank, and the treated water is discharged from the aerobic tank.

The processing conditions by the anaerobic-aerobic circulation method are as described below. The anaerobic tank and the aerobic tank each have a capacity of 5 liters, and the ratio of the return circulation flow rate (Qr) of the sludge mixed liquid from the anaerobic tank to the aerobic tank and the inflowing wastewater amount (Qs) (γ = Qr / Q
s) was 2.5 and the COD load was 1 kg / m ³ · day. The dissolved oxygen concentrations in the aerobic tank and the anaerobic tank were 3 mg / liter and 0 mg / liter, respectively.

The quality of the resulting treated water is COD9.
0ppm, NH ₃ 1~5mg-N / l, T-N2
0-40mg-N / L, SO ₄ ^-2 3260mg
-S / liter. There was a bad odor due to the generation of hydrogen sulfide during the treatment, and the ability to remove COD components also decreased. From the results of Example 1 and Comparative Examples 1 and 2, by controlling the dissolved oxygen in the biological filtration tank, it is possible to remove the COD component and the inorganic nitrogen component in the same tank without generating a bad odor due to hydrogen sulfide. You can see that Example 2 The same liquid as that used for biological filtration in Example 1 was treated using the activated sludge treatment method. However, the dilution rate is 4 times,
Marine organisms collected from the sea were used for biological treatment. Made of polyurethane as a carrier for microorganisms in the aeration tank.
A cubic sponge of m was added at 15% of the aeration tank volume. The small holes in the sponge are not independent holes but are continuous with each other, and the outside and inside of the sponge are connected.

The sponge freely moves around in the aeration tank due to aeration and mechanical stirring. MLSS in the aeration tank is 50
It is 00 ppm. The activated sludge treatment was carried out for a hydraulic retention time (hereinafter referred to as HRT) of 1 day. The dissolved oxygen in the aeration tank was controlled to 0.5 to 1 mg / l. The quality of the treated water obtained as a result was 60 ppm COD, 1 to 4 mg NH _3.
-N / l, T-N30~50mg-N / l, was SO ₄ ^-2 6400mg-S / liter.
Almost no bad odor was generated by hydrogen sulfide during the treatment. Comparative Example 3 In the activated sludge process of Example 2, the dissolved oxygen concentration in the aeration tank was set to 4 to 5 mg / l, and the same liquid as that used for biological treatment in Example 2 was used for the treatment.
The quality of the treated water obtained was 60 ppm COD, NH ₃ --N
1-5 mg-N / liter, T-N 190-200 mg
-N / l, it was SO ₄ ^{2- 6580mg-S} / liter. No odor was generated by hydrogen sulfide during the treatment. Comparative Example 4 Using the same liquid as the liquid used in the activated sludge treatment method in Example 2 (4-fold diluted solution) and using marine microorganisms in the same manner as in Example 2, treatment by the anaerobic-aerobic circulation method was performed. It was The treatment conditions were the same as in Comparative Example 2.

The quality of the treated water obtained as a result is COD1.
20ppm, NH ₃ 5~10mg-N / l, T-
N50~70mg-N / l, SO ₄ ^-2 6140
It was mg-S / liter. During the treatment, a bad odor due to the generation of hydrogen sulfide was observed, and the COD removing ability was lowered. From the results of Example 2, Comparative Example 3 and Comparative Example 4, in the activated sludge treatment, a sponge made of polyurethane in the shape of a cube of 10 mm on a side having small holes continuously connected from the inside to the outside in the aeration tank. By adding 15% of the aeration tank volume to move freely in the aeration tank and controlling the dissolved oxygen in the aeration tank to 0.5 to 1 mg / liter, most of the offensive odor caused by hydrogen sulfide is generated. It can be seen that the COD component and the inorganic nitrogen component can be removed without using the same tank.

Table 1 shows the results of these measurements.

[0048]

[Table 1]

From these results, according to the method of the present invention, C
It is apparent that the treated water of high quality can be obtained without the generation of a bad odor due to hydrogen sulfide produced by highly treating the OD component and the nitrogen component and reducing the inorganic sulfur compound.

[0050]

INDUSTRIAL APPLICABILITY According to the present invention, inorganic nitrogen compounds and CO, such as photographic processing waste liquid, brewing and pharmaceutical integrated waste water,
COD and nitrogen components can be highly removed by biological treatment of organic wastewater containing a large amount of inorganic sulfur compounds including D component, and the malodor caused by hydrogen sulfide generated during the reduction of inorganic sulfur compounds during the treatment. Never occurs.

[Brief description of drawings]

1 shows a schematic view of a biological treatment tank having an aerobic fixed bed used in Example 1. FIG.

[Explanation of symbols]

 1 Biological treatment tank 2 Filter medium 3 Air diffuser 4 Inlet pipe 5 Drain pipe 6 Dissolved oxygen meter

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Claims (1)

[Claims] 1. An inorganic nitrogen compound of 3000 mg-N / liter or less, a COD component of 100 ppm or less and 30 m.
For organic wastewater containing g-S / liter or more of inorganic sulfur compounds, the biological treatment of any of the following (A) to (C) is performed under the condition of dissolved oxygen concentration of 0.3 to 3 mg / liter. A characteristic wastewater treatment method. (A) Biological filtration method (B) Rotating disk method (C) Activated sludge method in which a carrier for microorganisms is suspended in the aeration tank so that it can be freely moved for treatment