JPH04244299A - Treatment of waste photographic processing solution - Google Patents

Abstract

PURPOSE:To stably and economically make a waste solution harmless in high yield without generating harmful gas or tar by subjecting a liquid mixture of a silver recovery system waste solution and a developing system waste solution in photographic processing to biological oxidation treatment and subsequently subjecting the treated mixture to electrolytic oxidation treatment. CONSTITUTION:At first, a silver recovery system waste solution and a developing system waste solution are mixed to be subjected to biological oxidation treatment. In this process, a biologically decomposable material is effectively decomposed and a COD value can be reduced. The treated water from the biological treatment process is subsequently subjected to electrolytic oxidation treatment. At this time, when alkali is added so as not to make the treated liquid acidic at the time of electrolysis, the generation of halogen gas such as bromine gas or chlorine gas is suppressed and, further, the COD value can be also efficiently lowered. In this process, a material poor in biological decomposition properties such as a chelating agent including EDTA is effectively treated. By performing biological treatment at first, the generation of harmful gas in electrolytic oxidation treatment can be prevented and the contamination of an electrode with tar can be also prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for reducing the pollution load of processing waste liquid of silver halide photographic light-sensitive materials.

0002

[Prior Art] Photographic processing waste liquid generated from the processing of black-and-white and color silver halide photographic light-sensitive materials usually contains a large amount of silver ions eluted from the light-sensitive materials for the purpose of recovering silver, which is a valuable metal. ) and other types (non-silver-containing types) and other types (non-silver-containing types), and silver is recovered from the silver-containing types by a waste liquid treatment company. In general, used processing waste liquids from bleaching and single-bath bleach-fixing processes in fixing processing and color light-sensitive material processing are classified as silver-containing, and used processing waste liquids from developing processing are classified as non-silver-containing. Spent processing waste liquids from water washing and stabilization treatments are classified as either silver-containing or non-silver-containing, depending on the concentration of silver ions contained.

[0003] Conventionally, as a treatment method for reducing the pollution load of these photographic processing waste liquids, a chemical treatment method (Japanese Patent Laid-Open No. 53
-12152, Japanese Patent Publication No. 57-37396, Japanese Patent Publication No. 1983
1-241746 etc.), ion exchange method (Special Publication No. 1-241746, etc.)
No. 37704, Special Publication No. 53-383, Special Publication No. 53-4
3271, etc.), reverse osmosis method (Japanese Patent Publication No. 50-22463), activated sludge method (Japanese Patent Publication No. 55-49559, Patent Publication No. 5
1-12943, etc.), electrolytic oxidation method (Japanese Patent Application Laid-Open No. 1984-1984)
No. 462, JP-A-49-119458, etc.) are known. However, each of these methods has the following drawbacks.

Chemical treatment methods include hydrogen peroxide, persulfate,
Treatment methods by adding perhalogenates, halous acids, and hypohalous acids are known, but they all have extremely poor treatment efficiency for photographic waste liquids that have high COD (chemical oxygen demand) values. This results in the constant use of more drugs than necessary, resulting in higher operating costs. Also, when using resin or membranes such as ion exchange method or reverse osmosis method,
The resin and membrane need to be replaced frequently due to adsorption of substances that easily become polymeric, such as developing agents, and dirt, which tends to increase operating costs.

Although the activated sludge method has low operating costs, it is not very effective against materials with poor biodegradability, especially when using chelating agents such as EDTA (ethylenediaminetetraacetic acid), which is contained in large amounts in photographic waste liquid. Almost never processed.

[0006] Although the electrolytic oxidation method has strong oxidizing power,
■When oxidizing and decomposing wastewater with a high COD value, a large amount of current is required, resulting in high equipment costs and long processing times. ■Organic compounds such as developing agents easily polymerize and contaminate the electrodes. ■When decomposing lower sulfur compounds such as thiosulfates, harmful gases such as hydrogen sulfide are generated. ■In many cases, the decomposition of organic compounds stops at the level of lower fatty acids such as acetic acid and propionic acid, and since these have a BOD (biological oxygen demand) load, the reduction of BOD values may not be sufficient, etc. There are problems.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for effectively solving the above problems. That is, the first object of the present invention is to establish an effective and inexpensive means for detoxifying photographic waste liquid, which causes no environmental pollution in terms of both water quality and the atmosphere.

The second aspect of the present invention is to use biodegradable materials and ED.
The object of the present invention is to provide an effective means for detoxifying photographic processing waste liquid containing materials with poor biodegradability such as chelating agents such as TA.

The third aspect of the present invention is to remove hydrogen sulfide, bromine, and chlorine when electrolytically oxidizing photographic processing waste liquid containing lower sulfur compounds such as thiosulfates and halogen ions such as bromide ions and chloride ions. The purpose of the present invention is to provide an efficient means of processing without generating harmful gases.

A fourth object of the present invention is to provide a means for efficiently treating an electrode without contaminating it when performing an electrolytic oxidation treatment on a developing system waste liquid containing aromatic compounds such as a developing agent. purpose.

[0011]

[Means for Solving the Problems] As a result of various studies, the present inventors have found that the objects of the present invention can be effectively achieved by using the following means for photographic processing waste liquid. That is, a method for processing a photographic processing waste solution, which comprises subjecting a mixed solution of a silver recovery system waste solution and a developing system waste solution in photographic processing to a biological oxidation treatment and then an electrolytic oxidation treatment.

The present invention will be explained in detail. The photographic processing waste liquid used in the method of the present invention is a processing liquid produced when a silver halide photographic light-sensitive material is developed. The silver halide photosensitive materials mentioned here include color photosensitive materials and black and white photosensitive materials. For example, color photosensitive materials include color paper, color reversal paper, color negative film for photography, color reversal film, negative or positive film for movies, direct positive color photosensitive materials, etc., and black and white photosensitive materials include X-ray film, Examples include photosensitive materials for printing, microfilm, and black and white film for photography.

Usually, the used processing waste liquid discharged from these processes contains a large amount of silver ions eluted from the silver halide photographic light-sensitive material into the processing liquid for the purpose of recovering silver, which is a valuable metal. The silver-containing type) and other types (non-silver-containing type) are collected. In general, used processing waste liquid from fixing processing in black and white development, bleaching processing in color development, fixing processing and bleach-fixing processing is classified as silver-containing, while used processing waste liquid from development processing in color development and black and white development does not contain silver. It is classified as silver. The used processing waste liquid from the water washing treatment and stabilization treatment in color development and black-and-white development is classified into silver-containing type or non-silver-containing type depending on the concentration of silver ions contained therein. In the present invention, a silver-containing waste liquid subjected to silver recovery treatment is used as a silver recovery waste liquid, and a non-silver-containing waste liquid is used as a developing system waste liquid.

(a) First, a silver recovery system waste liquid and a developing system waste liquid are mixed and subjected to biological oxidation treatment. If the concentration of inorganic salts in the waste liquid is too high, it is preferable to dilute it to 3% or less, which is the concentration of inorganic salts in seawater, before treatment, as this will stabilize the biota. In addition, if there is a shortage of phosphorus in the waste liquid, add phosphates (for example, KH2PO4, K2HPO4
, NaH2PO4 .2H2O, Na2HPO4) before the treatment, the biota will be stabilized, which is preferable. During the treatment, alkali (sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, etc.) is added to neutralize the sulfuric acid produced by the oxidation of lower sulfur compounds such as thiosulfate and sulfite. In order to keep the biota healthy, it is preferable to maintain the pH at around neutrality so that the pH does not drop too much, and the preferable pH range is from 5.5 to 8.5, particularly preferably from 5.8 to 7.5.

[0015] Examples of the biological oxidation treatment method in the present invention include an activated sludge method, a lagoon method, a trickling filter method, and a rotating disk method. Then you can use anything. Especially Thi
genus obacillus, genus Thiothrix, B
It is preferable to use activated sludge containing biota containing sulfur-oxidizing bacteria such as the genus Eggiatoa, since the bacteria can be acclimatized more quickly and lower sulfur compounds can be efficiently oxidized. For more specific methods of biological treatment, please refer to "Maintenance and Management Technology of Activated Sludge Method" by Toshiro Sakurai.
It is described in "New Activated Sludge Method" by Ryuichi Sudo (published by Science and Technology Development Center), by Sho Hashimoto, and by Ryuichi Sudo (published by Industrial Water Research Association).

[0016] In this biological oxidation process, the biodegradable material is effectively decomposed and the COD value is reduced. As a result, the subsequent electrolytic oxidation treatment step (b)
This can reduce the load and reduce power consumption. In addition, since lower sulfur compounds such as thiosulfate ions and sulfite ions contained in the waste liquid are oxidized to sulfate ions, generation of harmful gases such as hydrogen sulfide is prevented in the subsequent electrolytic oxidation treatment step (b). be able to.

(b) The treated water that has undergone the biological treatment step (a) is then subjected to electrolytic oxidation treatment. At that time, alkali (
For example, adding sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate) to prevent the treatment solution from becoming acidic during electrolysis suppresses the generation of halogen gases such as bromine gas and chlorine gas, and further increases the COD value. This is preferable because it can also reduce the amount of water efficiently. The alkali to be added may be in the form of a solid, an aqueous solution or a suspension, and an appropriate amount may be added in advance before electrolytic oxidation treatment, or p.
It may also be added in conjunction with the H controller. During the electrolytic oxidation treatment, the pH is preferably maintained at 7 or higher, particularly preferably 8 or higher. In the electrolytic oxidation treatment in the method of the present invention, any noble electrode that does not wear out even if the anodic oxidation is performed continuously can be used without particular restriction, but a sufficiently noble electrode that is resistant to oxidation is preferred. Specifically, a material in which the surface of a titanium base material is covered with lead dioxide, platinum, platinum iridium, iridium dioxide, etc. (for example, product name: EXERORD, manufactured by Nippon Carlit Co., Ltd.) is preferable. These anodes can apply high voltage and can efficiently electrolytically oxidize alcohols, aldehydes, carboxylic acids, etc. A voltage of 2 to 10 V, preferably 2 to 8 V per electrode pair is used.

On the other hand, as the cathode, any material may be used as long as it has corrosion resistance and conductivity so as not to cause corrosion while electrolysis is stopped, but a stainless steel plate (or rod) is most suitable. Of course, various carbon electrodes and various metal electrodes can also be used. Anode/cathode pairs can be made by placing the respective electrode plates facing each other at appropriate intervals, or by sandwich-type pairs in which an anode is sandwiched between cathode plates from both sides, or a cathode is sandwiched between anodes from both sides. structure is taken. Here, the shape of the electrode may be any shape such as linear, plate-like, net-like, cloth-like, or spherical, but it is preferable that the electrode has a larger surface area.

The electrolytic cell may be of either a continuous type or a batch type, as long as the filtered separation liquid remains there for a sufficient period of time necessary for the reaction. In addition, stirring in the electrolytic cell can be done by rotating electrodes, using gas generated by electrolysis, blowing gas, moving the liquid with a rotating plate or rod, moving the liquid using a pump or gravity, etc. Any material that moves on the electrode surface may be used. Further, a metal or a metal compound may be added as an electrolytic catalyst.

The amount of current expressed as the product of the flowing current and time is 0.1 to 10 times the equivalent to the COD value.
00 times, preferably 0.5 times to 100 times. Here, the equivalent to the COD value is expressed as twice the product of the COD value removed by the atomic weight of oxygen and the Faraday constant.

In many cases, it is possible to achieve a level that can be discharged into sewers or rivers through the above steps, but especially when high concentration waste liquid is used, it is possible to further reduce the level of waste by combining activated carbon adsorption treatment. can.

The treatment method of the present invention can effectively reduce the COD value by performing electrolytic oxidation treatment after biological treatment. This effect cannot be obtained by performing biological treatment after electrolytic oxidation treatment.

Furthermore, in the electrolytic oxidation treatment of the present invention, by performing biological treatment first, it is possible to prevent the generation of harmful gases and also to prevent tar contamination of the electrodes. Biological treatment oxidizes thiosulfate ions to sulfate ions, thus preventing the generation of hydrogen sulfide, and decomposing aromatic compounds such as developing agents to prevent polymerization. This is thought to be due to the fact that

Furthermore, materials with poor biodegradability such as chelating agents such as EDTA are hardly treated in biological treatment, but are effectively treated in the subsequent electrolytic oxidation treatment. This was also a surprising effect that could not be obtained even if biological treatment was performed after electrolytic oxidation treatment.

[0025] Furthermore, according to the present invention, by mixing the silver recovery system waste liquid and the developer waste liquid for processing, the processing tank can be shared, and the control system can be unified, thereby reducing the equipment cost. can. Furthermore, maintenance operations during operation can be facilitated.

As described above, the treatment method of the present invention is a method that effectively combines the advantages of low-cost biological treatment and high decomposition ability of electrolytic oxidation treatment, and minimizes cost increase due to power consumption. Substances that cause gas and tar generation during the treatment process are decomposed by biological treatment in the previous stage. This makes it possible to obtain a clear processing liquid at minimum cost.

The photographic processing waste liquid applied to the present invention has photographic processing liquid components as its main components.
In addition to materials added to photographic processing solutions, reaction products such as oxidized developing agents, sulfates, and halides produced during photographic processing, and trace amounts of gelatin dissolved from photosensitive materials,
Contains ingredients such as surfactants.

Photographic processing solutions include color processing solutions, black-and-white processing solutions, reducing solutions used in plate-making operations, and development processing tank cleaning solutions. Examples include image stabilizing liquid.

Color developing solutions usually contain an aromatic primary amine color developing agent as a main component. It is mainly p-phenylenediamine derivatives, typical examples being N,N
-diethyl-p-phenylenediamine, 2-amino-5-
diethylaminotoluene, 2-methyl-4-[N-ethyl-N-(β-hydroxyethyl)amino]aniline,
N-ethyl-N-(β-methanesulfonamidoethyl)
-3-methyl-4-aminoaniline. In addition, these p-phenylenediamine derivatives are sulfates, hydrochlorides,
Salts such as sulfites and p-toluenesulfonates. The content of the aromatic primary amine developing agent ranges from about 0.5 g to about 10 g per liter of developer solution.

In addition, 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, and the like.

Color and black and white developers contain preservatives such as
It usually contains sulfites such as sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, sodium metasulfite, potassium metasulfite, and carbonyl sulfite adducts, and the content of these is 0g per liter of developer. ~5g.

Color and black and white developers contain various hydroxylamines as preservatives. Both substituted and unsubstituted hydroxylamines can be used. Substituted products include those in which the nitrogen atom of hydroxyalumines is substituted with a lower alkyl group, especially N substituted with two alkyl groups (for example, carbon number 1 to 3).
, N-dialkyl-substituted hydroxylamines. Also used are combinations of N,N-dialkyl substituted hydroxylamines and alkanolamines such as triethanolamine. The content of hydroxylamines is 0 to 5 g per liter of developer.

Color and black and white developers have a pH of 9-12. Various buffers are used to maintain the above pH. Buffers include carbonate, phosphate, borate, tetraborate, hydroxybenzoate, glycine salt, N
, N-dimethylglycine salt, leucine salt, norleucine salt, guanine salt, 3,4-dihydroxyphenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, Proline salts, trishydrocyaminomethane salts, lysine salts, etc. can be used. In particular, carbonates, phosphates, tetraborates, and hydroxybenzoates have excellent solubility and buffering ability in the high pH range of pH 9.0 or higher, and even when added to the developer, they do not adversely affect photographic performance. These buffering agents are often used because they have the advantages of being free from fog (fogging, etc.) and being inexpensive. The amount of the buffer added to the developer is usually 0.1 mol to 1 mol per liter of the developer.

[0034] In addition, various chelating agents are added to the developer to prevent precipitation of calcium or magnesium, or to improve the stability of the developer. Typical examples include nitrilotriacetic acid, diethylenetriaminepentaacetic acid, nitrilo-N,N,N-trimerimethylenephosphonic acid, ethylenediamine-N,N,N',N'-tetramethylenephosphonic acid, and 1,3-diamino-2 -propanoltetraacetic acid, transcyclohexanediaminetetraacetic acid, 1,3-diaminopropanetetraacetic acid, 2-phosphonobutane-1,2,
4-tricarboxylic acid, 1-hydroxyethylidene-1,
Examples include 1-diphosphonic acid. Two or more of these chelating agents may be used in combination, if necessary.

The developer contains various development accelerators. As the development accelerator, thioether compounds, p-phenylenediamine compounds, quaternary ammonium salts, p-
These include aminophenols, amine compounds, polyalkylene oxides, 1-phenyl-3-pyrazolidones, hydrazines, mesoion type compounds, thione type compounds, imidazoles, and the like.

Many color developers for color paper are
It contains alkylene glycols and benzyl alcohols along with the above 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 do not contain these alcohols.

[0037]Although the developer often contains bromide ions for the purpose of preventing fogging, it is also possible to use a developer that does not contain bromide ions for photosensitive materials containing silver chloride as the main ingredient. be. In addition, N is used as an inorganic antifoggant.
It may contain compounds that provide chloride ions, such as aCl and KCl. They also often contain various organic antifoggants. As an organic antifoggant,
For example, it may contain adenines, benzimidazoles, benztriazoles, and tetrazoles. The content of these antifoggants is 0.010 g to 2 g per liter of developer. These antifoggants include those that are eluted from the photosensitive material during processing and accumulate in the developer. In particular, in the present invention, it is also possible to effectively treat waste liquids in which the total concentration of halogen ions, such as bromide ions and chloride ions, is 1 mmol or more per liter of mixed liquid. This is particularly effective when the bromide ion concentration is 1 mmol or more per liter of the mixed solution.

The developing solution also contains various surfactants such as alkylphosphonic acids, arylphosphonic acids, fatty acid carboxylic acids, and aromatic carboxylic acids.

In black-and-white photographic processing, a fixing process is performed after the developing process. In color photographic processing, a bleaching process is usually performed between the developing process and the fixing process, and the bleaching process is sometimes performed simultaneously with the fixing process by bleach-fixing (Brix). The bleaching solution contains iron (II) as an oxidizing agent.
I) or Co(III) EDTA, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, 1,3-diamino-propanetetraacetic acid salt, phosphonocarboxylate salt, persulfate salt, quinones, etc. are included. In addition, it may contain appropriate rehalogenating agents such as alkali bromide and ammonium bromide, borates, carbonates, and nitrates. Fixers and bleach-fixers usually contain thiosulfates (sodium salts,
ammonium salts), acetates, borates, ammonium or potassium alum sulfites, etc.

In the processing of silver halide photographic materials, it is common to perform a fixing process or a bleach-fixing process, followed by washing with water and/or a stabilizing process. In the water washing process, problems such as bacteria breeding in the processing tank and the resulting floating substances adhering to the photosensitive material may occur. As a solution to this problem, calcium ions, as described in Japanese Patent Application Laid-Open No. 131632/1982, are added to the washing water.
A method of reducing magnesium ions can be used. In addition, chlorine-based disinfectants such as isothiazolone compounds, cyabendazole, chlorinated sodium isocyanurate, and other benzotriazoles described in JP-A No. 57-8542, "Chemistry of Antibacterial and Antifungal Agents" by Hiroshi Horiguchi , "Sterilization, sterilization, and anti-mildew technology of microorganisms" edited by Sanitation Technology Society, and "Encyclopedia of antibacterial and anti-fungal agents" edited by Japan Society of Antibacterial and Antifungal Agents may also be used.

[0041] Following such washing treatment with washing water, or instead of washing treatment, stabilization treatment using a stabilizing bath may be performed. An example thereof is a stabilizing bath containing formalin and a surfactant, which is used as a final bath for color photographic materials. Various chelating agents and antifungal agents can also be added to this stabilizing bath.

[0042]

EXAMPLES The present invention will be explained in more detail below based on Examples, but the present invention is not limited thereto. [Description of waste liquid used] Commercially available photographed multilayer color negative film, Fujicolor SUPER HG (hereinafter referred to as SHG-
)100, SHG-200, SHG-400, SHG-
1600, REALA (all product names, manufactured by Fuji Photo Film Co., Ltd.), Kodacolor GOLD (hereinafter referred to as GOLD-) 10
0, GOLD-200, GOLD-400, GOLD-
1600, Ector 25, Ector 125, Ector 1
000 (all product names, manufactured by Eastman Kodak), Conicolor GX (hereinafter referred to as GX-) 100, GX200, G
X-400, GX-3200, Konica Color GXII (
Hereinafter, GXII-) 100 and GX-100M (all product names, manufactured by Konica) will be mixed together without any particular distinction, and will be sequentially described as FP90 film processor for minilab.
Processing was carried out using 0AL (trade name, manufactured by Fuji Photo Film Co., Ltd.) using developed color negative CN-16Q (trade name, manufactured by Fuji Photo Film Co., Ltd.) as a processing liquid. The overflow liquids from the developing bath and washing bath were used as color negative developing system waste liquid, and the overflow liquids from the bleaching bath and fixing bath were used as color negative bleaching/fixing system waste liquid. In addition, prints were printed from the color negative onto commercially available color paper (Fuji Color Paper SUPER, FA, manufactured by Fuji Photo Film Co., Ltd.), and processed using Fuji Mini Lab Champion FA-170 printer processor PP1800B (product name, manufactured by Fuji Photo Film Co., Ltd.). Processing was performed using CP-43FA (trade name, manufactured by Fuji Photo Film Co., Ltd.), which has been processed for color paper, as a liquid. The overflow liquid of the developing bath at this time was used as a color paper development system waste liquid, and the overflow liquid of the bleach-fixing bath and the washing bath was used as a color paper bleach-fixing system waste liquid. A 1:1 mixture of color negative developing system waste liquid and color paper developing system waste liquid is called color developing system waste liquid, and a 1:1 mixture of color negative bleaching/fixing system waste liquid and color paper bleaching/fixing system waste liquid is called color bleaching.・Used as fixing system waste liquid.

Commercially available black and white negative films Neopan SS, Neopan 400 PRESTO, Neopan 16
00SUPER PRESTO (trade name, manufactured by Fuji Photo Film Co., Ltd.) was mixed with various types without particular distinction, and the waste liquid was treated sequentially using the developer Fujidol and the fixer Fujifix (trade name, manufactured by Fuji Photo Film Co., Ltd.). 5 liters each and commercially available black and white paper (
Prints were printed from negatives on Fujibro WP (manufactured by Fuji Photo Film Co., Ltd.), and 5 liters each of waste liquid was processed using the developer Corrector and the fixer FujiFix (all trade names, made by Fuji Photo Film Co., Ltd.), and medical grade X. Ray photosensitive materials, MI-SF and MI-SFII (all trade names, manufactured by Fuji Photo Film Co., Ltd.) were mixed with developer RD-3 and fixer F.
10 liters each of the waste liquid from processing with uji-F (all trade names, manufactured by Fuji Photo Film Co., Ltd.) and developer G of the Fuji GRADEX series printing photosensitive material system.
10 liters each of waste liquid from R-D1 and fixer GR-F1 (all trade names, manufactured by Fuji Photo Film Co., Ltd.) were divided into a developer and a fixer and mixed to make 30 liters each. It was used as waste liquid of black and white fixing system.

A color developing system waste liquid and a black and white developing system waste liquid were mixed at a ratio of 1:1 to obtain a developing system waste liquid. In addition, the color bleaching/fixing system waste liquid and the black and white fixing system waste liquid are mixed at a ratio of 1:1,
The silver recovery treated liquid was used as silver recovery system waste liquid. In this example, a processing solution was used in which the developing system waste solution and the silver recovery system waste solution were mixed at a ratio of 1:1.

[0045] The COD value of the above mixed liquid is 45 according to the manganese method.
000 ppm, and this mixed solution contains 0.084 mol of hydroquinone and 0.01 mol of N-ethyl-N-(β-methanesulfonamidoethyl)-3-methyl-4 per liter of the mixed solution as developing agents. -aminoaniline, 0.015 mol of 2-methyl-4-[N-ethyl-
Contains N-(β-hydroxyethyl)amino]aniline, and also contains 0.31 mol of thiosulfate ion and 0.12 mol of sulfite ion per liter of mixed liquid as lower sulfur compounds, and as a chelating agent. The mixture contained 0.99 mmol of EDTA per liter. Also, bromide ion is 0.04 per liter of mixed liquid.
7 mol, chloride ion is 0.0 per liter of mixed solution
It contained 0.4 mole. Further, the concentration of inorganic salts contained in the mixed liquid was 12%.

Example 1 The above mixed solution was diluted 10 times with tap water, and phosphorus was added to this solution in the form of dipotassium hydrogen phosphate at a COD value (4500p).
pm) was added in an amount corresponding to 3% of pm). Furthermore, calcium ions and magnesium ions are added at 10ppm and 2p, respectively.
pm. This waste liquid was converted into activated sludge containing sulfur-oxidizing bacteria (MLSS (activated sludge suspended solids) 4500p
Continuous treatment was carried out at 2 days (pm) with an average residence time of 2 days. The generated sulfuric acid was neutralized with a 10% aqueous sodium hydroxide solution, and the pH inside the aeration tank was maintained at not lower than 6.6. In the above continuous biological treatment, the treated liquid after reaching a steady state was used as the treated water in step (a). The filtrate, which has been filtered to remove suspended matter from this treated water, is used as an anode with a lead dioxide electrode (
Electrolytic oxidation treatment was carried out by dispensing the solution into five 2-liter capacity electrolytic cells connected in series, each having a stainless steel (SUS316) plate attached to the cathode on both sides of the anode (LD400 model, manufactured by Nippon Cartrit Co., Ltd.) connected in series. A current of 10 A was applied while vigorously stirring. (Above, step (b))
In the above treatment, the data of treated water 1 and 2, which were treated by changing the energization time in step (b), are shown in No. 1 in Table 1.
1.No. Shown in 2. Note that the pH of both treatment solutions was about 1.9. In this way, by the treatment of the present invention, C
It was possible to obtain clear treated water with a low pollution load, with an OD value of 330 ppm or less and EDTA of 0.01 mmol or less. Furthermore, no hydrogen sulfide gas was generated in any of the treatments, and the anode was not contaminated. By further repeating the above operations, it was possible to continue processing with good reproducibility.

Example 2 After carrying out the same process (a) as in Example 1, in step (b), one electrolytic cell similar to Example 1 was charged with pH
Attach the controller and adjust the pH during electrolytic oxidation to 8±0.1 while adding 10% sodium hydroxide aqueous solution.
A current of 10 A was applied while stirring strongly. In the above treatment, the data of treated water 3 and 4, which were treated by changing the energization time in step (b), are shown in Table 1.
o. 3.No. 4. As in Example 1, the treatment of the present invention resulted in a COD value of 140 ppm or less, EDTA
It was possible to obtain clear treated water with a small pollution load of 0.01 mmol or less. No. of Example 1 1,
No. As is clear from comparison with No. 2, the COD value can be reduced even with the same energization time. In addition, no hydrogen sulfide gas was generated in any of the treatments, and not only was the anode not contaminated, but no halogen gas was generated at all.

Example 3 Treated water 2 in Example 1 and treated water 2 in Example 2 were treated with granular activated carbon TYPESGL (manufactured by Toyo Calgon Co., Ltd.).
When the treated water was poured into a column, the COD values of the resulting treated water were 50 ppm and 27 ppm, respectively, indicating good results.

Comparative Example 1 The same treatment as in Example 1 was carried out without performing step (a) in Example 1. Such treated water5,6
The data are shown in Table 1. 5, No. 6. Compared to Example 1, the COD value did not decrease sufficiently during the same current application time, and hydrogen sulfide gas was generated during the electrolytic oxidation treatment. Furthermore, EDTA could not be completely decomposed. Additionally, tar is generated, which significantly contaminates the electrodes.
In order to perform repeated treatments, the tar adhering to the electrodes had to be removed.

[0050]

[Table 1]

Comparative Example 2 In Comparative Example 1, for the treated water 7 that was energized for 6 hours, phosphorus was added to the COD value (
1100 ppm), and further added calcium ions and magnesium ions at 10 ppm each.
, 2 ppm. Furthermore, a 10% aqueous sodium hydroxide solution was added to bring the inside of the aeration tank to pH 7. This liquid was mixed with activated sludge (MLSS45) containing sulfur-oxidizing bacteria.
Continuous biological oxidation treatment was carried out at 00 ppm) with an average residence time of 2 days. That is, contrary to the treatment process of the present invention, the electrolytic oxidation treatment was performed and then the biological oxidation treatment was performed. The COD value of this treated water was 550 ppm, and Example 1
Compared to that, the reduction was still not sufficient at the same energization time. Also, the concentration of EDTA is 0.08 mmol,
It was not completely disassembled.

[0052]

[Effects of the Invention] By using the processing method of the present invention, photographic processing waste liquid containing both biodegradable materials and materials with poor biodegradability such as chelating agents such as EDTA can be processed without harmful gases or tar. It can be processed stably and economically at a high processing rate without causing any problems.

Claims (2)

[Claims] 1. A method for treating a photographic processing waste liquid, which comprises subjecting a mixed liquid of a silver recovery system waste liquid and a developing system waste liquid in photographic processing to a biological oxidation treatment and then an electrolytic oxidation treatment. 2. The method for treating photographic processing waste liquid according to claim 1, wherein an alkali is added in the electrolytic oxidation treatment.