JPH04197489A - Treatment of waste water containing oxidizable substance - Google Patents

Abstract

PURPOSE:To efficiently reduce the amount of the oxidizable substance in waste water by adjusting the pH of waste water containing the oxidizable substance to 10 or more to allow oxygen or oxygen-containing gas to act on the waste water to subject the oxidizable substance to oxidative decomposition and subsequently electrolyzing the treated water. CONSTITUTION:In a process (hereinbelow referrent to as 'the first process') wherein the pH of waste water containing an oxidizable substance is adjusted to 10 or more and oxygen or oxygen-containing gas is allowed to act on this waste water to subject the oxidizable substance to oxidative decomposition, the oxidizable substance contained in the waste water is reacted with oxygen to reduce COD value. When the pH of the waste water is adjusted to 10 or more, reaction is well advanced and the reducing degree of the COD value is increased. By this method, the power consumption of the succeeding process for electrolyzing the treated water obtained in the first process is reduced. Further, the electrode and electrolytic cell used in electrolysis can be made small and a treatment time can be shortened. By using the aforementioned method, clear treated water can efficiently and continuously be obtained from waste water within a short time over a long time.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to waste liquids containing oxidizable substances, particularly waste liquids that are polymerized by electrolytic oxidation to produce polymers with a molecular weight of 1000 or more, or substances that are insoluble in water. Oxidizable substances in waste liquids containing organic substances that produce organic substances, such as photographic waste liquids from developing solutions and fixing solutions, are purified by electrolytic oxidation during electrolysis, and their high COD value (chemical oxygen demand) is purified. The present invention relates to a treatment method for easily removing components having .

[Conventional technology]

When dumping liquid waste (waste liquid) or discharging it into rivers or sewage, it is safe to meet certain standards for environmental pollution factors such as toxic metals, PFL, oxygen consumption, and toxic organic compounds such as trichlorethylene. must be confirmed.

Conventionally, various effective detoxification methods have been implemented for large-scale liquid industrial waste (for example, several tons or more discharged per day), and there are no problems, but for small-scale liquid waste, While it is difficult to install large-scale equipment, it often does not meet the permissible requirements of the Sewage Law to dispose of it into the sewer system.For example, small and medium-sized printing plates, photo processing,
Many of the waste fluids discharged from factories such as metal processing emlating and food processing factories are equivalent to this.When it comes to detoxifying these small-scale waste fluids, unlike the case of large-scale treatment,
The purpose must be sufficiently achieved using simple means and a small device, and various methods have been proposed or implemented to meet this requirement.

For example, in order to reduce COD (oxygen consumption is represented by COD (chemical oxygen consumption)), chemical oxidation methods using chlorine, hypochlorite, ozone, etc. are used, especially hydrogen peroxide and metals or metals. A method using a compound, activated carbon,
Including adsorption removal methods using inorganic adsorbents or organic polymer materials, evaporation methods that heat and evaporate waste liquid, and trickling filter methods.
Various small-scale biological treatment methods that simplify activated sludge treatment,
Reverse osmosis and dialysis methods, which separate waste liquid into reusable concentrated liquid and disposable diluted liquid, are being implemented.

[Problems to be solved by the invention] These various methods are effective for reducing COD, effective for removing harmful metals, suitable for concentrated liquids but not suitable for dilute liquids, Or the opposite is true. However, when the environmental contamination factors in the waste liquid are multiple and complex (which is usually the case), it is difficult for either method to detoxify the waste liquid to a sufficiently satisfactory level.

An example of such a waste liquid is a silver halide photographic material processing waste liquid. This waste liquid includes developing waste, fixing waste, bleaching waste, or bleach-fixing waste discharged in the photographic processing process, or waste liquid from other liquid baths, and contains organic and inorganic COD contributing components, heavy metal compounds such as silver and iron. , contains high concentrations of salts, especially large amounts of bromide and iodide ions, and environmental pollution factors include COD, BOD, heavy metals, pH in some cases, and phenols. Therefore, detoxification treatment is a difficult problem because it must be an effective means from each aspect.

Therefore, an evaporation method can be cited as a solution for processing all at once with one means. That is, if the waste liquid is evaporated into a concentrated waste liquid or solid sludge residue that is easy to dispose of, it is discharged into the environment in liquid form.

Since there will be no waste, the problems of various water pollution factors mentioned above will be solved. However, a large amount of steam is generated during this process, and volatile substances enter into the steam, resulting in new problems such as foul odors and air pollution due to harmful substances. Therefore, one possible measure is to re-condense the evaporated gas and recover it as a liquid, but the COD of this condensed liquid becomes a new environmental pollution factor.

In addition, a method of treating evaporation condensate of waste liquid with activated carbon is known, but in the case of many photographic processing waste liquids, there are problems such as the short lifespan of the activated carbon column and the high frequency of replacement (replacement is time-consuming). It became.

On the other hand, conventional electrolytic oxidation treatment methods (e.g., JP-A-63-116796) for silver halide photographic processing waste liquids require a large amount of electric current to oxidize and decompose waste liquids containing large amounts of oxidizable substances. There were problems such as high equipment costs and long processing times; and (1) waste liquid containing substances that easily convert into polymers, such as compounds with aromatic rings, contaminating the electrodes.

The present invention aims to provide a new method that effectively solves the above problems.

That is, the first object of the present invention is to establish an effective detoxification means that does not cause environmental pollution of both the water quality and the air of waste liquid as described above.

Moreover, secondly, the present invention has many types of contained components, and
The purpose is to provide a cheap, simple, and reliable means of abatement suitable for concentrated waste liquid.

A third object of the present invention is to provide an effective means for eliminating harmful substances from waste liquid containing substances that are polymerized by electrolytic oxidation during electrolysis and easily contaminate electrodes and the like.

Furthermore, a fourth object of the present invention is to provide a method for shortening the time required for detoxifying waste liquid as described above and for performing the treatment at a high level.

Particularly, it is an object of the present invention to provide a processing method for photographic processing waste liquid in which the above-mentioned objectives can be particularly effectively achieved.

[Means to solve the problem]

As a result of various studies, the present inventors found that the object of the present invention can be effectively achieved by using the following means.

In the present invention, after treating the waste liquid as described above with oxygen,
The above-mentioned problems were solved by electrolyzing the treated water.

That is, the present invention allows waste liquid containing oxidizable substances to be
810 or higher, the oxidizable substance is oxidized and decomposed by the action of oxygen or a gas containing oxygen, and the resulting treated water is then electrolyzed. .

Furthermore, the present invention is particularly effective for waste liquids that produce polymers with a molecular weight of 1,000 or more through electrolytic oxidation during electrolysis, or that contain substances that are insoluble in water.

Specifically, the present invention is particularly effective when the waste liquid is an aqueous solution and is a silver halide photographic processing waste liquid.

The present invention will be explained in further detail.

In the present invention, the waste liquid containing oxidizable substances is
As described above, in the step of oxidizing and decomposing the oxidizable substance by applying oxygen or a gas containing oxygen (hereinafter referred to as the "first step"), the oxidizable substance contained in the waste liquid is reacted with oxygen. It depends on whether the COD value is reduced or not.

At this time, when the pH of the waste liquid is set to 10 or more, the reaction proceeds well and the degree of reduction in the COD value increases. This reduces power consumption in the subsequent step of electrolyzing the treated water obtained in the first step (hereinafter referred to as "second step"). Therefore, the electrodes and electrolytic bath used for the electrolysis can be made smaller, and the processing time can also be shortened.

Furthermore, when waste liquid is electrolyzed without the first step, the electrodes are often contaminated with tar-like substances, reducing current efficiency, and periodic cleaning of the electrodes is required.

However, surprisingly, no such electrode contamination was observed in the method of the present invention. Therefore, when the method of the present invention is used, clear treated water can be obtained continuously from wastewater in a short time and efficiently over a long period of time.

Next, the processing steps of the present invention will be explained.

(1) If the waste liquid containing oxidizable substances is not p) 10 or more, it is also mixed with solid or aqueous solutions or suspensions of hydroxides of alkali metals such as sodium and potassium, or alkaline earth metals such as calcium and barium. The pH of the waste liquid is adjusted to 10 or higher, preferably 11 or higher, and more preferably 13 or higher.

(2) Next, oxygen or an oxygen-containing gas such as air is aerated into the waste liquid made alkaline to a pH of 10 or more in (1). The amount of aeration at this time is preferably 1j of waste liquid! 40 as the amount of oxygen at 25℃ and la't-
ffi or more, more preferably 801 or more
The appropriate ventilation time is 5 to 300 minutes, but 40 minutes
~200 minutes is preferable since the total power consumption including the second step can be reduced.

The contact method at this time can be any of the following methods: aeration into the liquid, passing the liquid through a stream of air (by shower, etc.), or strong stirring.If precipitates are formed in the liquid after this treatment. It is preferable to separate and remove it before proceeding to the next step.

(3) Next, the liquid treated in (2) is electrolyzed and subjected to electrolytic oxidation. In order to perform strong electrolytic oxidation, it is better to have a high oxygen generation potential at the anode, so it is preferable to use a non-toxic electrode material as the anode. Practically, in the method of the present invention, any electrode that does not wear out even when electrolytically oxidized continuously can be used as the anode without any particular restrictions. If the waste liquid contains highly reducing organic compounds such as developing agents or alcohols, the anode should preferably be a sufficiently reductive electrode that is resistant to oxidation. Specifically, lead dioxide, platinum, platinum iridium, etc. The surface of the titanium base material is covered with iridium dioxide, etc. (for example, the product Meiko Xerode, manufactured by Nippon Carlit Co., Ltd.) is preferable.These anodes can apply high voltage, and alcohol,
Efficient electrolytic oxidation of aldehydes, carboxylic acids, etc. A voltage of 2 to IOV, 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. An anode/cathode pair is a sandwich type in which each electrode plate is placed opposite each other at appropriate intervals, or the anode is sandwiched between the cathode plates from both sides, or the anode is sandwiched between the cathode and the anode from both sides. An appropriate structure such as a pair is taken.The shape of the electrode may be any shape such as linear, plate, net, cloth, or spherical, but the larger the surface area of the electrode, the more preferable.The electrolytic cell is a continuous type, In either batch type, it is sufficient for the waste liquid to remain for a sufficient period of time required for the reaction, and the stirring in the electrolytic cell can be done by rotating electrodes, by using gas generated by electrolysis, by blowing gas, by using a rotating plate, or by Any device that moves the liquid on the electrode surface may be used, such as one that moves the liquid with a rod, a pump, or one that uses gravity.

Further, a metal or a metal compound may be added as an electrolytic catalyst.

After completing the above treatment steps, it is preferable to perform filtration separation, activated carbon treatment, or treatment with activated sludge alone or in combination.

In addition, between the first step and the second step of the present invention, the liquid is once made neutral or acidic to remove the generated insoluble matter, or the decomposition is accelerated by neutrality or acidity, and further Advanced processing is also possible.

In the present invention, it is preferable to make it acidic. In this case, the acid used to make it acidic is preferably sulfuric acid, hydrochloric acid, nitric acid, etc., but it is preferable to make the pH 2 or less. In order to generate and dissipate, a treatment may be performed to add an alkali that generates insoluble matter, and the alkali used at this time is preferably an alkaline earth metal chloride, hydroxide, or oxide. Preferably, calcium hydroxide is used.

Waste liquids to which the method of the present invention can be applied include photographic processing waste liquids, electroplating waste liquids, and various other conductive industrial waste liquids.In the present invention, by air oxidation in alkaline conditions, polymerization etc. Since substances that are easily insolubilized in the step change to water-soluble compounds, it is possible to prevent electrode contamination in the second step.

The present invention uses hydroquinone and aromatic primary amines at 0.0
1-■ol~10mol/j! It is particularly effective for waste liquids containing Hydroquinone becomes quinhydrone in electrolytic oxidation and becomes insolubilized, and developing agents such as aromatic primary amines become polymers with a molecular weight of 1000 or more and become tar due to electrolytic oxidation.However, in the present invention, electrolytic oxidation Insolubilization and tar formation can be prevented without affecting.

Specifically, hydroquinone used in photographic processing is il.
[By chemical reaction, it changes to benzoquinone and then to more water-soluble polyhydroxybenzene and carboxylic acid.

The photographic processing waste liquid for which the method of the present invention is particularly effective will be described below.

The photographic processing waste liquid is mainly composed of photographic processing liquid components. In addition, photographic processing waste liquid also contains reaction products such as oxidized products of developing agents, sulfates, and halides produced during the photographic processing process, as well as components such as trace amounts of gelatin and surfactants dissolved from photosensitive materials. It is.

Photographic processing liquids include color processing liquids, black and white processing liquids, reducing liquids used in plate-making operations, and development processing tank cleaning liquids.Photographic processing liquids include black and white developers, color developers, fixing solutions, bleaching solutions, and bleach-fixing solutions. , image stabilizing liquid, etc.

The method of the present invention is particularly effective for waste liquid containing a developer (black and white developer, color developer).

Therefore, the composition of the developer will be explained below.

Many color developers for color paper contain alkylene glycols and benzyl alcohols along with color developing agents, sulfites, hydroxylamine salts, carbonates, water softeners, and the like. On the other hand, color developing solutions for color negatives, color developing solutions for color positives, and some color developing solutions for color paper do not contain these alcohols. Even if the amount of waste liquid is 1% by weight or less, it maintains high current efficiency or exhibits oxidizing ability down to a low COD level, so it is more advantageous than conventional methods.

Color developers usually contain aromatic primary amine color developing agents. It is mainly P-phenylenediamine derivatives, typical examples are N,N-diethyl-p-phenylenediamine, 2-amino-5-diethylaminotoluene, 2-methyl-4-(N-ethyl-N-(β -hydroxyethyl)aminocoaniline, N-ethyl-N-(β-
Methanesulfonamidoethyl)-3-methyl-4-aminoaniline. Further, these p-phenylenediamine derivatives are salts such as sulfate, hydrochloride, sulfite, and p-)luenesulfonate. The content of the aromatic primary developing agent ranges from about 0.5 g to about 10 g per 11 color developer solution.

Color developing solutions contain various hydroxylamines as preservatives. Hydroxylamines can be substituted or unsubstituted. In the case of substituted hydroxylamines, the nitrogen atom of hydroxylamines is substituted with a lower alkyl group, especially two alkyl groups (for example, carbon number 1 to 3). Substituted hydroxylamines. The content of hydroxylamines is 0 to 5 g per 11 of the color developing solution.

In addition, the black and white developer contains ■-phenyl-3-pyrazolidone, 1-phenyl-4-hydroxymethyl-4-methyl-3-pyrazolidone, N-methyl-p-aminophenol and its sulfate, hydroquinone and its sulfonic acid. Contains salt etc.

Color and black and white developers usually contain sulfites such as sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, sodium metasulfite, potassium metasulfite, and carbonyl sulfite adducts as preservatives. , the content of these is Og~5gel. Other preservatives include N and N- for color and black and white developers.
Combinations of dialkyl-substituted hydroxylamines and alkanolamines such as triethanolamine are also used.

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 salt, trishydrodiaminomethane salt, lysine salt, etc. Can be used. Especially carbonates, phosphates, tetraborates,
Hydroxybenzoate has the advantages of excellent solubility and buffering capacity in the high pH 8I range of pH 9.0 or higher, no adverse effects on photographic performance (such as capri) when added to the developer, and low cost. These buffers are often used.

The amount of the buffer added to the developer is usually 0.1 mol/l to 1
Mol/It.

In addition, the developer solution contains various lactate agents that are added as calcium and magnesium precipitation preventive agents or to improve the stability of the developer solution. Typical examples thereof are nitrilotriacetic acid, diethylenetriaminepentaacetic acid, nitrilo-N,N,N-)limerymethylenephosphonic acid, and ethylenediamine-N.

N, N', N'-tetramethylenephosphonic acid, l.

3-diamino-2-propatoltetraacetic acid, transcyclohexanediaminetetraacetic acid, 1,3-diaminopropanetetraacetic acid, 2-phosphonobutane-1゜2.4-)licarboxylic acid, l-hydroxyethylidene-1,l-diphosphone such as acids. Two or more of these chelating agents may be used in combination, if necessary.

The developer contains various development accelerators. Examples of development accelerators include thioether compounds, p-hunylene diamine compounds, quaternary ammonium salts, p-aminophenols, amine compounds, polyalkylene oxides,
These include l-phenyl-3-pyrazolidones, hydrazines, meso ion type compounds, thione type compounds, imigazoles and the like.

Furthermore, although the developer often contains bromide ions for the purpose of preventing fogging, a developer that does not contain bromide ions may be used for photosensitive materials containing silver chloride as a main ingredient. In addition, NaCl1 and M are used as inorganic antifoggants.
It may contain a compound that provides chlorine ions, such as CI, and may also contain various organic anti-capri agents if necessary.

As the organic anti-capri agent, for example, adenine, benzimidazole, benzimidazole and tetrazole may be contained. The content of these antifoggants is 0.010 g to 2 g per liter of developer. These antifoggants are eluted from the photosensitive material during processing,
This also includes those that accumulate in the developer.

In addition, various surfactants such as alkyl sulfonic acids, aryl phosphonic acids, fatty acid carboxylic acids, and aromatic acid carboxylic acids may be contained as necessary.

In photographic processing, development is usually followed by bleaching, and sometimes bleaching is carried out simultaneously with fixing in a single bath bleach-fix (Brix). The method of the present invention can also be applied to such treated waste liquid. The bleaching solution contains iron (If) as an oxidizing agent.
f) or Co(II) EDTA, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, 1,3-diaminopropanetetraacetate, phosphonocarboxylate and other persulfates,
Contains quinones. In addition, rehalogenating agents such as alkali bromide and ammonium bromide, borates,
It may also contain carbonates and nitrates as appropriate. The fixing solution and bleach-fixing solution may contain thiosulfate (sodium salt, ammonium salt), acetate, borate, ammonium or potassium alum sulfite.

When carrying out the method of the present invention, known antifungal agents and antibacterial agents can be used in the waste liquid as necessary so that the work can be carried out stably over a long period of time.

Due to the nature of electrolytic oxidation when processing waste liquid from photographic processing, the method of the present invention can be used in small-scale photo labs called minilabs, microfilm processing in office documentaries, printing, plate making, color copiers, etc. It is suitable for implementation in small-scale photo processing facilities such as

That is, the method of the present invention can be applied to the following waste liquids.

1) Printing plate factory: Various waste liquids such as black and white/color developing solution, fixing solution, bleaching solution, etching solution, reducing solution, picture shells, inks, organic solvents, tank cleaning solution, etc.

These can be processed in batches.

li) Color laboratory: black and white/color developer, fixer, bleach, bleach-fixer, image stabilizing bath, and other processing bath effluents.

In particular, it is suitable for small-scale labs called mini-labs and satellite labs.

Preferred implementation IIIm is: ■ Collect and process the discharged liquid from each of the above baths, and allow the washing water to flow as it is; ■ When using a multi-stage countercurrent water-saving washing method or a method in which the stabilization bath also serves as washing, each All discharged liquid can be mixed and processed.

ii) Offices and stores: Offices that perform documentation using microfilm printer processors and reader printers such as Mikle 1200 (product name, manufactured by Fuji Photo Film Co., Ltd.), printers that print copies of drawings from drawings, etc. Fluid discharged from design offices that use processors, processors in stores that make color copies, and take in-store photos of instant prints, etc.

iv) Other discharges from food processing, metal plating, etc. where the amount of waste liquid is relatively small and the contents contain various environmental pollutants and/or are concentrated and contain COD contributing components with low boiling points. liquid.

[Effect]

In the present invention, by performing alkaline air oxidation, substances in the waste liquid that are easily insolubilized by polymerization etc. during electrolytic oxidation during electrolysis are changed into compounds that are difficult to be insolubilized.
Electrode contamination is less likely to occur in the second step. Furthermore, when the waste liquid is electrolyzed in the second step, the oxidizable substances are efficiently oxidized and changed at the anode, resulting in a decrease in the COD value.

〔Example〕

Next, the present invention will be explained in more detail based on examples.

Example 1 Commercially available photographed multilayer color negative film Fujicolor S
[IPIl! RHG (hereinafter referred to as 5HG-) 100, SHG
-200,5HG-400,5HG-1600,RE
ALA (the above product names, manufactured by Fuji Photo Film Co., Ltd.), Fujicolor-GOLD (hereinafter GOL [l -) 100, GO
LD-200, GOLD-400, GOLD-16
00, Efter 25, Efter 125, Efter 100
0 (the above product names, manufactured by Eastman Kodak Company), Conicolor GX (hereinafter GX->100., GX-200,
GX-400, GX-3200, :l=color GX
I[(hereinafter referred to as GXI[-)100, GX-100M (the above product names, manufactured by Konica Corporation) are not particularly distinguished, and various types are mixed and successively made into a film processor EP for minilab.
900AL (trade name, manufactured by Fuji Photo Film Co., Ltd.) and color negative developer CN-160 (trade name, manufactured by Fuji Photo Film Co., Ltd.) as a processing solution.
(manufactured by Fuji Photo Film Co., Ltd.), and the overflow liquid of the developing bath at this time was used as color negative development processing waste liquid. In addition, prints were printed from the color negative onto commercially available color paper (Fuji Color Paper 5UPER, FA, manufactured by Fuji Photo Film Co., Ltd.), and the printer processor PP18 of Fuji Mini Lab Champion FA-170 was printed.
00B (trade name, manufactured by Fuji Photo Film Co., Ltd.) using CP-43FA (trade name, manufactured by Fuji Photo Film Co., Ltd.) for color paper as a processing solution, and the overflow liquid of the developing bath at this time. was used as a paper developing solution.

A negative waste liquid and a paper waste liquid were mixed in a ratio of 1=1 and diluted three times to obtain a color photographic developing waste liquid.

Commercially available black and white negative film Neopan SS, Neopan 400 PRESTO, Neopa: /16005UP
ERPRESTO (trade name, manufactured by Fuji Photo Film Co., Ltd.) was mixed with various kinds without particular distinction and sequentially treated using developer Fujidol (trade name, manufactured by Fuji Photo Film Co., Ltd.). 50 m of waste liquid was mixed with commercially available black and white paper. (Fuji Blow P manufactured by Fuji Photo Film Co., Ltd.) from negatives and processed using developer Corretor (trade name, manufactured by Fuji Photo Film Co., Ltd.). Old -3FI [(all product names, manufactured by Fuji Photo Film Co., Ltd.) was added to developer R[1-3(
100d and Fuji GRADEX, a printing sensitive material system.
System developer Gl? A waste liquid of -DI and a fixer (all trade names, manufactured by Fuji Photo Film Co., Ltd.) was mixed with 10011 to form a solution of 300 m, which was used as a black and white photographic developing waste liquid.

The developer waste solutions for color photographs and black and white photographs were mixed in a ratio of 1=1 to obtain a photographic processing developer waste solution.

In the first step, the photographic development waste solution 10 (ld) was taken into a beaker and sodium hydroxide was added to it to adjust the pH to 13. Air was bubbled through this solution at a rate of 400 m/min for 120 minutes. As a process, electrolysis is carried out in an electrolytic cell consisting of a lead dioxide electrode (LD 400 type, manufactured by Nippon Carlit Co., Ltd.) as an anode and a stainless steel (SIIS 316) plate as a cathode on both sides of the anode so as to sandwich the anode. was generated. In the electrolytic cell, a current of 2.5 A was applied while stirring the liquid strongly. The liquid after this treatment was designated as sample floor 1. During the above treatment, the aeration time in the first step was changed to 60 minutes and 30 minutes, respectively.
In addition, the solutions obtained by changing the PR in the first step to 11 were designated as sample N112.3.4. Furthermore, for comparison, the first step was omitted, and pn was 9.
The sample size of each sample was 5°6. Table 1 shows the results of each waste liquid treatment performed in this manner.

(hereinafter T, 8: white) In Table 1, samples N111-4 not only have less floating matter generation and electrode contamination during electrolysis than samples 5-6,
It can be seen that more advanced COD removal can be achieved with much less power consumption. Furthermore, in sample holes 1 and 2, no floating matter was generated and the power consumption was low, which indicates that the conditions are more favorable.

Example 2 All of the bleaching, bleach-fixing, and fixing solutions corresponding to each process were mixed with the developing processing waste solution used in Example 1 to obtain a photographic processing developing and fixing waste solution. The CODw- of this liquid is 470
It was 00pp-.

This photographic processing developing/fixing waste solution 10 (ld) was taken, 40 g of calcium hydroxide was added thereto to adjust the pH to 12.1, and air was aerated at 4001 d/min for 80 minutes. After adjusting the pH to 1.5 with sulfuric acid, air was aerated at 400 d/min for 60 minutes. After the generated precipitate was filtered off, the filtrate was adjusted to pH 9, and then subjected to electrolysis treatment. Same conditions as in Example 1. Electricity was applied for 10 hours.!The deburdening pressure was 3.Ov on average.

The COD of the liquid after treatment is 1200 ppm, 47
．． A high treatment rate of 5% was achieved, and no dirt was observed to adhere to the electrodes.

Example 3 The liquid obtained in sample N11l of Example 1 was poured into a column packed with granular activated carbon TYPE SGL (manufactured by Toyo Carbon Co., Ltd.). The CoD of the obtained treatment solution is 12
It was possible to significantly reduce the amount to 0 ppm.

〔Effect of the invention〕

The present invention can efficiently reduce the amount of oxidizable substances in waste liquid containing oxidizable substances. In addition, during electrolysis to perform electrolytic oxidation, sticky substances are not generated and the electrodes are not contaminated, so the electrolytic voltage does not become high and electrolysis can be performed continuously. . This makes management easier.

The present invention is particularly capable of processing small to medium-sized waste liquids inexpensively, easily, and reliably.

The method of the present invention has the advantage of being less labor-intensive and therefore easier to automate than the typical microbial decomposition method used as other conventional waste liquid treatment means.

Claims (3)

[Claims] (1) A waste liquid containing an oxidizable substance is adjusted to pH 10 or higher, and oxygen or a gas containing oxygen is applied to oxidize and decompose the oxidizable substance, and the resulting treated water is then electrolyzed. A method for treating waste liquid containing oxidizable substances. (2) The oxidizable substance-containing waste liquid is a waste liquid that produces a polymer having a molecular weight of 1000 or more through electrolytic oxidation in electrolysis, or is a waste liquid that contains a water-insoluble substance. A method for treating waste liquid containing oxidizing substances. (3) The method for treating an oxidizable substance-containing waste liquid according to claim 1, wherein the oxidizable substance-containing waste liquid is a silver halide photographic processing waste liquid.