JPH04200798A - Treatment of waste photographic processing solution - Google Patents

Abstract

PURPOSE:To stably subject a waste photographic processing solution to biological treatment with high treatment efficiency by adding a predetermined amount of phosphorus to a liquid mixture of the waste solution of a silver recovery system and the waste solution of a developer system in photographic treatment as a nutritive substrate, and treating this mixture with a biological phase containing sulfur oxidizing bacteria. CONSTITUTION:The waste solution of a silver recovery system and the waste solution of a developer system in photographic treatment are mixed and phosphorus is added to the resulting liquid mixture as a nutritive substrate so as to be contained in an amount of at least 2% of the COD value of the liquid mixture. Subsequently, this liquid is subjected to biological treatment using a biological phase containing sulfur oxidizing bacteria. Phosphorus may be added in a form of phosphate of every kind such as KH2PO4, K2HPO4, NaH2PO4.2H2O or Na2HPO4 and can also be added as phosphoric acid or other phosphorus compound. As sulfur oxidizing baceria, intermedius of the genus Thiobacillus, the genus Thiothrix such as Thiobacillus perometabolis and the genus Beggiatoa are designated.

Description

[Detailed Description of the Invention] 3 Industrial Application Fields] The present invention relates to a method for treating photographic processing waste liquid,
Specifically, the present invention relates to a method of biologically treating photographic processing waste liquid containing high concentrations of reducing inorganic sulfur compounds and organic compounds.

[Conventional technology]

Photographic processing waste liquid contains many types of inorganic and organic compounds and is highly concentrated, so it cannot be directly discharged into sewage or rivers, so it must be treated. Many methods have been studied.

Conventionally, the activated sludge method (
For example, Japanese Patent Publication No. 55-49ssc+, Japanese Patent Publication No. 48-
13265, JP-A-50-2353, etc.)
, Mofaho (Japanese Unexamined Patent Publication No. 49-89347 and Japanese Patent Publication No. 1989-56)
33996, etc.), electrolytic oxidation method (JP-A-49-1194)
58, Japanese Patent Publication No. 53-43478, etc.), ion exchange method (Japanese Patent Publication No. 51-37704, Japanese Patent Publication No. 53-383, etc.), reverse osmosis method (Japanese Patent Publication No. 50-22463, etc.), chemical treatment method (Unexamined Japanese Patent Publication No. 5312152, Publication No. 57-373
No. 96, JP-A No. 61-241746, etc.) are known, but each has the following drawbacks.

Regarding the activated sludge method, for example, Japanese Patent Publication No. 55-49559
Concentrated oxygen gas (Oz>20.9%) as described in the publication
Even if the activated sludge method using aeration is used, unless the initial BOD value of the waste liquid is adjusted and maintained at a maximum of 3000 ppm, the decomposition of BOD-COD components in the next secondary treatment process cannot be done efficiently within an appropriate time. Therefore, it was difficult to apply it to high-concentration waste liquids with a BOD of 3000 ppm or more. Furthermore, in Japanese Patent Application Laid-Open No. 50-2353, a thiosulfate-containing liquid and a 1,000-ohacteria-containing liquid are mixed,
A method for oxidizing a thiosulfate-containing liquid is disclosed, which is characterized by adjusting the pH to 4 to 9 and reducing the content of nitrogen compounds to 0.1% or less as nitrite before aeration. When the treatment method is used for photographic fixing waste liquid, which is a part of photographic processing waste liquid, there are problems such as disintegration of sludge and insufficient treatment efficiency.

The electrolytic oxidation method has high equipment costs and the electrodes are easily contaminated. Ion exchange methods and reverse osmosis methods tend to fatigue the resin and membrane (soon become unusable) when dealing with concentrated photographic waste liquids.Furthermore, chemical processing methods use hydrogen peroxide, persulfates, perhalogens, etc. Treatment methods by adding acid salts, halous acid, and hypohalous acid are known, but they all have extremely low treatment efficiency for photographic waste liquid with high COD concentrations, and excessive chemicals are always used. I will do it.

[Problem to be solved by the invention] In order to make the processing of photographic processing waste liquid simple and technically easy, it is necessary to minimize the number of steps and do not require the addition of special chemicals. It is necessary that
Furthermore, since photographic processing is divided into several steps, waste liquid is generated from each of these steps, and it would be extremely complicated to treat each of these waste liquids separately, so it is desirable to treat them all at once. This is particularly desirable in small-scale photographic processing facilities.

An object of the present invention is to provide a treatment method that maintains a stable state over a long period of time and at the same time achieves a high treatment rate when directly biologically treating high-concentration photographic processing waste liquid by simple air aeration without pre-treatment. .

[Means to solve the problem]

As a result of various studies on biological treatment of photographic processing waste liquid, the present inventor found that the object of the present invention can be effectively achieved by using the following means.

That is, a silver recovery system waste solution and a developer system waste solution in photographic processing are mixed, phosphorus is added as a nutrient substrate to the mixed solution so that it contains at least 2% of the CCD value of the mixed solution, and the solution is mixed with sulfur. This is a method for treating photographic processing waste liquid, which is characterized by biological treatment using biota containing oxidizing bacteria.

Note that the CCD value used in the present invention is the value obtained when oxidizing using potassium permanganate, that is, CCD value.
Although it is based on the value expressed by OD□, it is simply referred to as the "CCD value" for ease of display.

In the biological treatment mentioned above, the pH of the biota is 5.5 to 8.
．． 5, preferably 6.5 to 7.0, the action of sulfur-oxidizing bacteria in the biological treatment can be actively performed.

Further, in the present invention, the mixed liquid has a CCD value of 3000.
Even high concentrations of ~8000 ppm can be treated satisfactorily.

It is preferable that the mixed liquid contains phosphorus as a nutritional substrate in an amount of 2% to 5% of the CCD value of the mixed liquid. When adding phosphorus, KH, PO,, L
HPO,,Na)1. PO, 2LO1Na2HPO.

It may be added in the form of various phosphates such as phosphoric acid or other phosphorus compounds.

The silver recovery system waste liquid treated in the present invention includes color photographs and/or
It also refers to the waste liquid obtained by recovering silver from the waste liquid from the process related to silver removal (desilvering), which consists of fixing baths, bleach-fixing baths, bleaching baths, etc. in black-and-white photographic processing, and is a reducing inorganic sulfur compound. The developer waste liquid containing large amounts of ammonium thiosulfate and sodium sulfite is the waste liquid from the developer, stabilizing bath, washing bath, etc. in color photography and/or black and white photographic processing, and contains high concentrations of organic compounds such as hydroquinone, Contains large amounts of color developing agents, etc.

In the present invention, as the sulfur oxidizing bacteria used for biological treatment, previously known sulfur oxidizing bacteria are used. For example, Th1obacillus of the genus Th1obacillus
illus thioparus, Th1obacillus
lusneopolitanus, Th1obacil
lus neollus, Thiobacillus
intermedius, Th1obacillus
perometabolis, the genus Th1othrix, and the genus Beggiatoa.

In the treatment method of the present invention, it is preferable that ordinary activated sludge is also present, since a large amount of organic compounds coming in from developer waste liquid is also treated, and the biological treatment includes sulfur-oxidizing bacteria. Activated sludge is used.

Therefore, the biological treatment conditions are set so that not only the sulfur-oxidizing bacteria exhibit sufficient activity, but also the activated sludge is maintained in a state where it exhibits sufficient activity.

Conventionally, Japanese Patent Application Laid-Open No. 55-106597 discloses that wastewater containing thiosulfate ions, such as wastewater from a sulfide ore mine, is mixed with a solution containing sulfur bacteria and a solution containing nutrients for the sulfur bacteria for aeration. JP-A-50-2353 discloses a method of mixing thiosulfate-containing waste liquid such as photographic fixing waste with a thiobacteria-containing liquid and aerating it. Both of these methods were aimed at oxidizing thiosulfate ions, and did not contain high concentrations of organic compounds, and there was no knowledge of biological treatment that contained organic compounds.

In the present invention, thiosulfate ions and the like are removed by biological treatment of the mixed liquid using a biological phase containing sulfur-oxidizing bacteria, and organic compounds such as O2 are removed.
It can be removed together with the D acid component. In this biological treatment, in order to fully activate the sulfur oxidizing bacteria, an oxygen-containing gas such as air is passed through and aerated.

The photographic processing waste liquid processed by the method of the present invention is a processing waste liquid produced when a silver halide photosensitive material is developed. Here, the photosensitive materials include color photosensitive materials as well as black and white photosensitive materials. For example, color paper, color reversal paper, color negative film for shadows, color reversal film,
In addition to negative or positive films for movies, direct positive color photosensitive materials, etc., X-ray films, photosensitive materials for printing, microfilms, black and white films for side shadows, etc. can be mentioned.

Since the photographic processing waste liquid is generated from the photographic processing liquid used in the photographic processing, the photographic processing liquid component is the main component. 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 solutions include color processing solutions, black-and-white processing solutions, reducing solutions used in plate-making operations, development processing tank cleaning solutions, and the like.Photographic processing solutions also consist of developing solutions, fixing solutions, bleaching solutions, image stabilizing solutions, and the like.

The developer-based waste liquid used in the present invention has components contained in the developer as a main component.

Many color paper developers contain alkylene glycols and hensyl alcohols along with color developing agents, sulfites, hydroxylamine salts, carbonates, water softeners, and the like. On the other hand, developer solutions for color screws, developer solutions for color positives, and some developer solutions for color paper do not contain these alcohols.

Color developers typically contain aromatic primary amine color developing agents. 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)aminoaniline, N-ethyl-N-(β-methanesulfonamidoethyl)-3-methyl-4-aminoaniline.These p-phenylenediamine derivatives are also available as sulfates, hydrochlorides, and sulfites. , P-1-luenesulfonate, etc. The content of the aromatic primary amine developing agent is about 0.5 g to about 10 g per 11 of the developing solution.
g range.

Color developers 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 determined by color development! 1! It is 0 to 5 g per serving.

In addition, the black and white developer contains 1-phenyl-3-pyrazolidone, 1-phenyl-4-hydroxymethyl-4-methyl-3-birapritone, N-methyl-p-aminephenol and its sulfate, hydroquinone and its sulfone. Contains salts, 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. , these contents are Og~5g/! It is. 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.

In order to retain the above P) (, each [! buffer is used. Buffers include carbonate, phosphate, borate,
Tetraborate, hydroxybenzoate, Grin's salt, N,
N-dimethylgrin salt, leucine salt, norloin salt, guanine salt, 3,4-nhydroquinophenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine Salts, proline salts, trishydrosoaminomethane 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 9.0 or higher, and even when added to the developer, they do not affect photographic performance. These buffers are often used because they have the advantages of no adverse effects (fogging, etc.) on the developer and are inexpensive.The amount of buffer added to the developer is usually 0.1 mol/l.
It is 1 mol/l.

In addition, the developing solution contains various lactate agents, which are added as anti-settling agents for calcium and mag2sium, or to improve the stability of the developing solution. Typical examples thereof are nitrilotriacetic acid, diethylenetriaminepentaacetic acid, nitrilo-N,N,N-trimethomethylenephosphonic acid, and ethylenediamine-N.

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

3-diamino-2-propatoltetraacetic acid, transcyclohexanediaminetetraacetic acid, l,3-diaminopropanetetraacetic acid, 2-phosphonobutane-1゜2.4-tricarboxylic acid, 1-hydroquinethylidene-1,1-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-phenylenecyamine compounds, quaternary ammonium salts, p-aminophenols, amine compounds, polyalkylene oxides,
These include 1-phenyl-3-pyrazolidones, hydrazines, meso ion type compounds, thione type compounds, imidazoles 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, Na Cf and K are used as inorganic antifoggants.
It may contain a compound that provides chlorine ions, such as Cl. Additionally, various organic antifoggants may be contained as required. The organic antifoggant may include, for example, adenines, hendaimidazoles, henztriazoles, and tetrazoles.

The content of these antifoggants is 0.0 per 11 parts of the developer.
It is 10 g to 2 g. These antifoggants include those that are eluted from the photosensitive material during processing and accumulate in the developer.

Moreover, various surfactants such as alkylphosphonic acid, arylphosphonic acid, fatty acid carboxylic acid, aromatic acid carboxylic acid, etc. may be contained as necessary.

Examples of the silver recovery system waste liquid used in the present invention include waste liquids from fixing solutions and bleach-fixing solutions treated for silver recovery.

In black photographic processing, fixing is performed after development. Furthermore, in color photographic processing, bleach-fixing is usually carried out between development and fixing, and sometimes bleaching is carried out simultaneously with fixing in one-bath bleach-fixing (Brix). The bleaching solution contains EDTA, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, 1,3-diamino-propanetetraacetic acid, phosphonocarboxylate, and other persulfates as oxidizing agents.
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.

In processing silver halide photographic materials, it is common to carry out a fixing process or a one-bath bleach-fixing process, followed by washing with water and/or a stabilizing process.

The pH of washing water in processing photosensitive materials is 4-9, preferably 5-8. Furthermore, instead of washing with water, the photosensitive material can be directly processed with a stabilizing solution.

In such stabilization treatment, Japanese Patent Application Laid-Open No. 57-854
All known methods described in No. 3, No. 5B-14834, and No. 60-220345 can be used.

Further, following the water washing treatment, a further stabilization treatment may be carried out, such as a stabilizing bath containing formalin and a surfactant, which is used as a final bath for color photosensitive materials for photography. .

Various cleaning agents and antifungal agents can also be added to this stabilizing bath.

The photographic processing waste liquid is a mixture of waste liquids from the various processing baths for color light-sensitive materials and black and white light-sensitive materials described above.

The main components and concentration range of the silver recovery system waste liquid to be treated in the present invention are ammonium thiosulfate 20 to 150 g/N
, sodium sulfite 1-10g/l, acetic acid 0-50g/l
l, EDTA ferrous ammonium 2-40 g/r, for example ammonium thiosulfate salt 90 g/ffi
, sodium sulfite approx. 5g/f, acetic acid approx. 15g/f, E
DTA ferrous ammonium approx. 7E/! .

In addition, the main components and their concentration ranges in the developer system waste used are hydroquinone 4 to 30 g/N, color developer i
Main i 1-15g/j # Hensyl Alcohol 0-5g/
2. Hydroxylamine 0~4 g/R1 acetic acid 0~
4g/! , 5-sulfosalicylic acid O~20 g/l, examples of which are about 11 g/l of hydroquinone, about 3 g/l of color developing agent! , Hensyl alcohol approx. 2g/
I! ,, Hydroxylamine approx. 1g/2, Acetic acid approx. 1g/2
j2.5-sulfosalicylic acid about 7 g/l.

Examples of the concentration values of these components are typical values, and the application of the present invention is not limited to waste liquids having these values.

Waste liquid containing silver is subjected to silver recovery treatment before being subjected to biological treatment.

Methods for recovering silver include a method in which silver is precipitated using electrolysis, a method in which steel wool is introduced and silver in the solution is precipitated on the steel wool by utilizing the difference in ionization tendency between iron and silver; A method of adding a sodium sulfide solution to precipitate silver as silver sulfide can be used.

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

(1) A mixture of silver recovery system waste liquid and developer system waste liquid is used. The mixing ratio of both waste liquids can be varied.

Since this mixed waste liquid has a high inorganic salt concentration and cannot be subjected to biological treatment as it is, it is diluted with water, for example, 6 to 15 times so that the salt concentration is lower than that of seawater. If the degree of dilution is high, the equipment will become large and the cost of land and equipment will increase significantly, so it is preferable to carry out the dilution at the lowest possible degree.For example, the present invention can be applied to waste liquid with a COD value of 3000 ppm or less, COD value 3000-8000
Application to high concentration waste liquids of ppm is preferred.

(2) Add phosphorus to a concentration of 2% or more of the COD value of the liquid to be treated. Further, it is preferable to add an appropriate amount of metal elements such as calcium and magnesium into the aeration tank. At this time, either or all of calcium and magnesium may be added in advance to the solution prepared in (1). In addition, since phosphorus will have its effect if it is present in the next biological treatment stage, it is not necessarily necessary to add it before the mixed liquid is transferred to the biological treatment, and it is not necessary to add phosphorus to the mixed liquid put into the biological treatment. It may be added.

(3) Biologically treating the mixed solution. The biological treatment method in the present invention includes an activated sludge method, a floating bed method, a contact filter bed method, a rotating plate contact method, a contact aeration method, and other biological contact oxidation methods. For more specific methods of these biological treatments, please refer to [Biological Water Treatment Technology and Devices] Chemical Engineering Society'a
(Baifukan), “Maintenance and management technology of activated sludge method” Toshibe Sakurai,
It is described in books such as Takashi Sudo (supervising author) (published by Science and Technology Development Center).

Among these biological treatments, treatment with activated sludge containing sulfur-oxidizing bacteria is preferred. In the case of continuous activated sludge treatment, the residence time is preferably 1 to 2 days. Batch-type activated sludge treatment can also be applied, for example, one cycle is one day, with 2 hours of inflow, 17 hours of aeration, 2 hours of settling, 2 hours of discharge, and 2 hours of waiting time.
Processing is carried out through steps such as R1 time. In both continuous and batch methods, it is preferable to maintain the pH in the aeration tank at 5.5 to 8.5, preferably 6.5 to 70. Furthermore, the above-mentioned phosphorus acts as a nutritional substrate.

〔Example〕 Next, the present invention will be explained in more detail with reference to Examples.

Example 1 0 7 mi ゛ and ゛ 7
− ゛のMU 0
几.

Silver recovery system waste liquid (color photographic processing CN-16 fixing liquid, C
A mixture of bleach and fixer of N-'λ, bleach-fixer of CP-Cen, bleach-fixer of CP-23, and black-and-white photographic processing fixer l earthwork, GRFI waste solution and water were added at 4.1% each.
3, 2, 7. 3.2 ratio and then subjected to silver recovery treatment) and developer system waste liquid (color photographic processing CN-16,
The developer solutions of Tachibana 2 and 14, CI"-23, and the waste liquid and water of black and white photographic processing developer RD3 and GRDI I were mixed in a ratio of 4, 1, 3.2.7.3.2, respectively. This solution was mixed at a volume ratio of 1:1.This solution had a high inorganic salt concentration of 12% and was not suitable for biological treatment, so it was diluted 10 times with tap water.Phosphorus was added to this solution. An amount corresponding to about 3% of the COD value (about 4700 ppm) was added in the form of dipotassium phosphate hydrogen.Furthermore, carnoum ions and magnesium ions were added at 1 oppm and 2 ppm, respectively. pH was 8.5.

This waste liquid is processed into activated sludge containing sulfur-oxidizing bacteria (MLS S
Continuous treatment was carried out at 4500 ppm). The activated sludge containing sulfur-oxidizing bacteria was one that had been acclimatized by continuously applying a 10-fold diluted silver recovery system waste solution (COD approximately 4500 ppm) for one month with a residence time of two days. Residence time was 2 days.

The generated sulfuric acid was neutralized with a 10% aqueous sodium hydroxide solution, and the pH of the liquid in the aeration tank was maintained so as not to fall below 6.6. A pH controller (FC-10 type manufactured by Tokyo Rika) was used for the pHff1 section.

The processing results are shown in Table 1. Note that the activated sludge continued to maintain a good condition for at least two months.

The underlined symbols for each of the above-mentioned methods are the trade names of Fuji Photo Film ■'s imaginary solution, and the composition of only the main components of each method is shown below.

Silver recovery system CN-16 sodium sulfite 13 g/l, ammonium thiosulfate 120 g/f, EDT octaron octaammonium 5/I CN-160 sodium sulfite Hg/l, ammonium thiosulfate 130 g/I2. EDTA ferrous ammonium 100g/1 CP-20 subtilF+)' Jum 2g/f! , +:t
Gal! 7 ammonium 4Bg/l, EDT＾ferrous ammonium 20g/I CP-23 sodium sulfite 3 g/l, ammonium thiosulfate 50 g/l, EDTA ferrous ammonium 25 g/l, Fuji F sodium sulfite 6 g/E, ammonium thiosulfate 100 g / r GRFI Sodium sulfite 7 g / 1,
Ammonium thiosulfate 135g/n Developer system CN-16 developing agent 5g/2, Sodium sulfite 3g/n
ρ CN-160 developing crude drug 7 g/1. Sodium sulfite 4
g/I CP-20 developer 4 g/i, sodium sulfite 1 g/1. Hensyl Alcohol I1g/ICP-2
3 developing agent 5 g/l, sodium sulfite 1.5
g/1. Benzyl alcohol 13g/IRD3 Sodium sulfite 22g/1. Hydroquinone 12g/
1 GRDI Sodium sulfite 32g/l, 7h
Idoquinone 9 g/! Example 2 0 ”(and ゛ ′(゛)
A 6 fL 几Calcium and magnesium were added at the same concentration as in Example 1 to a 6-fold dilution of the 1:1 mixture of silver recovery system waste and developer system waste used in Example 1.

In addition, phosphorus was added in the form of dipotassium phosphate-hydrogen in an amount corresponding to 3% of the COD value of the solution (approximately 7800 pps+). This solution was subjected to biological treatment in the same manner as in Example 1 using activated sludge containing sulfur-oxidizing bacteria. The results are shown in Table 1.

The activated sludge remained in good condition for at least one month.

Example 3 The same process as in Example 1 was carried out except that the amount of phosphorus added was 2% of the COD value (approximately 4700 ppm).

The results are shown in Table 1.

The activated sludge continued to be maintained in good condition for at least two months.

In the above-mentioned Example 1, the 1:1 mixed 10-fold diluted solution of silver recovery system waste liquid and developer system waste liquid has a concentration of 20-fold dilution for each of the silver recovery system waste liquid and developer system waste liquid. Therefore, as shown in Comparative Examples 1 and 2 below, treatment experiments were carried out using 20-fold diluted solutions of silver recovery system waste liquid and developer system waste liquid, respectively.

Comparative Example 1 The silver recovery system waste liquid used in Example 1 was diluted 20 times with water. After adding phosphorus, calcium ions, and magnesium ions to this solution in the same proportions as in Example 1, biological treatment was performed using activated sludge containing sulfur-oxidizing bacteria in the same manner as in Example 1. The results are shown in Table 1. Furthermore, the activated sludge continued to maintain good condition for at least two months.

Comparative Example 2 The waste developer solution used in Example 1 was diluted 20 times with water. After adding phosphorus, calcium ions, and magnesium ions to this solution in the same proportions as in Example 1, biological treatment was performed using activated sludge containing sulfur-oxidizing bacteria in the same manner as in Example 1. The results are shown in Table 1. show.

Note that the MLSS of the activated sludge began to decrease around three weeks after the start of the experiment and could not maintain a good state for more than two months.

Comparative Example 3 1=1 of silver recovery system waste liquid and developer system waste liquid used in Example 1
Calcium ions and magnesium ions were added to a 10-fold diluted solution of the mixed solution at the same concentration as in Example 1. Furthermore, phosphorus corresponding to 1% of the COD value of the solution (approximately 4700 ppm) was added in the form of dipotassium phosphate-hydrogen. This solution was subjected to biological treatment in the same manner as in Example 1 using activated sludge containing sulfur-oxidizing bacteria.

The results are shown in Table 1.

Furthermore, the activated sludge began to be dismantled three weeks after the start of the experiment.
It is no longer possible to maintain good processing.

As can be seen from the results shown in Examples 1 and 2 and Table 1, the present invention can reduce the BOD value to 300, which was previously difficult.
Biological treatment of photographic waste liquid with a high concentration of more than 0 ppm can be achieved stably and at a high treatment rate.

Furthermore, as is clear from Table 1, the mixed treatment of silver recovery system waste and developer system waste of the present invention maintains the activated sludge in a better condition compared to the treatment of developer system waste alone as in Comparative Example 2. However, it not only can treat developer waste, but also
An improvement in processing rate can be achieved.

Further, according to Comparative Example and Example 3, the amount of phosphorus added in the present invention needs to be 2% or more of the liquid to be treated. Furthermore, if water containing an appropriate amount of calcium and magnesium, such as tap water or well water, is used as dilution water, it is possible to obtain almost the same treatment results without adding calcium ions or magnesium ions as when they are added. Therefore, addition of calcium ions and magnesium ions can be omitted depending on the type of dilution water.

(Effects of the Invention) According to the present invention, high-concentration photographic processing waste liquid containing a reducing inorganic sulfur compound and an organic compound such as a developer can be biologically treated stably and at a high treatment rate. In particular, the present invention has a COD value of 3000 to 8000 ppm, which could not be treated conventionally.
It is possible to biologically treat high-concentration photographic processing waste liquid to obtain treated water with a low COD value. Photographic processing waste liquid is difficult to biologically treat because it has a high salt concentration, but the present invention allows biological treatment to be continued stably over a long period of time without much dilution.

Claims (3)

[Claims] (1) Mix the silver recovery system waste liquid and the developer system waste liquid in photographic processing, add phosphorus as a nutritional substrate to the mixed liquid so that it contains at least 2% of the COD value of the mixed liquid, and A method for treating photographic processing waste liquid characterized by biological treatment using biota containing sulfur-oxidizing bacteria. (2) The method for treating photographic processing waste liquid according to claim 1, wherein the pH of the biota in the biological treatment is 5.5 to 8.5. (3) The mixed liquid has a COD value of 3000 to 8000 pp
Claim 1 or Claim 2 characterized in that it is of m.
The method for treating the photographic processing waste liquid described.