JPH0797696A - Treatment of photographic processing waste liquid and linsing water - Google Patents

Abstract

PURPOSE:To efficiently recover electrolytic silver from a development processing waste liquid by using electrolytic tanks without forming silver sulfide and also efficiently decompose the BOD and COD materials by using the electrolytic oxidation and further water pollution, etc., can be prevented from occurring. CONSTITUTION:In this treatment that is a system for electrolytically oxidizing a photographic processing waste liquid, two electrolytic tanks are arranged in series so as to share the functions between them. Namely, the recovery of electrolytic silver is performed mainly by the first electrolytic tank 21A or 21B and the electrolytic oxidation of the harmful substances in the photographic processing waste solution is performed by the second electrolytic tank 41 to reduce the iodine consumption and BOD of the treated waste solution to the allowable levels for discharging it into the sewage. Also the electrolysis in the second electrolytic tank 41 is performed through applying higher voltage as compared with the electrolysis in the first electrolytic tank 21A or 21B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrolytically treating a photographic processing waste liquid of a developing machine to recover silver and oxidize harmful substances.

[0002]

2. Description of the Related Art A bleach-fixing solution for processing a light-sensitive material or a photographic processing waste solution of a fixing solution has a high silver concentration, a large pollution load, and a valuable resource value. Is being done. As a method for recovering silver from this photographic processing waste liquid, a chemical reduction method introduced in JP-A-2-247396 is well known.

That is, a reducing agent such as formic acid, oxalic acid, hydrazine or the like, sodium sulfide, sodium hydrogen sulfide, hydrogen peroxide or the like is added to a photographic processing waste liquid to reduce silver ions and precipitate as silver, silver sulfide or silver oxide. , The method of collecting this is known.

Regarding the oxidation treatment method of the photographic processing waste liquid, the BOD and COD components in the waste liquid are oxidatively decomposed by the addition of an oxidizing agent such as a hydrogen peroxide oxidation method and a hypochlorous acid oxidation method, and the effluent can be poured into the sewage. In addition to the above technology, ozone oxidation and electrolytic oxidation are known.

[0005]

In the silver recovery by electrolysis, when sulfides of H ₂ S ²⁻ , SH ⁻ are particularly generated by the anodic oxidation reaction of thiosulfate ions, the silver ions react with them to form silver sulfide. Become. Since silver sulfide is black and has very fine particles, it is difficult to collect it, and it adversely affects the light-sensitive material being processed. Therefore, in-line silver recovery has a considerable problem.

Further, regarding the oxidation method of the photographic processing waste liquid, it is necessary to administer a chemical agent for both hydrogen peroxide oxidation and hypochlorous acid oxidation, and there is a problem that ozone oxidation is expensive. Since neither of the oxidation methods has the ability to recover silver, it is necessary to take another means for recovering silver. On the other hand, the electrolytic oxidation method tries to recover silver by a cathode reaction and oxidatively decompose BOD and COD producing components by an anodic reaction, but the anodic oxidation reaction has a high voltage dependency, and it is necessary to raise the voltage. This significantly increases the decomposition efficiency. However, if the voltage is increased when silver is simultaneously recovered, silver sulfide is produced, and if the voltage is decreased, the efficiency of the oxidative decomposition reaction of BOD and COD at the anode becomes poor.

The present invention solves the above problems and efficiently and stably recovers electrolytic silver and decomposes BOD and COD component materials by electrolytic oxidation in an electrolytic cell, recovers silver as a valuable resource and saves water and water. The objective is to provide means for advancing measures against environmental problems.

[0008]

This object is achieved by any one of the following technical means a, b, c, d, e, f, g, h, i, j and k.

(A) A system for electrolytically oxidizing a photographic processing waste liquid, in which two electrolytic cells are connected in series to share functions, and electrolytic silver is mainly recovered in the first electrolytic cell, and second electrolytic cell is used. Is a method for treating a photographic processing waste liquid, characterized in that a harmful substance in the processing waste liquid is electrolytically oxidized by electrolyzing at a higher voltage than the first electrolytic cell.

(B) A method for treating a photographic processing waste liquid, wherein the electrolysis voltage of the first electrolytic cell is set in the range of 0.7 to 1.5 V in the item (a).

(C) A method for treating a photographic processing waste liquid, wherein the electrolysis voltage of the second electrolytic cell is set to 1.5 V or more in item a or b.

(D) A method for treating a photographic processing waste liquid, characterized in that the electrolysis is carried out under the condition that the current density of the second electrolytic cell is 1 to 10 A / dm ² in any one of the terms a, b and c.

(E) Two electrolytic cells are connected in series to form a first
Electrolytic oxidation of harmful substances in photo-processed wash water by electrolytically collecting electrolytic silver in the electrolyzer and electrolysis of the second electrolyzer at a higher voltage than in the first electrolyzer. That is, the first electrolysis tank and the water washing tank are circulated by a circulation pump, and the pipe for returning from the first electrolysis tank to the water washing tank is branched into two parts, and a part of the washing water is flown to the second electrolysis tank to make one pass. A method for treating photographic processed washing water, which is characterized by processing.

(F) The two electrolytic cells are connected in series to form a first
Electrolytic oxidation of harmful substances in photo-processed wash water by electrolytically collecting electrolytic silver in the electrolyzer and electrolysis of the second electrolyzer at a higher voltage than in the first electrolyzer. And the overflow liquid from the washing tank is
The method for treating photographic-processed rinsing water is characterized in that treatment is performed in one pass in the order from the electrolytic cell to the second electrolytic cell.

(G) A method for treating a photographic processing waste liquid, which comprises subjecting an integrated waste liquid for development, fixing and washing to electrolytic oxidation treatment using the system of the items a and f.

(H) A, b, c, d, e, f and a, b, c, d, e, f and a means for removing coloring components from the treatment waste liquid electrolyzed in each of the electrolysis cells by an adsorbent are added to the electrolysis cells The method for processing a photographic processing waste liquid according to any one of g.

(I) a, b, c, d, e, f, g and h
2. The method for treating a photographic processing waste liquid according to any one of the items 1 to 3, wherein the step of adjusting the pH value by replenishing an alkaline agent is added to the step before the processing of the second electrolytic cell.

(J) A method for treating a photographic processing waste liquid according to item (i), wherein the alkaline agent is an overflow liquid of the developing liquid.

(K) At least the BOD component substance is oxidatively decomposed by the first step of recovering silver at a low voltage electrolysis voltage and then the second step of electrolysis at a voltage higher than the low voltage. A method for treating photographic processing waste liquid, which is characterized by the above.

[0020]

[Function] The processing waste liquid (including washing water) of the automatic processing machine is put in the electrolytic cell, and silver is recovered at the cathode. However, when the voltage of the electrolytic cell is set to 1.5 V or more and the current density increases, silver sulfide is generated. You can
The fine black particles start to settle, and it becomes difficult to collect them, which adversely affects the photosensitive material. Therefore, it was found that the generation of silver sulfide and the like disappeared when the voltage was reduced to 1.5 V or less, which was convenient for silver recovery and had no adverse effect on the photosensitive material.

On the other hand, according to the anodic reaction of electrolytic oxidation method, BO
Experimental results have shown that the decomposition of the D and COD components by electrolytic oxidation is inefficient unless the electrolytic voltage is increased and the current density is increased.

Therefore, in the present invention, both the silver recovery and the decomposition work of BOD and COD by electrolytic oxidation are performed in one electrolytic cell, and both are performed in different electrolytic cells. First, the first electrolytic cell is used. Silver recovery at a low voltage of 0.7 to 1.5 V or less,
Next, oxidative decomposition of BOD and COD products is efficiently carried out at a high voltage in the second electrolytic cell without any trouble, and by providing an adsorbent such as activated carbon in each electrolytic cell, harmful substances such as sulfide are generated. The colored component of the substance can be adsorbed to enhance the deodorizing effect, and the pH adjusting agent of the treatment waste liquid is added before the treatment in the second electrolytic cell to remove the treatment waste liquid.
It becomes possible to keep the pH within the standard value of the pollution load regulation. This is because if the pH becomes acidic during electrolytic oxidation in the second electrolytic cell, there is a high possibility that hydrogen sulfide will be generated. When a developer is used as the alkaline agent, it is easy to handle.

[0023]

EXAMPLE A first example of the present invention will be described with reference to the drawings.

The washing water tank 13 of the automatic processing machine and the first electrolytic cell 21 are connected as shown in the flow chart of FIG. 1 and most of the washing water is circulated through a pump 31 and a valve 32 installed in the pipe. Collect silver. Furthermore, the pipe that returns from the first electrolysis tank 21 to the washing water tank 13 is branched in the middle, and a part of the washing water is supplied to the second electrolysis tank.
It is discharged to 41, electrolytically oxidized in one pass and discharged.
At this time, the first electrolytic cell 21 electrolyzes at a low voltage of 0.7 to 1.5 V or less to prevent generation of silver sulfide. The second electrolyzer
41 is higher voltage than the first electrolytic cell 21 and current density is 17-67mA /
It is electrolytically treated with dm ² .

First, a silver recovery test using the first electrolytic cell 21 will be described.

As a model of the treatment waste liquid, the following compositions were prepared to prepare simulated washing water.

Ammonium thiosulfate 70% solution 2.32 ml Sodium sulfite 95 ml Silver ion 60 mg Iodine consumption about 1600 ppm pH value 6.0 was put into 1 liter of water to make an aqueous solution.

As shown in the configuration diagram of FIG. 2, the structure of the first electrolytic cell 21 is such that the anode material is 26 graphite plates and the cathode material is 25 punching plates with SUS316 aperture ratio 11%. 1mm Cathode area is 3m ² The size of the electrolytic cell is 50cm × 21cm × 38cm. In the electrolytic cell 21, the anode plate 22 and the cathode plate 23 are arranged in parallel and the end of the anode is formed.
A part of 22A is cut out so that the washing water meanders and flows.

As an electrolysis condition, a constant voltage of 1.0 V is applied, a flow rate is 4.0 liter / min, and a temperature is room temperature, and an electrolysis test as shown in the flow chart of FIG. 3 is performed. As shown in FIG. It was found that the silver concentration decreased to 3 ppm after 30 minutes of electrolysis, and finally the electrolysis could be recovered to 0.3 ppm or less after electrolysis for 3 hours.

Next, an electrolytic oxidation test using the second electrolytic cell 41 will be described.

An aqueous solution having the following composition was used as a pseudo-running washing water of the washing water waste liquid after the silver recovery.

Ammonium thiosulfate 70% solution 1.45 ml Sodium sulfite 59 mg Iodine consumption about 1600 ppm pH value 6.0 was dissolved in 1 liter of water to give an aqueous solution. 20 this
It was put in a liter washing water tank 13 and allowed to flow in one pass as shown in the flow diagram of FIG. 5 to perform an electrolytic oxidation test. The second electrolytic cell 41 in the flow chart of FIG. 5 is provided with the anode plate 42, the cathode plate 43, and the notch portion of the anode end portion 42A, and its structure is exactly the same as that of the first electrolytic cell 21. Yes, they are the same size.

As electrolysis conditions, the simulated running wash water was subjected to one-pass treatment with a current value of 20 A constant current (current density of 67 mA / dm ² ) and a temperature of room temperature, and the flow velocity and electrolysis time were changed as follows. .

Flow rate 2.0, 1.0, 0.5 liter / min Electrolysis time 1.5, 3.0, 6.0 min Then, iodine consumption of the discharged liquid and pH were measured.

As a result, as shown in the graph of FIG. 6, the electrolysis time was 6 minutes or longer, and the iodine consumption was 220 ppm or less, which was a standard value.

As for the pH, as shown in the flow chart of FIG.
It was possible to maintain the pH within the range of 5.8 to 8.6 as shown in the graph of FIG. Further, this makes it possible to prevent the pH from becoming acidic during electrolysis and suppress the generation of hydrogen sulfide.

A second embodiment of the present invention will be described with reference to the drawings.

The washing water tank 13, the first electrolytic tank 21, and the second electrolytic tank 41 are connected as shown in the flow chart of FIG. 9, and the washing water is treated and discharged in one pass.

The first electrolytic cell 21 collects silver at a low voltage (0.7 to 1.5 V or less), and the second electrolytic cell 41 is the first electrolytic cell 21.
The object of the present invention was achieved by processing at higher voltage and higher current density.

As a third embodiment of the present invention, processing of the photographic processing integrated waste liquid will be described with reference to the flow chart of FIG.

An electrolytic cell for the fixing cell 12 as the first electrolytic cell 21
21A and an electrolytic bath 21B for the washing water bath 13 are provided to collect electrolytic silver. Then, the overflow liquid from the developing tank 11 and the overflow liquid after silver recovery from the fixing tank 12 are stored in the stock tank 27, and are mixed little by little with the silver-recovered washing water, and the second electrolytic tank 41 is used. Perform one-pass electrolytic oxidation treatment.

Here, the two first electrolytic cells 21A and 21B are electrolyzed at a low voltage (0.7 to 1.5 V or less) to prevent the formation of silver sulfide.

In the second electrolytic cell 41, the current density is 1 to
Since electrolysis is performed at 10 A / dm ² , it is desirable to use a DSA electrode as the anode material.

Since the current density is high, the second electrolytic cell 41 can be miniaturized, but the pH adjusting agent tank 47 can be injected at a proper time through the pump 48 and the valve 49 as a pH adjusting means for changing the pH. There is. Of course, a part of the overflow liquid in the developing tank can be used as the pH adjusting agent. Thus, the object of the method of the present invention can be achieved also in this embodiment.

In addition to the above-mentioned embodiment, the first and second electrolytic cells are arranged in series in the same cell, or are provided a little apart from each other. After the recovery process, enter the basin with high electrolysis voltage
The process of removing the D component may be performed in one tank. Further, in any of the above examples, the deodorizing effect can be enhanced by providing an adsorbent in the electrolytic cell and absorbing the coloring component in the photographic processing waste liquid or the washing water.

[0046]

EFFECT OF THE INVENTION Silver recovery from photographic processing solutions and BOD, C
By the method of the present invention in which the oxidative decomposition action of the OD generation substance is passed through different electrolytic cells and the voltage is maintained at low voltage and high voltage, respectively, silver can be recovered without generating silver sulfide and harmful BOD and COD are generated. The oxidative decomposition of substances can now be performed efficiently at high speed.

Further, it becomes possible to smoothly improve the fear that the photographic processing waste liquid will affect the water quality and the like.

[Brief description of drawings]

FIG. 1 is an overall flow chart of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a first electrolytic cell according to the first embodiment of the present invention.

FIG. 3 is a flow chart of silver recovery by the first electrolytic cell.

FIG. 4 is a diagram showing changes in silver concentration in the first electrolytic cell.

FIG. 5 is a flow configuration diagram in the second electrolytic cell.

FIG. 6 is a diagram showing changes in iodine consumption with electrolysis time.

FIG. 7 is a flow chart in which an overflow developer is added as an alkaline agent.

FIG. 8 is a pH change diagram with electrolysis time.

FIG. 9 is a one-pass flow chart of the second embodiment of the present invention.

FIG. 10 is an overall waste liquid treatment flow chart as a third embodiment of the present invention.

[Explanation of symbols]

 11 Developing tank 12 Fixing tank 13 Washing water tank 21, 21A, 21B First electrolytic tank 22, 42 Anode 23, 43 Cathode 27 Stock tank 41 Second electrolytic tank 47 pH adjusting agent tank

Claims (11)

[Claims] 1. A system for electrolytically oxidizing a photographic processing waste liquid, wherein two electrolytic cells are connected in series to share the functions,
Photographic processing characterized in that electrolytic silver is mainly recovered in the first electrolytic cell, and second electrolytic cell is electrolyzed at a higher voltage than the first electrolytic cell to electrolytically oxidize harmful substances in the processing waste liquid. Waste liquid treatment method. 2. A method for treating a photographic processing waste liquid according to claim 1, wherein the electrolysis voltage of the first electrolytic cell is set in the range of 0.7 to 1.5V. 3. The method for treating photographic processing waste liquid according to claim 1 or 2, wherein the electrolysis voltage of the second electrolytic cell is 1.5 V or more. 4. A method for treating a photographic processing waste liquid according to claim 1, wherein the second electrolytic cell is electrolyzed under a condition of a current density of 1 to 10 A / dm ² . 5. A photograph in which two electrolyzers are connected in series, and mainly electrolytic silver is recovered in the first electrolyzer, and the second electrolyzer is electrolyzed at a higher voltage than the first electrolyzer. This is a method of photo-processing wash water that electrolytically oxidizes harmful substances in the wash water. It uses two circulation pipes to circulate the first electrolysis tank and the water washing tank with a circulation pump to return the water from the first electrolysis tank to the water washing tank. A method of treating photographic treated rinsing water, characterized by branching and partly rinsing water flowing into a second electrolytic cell for treatment in one pass. 6. A method in which two electrolyzers are connected in series and electrolytic silver is mainly recovered in the first electrolyzer, and the second electrolyzer is electrolyzed at a higher voltage than the first electrolyzer. A method for treating photographic treated water by electrolytically oxidizing harmful substances in the treated water, in which overflow liquid from the washing tank is treated in a single pass in the order from the first electrolytic cell to the second electrolytic cell. A method for treating photographic processed rinsing water, which is characterized in that 7. A processing method for a photographic processing waste liquid, which comprises subjecting an integrated waste liquid for development, fixing and washing to electrolytic oxidation treatment using the system according to claim 1. 8. The electrolytic cell is provided with a means for removing a coloring component by an adsorbent from a treatment waste liquid electrolyzed in each electrolytic cell. Photoprocessing waste liquid treatment method. 9. The pH according to any one of claims 1 to 8.
A method for treating a photographic processing waste liquid, wherein a step of adjusting a value by replenishing an alkaline agent is added to a step before the treatment of the second electrolytic cell. 10. The method for treating a photographic processing waste liquid according to claim 9, wherein the alkaline agent is an overflow liquid of a developing solution. 11. At least a BOD component substance is oxidatively decomposed by a first step of recovering silver at a low electrolysis voltage and a second step of electrolyzing at a voltage higher than the low voltage. A method for treating photographic waste liquid, which is characterized by: