JPH03229688A - Method for evaporative concentration of waste photographic processing solution and defoaming agent added to same waste solution - Google Patents

Abstract

PURPOSE:To obtain an evaporative concn. method suppressing the generation of gas, in concentrating a waste photographic processing solution by connecting a vacuum means to evaporate said waste solution under heating in a vacuum state, by adding a defoaming agent to the waste photographic processing solution. CONSTITUTION:A heating means 2 is three-dimensionally arranged in a housing 1 to be present inside and outside of the liquid in a liquid sump part 4 so as to cross the solution level A of the waste photographic processing solution supplied from an injection port P. The solution pumped up by a feed means 3 is injected to the heating means 2 from a liquid emitting port R. A moisture condensing part 5 having a cooling means arranged thereto is formed to the upper part of the housing 1 and a vacuum apparatus 7 provided with a suction pump 6 is connected to the housing 1 to evacuate the housing 1 to hold the pressure therein to about 30-60mmHg. In order to prevent the generation of gas, a silicone defoaming agent is supplied to the waste photographic processing solution from an injection port Q. By this constitution, a method for the evaporative concn. of the waste photographic processing solution suppressing the generation of gas can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a processing technology for efficiently removing moisture from photographic processing waste liquid by evaporation concentration, reducing the amount of waste involved in disposal, and preventing the generation of unpleasant gases. Regarding.

[Conventional technology]

Photographic processing waste liquid is a waste product of the photographic processing liquid used to develop silver salt photosensitive materials.In addition to the chemical components prepared from the beginning, it also contains components eluted from the silver salt photosensitive materials and chemical reactions. Because it contains products, it has a negative effect on photographic processing.In order to maintain good photographic processing, it is necessary to replenish the new solution according to the amount of processed light-sensitive material to compensate for its performance and eliminate unnecessary contaminating components. Discard aged liquid.

This is photographic processing waste liquid. The amount of waste varies depending on the type of photographic processing, but for example, it can be as much as 0.03 CC/am2.

Here, the amount of liquid is expressed in terms of the area of the photosensitive material to be processed. Therefore, when a large amount of photographic processing is carried out continuously as a business, a large amount of photographic processing waste is generated, and it is difficult to find a place to store it until a collection company is asked to detoxify it. Ta.

Collection companies use methods such as electrolysis to recover the silver contained in photographic processing waste liquid, or treat it to make it non-polluting, but these recovery methods are very costly, so we are trying to somehow reduce the amount of photographic processing waste liquid. Efforts have been made to make the area pollution-free. Are there any known methods such as activated sludge method, evaporation method, electrolytic oxidation method, reverse osmosis method, chemical treatment method, etc., but these methods are still not efficient;
It was expensive and did not meet widespread demand.

If the water is separated from the photographic processing waste and the harmless water is dumped, there will be less solid components remaining, and it is also advantageous in terms of recovery processing, so in recent years, water has been removed using the evaporation concentration method. Many improvements have been made. But the problem is,
When photographic processing waste liquid is heated and evaporated, not only water evaporates, but also unpleasant gases are generated, so water cannot be easily removed using existing distillation means. Therefore, large-scale equipment with waste countermeasures is required, so from the cost, cost, and management standpoint, it is considered that large-scale processing companies should install it, and the simplification that was required. This deviates from the aim of saving space and cost.

It is not permissible to dump photographic processing waste into nature due to its high pollution burden. However, the amount of photographic processing waste liquid generated is large, and even a relatively small-scale photographic processing company generates about IO liters per day, and the cost of securing storage space and paying the waste liquid processing company is large.

Therefore, there was a strong need for a method that could easily reduce the amount of photographic processing waste immediately close to where it is generated. As a means of reducing the amount of photographic processing waste liquid, there is a means of separating and removing the water content, and a specific method thereof is evaporation concentration method. Generally, photographic processing solutions only contain about 70g of salts per liter, and the rest is water, and there is no big difference even if it is photographic processing waste, so if this water can be removed, there will be no problem with the storage location mentioned above. will disappear. However, in order to evaporate and concentrate until the water is completely removed from photographic processing waste liquid,
Needless to say, this requires a large amount of energy and is rather uneconomical. On the other hand, when applying evaporation treatment to boat fishing, in the case of photographic processing waste liquid, unpleasant scum or harmful gases are generated, so that it cannot be put to practical use without considerable ingenuity. That is, harmful or malodorous residues such as sulfur dioxide gas, hydrogen sulfide, and ammonia gas are generated. Ammonium thiosulfate and sulfite (ammonium salt,
It is caused by the decomposition of salts (sodium salts or potassium salts) at high temperatures, so it is a good idea to take countermeasures based on this.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide an evaporative concentration method that suppresses gas generation when evaporating and concentrating photographic processing waste liquid.

[Means to solve the problem]

The purpose of this is to eliminate the generation of unpleasant scum by adding an antifoaming agent to the photographic processing waste liquid when the photographic processing waste liquid is heated and evaporated and concentrated under reduced pressure by connecting a pressure reduction means.
A method for evaporating and concentrating photographic processing waste liquid characterized by the following: or when the photographic processing waste liquid is concentrated by heating and evaporating under reduced pressure by connecting a depressurizing means, the method is added to the photographic processing waste liquid in order to eliminate the generation of unpleasant scum. This is achieved by using a silicone antifoaming agent.

〔Example〕

In this invention, the pressure reducing means is, for example, a vacuum pump, which has the ability to continuously suck out gas from a finite space, and makes the gas pressure within the finite space lower than the outside atmospheric pressure. In this invention, a housing for evaporative concentration of photographic processing waste liquid is applied as the limited space, and the gas pressure value to be reduced allows moisture to evaporate during heating and evaporation of photographic processing waste liquid, causing unpleasant or harmful This is set to a range that suppresses the generation of dust bubbles, and in this example, the range is set to 30.
Good results have been obtained at ~60 mmHg.

Furthermore, the generated water vapor has a large volumetric expansion and will quickly break the reduced pressure state. Therefore, the capacity of the pressure reducing means is increased to immediately absorb the pressure increase generated by the water vapor, and the gas inside the housing is In order to maintain the pressure at a specified value, a pressure gauge was provided to control the operation of the pressure reducing means. Next, the reason for heating and evaporating in a reduced pressure state is that it is known that the boiling point of a liquid is lowered in a reduced pressure state, and it is particularly effective in accelerating the evaporation of water at low temperatures. The main reason for this is that the temperature range does not generate unpleasant or harmful residue. However, in a configuration in which the photographic processing waste liquid is brought into contact with a heating means under reduced pressure to transfer heat and perform evaporative concentration, dregs bubbles may be generated in the photographic processing waste liquid that touches the surface of the heating means, and this should be prevented. This also became necessary as a gas countermeasure. Therefore, in this invention, an antifoaming agent is added and the photographic processing waste liquid is evaporated and concentrated under reduced pressure.

As the evaporation concentration progresses, the state of bubble generation changes, so the amount or timing of addition of the antifoaming agent may be controlled in accordance with the change. As this antifoaming agent, a Noricon type antifoaming agent as shown by the following chemical formula was used in the examples.

The amount added is preferably 0.001g#2~lOg/(
2, more preferably 0. O1g/ff -1gIQ. This antifoaming agent can be obtained from Dow Corning Co., Shin-Etsu Silicone Co., Ltd., Renricorn Co., Ltd., and Nippon Unicar Co., Ltd.

The antifoaming agent is not limited to those mentioned above, but any antifoaming agent may be used as long as it is compatible with each treatment liquid and suppresses the generation of gas bubbles for the above reasons.

FIG. 1 shows a schematic diagram of an evaporative concentration apparatus for photographic processing waste liquid according to an embodiment using the method of the present invention.

In FIG. 1, a heating means 2 is arranged three-dimensionally in the housing 1, and extends over the liquid level A of the photographic processing waste liquid supplied from the inlet P, into and out of the liquid reservoir 4. exist. The liquid pumped up by the feeding means 3 is ejected from the discharge port R toward the heating means 2. In addition, a portion 5 for condensing moisture provided with a cooling means 8 is formed in the upper portion of the housing l, and a pressure reducing device 7 provided with a suction pump 6 is connected to the housing l. Apply vacuum and maintain at 30-59 mmHg.

In this state, active water vapor is generated from the photographic processing waste liquid heated by the heating means 2, and evaporation and concentration proceed.
At the same time, bubbles are likely to be generated from the liquid. When bubbles are generated, there is a part on the surface of the heating means that does not touch the photographic processing liquid, and this part is not cooled, so the surface temperature of the part exceeds the specified value, so the photographic processing waste liquid that comes into contact with it next. will be thermally decomposed and generate scum. In order to prevent this phenomenon, an antifoaming agent was supplied from the injection port Q to the photographic processing waste liquid.

〔Effect of the invention〕

With this structure, it is possible to provide an evaporative concentration method that suppresses the generation of scum during evaporative concentration of photographic processing waste liquid, and an antifoaming agent to be added to the waste liquid. Therefore, it is possible to put into practical use a compact device that can easily concentrate and reduce the amount of photographic processing waste close to the device that generates it.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus using the method of the present invention. ■...Housing 2...Heating means 3...Liquid feeding means 4...Liquid reservoir 5...Part that condenses moisture/Suction bow 7...Pressure reduction device

Claims (2)

[Claims] (1) A defoaming agent is added to the photographic processing waste liquid when the photographic processing waste liquid is heated to evaporate and concentrated under reduced pressure by connecting a pressure reduction means, thereby eliminating unpleasant gas generation. Method for evaporating and concentrating photographic processing waste liquid. (2) A silicone antifoaming agent that is added to the photographic processing waste liquid in order to eliminate the generation of unpleasant gas when the photographic processing waste liquid is concentrated by heating and evaporating under reduced pressure by connecting a pressure reducing means.