JPH091128A - Waste liquid treatment method - Google Patents

Abstract

(57) [Summary] [Structure] When the waste liquid is evaporated and dried to form a solid,
A method for treating waste liquid, which comprises heating and drying the waste liquid in the presence of a predetermined amount of layered silicate mineral. [Effect] The waste liquid that cannot be discarded as it is can be inexpensively and easily made into a solid substance that can be discarded. In addition, this solid substance is easy to handle because its particles are smooth and does not adhere to the container, and it also satisfies the elution test standards for substances that cause environmental pollution. Also, by making the waste liquid such a solid matter,
The volume of waste can be remarkably reduced, and waste disposal can be done easily without taking up space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating waste liquid. More specifically, it relates to a method for converting waste liquid into a solid material that can be discarded.

[0002]

2. Description of the Related Art When discarding a liquid waste (waste liquid) containing environmental pollutants such as metals and various chemical substances, the safety of pH, chemical oxygen demand (COD), harmful metal content, etc. Must be processed so as to meet certain criteria. When discarding a large amount of waste liquid every day, large-scale equipment is used for pollution-free processing, but it is difficult to install and use such equipment in small and medium-sized factories, so large-scale equipment is used. A treatment method that does not require is proposed and put to practical use. For example, a small biodegradation method such as an electrolytic oxidation method, an adsorption removal method, a sprinkling filter method, and a dialysis method are used. Each of these methods has features such as effective reduction of COD, effective removal of harmful metals, suitable for concentrated liquid but not diluted liquid, and vice versa. The treatment method is selected according to the nature of the waste liquid.However, if there are multiple environmental pollution factors in the waste liquid and the composition is complicated, it is difficult to detoxify the waste liquid by either method. Many. As one of such waste liquid treatment methods, an evaporation method has been used in which the waste liquid is concentrated by evaporation to produce a concentrated waste liquid or solid sludge.
In this method, since the viscosity of the waste liquid increases with the concentration, the concentrated waste liquid adheres to the inside of the container, and it is difficult to discharge and dry the concentrated waste liquid.

[0003]

Accordingly, the present invention provides
It is an object of the present invention to provide an inexpensive and simple method for producing a solid material that can be discarded and is easy to handle.

[0004]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found that when a layered silicate is added to a waste liquid and then heated and dried, it has no adhesiveness and is a dry solid. They have found that they can be made into things, and have completed the present invention based on this finding. That is, the present invention provides (1) treatment of a waste liquid, which comprises heating and drying the waste liquid in the coexistence of a predetermined amount of a layered silicate mineral in evaporating and drying the waste liquid into a solid. Method, (2) the waste liquid is an industrial waste, the method for treating the waste liquid according to the item (1), (3) the waste liquid is a waste liquid for processing a silver halide photographic light-sensitive material, the waste liquid according to the item (1) or (2) The present invention provides a treatment method and (4) the treatment method for waste liquid according to the above (1), (2) or (3), wherein the layered silicate mineral is bentonite or saponite.

The present invention will be described in more detail below. The waste liquid in the present invention refers to a waste liquid containing environmental pollutants such as metals and chemical substances, and there is no particular limitation on the composition or concentration, and it can be performed on any thing, but preferably a plurality of metal species It is suitable for treating waste liquid containing chemical substances. Examples of the waste liquid treated in the present invention include waste liquids as industrial wastes, specifically various waste liquids discharged in printing plate making, photographic processing, metal processing, food processing, etc., and particularly photographic processing Waste liquids discharged in the process, such as silver halide photographic processing waste liquids (waste liquids from processing of development, fixing, bleaching and bleach-fixing) are preferred.

The layered silicate mineral used in the present invention is generally called a clay mineral, and examples thereof include smectite montmorillonite, beidellite, nontronite, saponite, and hectorite. Any of these natural products or synthetic products may be used. Bentonite, acid clay, etc. may be used, and further, those showing swellability in water and those not showing swelling can be used. These may be used alone or in combination of two or more. Preferably, a natural or synthetic product of saponite or bentonite is used. When coexisting in the waste liquid before heating, the water content is 20% by weight or less, and the particle size is 100μ.
A layered silicate mineral having a size of m or less is preferable.

The amount of the layered silicate mineral coexisting in the waste liquid to be treated is usually 10% by weight or more and less than 95% by weight, preferably 30 to 90% by weight, based on the solid content in the waste liquid. The amount of the layered silicate mineral added varies depending on the composition and concentration of the waste liquid, and it is preferable that the solid content in the waste liquid is large when it is 10% by weight or more and small when it is 5% by weight or less.
If the amount of layered silicate mineral is too large, it exceeds the amount necessary to adsorb and concentrate the solid content in the waste liquid, which not only increases the drying process time but also wastes the layered silicate mineral. . On the other hand, if the amount of the layered silicate mineral is too small, the adsorption and concentration of the solid content in the waste liquid cannot be sufficiently achieved, so that there is a problem that unadsorbed harmful substances are eluted from the waste.

The waste liquid in which the layered silicate mineral is coexisted is stirred until it becomes uniform, and then concentrated and dried. Concentration and drying may be carried out by any ordinary heating method, and for example, an electrothermal dryer such as a drum dryer or a CD dryer, a spray dryer, a fluidized bed dryer or the like can be used.
The waste liquid is heated preferably at 40 to 200 ° C., more preferably 80 to 150 ° C., and dried until the water content becomes 20% by weight or less, preferably 10% by weight or less.
The solid thus obtained has no adhesiveness and is easy to handle. In addition, the amount of waste that becomes an environmental pollutant elutes from solids is small, and it meets certain environmental standards, and can be discarded.

[0009]

According to the present invention, waste liquid that cannot be discarded as it is can be easily and inexpensively converted into a solid substance that can be discarded. In addition, the solid matter obtained in the present invention is easy to handle because its particles are smooth and does not adhere to the container, and it also meets the criteria of the elution test for substances that cause environmental pollution. In addition, by using the waste liquid as such a solid material, the bulk of the waste can be remarkably reduced, and the waste disposal can be performed easily without taking up a lot of space.

[0010]

Next, the present invention will be described in more detail with reference to examples. Example 1 1000 ml of silver halide photographic processing waste liquid discharged from a small developing processor of a photo shop in Kuroiso City (solid content 12 g / 1
Sodium bentonite (Kunibond HB
(Trade name, manufactured by Kunimine Industry Co., Ltd., particle size 74 μm) 66
After adding g and stirring uniformly, the mixture was placed in a porcelain vat vat and dried with a blower dryer at 105 ± 5 ° C. until the water content was 3% by weight to obtain a dry solid. Similarly, in the same photographic processing waste liquid of 1000 ml, 78 g of Kunibond HB and 9
5 g and 114 g were added and dried to obtain dry solids. The amount of each of these solids in a 100 g Buchner funnel was washed with 1000 ml of water, and the amount of effluent was measured by the evaporation dryness method. As a comparison, the same photographic waste liquid was treated in exactly the same manner except that Kunibond HB was not added.
The amount of effluent was measured by washing with 00 ml of water. The results are shown in Table 1. Also, 1000 ml of water obtained by washing 100 g of a solid substance prepared by adding 95 g of the above Kunibond HB with water
For cadmium, mercury, lead, organic phosphorus, arsenic, cyanide, and copper, the elution amount was measured according to the method described in Table 2. The results are shown in Table 2.

[0011]

[Table 1]

[0012]

[Table 2]

All the solids obtained had no adhesiveness, the particles were dry, and they were easy to remove from the container and handle. From the results in Table 1, it can be seen that a harmful solid substance in the photographic processing waste liquid is fixed and a dry solid substance in a form in which it does not flow out into water is obtained. In addition, as is clear from the results of Table 2, the amount of environmental pollutant elution in the dried solid matter is small for each component and is below the reference value, and the solid matter obtained by the method of the present invention can be disposed of. I understand.

Example 2 The same KuniBond HB and calcium bentonite (KuniBond (trade name, manufactured by Kunimine Industries Co., Ltd.) having a particle size of 74 μm) used in Example 1 were added to 1000 ml of the same photographic processing waste liquid as used in Example 1. 1: 1 mixed with 110
g and treated in the same manner as in Example 1 to obtain a dry solid.
As with the solid obtained in Example 1, this solid was smooth and easy to handle. In addition, 100g of this solid
Was washed with 1000 ml of water in the same manner as in Example 1, and the amount of outflow was measured, and it was 1.2 g.

Example 3 1000 ml of silver halide photographic processing waste liquid discharged from a small developing processor of a photo shop in Nishinasuno Town (solid content: 11.
6 g / 100 ml) was placed in a beaker, and synthetic saponite (Smecton (trade name, manufactured by Kunimine Industries Co., Ltd.), particle size 44
μm) was added and treated in the same manner as in Example 1 to obtain a dry solid. As with the solid obtained in Example 1, this solid also had no adhesion and was smooth. This solid 100
g was washed with 1000 ml of water in the same manner as in Example 1 to measure the amount of effluent. As a comparison, the same photoprocessing waste liquid,
A solid substance prepared by treating in exactly the same manner except that smectone was not added was also washed with 1000 ml of water in the same manner, and the amount of effluent was measured. Table 3 shows the results.

[0016]

[Table 3]

Comparative Example 1 Zeolite (manufactured by Nitto Koka Kogyo Co., Ltd., particle size: 105 μm) was added to 1000 ml of the same photographic processing waste liquid as used in Example 1.
The same treatment and drying as in Example 1 were carried out except that 15 g was added. As the concentration increased, the viscosity of the waste liquid increased, and the concentrate adhered to the inner wall of the container, making it difficult to discharge.

Comparative Example 2 Treatment and drying were carried out in the same manner as in Example 1 except that 110 g of calcium carbonate (manufactured by Kunimine Industries Co., Ltd., particle size 60 μm) was added to 1000 ml of the same photographic processing waste liquid as used in Example 1. went. As in Comparative Example 1, the concentrate became highly viscous and adhered to the inside of the container and was difficult to discharge.

Claims (4)

[Claims] 1. When evaporating and drying the waste liquid to form a solid, the waste liquid is heated in the presence of a predetermined amount of a layered silicate mineral,
A method for treating waste liquid, which comprises drying to dryness. 2. The method for treating waste liquid according to claim 1, wherein the waste liquid is industrial waste. 3. The method for treating a waste liquid according to claim 1, wherein the waste liquid is a silver halide photographic light-sensitive material processing waste liquid. 4. The method for treating waste liquid according to claim 1, 2 or 3, wherein the layered silicate mineral is bentonite or saponite.