JP2000256006A - Method for refining activated carbon and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove impurities in activated carbon for a short time without using the large quantity of water by continuously supplying water and air to an activated carbon layer, in which the activated carbon is filled. SOLUTION: The device for refining the activated carbon is constituted of a supply part 1 of water, an air supply part 2, a diffusion pipe 3, wire gauze 4 supporting the activated carbon, the activated carbon layer 5 filled with the activated carbon, an over-flow vessel 6 for receiving water over-flowed, an outlet part 7 for water and wire gauze 8 for preventing the scattering of the activated carbon. A system for flowing both water and air in parallel from the lower part of the activated carbon layer 5 is preferable. Aeration holes of the diffusion pipe 3 are provided in the lower 1/5 part of the side surface part of the activated carbon layer 5. The water is supplied at a space velocity equal to or above the fluidization starting velocity of the activated carbon layer 5 and at a velocity that the expansion coefficient of the activated carbon layer 5 due to the flow of the water becomes >=5%. The supply rate of the air is preferably >=0.5 m/min in linear velocity and 0.05-1.0 in the (space velocity of water)/(space velocity of air). The water or air is intermittently supplied at a short interval until cleaning waste water reaches pH 5-9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and a device for purifying activated carbon. More specifically, the present invention relates to a method of purifying activated carbon by continuously supplying water and air to an activated carbon layer filled with activated carbon, and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, removal of impurities such as metals and oxides or chlorides thereof in activated carbon has been carried out by immersing activated carbon in water or packing activated carbon into a column and passing washing water through. Have been done. Further, a purification method of adding an acid such as hydrochloric acid or sulfuric acid at the same time to neutralize those impurities or adjusting the water temperature to promote elution is generally used.

[0003] In recent years, activated carbon used mainly in the field of water treatment, such as water treatment and wastewater treatment, has been desired to remove impurities in the activated carbon as much as possible. In the production of activated carbon, the purification process of activated carbon has become very important.In general, impurities are eluted with a large amount of washing water to neutralize or neutralize the activated carbon. In order to promote elution, a large amount of acid such as hydrochloric acid or sulfuric acid is added.

Conventionally, there has been known a method of using water and air for cleaning an adsorption tank or a biological activated carbon treatment tower for treating wastewater such as sewage or industrial wastewater. For example, JP
Japanese Unexamined Patent Publication No. Hei 4-126688 and Japanese Unexamined Patent Publication No. Hei 5-236664 disclose an adsorption tank in which washing operation and removal of used activated carbon are made efficient.
In the publication, a method for cleaning a biological activated carbon treatment tower is disclosed. However, any of the methods disclosed in these methods is a method of reducing the pressure loss of a tank or a tower by removing SS components attached to activated carbon and suspended substances accumulated in an activated carbon layer. The supply of water is stopped, and then air is supplied to separate the SS component attached from the activated carbon surface, and the SS component and the like that have been separated are removed from the system by flowing washing water.

[0005]

However, in a purification method using a large amount of washing water or acid, purification requires a long time and is inefficient, and additional purification equipment is required to compensate for this. Inevitably, the equipment becomes huge. In addition, since a large amount of washing water and acid are used, their waste is increased, and a problem of wastewater treatment occurs. Further, according to the method disclosed in the above publication, the SS component can be separated from the surface portion of the activated carbon, but the activated carbon cannot be purified. Therefore, an object of the present invention is to provide an efficient activated carbon purification method and an apparatus thereof that use a small amount of water and can remove impurities in the activated carbon in a short time.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and continuously supply air together with washing water to purify activated carbon.
The present inventors have found that impurities in activated carbon can be efficiently removed, and have reached the present invention. That is, the present invention is a method for purifying activated carbon, which comprises continuously supplying water and air to an activated carbon layer filled with activated carbon.

Another invention of the present invention is an activated carbon refining apparatus comprising an activated carbon layer filled with activated carbon obtained by activating or regenerating, having a supply section and an outlet section for air and water for purification. .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The activated carbon used in the present invention includes those produced from charcoal, coal, coconut shell, coke, resin, petroleum pitch and the like.
Various raw material carbides such as wood, coal, resin, and pitch are activated by a method such as gas activation, steam activation, or chemical activation by activating with a chemical such as zinc chloride or phosphoric acid.

Although the content and composition of impurities in the activated carbon vary depending on the starting materials, woody, coal and coconut shells have a large amount of impurities. It is particularly effective for removing impurities in activated carbon. The refining method and the refining apparatus of the present invention can be applied not only to the activated carbon described above but also to the so-called carbonized one before the activation, and the activated carbon regenerated after being used for various purposes.

[0010] The purification method and purification apparatus of the present invention are also effective for the purification of acid-treated activated carbon. As described above, in the purification of activated carbon, an acid treatment such as addition of an acid such as hydrochloric acid or sulfuric acid is also performed to neutralize impurities in the activated carbon or promote elution. It is common to wash with water to remove it. In general, hydrochloric acid is often used as an acid, and hydrochloric acid may be easily adsorbed on activated carbon.If activated carbon after acid treatment is directly charged into activated carbon or the like and passed through, the acid is eluted and the pH of the outlet water is reduced. descend. Therefore, after the acid treatment, washing and purifying with a large amount of water are usually performed.

In order to purify activated carbon by the purification method of the present invention, activated carbon particles are packed into a column having a supply section for supplying air and water to form an activated carbon layer, and water and air are continuously supplied. I just need. If water or air is supplied intermittently at short intervals, the refining effect may increase. It is preferable to provide a scattering prevention means such as a wire mesh at the upper part of the column and at the outlet side of the water so as to prevent the activated carbon from scattering. The waterfall means for supplying air may be any means that can supply air to the activated carbon layer, and a diffuser made of stainless steel, ceramics, plastic, etc. has a simple structure and is easy to install, and is preferably used. You.

The water and the air may be supplied by a countercurrent method in which water is supplied from the upper part of the activated carbon layer and air is supplied from a lower part of the activated carbon layer. Is preferred because of its greater purification effect. FIG. 1 shows a schematic view of an example of the activated carbon purification apparatus of the present invention. In FIG. 1, 1 is a water supply unit, 2 is an air supply unit, 3 is an air diffuser,
4 is a wire mesh for supporting activated carbon. 5 is an activated carbon layer filled with activated carbon, 6 is an overflow tank for receiving overflowed water, 7 is an outlet of water, and 8 is a wire mesh for preventing scattering of activated carbon. FIG. 2 is a diagram in which an air supply unit is provided on the side surface of the activated carbon layer.

[0013] The air outlet from the air diffuser (waterfall outlet)
The pores are preferably formed as small holes in order to prevent clogging by activated carbon particles or the like, and are preferably formed in a sintered plate shape so that air is supplied to the activated carbon layer as uniformly as possible. In addition, the waterfall means may be provided at the bottom of the activated carbon packed bed with a waterfall opening, but if it is provided on the side of the activated carbon layer, it is possible to reduce the influence of clogging by fine powder of activated carbon, which is preferable. . In this case, it is better to turn the waterfall slightly upward or to provide a wire mesh at the waterfall. It is preferable that the position where the waterfall means is provided be within about 1/5 of the lower part of the side surface. The water supply unit is usually provided at the bottom of the activated carbon layer, but is not limited. Tap water is sufficient as water used for the purification of activated carbon.

The main components of the impurities eluted from the activated carbon are those consisting of alkali metals or alkaline earth metals. The pH of the washing wastewater is measured, and the pH is adjusted to 5 to 9, preferably 6 to 8.5. Activated carbon can be efficiently purified by supplying water and air until the time comes. According to the ministerial ordinance on water quality standards based on the Water Supply Law, the pH value must be between 5.8 and
Since 8.6 is specified, the above-mentioned pH is also advantageous in this respect. The removal of impurities besides pH
It is also possible to measure metal ions by ion chromatography or to measure electrical conductivity.
The value is easy and easy to measure.

Generally, the fluidity of the activated carbon layer decreases as the particle size of the activated carbon increases and as the water temperature increases. Therefore, the ranges of the supply amounts of the air and the washing water cannot be completely defined, but there are preferable ranges of the supply rates of the supplied water and the air. As the water supply speed, the superficial water supply speed (there is no packing in the activated carbon layer,
Water supply rate assuming that only water was supplied)
It is preferable that the rate of fluidization of the activated carbon layer is higher than the fluidization start rate, and it is more preferable that the expansion rate of the activated carbon layer due to the flow of water is 5% or more, and more preferably 10% or more. The expansion coefficient of the activated carbon layer can be confirmed by changing the layer height of the activated carbon layer.

On the other hand, the supply speed of the air is usually 0.5 m / min or more as a linear velocity, but when the expansion rate is less than 10%, it is preferable to supply the air at a linear velocity of 1 m / min or more.
If the air supply speed is too low, the refining effect is small, and if it is too high, the activated carbon may be destroyed and the effect is not commensurate with it. Therefore, the superficial velocity of water / superficial velocity of air = 0.05 It is preferable to carry out at 1.0. Hereinafter, the present invention will be described specifically with reference to examples.

[0017]

EXAMPLES Example 1 and Comparative Example 1 5 liters (L) of a coal-based activated carbon having a particle size of 0.5 to 1.7 mm was placed in a column made of transparent PVC having a diameter of 8 cm and a total length of 2 m.
Was packed so as to have an activated carbon layer height of 1 m. 50 L / hour of tap water, SV10Hr as washing water from the bottom of the column
^-1 , air for aeration was supplied at 7 L / min. The state of the removal of impurities in the activated carbon was observed by the change over time of the pH. As a comparative example, the activated carbon was purified in the same manner except that air was not supplied. P of waste water discharged from activated carbon layer
The purification process is shown in FIG. 3, where H is the vertical axis and the water flow rate (cumulative water flow rate / filled amount of activated carbon) is the horizontal axis. When aeration was performed by supplying air, the pH of the washing wastewater became 8 or less by a water passage magnification of 40 times. In addition, the amount of water was less than 1/4 that of the case where no air was supplied, and the washing water could be largely saved.

Example 2 and Comparative Example 2 Activated carbon was purified in the same manner as in Example 1 except that the activated carbon was changed to a coconut shell-based activated carbon having a particle size of 0.5 to 1.7 mm. As a comparative example, purification was carried out in the same manner as described above except that no air was supplied. FIG. 4 shows the results. When aeration was performed by supplying air, the pH of the washing wastewater became 8 or less by a water passage magnification of 40 times. In addition, the amount of water was less than 1/4 that of the case where no air was supplied, and the washing water could be largely saved.

Example 3 and Comparative Example 3 5 L of a coal-based activated carbon having a particle size of 0.5 to 1.7 mm was placed in a transparent PVC activated carbon purification column having a diameter of 8 cm and a total length of 2 m.
(Activated carbon layer height 1 m). Water was stretched to a water level of 1.4 m, and hydrochloric acid was added dropwise while stirring the inside of the column tank until the water in the column reached pH 4, and acid treatment was performed. Then, tap water was added as washing water from the bottom of the column at 50 hours
L, air for aeration was supplied at 7 L / min. The state of the removal of impurities in the activated carbon was observed by the change over time of the pH. As a comparative example, the same test was performed without supplying air. As a result, when aeration is performed by supplying air, the pH of the washing wastewater becomes 7 by 20 times the water flow rate.
Became. The amount of water is less than 1/3 that of the case where no air is supplied, and the washing water can be largely saved.

[0020]

According to the method and apparatus for purifying activated carbon of the present invention, impurities in activated carbon can be efficiently removed by continuously supplying water and air to purify activated carbon. . Therefore, when refining activated carbon,
Wash water can be greatly reduced, and cost can be significantly reduced in the purification process.

[Brief description of the drawings]

FIG. 1 is an example of an activated carbon purifying apparatus of the present invention.

FIG. 2 is another example of the activated carbon purifying apparatus of the present invention.

FIG. 3 is a graph showing the progress of purification of activated carbon in Example 1 and Comparative Example 1.

FIG. 4 is a graph showing the progress of purification of activated carbon in Example 2 and Comparative Example 2.

FIG. 5 is a graph showing the purification process of activated carbon in Example 3 and Comparative Example 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Water supply part 2 ... Air supply part 3 ... Air diffuser 4 ... Wire mesh 5 ... Activated carbon layer 6 ... Overflow tank 7 ... Water outlet 8 ... Wire mesh

Claims (7)

[Claims] 1. A method for purifying activated carbon, comprising continuously supplying water and air to an activated carbon layer filled with activated carbon. 2. The method for purifying activated carbon according to claim 1, wherein water and air are continuously supplied until the pH of waste water discharged from the activated carbon layer becomes 5 to 9. 3. The method for purifying activated carbon according to claim 1, wherein the superficial velocity of the water is equal to or higher than the fluidization start velocity of the activated carbon layer. 4. The expansion coefficient of the activated carbon layer due to the flow of water is 5
% Of the activated carbon according to claim 3. 5. The superficial velocity of the water / superficial velocity of the air = 0.
The method for purifying activated carbon according to any one of claims 1 to 4, wherein the ratio is from 0.05 to 1.0. 6. An air and water supply unit and an outlet unit,
Activated carbon refiner consisting of an activated carbon layer filled with activated carbon. 7. The activated carbon refining apparatus according to claim 6, further comprising an air supply section on a side surface of the activated carbon layer.