JP3139123B2 - Extraction and supply method of granular activated carbon in fixed bed activated carbon treatment tower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying and extracting granular activated carbon to a fixed-bed activated carbon treatment tower in advanced water purification treatment as pretreatment of tap water or the like.

[0002]

2. Description of the Related Art In recent years, water pollution in rivers and lakes has been increasing due to the deterioration of the water environment in urban areas. There is a limit point in the chromaticity and odor removal effects. In particular, about 70% of the water sources used as tap water in Japan depend on surface water, such as lakes, dams and river water, and these lakes and dams have active biological activities associated with eutrophication. There is a generation of mold and algal odors due to the formation of organic matter, and organic matter and ammonia nitrogen contained in various wastewater flows into the river water, and these inflows are completely purified by the natural purification action of the river. We can't expect to do that.

[0003] In order to cope with the deterioration of the water quality of the water source due to such high economic growth, pre-chlorination is generally adopted. Trihalomethane which is an organic chlorine compound generated in a water purification process employing pre-chlorination is used. (THM) is known to have carcinogenicity. An advanced water purification system that introduces ozone treatment or a combined treatment of the ozone treatment and activated carbon treatment during the water purification operation process is being studied to eliminate mold and algal odors from such water sources and to take measures against carcinogens such as trihalomethane. Have been.

[0004] Activated carbon treatment, which is one of the above unit operations, refers to the adsorption and removal of mainly organic pollutants in raw water by utilizing the adsorption ability of coconut shell activated carbon, coal activated carbon, and charcoal activated carbon. It is a method, and it is distinguished into powdered activated carbon and granular activated carbon from the form of activated carbon. Further, a method using biological activated carbon obtained by adhering nitrifying bacteria or the like to activated carbon has also been attempted.

[0005] For example, as a method for producing granular activated carbon such as charcoal, there is known a method in which a crushed raw material is formed into a certain particle size using tar as a binder, followed by drying, firing and activation.

In a normal activated carbon treatment tower, raw water flows from the upper part of a fixed bed activated carbon treatment tower filled with granular activated carbon,
A method of discharging the water to be treated from the lower part of the treatment tower is generally adopted.

The above-mentioned ozone treatment is a method using ozone O _3, which has much more oxidizing power than chlorine, and removes off-flavor and chromaticity of raw water, increases biodegradability of organic substances, and requires chlorine. It is characterized in that an effect such as a reduction in the number is obtained.

[0008]

When the activated carbon treatment is performed in such an advanced water purification treatment step, as the adsorption of the substance to be adsorbed such as an organic pollutant to the activated carbon proceeds, the adsorbing capacity of the activated carbon gradually increases. Since the water quality decreases and the quality of the water to be treated gradually deteriorates, it is necessary to replace or replenish the activated carbon in the activated carbon treatment tower with new carbon at regular intervals.

Normally, it is not possible to detect which part of the activated carbon in the activated carbon treatment tower has deteriorated, and therefore, there is no work of selecting and extracting only the deteriorated activated carbon. Therefore, when the activated carbon has deteriorated, the fact is that a method of replacing all the activated carbon filled in the treatment tower is inevitable.

However, when the activated carbon treatment tower is replenished with new charcoal, it usually takes a long time to reach a steady state. For example, when biological activated carbon is taken as an example, biological activated carbon is removed from the treatment tower. It takes two to three months from the time of withdrawing and replenishing new charcoal to function as biological activated carbon, so that there is a problem that a trouble in operation occurs. In addition to the disadvantage that removal of ammonia nitrogen cannot be expected at the start of operation, the biodegradable organic substances that had been removed by the biological activated carbon treatment layer are now transferred to the activated carbon treatment layer. And the quality of the water to be treated is deteriorated.

In view of the above, the present invention has been made in view of the above, and it is possible to remove only the deteriorated activated carbon from the activated carbon treatment tower and replace it with new charcoal, thereby eliminating operational problems and reducing the function of the treatment tower. It is an object of the present invention to provide a method for extracting and supplying activated carbon, which can prevent the occurrence of an activated carbon.

[0012]

In order to achieve the above object, according to the present invention, raw water is first introduced into a treatment tower filled with granular activated carbon and the activated carbon is utilized by utilizing the adsorption capacity of the activated carbon. In a fixed bed activated carbon treatment tower in advanced water purification treatment in which pollutants in raw water are adsorbed and removed, a plurality of stages of sample water intakes are provided in the depth direction of the fixed bed activated carbon treatment tower, and sampling is performed from each sample water intake. The separated water is separately led to an absorptiometer to measure the absorbance, and when the measurement result indicates that the activated carbon has deteriorated, a predetermined amount of the deteriorated activated carbon is withdrawn from the activated carbon treatment tower by a drawing pump and supplied. A method for extracting and supplying granular activated carbon in which only the new coal extracted by the pump for supply is supplied is used as a means for realizing the method.

Further, according to claim 2, in addition to the above configuration,
The treated water flowing into the activated carbon treatment tower and the treated water flowing out of the activated carbon treatment tower are separately led to an absorptiometer to measure the absorbance, and from this measurement result, the overall adsorption capacity of the fixed bed activated carbon treatment tower is determined. Monitoring, when the adsorption capacity of the treatment tower is reduced, based on the measurement results at each of the sample water sampling ports, a predetermined amount of activated carbon that has been confirmed to have deteriorated is extracted by the extraction pump, and only the amount extracted by the supply pump is used. To supply new coal.

[0014] In addition, based on the correlation between the water passage time and the activated carbon of deterioration with respect to activated carbon treatment tower, immediately after passing the start of water to activated carbon treatment tower performs mainly the water sampling from the upper stage of the sample adopted Mizuguchi, water flow A monitoring method is provided that focuses on water sampling from the middle sampling port for a few months after the start, and water sampling from the lower sampling port after a longer period of time.

[0015]

According to the method for extracting and supplying granular activated carbon in the fixed-bed activated carbon treatment and the like, during operation of the activated carbon treatment tower, a plurality of stages of sample water sampling ports are provided so as not to affect the flow-down state of the activated carbon treatment tower. The sample is guided from each water sampling port to the absorptiometer while being sequentially switched, and the absorbance is measured to confirm the state of the activated carbon in the depth direction of the activated carbon treatment tower.

[0016] When deterioration of the activated carbon is confirmed from the measurement results, the activated carbon treatment is temporarily stopped, and activated carbon treated water stored in advance is introduced into the treatment tower to appropriately expand the activated carbon. A predetermined amount of the degraded activated carbon layer is withdrawn using a drawing pump, and then the amount of fresh carbon that has been drawn is supplied into the treatment tower using the activated carbon supply pump.

Also, by separately introducing water from the activated carbon treated water storage tank and the activated carbon treated water storage tank into the absorptiometer and measuring the absorbance, the adsorption ability of the activated carbon treatment tower itself to the treated water is monitored. When the adsorption capacity is reduced, it is determined that at least a part of the activated carbon filled in the treatment tower has deteriorated, and the state of the activated carbon in the depth direction is confirmed based on the operation mode described above, Only the deteriorated activated carbon is withdrawn, and new coal corresponding to the amount of the withdrawn is supplied.

Further, based on the knowledge about the correlation between the water flow time to the activated carbon treatment tower and the deterioration of the activated carbon, water is immediately taken from the upper sample water inlet immediately after the water flow to the activated carbon treatment tower is started. A monitoring method that focuses on water sampling from the sample water sampling port in the middle stage during the month and after a long period of time will be able to focus on water sampling from the sample water sampling port in the lower stage will also be possible, which will enable simplification of operation. .

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for supplying and extracting granular activated carbon in a fixed bed activated carbon treatment tower according to the present invention will be described below in detail.
In this example, first, in order to obtain knowledge on the function of activated carbon in a fixed-bed activated carbon treatment tower, (1) an adsorption characteristic experiment of activated carbon and (2) a biological activated carbon treatment experiment were performed.

(1) Experiment on Adsorption Characteristics of Activated Carbon In order to investigate the adsorption characteristics of activated carbon, humic acid and organic pollutants in mulch extract water were used as the substances to be adsorbed, and two types of activated carbon, coal-based activated carbon A and coconut-based activated carbon B, were used. Find the isotherm adsorption line,
The respective adsorption characteristics were compared.

The humic acid solution was prepared by adding 1 g of powdered humic acid to 1N.
A solution obtained by dissolving with 100 ml of NaOH and removing the ss component using a 0.45 μm membrane filter was used as a stock solution, and the pH was adjusted to 7.0 ± 0.2 with 0.1 N · H ₂ SO ₄ during the test.
And adjusted to a dilution concentration with purified water. Hull extract water was prepared by boiling 2 liters of humus with dechlorinated water for 1 hour, allowing it to cool, and sieving through a sieve to make 20 liters. This solution was subjected to coagulation sedimentation treatment, and the filtrate filtered with a 0.45 μm membrane filter was used as a humus extract stock solution. The water quality of the humus extract stock solution corresponds to the humus extract water that has been concentrated and adjusted about 50-fold. Activated carbon is crushed according to JIS
1474-1975.

In the adsorption test, each of the pulverized activated carbons was
５5.0 g, 0.02 to 1.0 g each in the range of 5 types, humic acid solution and humus extraction water 100 ml
Was added to a 200-ml vial containing, and the air was purged with nitrogen gas, followed by shaking with a constant-temperature shaker at 20 ° C for 24 hours until the equilibrium was reached. After shaking,
The activated carbon was removed with a 0.45 membrane filter, and the chromaticity of the filtrate, COD _Cr (chemical oxygen demand), DOC (soluble organic carbon), E260 (absorbance of sample water at a measurement wavelength of 260 nm), COD _Cr and E260 TH converted from
Isothermal adsorption curves were determined using five indices of MFP (trihalomethane generation ability), and the adsorption characteristics depending on the difference between activated carbon and the stock solution were examined. The result is shown in FIG.

In FIG. 5, the vertical axis represents the amount of adsorption Q per unit activated carbon (mg / g-AC), and the horizontal axis represents Ce / Ci (Ci:
Initial or inflow concentration, Ce: equilibrium or outflow concentration)
Q = k '(Ce / Ci) modified from the Freundlich equation
^{1 / n} was determined. Here, k ′ indicates the adsorption capacity of activated carbon, and the slope 1 / n indicates the ease of adsorption. Therefore, the smaller the slope 1 / n, the better the adsorption from low to high concentration regions. . The E260 is usually used as a measurement index of organic components in water.

As shown in FIG. 5, the coal-based activated carbon A has a higher adsorption capacity than the coconut shell-based activated carbon B, and the two indices except for the chromaticity and the estimated value of THMFP indicate that the slope 1 / n is 0. .9
Although the chromaticity, the slope of E260 and the value converted into THMFP are 1 / n of 0.6 to 0.7, it was found that adsorption was easy in a wide concentration range from low to high. The two indexes of DOC and COD _Cr show characteristics that are easily adsorbed in a high concentration region, but tend to be hardly adsorbed in a low concentration region. In particular, the chromaticity is most easily adsorbed and the adsorption capacity is large, but THMFP, which is the object to be removed with activated carbon, has the lowest value.

(2) Biological activated carbon treatment experiment A biological activated carbon treatment experiment was conducted based on the advanced water purification treatment experimental apparatus shown in FIG. 2 and the specifications and treatment conditions shown in Table 1.

[0026]

[Table 1]

In FIG. 2, reference numeral 1 denotes raw water, 2 denotes an ozone contact tank, and an air diffuser 2 disposed at an inner bottom of the ozone contact tank 2.
Ozone gas O ₃ obtained by an ozone generator (not shown) is released from a. 3 is a fixed bed activated carbon treatment tower filled with coconut shell activated carbon, and 4 and 5 are fixed bed activated carbon treatment towers filled with coal activated carbon. Therefore, in this experiment, three series of experiments of the treatment of the raw water 1 were carried out: ozone treatment + coconut shell activated carbon treatment, ozone treatment + coal activated carbon treatment, and coal activated carbon alone treatment. As the raw water 1 used in this experiment, assuming coagulated sedimentation treated water in a water purification plant, artificial sedimentation water extracted from the above-mentioned leaf decay degree was used.

The humus extract water is prepared by boiling 2 liters of humus with dechlorinated water for 1 hour, allowing it to cool, then filtering it through a sieve and preparing a solution prepared to 20 liters with a coagulant having an injection rate of 50 mg / l. The filtrate filtered through a 0.45 μm membrane filter was used as a humus extract stock solution. The method of pulverizing the activated carbon was performed in accordance with JIS 1474-1975, and the adsorption test was performed by weighing the pulverized activated carbon in a range of 0.02 to 1.0 g and adding 100 ml of humus extracted water to the mixture.
After adding to the vial and purging air with nitrogen gas, the mixture was shaken with a constant temperature shaker at 20 ° C. for 24 hours until the adsorption equilibrium was reached. After completion of the shaking, the activated carbon was removed with a 0.45 membrane filter, and the chromaticity, COD _Cr ,
T converted from DOC, E260, COD _Cr and E260
Isothermal adsorption lines were obtained using the five indexes of HMFP, and the adsorption characteristics depending on the difference of each activated carbon were examined.

The adsorption distribution of ammonia nitrogen (NH ₄ —N), E260, and DOC in the downflow direction of the raw water in each activated carbon treatment tower was measured by a single treatment using the coal-based activated carbon treatment tower 5 without performing ozone treatment. The measurement method used in this experiment was NH ₄ -N by ion chromatography, and other water quality analysis was in accordance with the 1985 version of the tap water test method.

FIG. 4 shows the measurement results on days 440 and 700 from the start of water flow. The vertical axis represents the residence time at the water sampling point in the depth direction of the activated carbon treatment layer and the residence time of the entire activated carbon treatment layer. And the horizontal axis represents the ratio of the outflow concentration to the inflow concentration of each index, Ce / Ci (Ci: inflow concentration,
Ce: outflow concentration).

The value of t / θ in the flow direction from the upper end of the activated carbon is 0.
440 day up to 2 and 700 day NH ₄ -N of Ce /
Ci ratios are 0.1 and 0.25, respectively, and t /
Ce / Ci in the range of θ from 0.2 to 1.0 was almost in an equilibrium state.

Further, ammonia nitrogen (NH ₄ -N) is removed by 75% or more in the surface portion of the activated carbon. Therefore, it is presumed that nitrifying bacteria which remove this ammonia nitrogen are present in a large amount in the surface portion of the activated carbon. Is done.

Comparing the changes of E260 on days 440 and 700, t / θ is 0.2 and the Ce / Ci ratio is 0.2.
There were around 6, but on day 440, it was removed deeper. On the other hand, on the 700th day, there was a tendency to elute again at the boundary of t / θ = 0.6, contrary to the 440th day. On the other hand, the DOC has a t / θ of 0 to 1.
The Ce / Ci ratio up to 0 is 0.55 and NH ₄ -N, E26
It was found that it was lower than 0 and further removed in a 0-dimensional manner.

Therefore, E260 is such that the slope 1 / n is 0.71
Despite being easily adsorbed in a wide concentration range of 9, it is considerably removed in the surface layer portion, so it is presumed that the removal effect by the biota is as large as that of ammoniacal nitrogen. Further, in the deep part where the biota is relatively small, the adsorbing ability of the activated carbon is reduced in about 700 days, which indicates that it is close to breakthrough.

FIG. 3 is a schematic diagram showing a model of the adsorption and removal characteristics of the biological activated carbon treatment layer 11 and the activated carbon treatment layer 12 in the fixed bed activated carbon treatment tower 10. It is shown as follows.

X = A + B where A: adsorbed amount by activated carbon B: adsorbed amount by organism As understood from the above model diagram, the biological activated carbon treated layer 11 mainly has the removal amount B as shown in the figure. ,
Organic matter and ammonia nitrogen are removed by living organisms, and other biodegradable organic matter and the like are mainly adsorbed by activated carbon as indicated by the activated carbon adsorption amount A.
Conversely, in the activated carbon treatment layer 12, the amount of removal of organic matter and ammonia nitrogen by the organism shown by B is small, and the amount of adsorption by activated carbon shown by A is large. Therefore, in the activated carbon treatment layer 12, the time required for the activated carbon adsorption amount A to reach the activated carbon saturated adsorption amount W is shorter than in the biological activated carbon treatment layer 11. Therefore, in such a fixed-bed activated carbon treatment tower 10, the activated carbon treatment layer 12 having reached the activated carbon saturated adsorption amount W quickly.
It can be understood that only the activated carbon, in other words, the activated carbon having reduced adsorption capacity, should be extracted and replaced with new carbon.

Therefore, in the present embodiment, based on the above findings, as shown in FIG. 1, a plurality of sample water sampling holes 13, 14, 15, 16 in the depth direction of the fixed bed activated carbon treatment tower 10 are provided.
, And filters F ₁ , F ₂ , F ₃ , F ₄ and valves V ₁ , V ₂ ,
Each sample is separately led to the absorptiometer 17 via V ₃ and V ₄ , the pump P ₁ and the switching valve V ₅ .

Reference numeral 18 denotes an activated carbon treated water storage tank, and reference numeral 19 denotes an activated carbon treated water storage tank.
From the activated carbon-treated water storage tank 19, the filter F ₆ , the valve V ₇ , the pump P _2, and the filter F ₅ , the valve V ₆ , the pump P _2, and the switching valve V _{5. 3} and are configured to direct the treated water absorption photometer 17 via the switching valve V _5.

In the above embodiment, the fixed bed activated carbon treatment tower 1
Although an example in which four sample water inlets are provided at 0 is shown, the number of water inlets is not limited to the above, and an appropriate number can be selected as needed.

A practical example of the drawing and supply of activated carbon based on such a configuration will be described below. First, as a basic operation,
In order not to affect the flow state of the activated carbon treatment tower 10,
Start pump P ₁ is opened only one valve from the valve V1, V2, V3, V4, direct the sample to the absorption photometer 17 via the switching valve V _5, spectrophotometric (E26
Measure 0). And valves V1, V2, V3, V4
By sequentially switching the measurement, the state of the activated carbon in the depth direction of the activated carbon treatment tower 10 is confirmed.

In the case where deterioration of the activated carbon is confirmed from the measurement result of E260 in this way, the activated carbon treatment is temporarily stopped, and in order to facilitate the extraction, the activated carbon treated water stored in advance is washed with a backwashing pump. The activated carbon is caused to flow into the treatment tower 10 by using the water or the like, and the activated water is expanded to about 150% by the treated water. The activated carbon layer was degraded from the bottom of the activated carbon treatment column 10 a predetermined amount withdrawn using a drawing pump P _4, activated carbon supply pump P ₅ new charcoal 20 in the wet state from the bottom of the treatment column 10, or (not shown) opposite Use the washing pump to supply as much activated carbon as it is pulled out. It is also possible to supply the activated carbon 20 from the upper portion of the processing tower 10 by using the activated carbon supply pump P _6.

Next, cleaning with air and backwashing are performed.
After the pulverized coal removal of the new coal 20 and the activated carbon backwashing, the operation of the activated carbon treatment tower 10 is restarted.

Next, an embodiment based on water quality monitoring as the activated carbon treatment tower 10 will be described below. Since first check adsorbability of pollutants fixed bed activated carbon treatment column 10, by switching the switching valve V ₅ to the pump P ₂ side, the filter F ₅ from the activated carbon treated water storage tank 18, the valve V _6, pump P ₂ and E260 to measure direct the water to be treated absorption photometer 17 via the switching valve V _5. Then it switches the switch valve V ₅ to the pump P ₃ side, the activated carbon treated water storage tank 1
The treated water is guided from 9 through the filter F ₆ , the valve V ₇ , the pump P ₃ and the switching valve V ₅ to the absorptiometer 17 and the E260 is measured in the same manner.

From the above measurement results, the fixed bed activated carbon treatment tower 1
It is possible to judge the adsorption capacity of the activated carbon itself, and when the adsorption capacity is periodically monitored and the adsorption capacity is reduced, at least a part of the activated carbon filled in the activated carbon treatment tower 10 is deteriorated. Judging that the activated carbon has been checked, the state of the activated carbon in the depth direction of the activated carbon treatment tower 10 is confirmed based on the basic operation mode described above, and the deteriorated activated carbon is withdrawn and fresh carbon equivalent to the withdrawn amount is supplied. .

As another monitoring example, immediately after the start of water flow to the activated carbon treatment tower 10, the sample water sampling ports 13, 14 are provided.
Water sampling from the water sampling ports 14 and 15 for several months after the start of water flow, and from the water sampling ports 15 and 16 after a long period of time (for example, one year or more). It is also possible to adopt an embodiment in which water sampling is performed with emphasis. This embodiment is a monitoring method derived from the knowledge on the correlation between the water flow time to the activated carbon treatment tower 10 and the deterioration of the activated carbon. This method does not require the continuous measurement of the absorbance, which simplifies the operation. There is an advantage that it is done.

[0046]

As described above in detail, according to the method for supplying and extracting granular activated carbon in the fixed bed activated carbon treatment tower according to the present invention, the following various effects can be obtained. That is,
When the pollutant adsorption capacity in the fixed-bed activated carbon treatment tower decreases, it is detected which part of the activated carbon in the depth direction inside the activated carbon treatment tower has deteriorated, and only the deteriorated activated carbon is selected and extracted to remove new coal. The task of refilling can be performed. Therefore, there is no need to replace all the activated carbon charged in the treatment tower, and the time required for the activated carbon to reach a steady state is shortened, so that there is no effect on operation.

Further, when the new coal is supplied, it is possible to eliminate the increase in the treatment load of the activated carbon treatment layer caused by the biodegradable organic substances, prevent breakthrough of the substance to be adsorbed, and further enhance the activated carbon treatment effect in the advanced water purification treatment apparatus. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic example of a method for extracting and supplying granular activated carbon in a fixed bed activated carbon treatment tower to which the present invention is applied.

FIG. 2 is a schematic diagram of an advanced water purification treatment experimental apparatus to which the present invention is applied.

FIG. 3 is a schematic diagram modeling the adsorption removal characteristics of a biological activated carbon treatment layer and an activated carbon treatment layer in a fixed bed activated carbon treatment tower.

FIG. 4 is a graph showing various measurement results over time in a downflow direction in an activated carbon treatment tower.

FIG. 5 is a graph showing an isothermal adsorption line of each organic substance index in activated carbon treatment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Raw water 2 ... Ozone contact tank 3, 4, 5 ... Activated carbon treatment tower 10 ... Fixed bed activated carbon treatment tower 11 ... Biological activated carbon treatment layer 12 ... Activated carbon treatment layer 13, 14, 15, 16 ... Sample water sampling port 17 ... Absorbance Total 18: Activated carbon treated water storage tank 19: Activated carbon treated water storage tank 20: New charcoal

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C02F 1/28 B01D 29/38

Claims (3)

(57) [Claims] 1. A fixed-bed activated carbon treatment tower in an advanced water purification treatment wherein raw water flows into a treatment tower filled with granular activated carbon, and a pollutant in the raw water is adsorbed and removed by utilizing the adsorption capacity of the activated carbon. In the fixed bed activated carbon treatment tower in the depth direction of a plurality of sample water inlets are provided, water collected from each sample water inlet is separately led to an absorptiometer, and the absorbance is measured. Characterized in that when the deterioration of the activated carbon is confirmed, a predetermined amount of the degraded activated carbon is withdrawn from the activated carbon treatment tower by the drawing pump and fresh carbon is supplied only by the amount withdrawn by the supply pump. A method for drawing and supplying granular activated carbon in a treatment tower. 2. A fixed-bed activated carbon treatment tower in an advanced water purification treatment in which raw water flows into a treatment tower filled with granular activated carbon, and a pollutant in the raw water is adsorbed and removed by utilizing the adsorption capacity of the activated carbon. In the fixed bed activated carbon treatment tower in the depth direction of a plurality of sample water inlets provided, water collected from each sample water inlet is separately led to an absorptiometer to measure the absorbance, while the activated carbon treatment tower The inflowing treated water and the treated water flowing out of the activated carbon treatment tower are separately led to the absorptiometer to measure the absorbance, and the overall adsorption capacity of the fixed bed activated carbon treatment tower is monitored from the measurement result. When the adsorption capacity of the treatment tower is reduced, a predetermined amount of activated carbon, which has been confirmed to be deteriorated, is extracted by the extraction pump based on the measurement result at each sample water inlet, and the amount of the activated carbon is extracted by the supply pump. And supplying the only new charcoal, drawing and the method of supplying the granular activated carbon in a fixed bed activated carbon treatment column. 3. Based on the correlation between the water flow time to the activated carbon treatment tower and the deterioration of the activated carbon, immediately after the start of water flow to the activated carbon treatment tower, the water sampling from the upper sample water sampling port is performed with priority. The fixed bed according to claim 1 or 2, wherein water sampling from the sample water sampling port at the middle stage is performed several months after the start of water, and water sampling from the sample water sampling port at the lower stage is performed after a long period of time. A method for drawing and supplying granular activated carbon in an activated carbon treatment tower.