JPH08211042A - Measurement of residual chlorine - Google Patents

Abstract

PURPOSE: To grasp the concn. of residual chlorine at an early stage by shortening the of time reaction of chlorine with ammonia nitrogen in chlorine treated water by applying pH control to sample water being chlorine treated water. CONSTITUTION: Sample water treated with chlorine is supplied to an overflow tank 13 through sample water supply pipelines 19, 15 and a dilute sulfuric acid soln. 35 is poured into the upper part of an acidity adjusting tank 5 through a diffuser 43 to make sample water acidic. This acidic sample water is supplied to an alkalinity adjusting tank 7 through a communication pipe 9 while the pH thereof is confirmed by an electrode 11. A sodium bicarbonate soln. 47 is poured into the tank 7 through a diffuser 55 to make the sample water alkaline. This alkaline sample water is sent to a residual chlorine concn. measuring means 63 trough piping 57 while the pH thereof is confirmed by an electrode 59 and the concn. of residual chlorine is measured by an electrode part 83. Namely, a dichloramine forming reaction time can be shortened by making treated water acidic and a dichloramine decomposing time and a nitrogen forming reaction time can be shortened by making treated water alkaline and, by the pH control of sample water, the reaction speed of ammonia nitrogen and chlorine is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chlorine treatment method in which chlorine is injected into treated water in a water purification process in a water purification plant or the like, and in particular, chlorine is injected into treated water containing ammoniacal nitrogen. In this case, it is possible to shorten the reaction time between ammoniacal nitrogen and chlorine to enable an accurate residual chlorine concentration to be grasped at an early stage.

[0002]

2. Description of the Related Art For example, a water purification process in a water purification plant is roughly as follows. First, river water or underflow water is taken in, and after it is subjected to a precipitation treatment, it is subjected to a filtration treatment at a rapid or slow speed, and further subjected to a necessary treatment and supplied as purified water. In this type of water purification process, so-called "chlorine treatment" is performed for the purpose of sterilization treatment and the like. The purpose of this kind of chlorine treatment is not only sterilization but also oxidation / decomposition of certain organic substances, oxidation of certain free metal ions, etc. is there. For such a purpose, conventionally, the chlorine treatment has been performed in three stages of pre-chlorination, middle-chlorination and post-chlorination.

However, recently, trihalomethane produced by chlorine treatment has become a big problem as a carcinogenic substance. Therefore, in order to suppress the formation of such trihalomethanes, the chlorine treatment which has been conventionally performed in three steps is performed by the intermediate chlorine treatment and the post-chlorine treatment, that is, the trihalomethane precursor that leads to the formation of trihalomethane is coagulated and precipitated. A method in which chlorine is treated after being treated and largely removed is adopted.

[0004]

The above-mentioned conventional structure has the following problems. First, when considering chlorination in a water purification process, ammoniacal nitrogen in treated water must be considered. That is, there is no problem when the content of ammoniacal nitrogen in the treated water is very small. However, when it exceeds 1.0 mg / l and reaches 1.0 mg / l, the free available chlorine causes It becomes extremely difficult to manage. That is, a large amount of chlorine injected by the ammonia nitrogen in the treated water is consumed, and it does not contribute to the original purpose.

More specifically, the equivalent reaction between chlorine and ammonia nitrogen is about (8-9): 1, and a large amount of chlorine is present in the reaction with ammonia nitrogen. It will be consumed. Further, the amount of ammoniacal nitrogen in the treated water is not constant and changes every day, and it is extremely difficult to deal with it.
Therefore, in order to effectively respond to ammonia nitrogen and obtain the desired chlorination effect, first, it is necessary to continuously measure the ammonia concentration in the treated water,
In addition, it becomes necessary to find a so-called "breakpoint" after adding chlorine in the treated water in advance and to determine the required chlorine amount.

However, it is extremely difficult to realize the above. In addition, if chlorine treatment is performed in the three steps of pre-chlorine treatment, medium-chlorine treatment, and post-chlorine treatment as in the past, for example, when effective results cannot be obtained by medium-chlorine treatment (injected chlorine It was possible to supplement this by post-chlorination, but in the case of trying to deal with only medium-chlorination, such Because it is not possible to deal with it. In other words, in the case of only the medium chlorine treatment, there is no time enough to grasp and process such a breakpoint. In other words, medium chlorination is usually performed in front of the filter basin, so the reaction time between chlorine and ammoniacal nitrogen cannot be taken sufficiently within the water treatment plant, and the problem is that the amount of post chlorine injected becomes unknown. is there.

That is, when a large amount of ammonia nitrogen is contained in the treated water, the break point described above must be accurately measured unless approximately two hours have passed after the treated water came into contact with chlorine. Because it is not possible to grasp. To explain it in more detail, first,
The reaction of ammonia nitrogen and chlorine is considered to go through the following reactions.

(Production of monochloramine)

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(Production of dichloramine)

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(Dechloramine decomposition and nitrogen generation)

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(Production of trichloramine)

[Chemical 4]

As described above, ammoniacal nitrogen reacts with chlorine to be finally decomposed into nitrogen, and a part of it becomes trichloramine. Then, nitrogen will be denitrified from the treated water, and it will take two hours to complete all the processes up to that point. In other words, when a large amount of ammonia nitrogen is contained in the treated water, the break point cannot be grasped until about two hours have passed after chlorine was injected into the treated water. The effective chlorine demand cannot be determined. However, as described above, when attempting to complete chlorine treatment with only medium chlorine treatment in order to suppress the generation of trihalomethane, that much is necessary to grasp the break point and determine the accurate chlorine demand. There was not enough time (when such time passed, the treated water had already been sent to the reservoir), and eventually there was a situation where the specified residual chlorine concentration could not be secured at the end. Will be done.

The present invention has been made on the basis of such a point, and an object thereof is to provide a reaction time between ammonia nitrogen and chlorine when chlorine is injected into treated water containing ammonia nitrogen. It is an object of the present invention to provide a residual chlorine measuring method that shortens the residual chlorine concentration in treated water and makes it possible to grasp the residual chlorine concentration at an early stage.

[0014]

In order to achieve the above object, the method for measuring residual chlorine according to the present invention is to extract a part of treated water into which chlorine is injected to obtain sample water, and subject the sample water to pH control. The reaction time between chlorine and ammoniacal nitrogen in the treated water is shortened, and then the residual chlorine concentration of the sample water is measured. At that time, it is possible to make the sample water alkaline. It is also possible to adjust the pH of the sample water to 8-9. Also, acidify the sample water to 2-1.
It can be considered that after 0 minutes, it becomes more alkaline.
Further, it is conceivable to measure the residual chlorine concentration with a continuous residual chlorine meter 2 to 15 minutes after the pH control of the sample water.

[0015]

That is, in the case of the residual chlorine treatment method according to the present invention, a part of the treated water into which chlorine has been injected is sampled, and the pH of the sample water is controlled, whereby ammonia nitrogen and chlorine are removed. It is intended to accelerate the reaction rate with and to grasp the residual chlorine concentration early. As the pH control, for example, there is a method of making it alkaline, and it is considered that first, it is made acidic and then made alkaline. That is, in the reaction between ammoniacal nitrogen and chlorine described in the description of the conventional example, it is known that the first monochloramine-forming reaction takes place in a relatively short time, and therefore the remaining reaction, that is, dichloramine. The reaction time between ammoniacal nitrogen and chlorine can be shortened by shortening the reaction for the formation of the above, the decomposition of dichloramine and the formation of nitrogen, and the reaction for the formation of trichloramine in a short time.

Therefore, the applicant of the present application tried various methods through many experiments, and as a result, by acidifying the treated water, the time of the reaction for producing dichloramine can be shortened, and the treated water can be treated. It was understood that the alkalinity can shorten the time required for the decomposition of dichloramine and the reaction of producing nitrogen. The chlorine treatment method according to the present invention is based on such a thing, and as described above, a part of the treated water into which chlorine is injected is collected as sample water, and the pH of the sample water is controlled. By doing so, the reaction rate between ammoniacal nitrogen and chlorine is accelerated, and then the residual chlorine concentration is attempted to be grasped at an early stage.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. In the case of the first embodiment, first, a part of the treated water which has been subjected to chlorine treatment is sampled, and the sample water is first acidified after a predetermined time,
It is then made alkaline after a predetermined time, whereby
It is intended to shorten the reaction time and measure the residual chlorine concentration in the sample water in such a state. Therefore, the overall configuration will be described with reference to the system diagram of FIG. The chlorine treatment device according to this embodiment is roughly divided into
PH control means 1 for controlling the pH of the sample water,
The residual chlorine measuring means 3 measures the residual chlorine concentration of the sample water whose pH is controlled by the pH controlling means 1.

The pH control means 1 is provided with an acid adjusting tank 5 and an alkali adjusting tank 7, and the acid adjusting tank 5 and the alkali adjusting tank 7 are connected to each other via a communication pipe 9 provided in the lower part. . A pH electrode 11 is inserted in the communication tube 9. An overflow tank 13 is installed at the upper end of the acid adjusting tank 5, and a part of the chlorine-treated treated water is sampled as sample water, and this sample water is supplied into the overflow vessel 13. That is,
A sample water supply pipe 15 is connected to the overflow tank 13, and another sample water supply pipe 19 is connected to the sample water supply pipe 15 via an opening / closing valve 17. The sample water supply pipe 19 has an on-off valve 2
1 is inserted, and a pressure gauge 23 is attached. Further, another on-off valve 25 is branched and connected to the sample water supply pipe 19. Then, the sample water is supplied into the overflow tank 13 through the sample water supply pipes 19 and 15 at, for example, 300 to 500 ml / min. An overflow pipe 27 is installed in the overflow tank 13, and the sample water overflowing in the overflow tank 13 is drained through the overflow pipe 27, the pipe 29, and the drain tank 31.

An acidic material storage tank 33 is arranged, and a dilute sulfuric acid solution 35 having a predetermined concentration as an acidic agent is stored in the acidic material storage tank 33. Then, the diluted sulfuric acid solution 35 is injected into the upper portion of the acidity adjusting tank 5 by the injection pump 37. A suction pipe 39 is connected to the suction side of the injection pump 37, and the discharge pipe 4 is connected to the discharge side.
1 is connected. The suction pipe 39 is immersed in the acid agent storage tank 33, and the discharge pipe 41 is connected to a diffuser device 43 attached to the upper portion of the acid adjusting tank 5. Then, the diluted sulfuric acid solution 35 in the acidifying agent acid tank 33 is sucked through the suction pipe 39 and is discharged into the diffuser device 43 through the discharge pipe 41. Then, the diluted sulfuric acid solution 35 is injected into the sample water to control the pH of the sample water to make it acidic.

An alkali agent storage tank 45 is installed near the alkali adjusting tank 7. In the alkaline agent storage tank 45, sodium bicarbonate (NaHC
An O ₃ ) solution 47 is stored, and an injection pump 49 is installed above the alkaline agent storage tank 45. A suction pipe 51 is connected to the suction side of the injection pump 49, and a discharge pipe 53 is connected to the discharge side. Then, via the suction pipe 51, the alkaline agent storage tank 45
The sodium bicarbonate solution 47 in the inside is sucked, and is injected into the diffuser 55 installed in the lower part in the alkali adjusting tank 7 through the discharge pipe 53. Thereby, the pH of the sample water is controlled to make it alkaline.

The sample water acidified in the acid adjusting tank 5 and then alkalinized in the alkali adjusting tank 7 is supplied with residual chlorine via a pipe 57 connected to the upper portion of the alkali adjusting tank 7. It is transferred to the concentration measuring means 3 side. In addition, at the upper end of the alkali adjustment tank 7, the pH
An electrode 59 is installed, an overflow pipe 61 is installed, and the pipe 57 is connected to the overflow pipe 61.

Next, the structure on the residual chlorine concentration measuring means 3 side will be described. The pipe 57 is the overflow tank 6
Connected to 3. In this overflow tank 63,
The supply pipe 65 is connected, and the sample water supplied into the overflow tank 63 via the pipe 57 is supplied to the electrode device 67 via the supply pipe 65. An overflow pipe 69 is connected to the overflow tank 63, and the sample water overflowed in the overflow tank 63 is drained via the overflow pipe 69. In addition, the overflow tank 63 has a pH
The buffer solution supply device 71 is connected. The pH buffer solution supply device 71 includes a tank 73 and an injection pump 75 installed on the tank 73. A pH 7 buffer solution 77 is contained in the tank 73.
A suction pipe 77 is connected to the suction side of the injection pump 75, and a discharge pipe 79 is connected to the discharge side. The discharge pipe 79 is connected to the overflow tank 63. Then, the pH buffer solution 77 is injected into the sample water in the overflow tank 63 to neutralize the alkaline sample water.

The electrode device 67 comprises a housing 81 and an electrode portion 83 installed in the housing 81. A sample water supply part 85 is formed at the lower end of the housing 81, and a sample water discharge part 87 is formed at the upper part. The supply pipe 65 is connected to the sample water supply unit 85, and the drainage pipe 89 is connected to the sample water discharge unit 87. Then, the sample water supplied through the supply pipe 65 and the sample water supply unit 85 passes through the electrode unit 83 and is drained to the drain tank 91 through the sample water discharge unit 87 and the drain pipe 89. At that time, the residual chlorine concentration in the sample water is measured by the electrode portion 83 and is indicated by the indicator 93.

The pH control means 1 and the residual chlorine concentration measuring means 3 shown in FIG. 1 are assembled as an apparatus in the state shown in FIG. Incidentally, reference numeral 95 in FIGS. 2 and 3,
Reference numeral 97 denotes a frame body, and these frame bodies 95, 9
7, each of the components described with reference to FIG. 1 is incorporated.

Next, the structure of the diffuser 43 installed in the acidity adjusting tank 5 of the pH control means 1 is shown in FIG.
It will be described with reference to FIGS. First, there is a core body 101, and the core body 101 has a structure as shown in FIGS. 8 and 9. The core body 101 includes a collar portion 101a and a cylindrical portion 101b extending downward from the collar portion 101a. A male screw portion 103 is formed at the tip of the cylindrical portion 101b. In addition, a hole 105 is formed in a cross shape in the orthogonal direction in the cylindrical portion 101b, and such a hole is formed in two steps.
The disc-shaped felt material 10 is provided on the cylindrical portion 101b.
7 are mounted in four stages, and in this state, the nut 109 is screwed into the male screw portion 103. A guide 111 is arranged on the upper side of the core body 101, and a through hole 111a is formed in the center of the guide 111. The guide 111 has a shape as shown in FIGS. 6 and 7. On the other hand, a protrusion 113 is provided at the center of the collar portion 101a, and the protrusion 113 is fitted in the through hole 111a. A connection tube 115 is connected to the protrusion 113. That is, a hole 114 communicating with the hole 105 is formed at the central position of the protrusion 113 and the cylindrical portion 101b, and the connection tube 115 is inserted into the hole 114. Then, the diluted sulfuric acid solution 35 supplied through the connection tube 115 permeates the felt material 107 arranged on the outer periphery through the holes 114 and 105, and then flows out to the outer peripheral portion. , Is mixed in the sample water in the acidity adjusting tank 5.

Next, the structure of the diffuser 55 installed at the lower end of the alkali adjusting tank 7 will be described with reference to FIGS. 10 to 14. First, there is a core body 121, and this core body 121 has a shape as shown in FIG. The core body 121 includes a flange portion 121a and a cylindrical portion 121b. A larger diameter flange 135 is formed below the flange 121a in the figure. The collar part 121a
A male screw portion 123 is formed on the. On the other hand, an opening 7a is formed at the lower end of the alkali adjusting tank 7, and a female screw portion 125 is formed in the opening 7a. The male screw portion 123 is screwed into the female screw portion 125, whereby the core body 121 is fixed to the alkali adjusting tank 7. A male screw portion 127 is formed on the upper end of the cylindrical portion 121b. Also, in the cylindrical portion 121b,
The holes 129 are formed in a cross shape in a direction orthogonal to each other, and such a hole is formed in two steps. The disc-shaped felt material 13 is formed on the cylindrical portion 121b.
1 is mounted in four stages, and in this state, the nut 133 is screwed into the male screw portion 127. The nut 127 has a shape as shown in FIG. A connection tube 137 is connected to the central portion of the collar portion 135 at the lower end of the core body 121. This connection tube 1
37 has a shape as shown in FIG. As shown in FIG. 13, a hole 138 is formed at the central position of the core body 121, and the hole 138 is extended to a place communicating with the hole 129 already described. Then, the connection tube 137 is inserted into the hole 138.

The operation will be described based on the above configuration. First, through the sample water supply pipes 19 and 15, a part of the treated water after chlorine is injected into the overflow tank 13 for a predetermined time is supplied as sample water. The sample water supplied into the overflow tank 13 enters the acid adjusting tank 5 from there. In the upper part of the acid adjusting tank 5, the diluted sulfuric acid solution 35 as an acid agent is added to the diffuser 4.
Injected via 3. This makes the sample water acidic. The sample water that became acidic in the acidity adjusting tank 5
It flows into the alkali adjusting tank 7 from below via the communication pipe 9. At that time, the pH of the sample water is adjusted by the pH electrode 11.
Is confirmed. Then, a sodium bicarbonate solution 47 as an alkaline agent is injected through the diffuser 55. Thereby, the sample water becomes alkaline. The alkalinized sample water is supplied from the upper end of the alkali adjusting tank 7 to the residual chlorine concentration measuring means 3 side via the pipe 57, and the residual chlorine concentration is to be measured there. Is displayed by the indicator 93. Also at that time, the pH of the sample water is confirmed by the pH electrode 59.

Then, some actual experimental examples will be shown. First, Experimental Example 1 is shown in FIG. In this case, the test water used had an ammoniacal nitrogen concentration of 1.0 mg / l, and the chlorine / ammonia ratio (CL / N ratio) was 7,
Four types of 8, 9, 10 were used. In addition, the pH is controlled 10 minutes after chlorine is injected. That is, 10 minutes after chlorine injection, diluted sulfuric acid 35 as an acid agent is injected to adjust the pH of the sample water to 5, and after 2 minutes, sodium bicarbonate solution 47 as an alkaline agent is added. After the injection, the pH of the sample water was adjusted to 9, and after 5 minutes, the residual chlorine concentration was measured. In addition, as a comparative example, four kinds of ammonia nitrogen concentration of 1.0 mg / l and chlorine / ammonia ratio (CL / N ratio) of 7, 8, 9, 10 were prepared. 2 hours after chlorine injection, the residual chlorine concentration was measured. As a result, the result as shown in FIG. 15 could be obtained. In the figure, ● represents the concentration of free chlorine in Experimental Example 1, and ■ represents the concentration of bound chlorine in Experimental Example 1. Further, ◯ is the concentration of free chlorine in the case of the comparative example, and □ is the concentration of bound chlorine in the case of the comparative example. As is clear from FIG. 15, as in this embodiment, p
By controlling H, it is possible to obtain a value that could not be obtained until 2 hours have elapsed in about 17 minutes, that is,
By controlling the pH, the reaction time between animonia nitrogen and chlorine can be greatly shortened.

Next, Experimental Example 2 is shown in FIG. In this case, the test water has an ammoniacal nitrogen concentration of 1.0 mg /
l of chlorine / ammonia ratio (CL / N
The ratio) was 8, 9 or 10. Further, the pH of the sample water is controlled 10 minutes after chlorine is injected. That is, 1 after injecting chlorine
After 0 minutes, a diluted sulfuric acid solution 35 as an acid agent was injected to adjust the pH to 5, and after 5 minutes, a sodium bicarbonate solution 47 as an alkaline agent was injected to adjust the pH to 8.2. After 5 minutes, the residual chlorine concentration was measured. In addition, as a comparative example, three kinds of ammonia / nitrogen concentration of 1.0 mg / l and chlorine / ammonia ratio (CL / N ratio) of 8, 9, and 10 were prepared and chlorine injection was performed. After 2 hours, the residual chlorine concentration was measured. As a result, the result as shown in FIG. 16 could be obtained. In the figure, ● indicates the concentration of free chlorine in Experimental Example 2, and ■ indicates the concentration of bound chlorine in Experimental Example 2. Further, ◯ is the concentration of free chlorine in the case of the comparative example, and □ is the concentration of bound chlorine in the case of the comparative example. FIG.
As is clear from the above, by controlling the pH as in this example, it is possible to obtain a value that could not be obtained until 2 hours have elapsed in about 20 minutes, that is, by controlling the pH, The reaction time between animonia nitrogen and chlorine can be greatly shortened.

Next, Experimental Example 3 is shown in FIG. In this case, the test water has an ammoniacal nitrogen concentration of 1.0 mg /
l of chlorine / ammonia ratio (CL / N
The ratio was 7, 8, 9, 10 and 4 types were used. In addition, the pH is controlled 10 minutes after chlorine is injected. That is, 10 minutes after chlorine was injected, diluted sulfuric acid solution 35 as an acid agent was injected to adjust the pH to 5, and after 5 minutes, sodium bicarbonate solution 47 as an alkaline agent was injected. P
H was set to 9, and 10 minutes after that, the residual chlorine concentration was measured. In addition, as a comparative example, four kinds of ammonia / nitrogen concentration of 1.0 mg / l and chlorine / ammonia ratio (CL / N ratio) of 7, 8, 9, 10 were prepared. The residual chlorine concentration was measured 2 hours after chlorine injection. As a result, the result as shown in FIG. 17 could be obtained. In the figure, ● represents the concentration of free chlorine in Experimental Example 3, and ■ represents the concentration of bound chlorine in Experimental Example 3. Further, ◯ is the concentration of free chlorine in the case of the comparative example, and □ is the concentration of bound chlorine in the case of the comparative example. FIG.
As is clear from the above, by controlling the pH as in this example, it is possible to obtain a value that could not be obtained until 2 hours have elapsed in about 20 minutes, that is, by controlling the pH, The reaction time between animonia nitrogen and chlorine can be greatly shortened.

According to this embodiment, the following effects can be obtained. First, by collecting a part of the treated water into which chlorine has been injected as sample water and subjecting the sample water to pH control, it is possible to shorten the reaction time between chlorine and ammonia nitrogen in the sample water, and thereby Now, it is now possible to grasp the accurate residual chlorine concentration after a few minutes, which could not be grasped until after about two hours had passed. Therefore, in order to suppress the production of trihalomethane, even when the chlorine treatment is only medium chlorine treatment,
It becomes possible to effectively deal with this, and it is possible to prevent the occurrence of a situation in which the required residual chlorine concentration cannot be secured at the terminal. Further, specifically explaining the reduction of the reaction time by the above pH control, first, by acidifying, it is possible to shorten the time required for the reaction of producing dichloramine among the reactions of chlorine and ammonia nitrogen. Moreover, the alkalinity can shorten the time required for the decomposition of dichloramine and the reaction of producing nitrogen. Further, in the acid adjusting tank 5 and the alkali adjusting tank 7, the diluted sulfuric acid solution 35 as an acid agent and the sodium bicarbonate solution 47 as an alkaline agent are injected through the diffusers 43 and 55, respectively. Can be mixed into the sample water early and surely. This can also accelerate the reaction between chlorine and ammoniacal nitrogen. Further, since the pH of the treated water is constantly monitored by the pH electrodes 11 and 59, it is possible to surely obtain a desired acidic state or alkaline state.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the case of the first embodiment,
As the pH control of the sample water, first, the sample water was made acidic and then made alkaline. However, in the case of the second embodiment, the pH of the sample water was controlled without making the sample water acidic. It is designed to be directly alkaline. The structure is shown in FIG. The same parts as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In this case, the tank functioning as the acidity adjusting tank in the first embodiment functions as the alkali adjusting tank 201, and the tank functioning as the alkali adjusting tank is used as the flow path. is there. A diffuser 205 is attached to the upper end of the alkali adjusting tank 201. The diffuser 205 has the same structure as the diffuser 43 in the first embodiment. The other structure is the same as that of the first embodiment, and the description thereof is omitted.

Then, some actual experimental examples will be shown. First, Experimental Example 4 is shown in FIG. In this case, the test water used had an ammoniacal nitrogen concentration of 1.0 mg / l, and the chlorine / ammonia ratio (CL / N ratio) was 7,
Four types of 8, 9, 10 were used. In addition, the pH is controlled 10 minutes after chlorine is injected. That is, 10 minutes after chlorine was injected, a sodium bicarbonate solution as an alkaline agent was injected to adjust the pH to 9, and 15 minutes thereafter, the residual chlorine concentration was measured. In addition, as a comparative example, the ammonia nitrogen concentration is 1.0 mg / l, and the chlorine / ammonia ratio (CL / N ratio) is 7, 8, 9, 10.
Different types were prepared and the residual chlorine concentration was measured 2 hours after chlorine injection. As a result, the result as shown in FIG. 19 could be obtained. In the figure, ● represents the concentration of free chlorine in Experimental Example 4, and ■ represents the concentration of bound chlorine in Experimental Example 4. Further, ◯ is the concentration of free chlorine in the case of the comparative example, and □ is the concentration of bound chlorine in the case of the comparative example.
As is clear from FIG. 19, by controlling the pH as in this example, it is possible to obtain a value that could not be obtained until 2 hours have elapsed in about 17 minutes, that is, the pH.
The reaction time between chlorine and the animoniogenic nitrogen can be greatly shortened by controlling

Next, Experimental Example 5 is shown in FIG. In this case, the test water has an ammoniacal nitrogen concentration of 1.0 mg /
l of chlorine / ammonia ratio (CL / N
The ratio was 7, 8, 9, 10 and 4 types were used. In addition, the pH is controlled 10 minutes after chlorine is injected. That is, 10 minutes after chlorine was injected, a sodium bicarbonate solution as an alkaline agent was injected to adjust pH to 9, and after 2 minutes, the residual chlorine concentration was measured. Also, as a comparative example,
Ammonia nitrogen concentration is 1.0 mg / 1 and chlorine / ammonia ratio (CL / N ratio) is 7, 8, 9,
Four kinds of 10 were prepared, and the residual chlorine concentration was measured 2 hours after chlorine injection. As a result, the result as shown in FIG. 20 could be obtained. In the figure, ● represents the concentration of free chlorine in Experimental Example 5, and ■ represents the concentration of bound chlorine in Experimental Example 5. Further, ◯ is the concentration of free chlorine in the case of the comparative example, and □ is the concentration of bound chlorine in the case of the comparative example. As is clear from FIG. 20, by controlling the pH as in this example, it is possible to obtain a value that could not be obtained until 2 hours have elapsed in about 20 minutes, that is, control the pH. Thus, the reaction time between chlorine and ammoniacal nitrogen can be significantly shortened.

Next, Experimental Example 6 is shown in FIG. In this case, the test water has an ammoniacal nitrogen concentration of 1.0 mg /
l of chlorine / ammonia ratio (CL / N
The ratio was 7, 8, 9, 10 and 4 types were used. In addition, the pH is controlled 10 minutes after chlorine is injected. That is, 10 minutes after chlorine was injected, a sodium bicarbonate solution as an alkaline agent was injected to adjust the pH to 8.2, and after 2 minutes, the residual chlorine concentration was measured. As a comparative example, the ammonia nitrogen concentration is 1.0 mg / l and the chlorine / ammonia ratio (CL / N ratio) is 7,
Prepare 4 kinds of 8, 9, 10 and 2 after chlorine injection
After a lapse of time, the residual chlorine concentration was measured. as a result,
The result as shown in FIG. 21 was able to be obtained. ● in the figure
Is the concentration of free chlorine in the case of Experimental Example 6, and ▪ is the concentration of bound chlorine in the case of Experimental Example 6. Further, ◯ is the concentration of free chlorine in the case of the comparative example, and □ is the concentration of bound chlorine in the case of the comparative example. As is apparent from FIG. 21, by controlling the pH as in the present example, a value that could not be obtained until 2 hours has passed in the past can be obtained in about 20 minutes, that is, the pH can be controlled. Thus, the reaction time between chlorine and ammoniacal nitrogen can be significantly shortened.

Next, Experimental Example 7 is shown in FIG. In this case, the test water has an ammoniacal nitrogen concentration of 1.0 mg /
l of chlorine / ammonia ratio (CL / N
The ratio was 7, 8, 9, 10 and 4 types were used. In addition, the pH is controlled 10 minutes after chlorine is injected. That is, 10 minutes after chlorine was injected, a sodium bicarbonate solution as an alkaline agent was injected to adjust the pH to 8.2, and 15 minutes thereafter, the residual chlorine concentration was measured. As a comparative example, the ammonia nitrogen concentration is 1.0 mg / 1 and the chlorine / ammonia ratio (CL / N ratio) is 7,
Prepare 4 kinds of 8, 9, 10 and 2 after chlorine injection
After a lapse of time, the residual chlorine concentration was measured. as a result,
The result as shown in FIG. 22 was able to be obtained. ● in the figure
Is the concentration of free chlorine in the case of Experimental Example 7, and ▪ is the concentration of bound chlorine in the case of Experimental Example 7. Further, ◯ is the concentration of free chlorine in the case of the comparative example, and □ is the concentration of bound chlorine in the case of the comparative example. As is apparent from FIG. 22, by controlling the pH as in the present example, it is possible to obtain a value that could not be obtained until 2 hours have elapsed in about 20 minutes, that is, control the pH. Thus, the reaction time between chlorine and ammoniacal nitrogen can be significantly shortened.

The present invention is not limited to the first and second embodiments. For example, in the first and second embodiments, the case where the material is made alkaline after being acidified has been described, but it may be configured as a method of only making the material acidic. As the types of the acidic agent and the alkaline agent, use of all known ones can be considered. Further, the times, conditions of sample water, and the like shown in each experimental example are examples, and the present invention is not limited thereto.

[0038]

As described in detail above, according to the residual chlorine measuring method of the present invention, the following effects can be obtained. First, a part of the treated water after a lapse of a predetermined time after injecting chlorine is collected as sample water, and p is added to the sample water.
By performing H control, the reaction time between chlorine and ammonia nitrogen can be shortened, so that the residual chlorine concentration of the sample water and thus the accurate residual chlorine concentration of the treated water can be grasped at an early stage. Became. For example, it is possible to shorten the time required for the decomposition of dichloramine and the reaction for producing nitrogen in the reaction between ammoniacal nitrogen and chlorine by making the sample water that has been sampled after chlorine has been injected for a predetermined time, alkaline. By doing so, the reaction time between ammoniacal nitrogen and chlorine can be shortened, and the residual chlorine concentration of the sample water and thus the treated water can be grasped at an early stage. Therefore, for example, it is possible to easily deal with the case where only the medium chlorine treatment is performed in the water purification process. In addition, by acidifying the sample water collected after a lapse of a predetermined time after injecting chlorine and making it alkaline after a predetermined time,
The time required for the production of dichloramine in the reaction between ammonia nitrogen and chlorine, the time required for the decomposition of dichloramine and the reaction for producing nitrogen can be shortened, thereby shortening the reaction time between ammonia nitrogen and chlorine. By doing so, the residual chlorine concentration in the sample water and further in the treated water can be grasped at an early stage. Therefore, for example, it is possible to easily deal with the case where only the medium chlorine treatment is performed in the water purification process.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention and is a system diagram showing a configuration of a residual chlorine measuring apparatus for carrying out a residual chlorine measuring method.

FIG. 2 is a front view showing a configuration of a residual chlorine measuring apparatus according to the first embodiment of the present invention.

FIG. 3 is a side view showing a configuration of a residual chlorine measuring device in a diagram showing a first embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of the diffuser in the first embodiment of the present invention.

FIG. 5 is a view showing the first embodiment of the present invention and is a top view showing the structure of the diffuser.

FIG. 6 is a cross-sectional view showing the structure of the guide of the diffuser in the first embodiment of the present invention.

FIG. 7 is a view showing a first embodiment of the present invention and is a top view showing a structure of a guide of a diffuser.

FIG. 8 is a view showing a first embodiment of the present invention and is a half cutaway view showing a structure of a core body of a diffuser.

FIG. 9 is a view showing the first embodiment of the present invention and is a top view showing the configuration of the core body of the diffuser.

FIG. 10 is a sectional view showing the structure of the diffuser in the first embodiment of the present invention.

FIG. 11 is a bottom view showing the structure of the diffuser in the first embodiment of the present invention.

FIG. 12 is a sectional view showing the structure of the nut of the diffuser in the first embodiment of the present invention.

FIG. 13 is a half sectional view showing a structure of a core body of a diffuser in a view showing a first embodiment of the present invention.

FIG. 14 is a front view showing the configuration of the connection pin of the diffuser in the view showing the first embodiment of the present invention.

FIG. 15 is a diagram showing Example 1 of the present invention and is a diagram showing Experimental Example 1;

FIG. 16 is a diagram showing a first embodiment of the present invention and is a diagram showing an experimental example 2;

FIG. 17 is a diagram showing a first embodiment of the present invention and is a diagram showing an experimental example 3;

FIG. 18 is a system diagram showing a configuration of a residual chlorine treatment apparatus for carrying out the residual chlorine measuring method according to the second embodiment of the present invention.

FIG. 19 is a diagram showing a second embodiment of the present invention and a diagram showing Experimental Example 4;

FIG. 20 is a diagram showing a second embodiment of the present invention and is a diagram showing an experimental example 5;

FIG. 21 is a diagram showing a second embodiment of the present invention and is a diagram showing an experimental example 6;

FIG. 22 is a diagram showing a second embodiment of the present invention and is a diagram showing an experimental example 7.

[Explanation of symbols]

 1 pH control means 3 Residual chlorine concentration measuring means 5 Acid adjustment tank 7 Alkali adjustment tank 33 Acid agent storage tank 35 Dilute sulfuric acid (acid agent) 37 Injection pump 45 Alkaline agent storage tank 47 Sodium bicarbonate solution (alkali agent) 49 Injection pump

Claims (5)

[Claims] 1. A part of treated water into which chlorine is injected is extracted to obtain sample water, and the pH of the sample water is controlled to shorten the reaction time between chlorine and ammonia nitrogen in the treated water. A method for measuring residual chlorine, characterized in that the residual chlorine concentration of water is measured. 2. The residual chlorine measuring method according to claim 1, wherein the sample water is made alkaline. 3. The residual chlorine measuring method according to claim 2, wherein the pH of the sample water is adjusted to 8-9. 4. The residual chlorine measuring method according to claim 1, wherein the sample water is acidified and then made alkaline after 2 to 10 minutes have elapsed. 5. The residual chlorine measuring method according to claim 1, 2 or 3 or 4, wherein after the sample water is subjected to pH control, the residual chlorine concentration is measured continuously by 2 to 15 minutes. A residual chlorine measuring method characterized in that the measurement is carried out by a residual chlorine meter.