JP6322882B2 - Pretreatment device for online measurement in water system, online measurement device using the pretreatment device for online measurement, pretreatment method in online measurement, and online measurement method using the pretreatment method - Google Patents

Description

  The present invention relates to a pretreatment device for online measurement in an aqueous system. More specifically, in a water system, a pretreatment device for online measurement used for analyzing water quality containing suspended solids and microorganisms, an online measurement device using the pretreatment device for online measurement, and a pretreatment in online measurement The present invention relates to a processing method and an on-line measurement method using the preprocessing method.

  Conventionally, an on-line water quality monitoring device has been used for the purpose of operating a water system facility stably and efficiently. For example, in Patent Document 1, the wastewater to be measured is diluted with water that does not include the water quality item for measurement, and after separating the solid organic substance and the solid inorganic substance from the diluted wastewater, the water quality of the separated liquid is automatically determined. An automatic water quality measurement method has been disclosed in which measurement can be stably performed for a long period of time by reducing clogging of the filter.

  In such on-line monitoring, suspended substances and living organisms are included in the monitored water, which often causes measurement interference and measurement device failure. Therefore, in order to prevent these obstacles, a pretreatment is usually performed to remove suspended substances and organisms present in the monitored water using a strainer or membrane before actual measurement. Yes.

  For example, in Patent Document 2, in a method for monitoring the concentration of a treatment agent containing an anionic polymer electrolyte on-stream, coarse particles in the sample water are removed using a strainer before introducing the sample water into the apparatus. A method is disclosed.

  For example, Patent Document 3 discloses a pretreatment method in which an anionic surfactant in test water is not attenuated by attaching an inline filter instead of a hollow fiber membrane filter in online analysis.

However, the pretreatment method using a conventional strainer or filter has the following problems.
(1) Although a particulate substance can be removed by a strainer, fouling derived from microorganisms cannot be suppressed.
(2) In order to suppress fouling caused by microorganisms, fine membranes such as microfilters (MF) and ultrafiltration membranes (UF) must be used. Increases frequency and replacement costs.
(3) Although the strainer and the membrane must be cleaned periodically, in order to lengthen this period, the strainer and the membrane must be enlarged. If the size is increased, the cost will be increased, and not only will the space be taken, but the amount of water held will increase, resulting in a delay in analysis. Moreover, it may fall depending on an analysis item because residence time becomes long. This phenomenon is a big risk in automating drug administration.
(4) Fouling by suspensions and microorganisms often requires irregular maintenance. For this reason, the dispatch schedule of the maintenance staff is difficult to manage and wastes.

JP 2000-46824 A JP-A-10-332595 JP 2002-236116 A

As described above, various problems exist in the conventional preprocessing method in the online measurement. In order to solve these problems, the following points are important.
(1) In order to prevent bacterial contamination of the on-line measuring device, it must have an advanced filtration function more than a micro filter (MF).
(2) The filtration surface is always clean enough to not affect the measurement.
(3) The maintenance frequency is low.
(4) It must be small.

  Therefore, in the present invention, a technique for preventing irregular fouling due to suspended substances and living organisms in on-line measurement and enabling stable and highly accurate water quality measurement even in the presence of high turbidity and bacteria. The main purpose is to provide.

  The inventor of the present application has intensively studied an effective method capable of solving the problems of the pretreatment technology in the online measurement, and by focusing attention on the filtration method in the pretreatment, the total amount filtration method conventionally performed in common sense. By converting the idea from (dead end filtration method) and adopting another filtration method, an effective pretreatment method was found even in the presence of high turbidity and bacteria, and the present invention was completed.

That is, in the present invention, first, a pretreatment device for measuring the water quality in the water system online,
From the water system, a sample water introduction unit for introducing sample water into the pretreatment device,
A filtration means equipped with an external pressure type hollow fiber membrane for filtering the sample water introduced from the sample water introduction part by a cross flow filtration method;
A filtered water delivery section for delivering filtered water filtered by the filtration means to an on-line measuring device;
A non-filtered water drainage unit for draining non-filtered water that has not been filtered by the filtering means;
An on-line measurement pretreatment device comprising at least:
In online measurement in a water system, a small amount of sample water is collected from the water system, and this is measured. Therefore, in the conventional pretreatment technique, it is common practice to perform total volume filtration (dead end filtration). On the other hand, in this invention, the idea was changed from the conventional technical common sense, and the cross flow filtration system which was normally employ | adopted only with the large sized water purification equipment was employ | adopted. In the cross-flow filtration method, a flow parallel to the membrane surface is generated, so that adhesion of suspended substances or the like to the membrane surface can be reduced.
In the pretreatment device for on-line measurement according to the present invention, it is preferable that the filtration means performs sample water filtration at a flow rate of 1 L / h or more and 10 L / h or less.
In addition, the membrane area of the external pressure type hollow fiber membrane is preferably designed to be 0.01 m ² or more and 0.3 m ² or less.
The pretreatment device for online measurement according to the present invention may further include a circulation unit that circulates the non-filtered water discharged by the non-filtered water discharge unit to the sample water introducing unit.
The hollow fiber membrane that can be used in the pretreatment device for on-line measurement according to the present invention preferably has a pore diameter designed to be 0.2 μm or less.
The pretreatment device for on-line measurement according to the present invention may further include an automatic cleaning mechanism that performs automatic cleaning of the external pressure hollow fiber membrane.
In this case, the automatic cleaning mechanism can perform one or more cleanings selected from air scrubbing cleaning, back-flow cleaning, and chemical cleaning.
When air scrubbing cleaning is employed in the automatic cleaning mechanism, it is preferable to perform air scrubbing cleaning in a state where the flow of sample water to the filtering means and filtration are stopped.
The pretreatment device for online measurement according to the present invention can be provided as pretreatment means in any existing online measurement device by utilizing its excellent processing effect.

Next, in the present invention, a pretreatment method for measuring water quality in a water system online,
A sampling step of sampling sample water from the water system;
A filtration step of filtering the sample water sampled in the sampling step by a cross-flow filtration method using an external pressure type hollow fiber membrane;
A filtered water delivery step for delivering the filtered water filtered in the filtration step to an online measuring device;
A non-filtered water draining step for draining non-filtered water that has not been filtered in the filtering step;
The present invention provides a pre-processing method in online measurement at least.
In the pretreatment method according to the present invention, the sample water is preferably filtered at a flow rate of 1 L / h or more and 10 L / h or less in the filtration step.
In addition, the membrane area of the external pressure type hollow fiber membrane is preferably designed to be 0.01 m ² or more and 0.3 m ² or less.
In the pretreatment method according to the present invention, a circulation step of circulating the non-filtered water discharged in the non-filtered water discharge step to the pretreatment device can be further performed.
The hollow fiber membrane that can be used in the pretreatment method according to the present invention is preferably designed to have a pore diameter of 0.2 μm or less.
In the pretreatment method according to the present invention, an automatic cleaning step of performing automatic cleaning for automatically cleaning the external pressure hollow fiber membrane can be further performed.
In this case, in the automatic cleaning step, one or more cleanings selected from air scrubbing cleaning, back-flow cleaning, and chemical cleaning can be performed.
When air scrubbing cleaning is employed in the automatic cleaning step, it is preferable to perform air scrubbing cleaning in a state in which water flow and filtration of sample water are stopped.
The pre-processing method according to the present invention can be used for pre-processing of any existing online measuring method by utilizing its excellent processing effect.

  According to the present invention, in the on-line measurement of an aqueous system, it is possible to prevent irregular fouling due to suspended substances and living organisms to reduce the frequency of maintenance, and it is difficult to cope with the conventional dead end type filter. Even in the presence of turbidity and bacteria, stable and highly accurate water quality measurement can be made possible.

It is a mimetic diagram showing typically a 1st embodiment of pretreatment device 1 for online measurement concerning the present invention. It is a mimetic diagram showing typically a cross flow filtration method. It is a schematic diagram which shows typically the filtration method using an external pressure type | formula hollow fiber membrane. It is a schematic diagram which shows typically 2nd Embodiment of the pretreatment apparatus 1 for online measurement which concerns on this invention. It is a schematic diagram which shows typically 3rd Embodiment of the pretreatment apparatus 1 for online measurement which concerns on this invention. It is a schematic diagram which shows typically 4th Embodiment of the pretreatment apparatus 1 for online measurement which concerns on this invention. It is a mimetic diagram showing typically a 1st embodiment of online measurement 10 concerning the present invention. It is a flowchart of the pre-processing method A and online measurement method B in the online measurement which concerns on this invention. It is a schematic diagram which shows typically the online measuring system used for the Example. In an Example, it is a drawing substitute graph which shows the comparison with the measured value after each pre-processing apparatus after one week progress, and the value of a manual analysis. It is a schematic diagram which shows typically total amount filtration (dead end filtration). It is a schematic diagram which shows typically the filtration method using an internal pressure type | formula hollow fiber membrane.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, embodiment described below shows an example of typical embodiment of this invention, and, thereby, the range of this invention is not interpreted narrowly.

<1. Pretreatment device for online measurement>
FIG. 1 is a schematic view schematically showing a first embodiment of a pretreatment device 1 for online measurement according to the present invention. The pretreatment device for online measurement 1 according to the present invention is broadly divided into at least a sample water introduction unit 11, a filtering means 12, a filtered water delivery unit 13, and a non-filtered water discharge unit. Further, if necessary, it is possible to further include a circulation means 15 and an automatic cleaning mechanism 16. Hereinafter, each means will be described in detail.

(1) Sample water introduction part 11
In the sample water introduction unit 11, sample water is introduced from the aqueous system to the pretreatment device 1. In the on-line measurement pretreatment apparatus 1 according to the present invention, a specific method for introducing sample water from the aqueous system to the pretreatment apparatus 1 is not particularly limited, and is usually used for introduction of sample water from the aqueous system to the pretreatment apparatus 1. It is possible to freely select and adopt the methods that are used. For example, an introduction method using a pump or the like can be employed.

  In the sample water introduction unit 11, the amount of sample water to be introduced from the aqueous system into the pretreatment device 1 is not particularly limited, and can be freely set according to the size of the filtering means 12 to be described later, the target measurement item, the measurement method, and the like. be able to. In the present invention, it is particularly preferable to sample the sample water from 50 mL to 500 mL. By making the amount of water sampled 50 mL or more, it is possible to improve the accuracy of measurement without being affected by the washing of the measurement cell or the retained water in the hollow fiber membrane or the sample line. In combination with the flow rate of the sample water to be performed, it is possible to contribute to the size reduction of the filtering means 12 and thus the pretreatment device 1.

(2) Filtration means 12
The filtering unit 12 is a unit that filters the sample water introduced from the sample water introducing unit 11. The pretreatment device for online measurement 1 according to the present invention is characterized in that the filtration means 12 performs filtration by a cross flow filtration method. As shown in FIG. 2, the cross-flow filtration is a method of filtering the filtered water so that the filtered water flows in parallel to the membrane surface by partially circulating the filtered water. On the other hand, the filtration method used in the conventional on-line measurement pretreatment device is a total amount filtration (dead end filtration) method. As shown in FIG. 11, the total amount filtration (dead end filtration) is a method of subjecting the whole amount to membrane filtration without circulating the water to be filtered supplied to the membrane surface.

  In online measurement in a water system, a small amount of sample water is collected from the water system, and this is measured. Therefore, in the conventional pretreatment technique, it is common practice to perform total volume filtration (dead end filtration). On the other hand, the cross flow filtration is usually employed only in a large water purification facility with a large amount of water. However, in the present invention, the concept was changed from conventional technical common sense, and it was found that the crossflow filtration method is very effective for online measurement in the presence of high turbidity and bacteria, and the crossflow filtration method was adopted.

  In the cross flow filtration method, as described above, since the water to be filtered flows in parallel to the membrane surface, it is possible to suppress adhesion of suspended substances and the like to the membrane surface.

  Further, in the cross flow filtration method, since the water to be filtered flows in parallel to the membrane surface, the sample water does not stay on the membrane surface unlike the total amount filtration (dead end filtration) method. Therefore, it is possible to suppress a decrease in the analysis value due to retention of sample water. In particular, it is used or metabolized by organisms such as highly reactive substances such as residual substances such as residual chlorine and hydrogen peroxide, reducing substances such as hydrazine and sulfite ions, ammonia, phosphate ions and organic substances. When analyzing a substance etc., the fall of the analysis value can be prevented effectively.

  Furthermore, the following effects can be obtained by adopting the cross flow filtration method. In the total amount filtration (dead end filtration), turbid substances and organisms removed by filtration due to their characteristics stay on the surface of the filtration membrane and in the unit. In particular, when measuring substances consumed / produced by living organisms or substances having an oxidizing / reducing action, they are affected by these accumulated substances. Conventionally, in order to reduce such influence, it has been necessary to increase the sample flow rate (permeation flow rate) and reduce the influence. However, in the present invention, by using a cross-flow filtration method and periodically cleaning using an automatic cleaning mechanism 16 to be described later, the membrane surface is kept clear, and the retained matter is not retained in the hollow fiber membrane unit. High accuracy can be obtained even with a small sample flow rate. Furthermore, since the measurement can be performed with a small sample flow rate, the hollow fiber membrane filtration unit can be miniaturized.

  The online measurement pretreatment apparatus 1 according to the present invention is characterized in that an external pressure type hollow fiber membrane is employed as the filtering means 12. As shown in FIG. 3, the external pressure hollow fiber membrane is a hollow fiber membrane of a type in which water to be filtered is supplied to the outside of the hollow fiber membrane and filtered from the outside to the inside of the hollow fiber membrane. On the other hand, as shown in FIG. 12, the internal pressure type hollow fiber membrane is a hollow fiber membrane in which water to be filtered flows inside the hollow fiber membrane and is filtered from the inside to the outside of the hollow fiber membrane.

  The internal pressure type is characterized by the fact that the flow velocity at the membrane surface can be kept high with a small flow rate, but the pressure loss tends to be high, and the suspended particles tend to block the flow path at the membrane inlet. Is unsuitable. In the internal pressure type, filtered water flows out to the shell side (the side of the container in which the hollow fiber membrane is stored and filtered). The shell side generally has a larger capacity than a tube made of a hollow fiber membrane, and a retention portion is easily formed. Therefore, in the case of performing analysis with a small amount of treated water as in online measurement, it is not suitable because it causes a delay or an error. On the other hand, the external pressure type can also be used when there are many suspended substances in the water to be filtered. In addition, when microfiltration or ultrafiltration is performed to remove bacteria, air scrubbing or backwashing is performed to prevent suspended particles from accumulating in slow flow areas such as between hollow fiber membranes. It is also possible to prevent. For these reasons, the on-line measurement pretreatment apparatus 1 according to the present invention employs an external pressure type hollow fiber membrane.

  In the pretreatment device 1 for on-line measurement according to the present invention, it is preferable that the filtration means 12 performs sample water filtration at a flow rate of 1 L / h or more and 10 L / h or less. When the flow rate is 1 L / h or more, a decrease in analysis value or the like can be suppressed, and when the flow rate is 10 L / h or less, the apparatus can be downsized.

  As described above, in the pretreatment device for online measurement according to the present invention, a highly accurate result can be obtained even with a small sample flow rate, so that the membrane area of the hollow fiber membrane can be reduced as will be described later. Further, by reducing the membrane area, it is possible to reduce the size and cost of incidental facilities necessary for membrane cleaning, etc. even when the cross flow filtration method is used.

In the pretreatment device for online measurement 1 according to the present invention, the membrane area of the hollow fiber membrane that can be used in the filtration means 12 is the amount of sample water collected, the type / size of the suspended matter and microorganisms present in the water system, It can be designed freely according to the amount. In the present invention, the membrane area of the external pressure hollow fiber membrane is particularly preferably designed to be 0.01 m ² or more and 0.3 m ² or less. By designing it to be 0.01 m ² or more, it is possible to suppress a decrease in filtration efficiency and improve the accuracy and efficiency of online measurement, and by designing it to be 0.3 m ² or less, pre-processing for online measurement The apparatus 1 can be miniaturized and can be incorporated into an on-line measuring apparatus, and the amount of accumulated water can be reduced.

  In the pretreatment device 1 for online measurement according to the present invention, the pore diameter of the hollow fiber membrane that can be used in the filtration means 12 is the type and size of the suspension and microorganisms present in the water system, and the flow rate required for the online measurement meter. It is possible to design freely according to such as. In the present invention, it is particularly preferable to design the pore diameter of the hollow fiber membrane to 0.2 μm or less. If the pore diameter of the hollow fiber membrane is designed to be 0.2 μm or less, it is possible to remove bacteria. Therefore, the pretreatment device 1 for online measurement according to the present invention can be applied to an aqueous system in which bacteria are present. Become.

  In the online measurement pretreatment apparatus 1 according to the present invention, the specific types of the hollow fiber membranes that can be used in the filtering means 12 are not particularly limited, and are usually used in the online measurement pretreatment apparatus 1. One or two or more possible hollow fiber membranes can be freely selected and used. Examples thereof include a microfilter (MF) and an ultrafiltration membrane (UF).

(3) Filtrated water delivery unit 13
In the filtered water sending part 13, the filtered water filtered by the filtering means 12 is sent to the online measuring device. In the pretreatment device 1 for online measurement according to the present invention, the specific method for sending filtered water from the pretreatment device 1 to the online measurement device is not particularly limited, and usually from the pretreatment device 1 to the online measurement device. The method used for sending the filtered water to the destination can be freely selected and adopted. For example, a delivery method using the filtered water flow in the filtration means 12 as it is, a delivery method using a pump or the like can be employed.

(4) Non-filtered water discharge part 14
Non-filtered water that has not been filtered by the filtering means 12 is drained from the non-filtered water discharge section 14. In the on-line measurement pretreatment apparatus 1 according to the present invention, the specific method for discharging the non-filtered water from the pretreatment apparatus 1 is not particularly limited, and any known discharge method can be freely selected and employed. For example, a discharge method using the water flow in the pretreatment apparatus 1 as it is, or a discharge method using a pump or the like can be employed.

(5) Circulation means 15
The circulation means 15 is means for circulating the non-filtered water discharged by the non-filtered water discharge unit 14 to the sample water introducing means 11. In the pretreatment device 1 for online measurement according to the present invention, the circulation means 15 is not an essential means, and it is possible to circulate non-filtered water to the sample water introduction means 11 using an external circulation facility. It can also be provided as part of the pre-processing device 1.

  FIG. 4 is a schematic view schematically showing a second embodiment of the online measurement pretreatment apparatus 1 according to the present invention. The online measurement preprocessing apparatus 1 according to the second embodiment is an example in which a circulation unit 15 is provided as a part of the preprocessing apparatus 1. In the pretreatment device 1 for online measurement according to the present invention, a specific circulation method of non-filtered water is not particularly limited, and a known circulation method can be freely selected and adopted. For example, a circulation method using the water flow in the pretreatment device 1 as it is, or a circulation method using a pump or the like can be adopted.

(6) Automatic cleaning mechanism 16
The automatic cleaning mechanism 16 functions to perform automatic cleaning of the external pressure hollow fiber membrane. In the pretreatment device 1 for online measurement according to the present invention, the automatic cleaning mechanism 16 is not an essential means, and the external pressure hollow fiber membrane can be cleaned using an external cleaning facility. It can also be provided as part of the processing apparatus 1. The on-line measurement pretreatment apparatus 1 according to the present invention is equipped with an automatic cleaning mechanism 16 and can be kept clean by periodically cleaning, so that fouling caused by irregular suspended substances and microorganisms can be maintained. Can be prevented.

  FIG. 5 is a schematic view schematically showing a third embodiment of the online measurement pretreatment apparatus 1 according to the present invention. The online measurement pretreatment device 1 according to the third embodiment is an example including an automatic cleaning mechanism 16 as a part of the pretreatment device 1. Further, the online measurement pretreatment device 1 according to the third embodiment is an embodiment designed so that air scrubbing cleaning and / or chemical cleaning can be performed as the automatic cleaning mechanism 16.

  More specifically, in the case of air scrubbing cleaning, compressed air is introduced from the automatic cleaning mechanism 16 using an air pump or the like. Then, the sample water and air in the filtration means 12 move up and down around the hollow fiber bundle, so that the adhering matter on the hollow fiber membrane surface can be washed with the vibration and shear force. In order to further enhance the effect of air scrubbing cleaning, it is preferable not to fix one of the hollow fiber membranes of the filtration means 12.

  When air scrubbing cleaning is employed in the automatic cleaning mechanism 16, it is preferable to perform air scrubbing cleaning in a state where the flow of sample water to the filtering means 12 and filtration are stopped. In conventional cross-flow filtration systems, air is blown together with physical fluctuations to increase the flow velocity on the membrane surface and enhance the cleaning effect by shearing force. Normally, sample water is filtered even during air scrubbing cleaning. It was common sense to do. However, in this embodiment, by performing the air scrubbing cleaning in a state where the flow of the sample water to the filtering means 12 and the filtration are stopped, the cleaning effect can be obtained with a smaller amount of air than the normal air flow rate. Therefore, it is possible to reduce the size and price of the apparatus. In addition, in the case where an oxidizable or reducing substance is a measurement target, it is possible to eliminate taking in a measurement value affected by air injection.

  Further, in the case of chemical cleaning, by temporarily stopping the introduction of the sample water into the online measurement pretreatment device 1 and introducing a predetermined drug from the automatic cleaning mechanism 16, the deposit on the hollow fiber membrane surface is cleaned. be able to.

  In the on-line measurement pretreatment device 1 according to the third embodiment, the motor-operated valve v is used to stop the introduction of sample water during automatic cleaning, and an electromagnetic valve is used to switch to introduction of compressed air or a medicine. However, the present invention is not limited to this, and can be freely designed according to the purpose and the structure of the apparatus.

  FIG. 6 is a schematic diagram schematically showing a fourth embodiment of the online measurement pretreatment apparatus 1 according to the present invention. The online measurement pretreatment device 1 according to the fourth embodiment is an embodiment designed so that the automatic cleaning mechanism 16 can perform back-flow cleaning. Specifically, water flow to the online measurement pretreatment device 1 is temporarily stopped, water is introduced from the automatic cleaning mechanism 16 or water containing a predetermined medicine if necessary, and reverse filtration is performed. Thus, the deposit on the hollow fiber membrane surface can be washed.

  In the on-line measurement pretreatment apparatus 1 according to the present invention, a specific automatic cleaning method used for the automatic cleaning mechanism 16 is not particularly limited, and a known automatic cleaning method can be freely selected and adopted. In the present invention, it is particularly preferable to employ air scrubbing cleaning among those exemplified above. Since air scrubbing cleaning is simple, the device can be simple and downsized, and the accumulated portion of sample water does not increase, so it is suitable as an automatic cleaning method for online analysis. In order to further enhance the effect of air scrubbing cleaning, it is desirable that one of the hollow fiber membranes is not fixed.

  In the automatic cleaning mechanism 16 described above, the above-described various automatic cleaning methods can be used alone, but in order to obtain a higher cleaning effect, it is also possible to perform cleaning in combination of two or more methods. is there. For example, by regularly performing air scrubbing cleaning and using chemical cleaning in combination with periodic maintenance, it is possible to maintain a clearer state for a long time, and as a result, the frequency of replacement of the hollow fiber membrane can be reduced. It is possible to reduce.

<2. Online measuring device 10>
The online measurement preprocessing apparatus 1 according to the present invention can be suitably used as a preprocessing means of the online measurement apparatus 10 by utilizing its high preprocessing effect. FIG. 7 is a schematic diagram schematically showing the first embodiment of the online measuring apparatus 10 according to the present invention. The online measurement device 10 according to the present invention is roughly provided with the online measurement pretreatment device 1 and a measurement meter 101. The means and the specific configuration of the online measurement preprocessing apparatus 1 are the same as described above, and thus the description thereof is omitted here.

  Since the pretreatment device 1 for online measurement according to the present invention can effectively remove suspended substances to microorganisms such as bacteria, it can be used for any online measurement. Items that can be measured by the measurement meter 101 are not particularly limited, and any substance can be measured. For example, highly reactive substances such as oxidizing substances such as residual chlorine and hydrogen peroxide, reducing substances such as hydrazine and sulfite ions, substances that are used or metabolized by organisms such as ammonia, phosphate ions, and organic substances Can be measured.

<3. Pretreatment Method A for Online Measurement>
FIG. 8 is a flowchart of the preprocessing method A and the online measurement method B in the online measurement according to the present invention. The pretreatment method A in the on-line measurement according to the present invention is a method of performing at least the sampling process I, the filtration process II, the filtered water delivery process III, and the non-filtered water draining process IV. Moreover, the circulation process V, the automatic washing process VI, etc. can also be performed as needed.

(1) Sampling process I
Sampling step I is a step of sampling sample water from the water system. In addition, since the specific method performed by the sampling process I is the same as the method performed by the sample water introduction part 11 of the said pretreatment apparatus 1 for online measurement, description is omitted here.

(2) Filtration step II
The filtration step II is a step of filtering the sample water sampled in the sampling step I by a cross flow filtration method using an external pressure type hollow fiber membrane. In addition, since the specific filtration method etc. which are performed by the filtration process II are the same as the method performed by the filtration means 12 of the said pretreatment apparatus 1 for online measurement, description is omitted here.

(3) Filtrated water delivery process III
The filtered water sending process III is a process of sending the filtered water filtered in the filtering process II to an online measuring device. The specific delivery method performed in the filtered water delivery process III is the same as the method performed in the filtered water delivery unit 13 of the on-line measurement pretreatment device 1, and will not be described here.

(4) Non-filtered water drainage process IV
The non-filtered water draining step IV is a step of draining the non-filtered water that has not been filtered in the filtering step II. The specific drainage method performed in the non-filtrated water draining step IV is the same as the method performed in the non-filtrated water discharge unit 14 of the on-line measurement pretreatment device 1, and therefore the description thereof is omitted here.

(5) Circulation process V
The circulation step V is a step of circulating the non-filtered water discharged in the non-filtered water discharging step to the pretreatment device. Although the circulation step V is not an essential step in the pretreatment method A according to the present invention, it is preferable to perform the circulation step V in order to keep the amount of sample water sampled in the on-line measurement to a small amount. In addition, since the specific circulation method etc. which are performed in the circulation process V are the same as the method which is performed by the circulation means 15 of the pretreatment device 1 for online measurement, the description is omitted here.

(6) Automatic cleaning process VI
In the automatic washing step VI, the external pressure hollow fiber membrane is automatically washed. Although the automatic cleaning step VI is not an essential step in the pretreatment method A according to the present invention, it can be performed to keep the membrane surface clear and prevent fouling due to irregular suspended substances and microorganisms. preferable. The specific cleaning method and the like performed in the automatic cleaning step VI are the same as the method performed by the automatic cleaning mechanism 16 of the online measurement pretreatment apparatus 1, and thus the description thereof is omitted here.

<4. Online measurement method B>
The pretreatment method A according to the present invention can be used for the pretreatment of the online measurement method B by utilizing its excellent treatment effect. The on-line measurement method B according to the present invention is a method for performing the pretreatment method A and the on-line measurement step VII. Note that the specific measurement method and the like performed in the online measurement process VII are the same as the method performed in the measuring instrument 101 of the online measurement pretreatment apparatus 1, and therefore the description thereof is omitted here.

  Hereinafter, the present invention will be described in more detail based on examples, and effects of the present invention will be verified. In addition, the Example demonstrated below shows an example of the typical Example of this invention, and, thereby, the range of this invention is not interpreted narrowly.

  In this example, in the on-line measurement of the water system, the measurement results obtained when the online measurement pretreatment device (pretreatment method) according to the present invention was used and when the existing online measurement pretreatment device was used. The difference between the two was examined. FIG. 9 schematically shows the online measurement system used in this example.

(1) Preparation of test water To the water of Nogi-machi, Tochigi Prefecture, adjust the turbidity to about 20-90 using a suspension of filtered backwash water for industrial water in Chiba Prefecture. Sodium chloride, sodium bicarbonate, Sodium hypochlorite was added to prepare test water containing a suspension.

(2) Water flow The test water adjusted as described above is prepared in a 200 L tank 102, and the flow rate of about 2 L / min is supplied to the pretreatment apparatus 1 according to the present invention and the conventional pretreatment apparatus 1 ′ using the cascade pump 103. The sample water was passed through. After passing water, the sample water was returned to the tank again. The pressure of the circulating water was approximately 0.2 MPa. About the sample water reduced by sampling, the sample water adjusted to the same water quality separately was replenished once / day. Since the residual chlorine concentration is consumed, sodium hypochlorite is supplied to a sodium hypochlorite control pump 105 using a polaro residual chlorine meter 104 (manufactured by TOADKK) so as to be about 0.7 mg / L. Was added using. In addition, the Polaro type residual chlorine meter (manufactured by TOADKK) was subjected to maintenance once a day in comparison with a manual analysis (HACH pocket residual chlorine meter, HACH 2470).

(3) Filtration conditions [Pretreatment device according to the present invention]
Using Kuraray Co., Ltd. (filtration area 0.1 m ² , filtration membrane pore diameter 0.1 μm), the system was operated with a filtration water amount of 0.06 m ³ / day and a membrane filtration flux of 0.6 m / day. In addition, air scrubbing cleaning was performed every 20 minutes for 1 minute using a small air compressor.
[Conventional pretreatment equipment]
Using a dead-end type hollow fiber membrane (manufactured by Mitsubishi Rayon Co., Ltd., “STELLAPORE JR”, filtration area 0.3 m ² , filtration membrane pore diameter 0.1 μm), filtration water volume 0.06 m ³ / day, membrane filtration flux It was operated at 0.6 m / day.

(4) Online measurement Online measurement was carried out using a colorimetric online measuring device manufactured by Kurita Kogyo Co., Ltd. The colorimetric method was a batch type measurement at intervals of 5 minutes in accordance with the DPD method of JIS.
Immediately after the start of filtration, and after 24 hours, 4 days, 1 week, 2 weeks, and 1 month after the start of filtration, the residual chlorine concentration, which is considered to be most susceptible to organism adhesion and sample retention, was measured and compared.
In addition, in the process of adding the free residual chlorine concentration to 2 mg / L once to the membrane after 1 week and then decaying, the analytical value of the device after each pretreatment device and the analytical value of the manual analysis Compared.

(5) Results When manual analysis is performed, when online measurement is performed using the pretreatment device according to the present invention (Example), and when online measurement is performed using a conventional pretreatment device (Comparative Example) Table 1 below shows the measurement results of each free residual chlorine concentration. When the conventional pretreatment method was used, the sample flow rate could not be secured sufficiently for 2 weeks and 1 month, resulting in an error of the online measuring device. Further, a comparison between the measured value after each pretreatment device after one week and the value of the manual analysis is shown in the drawing substitute graph of FIG.

  As shown in Table 1 and FIG. 11, when online measurement was performed using the pretreatment apparatus according to the present invention (Example), the measurement results almost the same as the results of the manual analysis were obtained even after a lapse of time from the start of filtration. I was able to get it. On the other hand, when online measurement was performed using a conventional pretreatment apparatus (comparative example), the error from the result of manual analysis increased as time passed from the start of filtration. This is thought to be due to the fact that the measured value was lowered due to the living organisms adhering to the membrane or the sample water remaining.

  From the results of the examples, it is understood that the on-line measurement using the pretreatment apparatus according to the present invention can perform stable and highly accurate water quality measurement even in an aqueous system that cannot be handled by a conventional dead-end filter. It was.

  According to the present invention, in the on-line measurement, it is possible to prevent irregular fouling due to suspended substances and living organisms and to reduce the maintenance frequency, and high turbidity that cannot be dealt with by a conventional dead-end filter. In addition, stable and highly accurate water quality measurement can be performed even in the presence of bacteria.

DESCRIPTION OF SYMBOLS 1 Pretreatment apparatus for online measurement 10 Online measurement apparatus 11 Sample water introduction part 12 Filtration means 13 Filtrated water delivery part 14 Non-filtrated water discharge part 15 Circulation means 16 Automatic washing mechanism 101 Meter 102 Tank 103 Cascade pump 104 Polaro residual chlorine Total 105 Sodium hypochlorite control pump A Pretreatment method B Online measurement method I Sampling process
II Filtration process
III Filtrated water delivery process
IV Non-filtered water drainage process V Circulation process
VI Automatic cleaning process
VII Online measurement process

Claims (12)

A pretreatment device for measuring water quality in a water system online,
From the water system, a sample water introduction unit for introducing sample water into the pretreatment device,
A filtration means equipped with an external pressure type hollow fiber membrane for filtering the sample water introduced from the sample water introduction part by a cross flow filtration method;
A filtered water delivery section for delivering filtered water filtered by the filtration means to an on-line measuring device;
A non-filtered water drainage unit for draining non-filtered water that has not been filtered by the filtering means;
An automatic cleaning mechanism that periodically performs automatic cleaning of the external pressure hollow fiber membrane,
In the automatic cleaning mechanism, air scrubbing cleaning is performed,
The pretreatment device for on-line measurement, wherein the air scrubbing cleaning is performed in a state where the flow of the sample water to the filtration means and the filtration are stopped.   The pretreatment device for on-line measurement according to claim 1, wherein the filtering means filters the sample water at a flow rate of 1 L / h or more and 10 L / h or less. The pretreatment device for online measurement according to claim 1 or 2, wherein a membrane area of the external pressure type hollow fiber membrane is 0.01 m ² or more and 0.3 m ² or less.   The pretreatment device for online measurement according to any one of claims 1 to 3, further comprising a circulation unit that circulates the non-filtered water discharged by the non-filtered water discharge unit to the sample water introduction unit. .   The pretreatment device for online measurement according to any one of claims 1 to 4, wherein a hole diameter of the hollow fiber membrane is 0.2 µm or less.   An on-line measurement device provided with the on-line measurement pretreatment device according to claim 1. A pretreatment method for measuring water quality in a water system online,
A sampling step of sampling sample water from the water system;
A filtration step of filtering the sample water sampled in the sampling step by a cross-flow filtration method using an external pressure type hollow fiber membrane;
A filtered water delivery step for delivering the filtered water filtered in the filtration step to an online measuring device;
A non-filtered water draining step for draining non-filtered water that has not been filtered in the filtering step;
An automatic cleaning step of periodically performing automatic cleaning of the external pressure hollow fiber membrane;
At least
In the automatic cleaning process, air scrubbing cleaning is performed,
A pretreatment method in on-line measurement, in which the air scrubbing cleaning is performed in a state in which sample water flow and filtration are stopped.   The pretreatment method in online measurement according to claim 7, wherein in the filtration step, the sample water is filtered at a flow rate of 1 L / h or more and 10 L / h or less. The pretreatment method in online measurement according to claim 7 or 8, wherein a membrane area of the external pressure type hollow fiber membrane is 0.01 m ² or more and 0.3 m ² or less.   The pretreatment method in online measurement according to any one of claims 7 to 9, further comprising a circulation step of circulating the nonfiltrated water discharged in the nonfiltrated water discharge step to a pretreatment device.   The pretreatment method in online measurement according to any one of claims 7 to 10, wherein the hole diameter of the hollow fiber membrane is 0.2 µm or less. The on-line measuring method which performs the pre-processing method as described in any one of Claims 7-11.