Powdered activated carbon injection control system, powdered activated carbon injection control method, powdered activated carbon injection control device, and program

Abstract

To optimize an injection rate of powdery activated carbon.SOLUTION: A powdery activated carbon injection control system comprises: algae detection / determination means for detecting algae contained in raw water to determine species of the algae; odor substance estimation means for estimating a kind of an odor substance emitted from the algae, from the species of the algae determined by the algae detection / determination means; odor substance concentration measurement means for measuring a concentration of an odor substance contained in the raw water or in treated water after powdery activated carbon injection treatment, targeting the kind of the odor substance estimated by the odor substance estimation means; and powdery activated carbon injection control means for calculating an injection rate of odor substance corresponding powdery activated carbon for making the concentration of the odor substance contained in water to be treated in a raw water receiving well equal to a target concentration by using at least the concentration of the odor substance measured by the odor substance concentration measurement means, and controlling an injection amount of powdery activated carbon to be injected into the water to be treated in the raw water receiving well or into water to be treated in a coagulant mixing pond on the basis of the injection rate of the odor substance corresponding powdery activated carbon.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a powdered activated carbon injection control system, a powdered activated carbon injection control method, a powdered activated carbon injection control device, and a program. [Background technology]

[0002] It is known that in dams, lakes, reservoirs, and other water sources for tap water, the progression of eutrophication causes the abnormal proliferation of algae (hereinafter also referred to as phytoplankton), which impedes water purification processes. Some of these algae produce odorous substances, such as a moldy smell, which cause an unpleasant odor in tap water. However, the odorous substances produced vary depending on the algae species, making water purification more difficult.

[0003] In addition to odorous substances, raw water for water purification treatment contains dissolved organic substances such as humic substances, suspended matter such as fine particles, and metal ions such as iron and manganese.

[0004] Meanwhile, at water purification plants, chemicals such as sodium hypochlorite are injected to remove metal ions such as iron and manganese and for disinfection purposes. However, when raw water contains dissolved organic matter, the chemicals react with the dissolved organic matter to produce disinfection by-products such as trihalomethanes and haloacetic acids, which are carcinogenic.

[0005] In many water purification plants, powdered activated carbon is injected to remove odorous substances and dissolved organic matter from raw water, and coagulants are injected to remove suspended solids. In water treatment systems using powdered activated carbon, the injection rate of powdered activated carbon must be adjusted depending on the type and concentration of odorous substances and the composition and concentration of dissolved organic matter in the treated water.

[0006] The jar test (hereinafter also referred to as the beaker test) is often used as a method for determining the injection rate of powdered activated carbon. In the jar test, water to be treated is collected in multiple beakers, and different amounts of powdered activated carbon are injected into each of the collected water samples to evaluate the removal rates of odorous substances and soluble organic substances, thereby determining the minimum injection rate of powdered activated carbon required to reduce the odor concentration and soluble organic substances to below the target concentration after treatment.

[0007] However, when determining the injection rate of powdered activated carbon by the jar test, it is very difficult to inject powdered activated carbon in accordance with changes in the water quality of the water being treated, and there is a risk of the injection rate being too high or too low. Furthermore, since it takes time to determine the optimal injection rate of powdered activated carbon using the jar test, the water quality of the water being treated may have changed by the time the optimal injection rate of powdered activated carbon is obtained.

[0008] In particular, it is known that the adsorption characteristics of odorous substances by powdered activated carbon are affected by the type of odorous substance and the molecular structure and concentration of coexisting soluble organic substances, and that adsorption can be inhibited.

[0009] Furthermore, when determining the injection rate of powdered activated carbon to be actually added, the injection rate is determined on the safe side compared to the injection rate obtained by the jar test, which results in excessive injection.

[0010] Powdered activated carbon has a very high unit price compared to other chemicals such as coagulants, sulfuric acid, and sodium hypochlorite. Therefore, excessive injection of powdered activated carbon can lead to a sharp rise in chemical costs. From an economic perspective, there is a need for a technology that can prevent excessive injection of powdered activated carbon and control the optimal injection rate of powdered activated carbon in response to changes in the quality of the water to be treated. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-288309 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-124593 [Patent Document 3] Japanese Patent Application Laid-Open No. 2018-134039 Summary of the Invention [Problem to be solved by the invention]

[0012] The problem to be solved by the present invention is to provide a powdered activated carbon injection control system, a powdered activated carbon injection control method, a powdered activated carbon injection control device, and a program that can optimize the injection rate of powdered activated carbon. [Means for solving the problem]

[0013] The powdered activated carbon injection control system of one embodiment includes an algae detection and determination means for detecting algae contained in raw water and determining the type of the algae; an odorant estimation means for estimating the type of odorant emitted by the algae from the type of algae determined by the algae detection and determination means; an odorant concentration measurement means for measuring the concentration of the odorant contained in the raw water or treated water after powdered activated carbon injection treatment, targeting the type of odorant estimated by the odorant estimation means; and a powdered activated carbon injection control means for calculating an odorant-specific powdered activated carbon injection rate using at least the odorant concentration measured by the odorant concentration measurement means to adjust the concentration of the odorant contained in the water to be treated in the receiving well to a target concentration, and for controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well or the water to be treated in the coagulant mixing basin based on the odorant-specific powdered activated carbon injection rate. and a soluble organic substance index measuring means for measuring at least one of the ultraviolet absorbance, fluorescence intensity, and soluble organic carbon concentration of the raw water as a soluble organic substance index value. The powdered activated carbon injection control means uses the soluble organic substance index value measured by the soluble organic substance index measuring means to calculate a soluble organic substance-specific powdered activated carbon injection rate for bringing the soluble organic substance residual rate in the water to be treated in the receiving well to a target residual rate, compares the soluble organic substance-specific powdered activated carbon injection rate with the odorous substance-specific powdered activated carbon injection rate, sets the larger powdered activated carbon injection rate as the powdered activated carbon injection rate, and controls the amount of powdered activated carbon to be injected into the water to be treated in the receiving well in accordance with the powdered activated carbon injection rate. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing an example of the configuration of a water treatment system according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of an algae detection and determination device 11. [Figure 3] FIG. 2 is a diagram showing an example of odorant reference information stored as an odorant reference database in the odorant estimation device 12. [Figure 4]FIG. 2 is a diagram showing an example of the configuration of an odorant concentration measuring device 13. [Figure 5A] 10 is a graph showing the relationship between the output change dV / dt of the odor sensor 13d and the concentration of the odorant "dimethylisoborneol," and an example of a conversion formula. FIG. [Figure 5B] 10 is a graph showing the relationship between the output change dV / dt of the odor sensor 13d and the concentration of the odorous substance "geosmin," and an example of a conversion formula. FIG. [Figure 5C] 10 is a graph showing the relationship between the output change dV / dt of the odor sensor 13d and the concentration of the odorant "2,4-decadienal," and an example of a conversion formula. FIG. [Figure 6A] 4 is a flowchart showing an example of an operation related to the powdered activated carbon injection control system of the first embodiment. [Figure 6B] 4 is a flowchart showing an example of detailed operation of setting processing and calculation processing related to the powdered activated carbon injection control system of the embodiment; [Figure 7] 1 is a graph showing the results of a test conducted by the inventors when dimethylisoborneol or geosmin was added to raw water from a certain water purification plant and the same powdered activated carbon injection treatment was carried out. [Figure 8] 1 is a graph showing test results when dimethylisoborneol was added to pure water and various mixture ratios of humic acid and fulvic acid were added, followed by powdered activated carbon injection treatment. [Figure 9] 1 is a graph showing test results when geosmin was added to pure water and various mixture ratios of humic acid and fulvic acid were added, followed by a powdered activated carbon injection treatment. [Figure 10] This graph shows the test results when a coagulant was added to the treated water, which had been adjusted to a raw water soluble organic carbon concentration DOCR of 2.5 (mg / L) and mixed water pH of 6.5, and then the water was rapidly stirred at 150 rpm for 10 minutes, and then slowly stirred at 80 rpm for 60 minutes. [Figure 11]This graph shows the test results when powdered activated carbon treatment was performed by rapidly stirring at 150 rpm for 60 minutes, adjusting the hydrogen ion concentration index (pH) to a specified value, adding a flocculant, rapidly stirring at 150 rpm for 10 minutes, and then slowly stirring at 80 rpm for 60 minutes. [Figure 12] Graph showing the relationship between specific absorbance SUVA and coefficient f. [Figure 13] FIG. 10 is a diagram showing an example of the configuration of an odorant concentration measuring device 13 according to a second embodiment. [Figure 14] FIG. 10 is a diagram showing an example of the configuration of a water treatment system according to a third embodiment. [Figure 15A] 10 is a flowchart showing an example of an operation related to the powdered activated carbon injection control system of the third embodiment. [Figure 15B] 4 is a flowchart showing an example of detailed operation of setting processing and calculation processing related to the powdered activated carbon injection control system of the embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments will be described with reference to the drawings.

[0016] First Embodiment First, the first embodiment will be described.

[0017] [System Configuration] FIG. 1 is a diagram showing an example of the configuration of a water treatment system according to the first embodiment.

[0018] Here, an example is shown in which the water treatment system according to this embodiment is applied to a water treatment facility using a rapid sand filtration method. However, the water treatment system according to this embodiment is not limited to water treatment facilities using a rapid sand filtration method, and can also be applied to water treatment facilities using other methods. For example, the water treatment system can be applied to water treatment facilities using a membrane filtration method or a sand filtration method.

[0019] The water treatment facility 1 shown in Figure 1 performs "adsorption treatment" and "coagulation treatment." Adsorption treatment is a process in which odorous substances and soluble organic substances contained in the arriving water are adsorbed and removed using powdered activated carbon. Coagulation treatment is a process in which turbid substances contained in the arriving water are coagulated and settled using a coagulant.

[0020] The water treatment facility 1 includes a receiving well 20, a powdered activated carbon injection device 21, a flocculant mixing basin 30, a flocculant injection device 31, a flocculation and sedimentation basin 40, and a filtering basin and a clear water basin (not shown).

[0021] Receiving well 20 receives raw water (water to be treated) delivered through piping 2 and stabilizes it as receiving water. This receiving well 20 is provided with a powdered activated carbon injector 21 for the adsorption treatment described above. The powdered activated carbon injector 21 performs powdered activated carbon injection treatment by injecting powdered activated carbon into the water to be treated. The powdered activated carbon injected into the water to be treated adsorbs odorous substances and soluble organic substances contained in the raw water. The water to be treated that has undergone adsorption treatment in receiving well 20 is led to coagulant mixing basin 30 through piping 3.

[0022] The coagulant mixing basin 30 receives the water to be treated, delivered through the pipe 3. A coagulant injector 31 is installed in the coagulant mixing basin 30 for the coagulation treatment described above. The coagulant injector 31 injects a coagulant into the water to be treated. The coagulant injected into the water to be treated coagulates suspended solids (turbidity) in the raw water, such as clay, bacteria, and algae, as well as the powdered activated carbon injected in the receiving well 20, to generate fine flocs. Aluminum-based and iron-based coagulants are preferred. Examples of aluminum-based coagulants include aluminum sulfate (aluminum sulfate) and polyaluminum chloride (PACl). Examples of iron-based coagulants include iron chloride, iron sulfate, and polysilica iron.

[0023] The coagulant mixing basin 30 is also provided with an oxidant injector 32 to adjust the hydrogen ion concentration index (pH value) of the water to be treated. The oxidant injector 32 injects an oxidant such as sulfuric acid into the water to be treated. The oxidant injected into the water to be treated changes the hydrogen ion concentration index (pH value) of the water to be treated.

[0024] The coagulant mixing basin 30 is also provided with an agitator 30a for agitating the water to be treated. This agitator 30a is constructed using, for example, a flash mixer. The water to be treated, into which the coagulant and oxidant have been injected in the coagulant mixing basin 30, is agitated by the agitator 30a to become mixed water, which is then led to the coagulation / sedimentation basin 40 via piping 4.

[0025] The water treatment system according to this embodiment includes a treated water quality target setting device 100, a powdered activated carbon injection control device 200, and a flocculant injection control device 300.

[0026] The treated water quality target setting device 100 sets target values for various physical quantities that indicate the water quality of the water to be treated. The powdered activated carbon injection control device 200 controls the powdered activated carbon injection device 21 that injects powdered activated carbon into the water to be treated in the receiving well 20. The coagulant injection control device 300 controls the coagulant injection device 31 that injects a coagulant into the water to be treated in the coagulant mixing basin 30 and the oxidant injection device 32 that injects an oxidant.

[0027] The treated water quality target setting device 100, powdered activated carbon injection control device 200, and flocculant injection control device 300 may be implemented together as a single computer, or each may be implemented as a separate computer. The powdered activated carbon injection control device 200 and flocculant injection control device 300 may also be implemented together as a single computer. The functions of the treated water quality target setting device 100, powdered activated carbon injection control device 200, and flocculant injection control device 300 may also be implemented as a program executed by a processor, such as a central processing unit, provided in the computer. Details of the treated water quality target setting device 100, powdered activated carbon injection control device 200, and flocculant injection control device 300 will be described later.

[0028] The piping 2 is equipped with a water quality meter set 10, an algae detection and determination device (algae detection and determination means) 11, an odorant estimation device (odorant estimation means) 12, an odorant concentration measurement device (odorant concentration measurement means) 13, a soluble organic substance indicator meter set (soluble organic substance indicator measurement means) 14, and a flow meter 15. At least these instruments and the powdered activated carbon injection control device 200 constitute a powdered activated carbon injection control system that controls the injection of powdered activated carbon.

[0029] The water quality meter set 10 measures the quality of raw water. This water quality meter set 10 includes a turbidity meter 10a that measures the turbidity of the raw water, an alkalinity meter 10b that measures the alkalinity of the raw water, a water thermometer 10c that measures the temperature of the raw water, and a hydrogen ion concentration index meter 10d that measures the hydrogen ion concentration (pH value) of the raw water. Data measured by these meters is supplied to the coagulant injection control device 300.

[0030] The algae detection and determination device 11 detects algae contained in raw water, determines the type of algae (attribute and / or species) and counts each type of algae, and generates algae information indicating the results. For example, the algae detection and determination device 11 samples a portion of the raw water from the pipe 2 into which the raw water flows, and observes the raw water with a special camera to detect target algae and determine their type (attribute and species). The algae information data generated by the algae detection and determination device 11 is supplied to the odorant estimation device 12. This algae information data may also be supplied to the powdered activated carbon injection control device 200.

[0031] The odorous substance estimation device 12 estimates the type of odorous substance emitted by the algae from the type of algae determined by the algae detection and determination device 11, based on the algae information sent from the algae detection and determination device 11. Data indicating the type of algae estimated by the odorous substance estimation device 12 is supplied to the odorous substance concentration measurement device 13. This data indicating the type of algae may also be supplied to the powdered activated carbon injection control device 200.

[0032] The odorant concentration measuring device 13 measures the concentration of odorants contained in the raw water for the types of odorants estimated by the odorant estimation device 12. The concentration data measured by the odorant concentration measuring device 13 is supplied to the powdered activated carbon injection control device 200.

[0033] The soluble organic matter indicator instrument set 14 measures at least one of the UV absorbance, fluorescence intensity, and dissolved organic carbon (DOC) of the raw water as the soluble organic matter indicator value. This soluble organic matter indicator instrument set 14 includes an UV absorbance meter 14a that measures the UV absorbance of the raw water, a fluorescence intensity meter 14b that measures the fluorescence intensity of the raw water, and a soluble organic carbon concentration meter (DOC meter) 14c that measures the soluble organic carbon concentration of the raw water. Data on the soluble organic matter indicator values measured by each meter are supplied to the powdered activated carbon injection control device 200.

[0034] The flow meter 15 measures the flow rate of the raw water. The flow rate data measured by the flow meter 15 is supplied to the powdered activated carbon injection control device 200.

[0035] In addition, a hydrogen ion concentration index meter (pH meter) 16 is provided in the coagulant mixing basin 30. This hydrogen ion concentration index meter 16 measures the hydrogen ion concentration index (pH value) of the mixed water in the coagulant mixing basin 30. Data on the hydrogen ion concentration index measured by the hydrogen ion concentration index meter 16 is supplied to the coagulant injection control device 300.

[0036] [Configuration of algae detection and determination device 11] FIG. 2 is a diagram showing an example of the configuration of the algae detection and determination device 11. As shown in FIG.

[0037] 2, the algae detection and determination device 11 includes, for example, an observation cell 11d consisting of a flow cell 11a, a light 11b, and a camera 11c, a computer 11f that detects algae contained in raw water based on images taken by the camera 11c, and has built-in image analysis software and an algae reference database that determine the type (attributes and species) of the detected algae and count each type of algae, and a display device 11g that displays the results processed by the computer 11f. The algae information generated by this algae detection and determination device 11 is supplied to an odorant estimation device 12.

[0038] The configuration of the algae detection and determination device 11 is not limited to the example shown in Fig. 2. Any other configuration may be adopted as long as it can achieve the same functions.

[0039] [Odorant reference information held by odorant estimation device 12] FIG. 3 is a diagram showing an example of odorant reference information stored in the odorant estimation device 12 as an odorant reference database.

[0040] The odorant reference information is information that indicates the relationship between various algae and the odorants produced by these algae. In the example of odorant reference information shown in Figure 3, the algae are listed as "Anabaena," "Oscillatoria," "Phormidium," and "Uroglena," and the corresponding odorants are listed as "geosmin," "2-MIB (dimethylisoborneol)," "2-MIB (dimethylisoborneol)," and "2,4-decadienal," respectively.

[0041] Based on this information, the odorant estimation device 12 estimates the type of odorant that is most likely to be contained in the raw water from the type of algae indicated in the algae information supplied from the algae detection and determination device 11. The odorant information indicating the type of odorant estimated by this odorant estimation device 12 is supplied to the odorant concentration measurement device 13 and the powdered activated carbon injection control device 200.

[0042] The odorant reference information is not limited to the example in Fig. 3. Other information may be used as long as it can achieve the same function.

[0043] [Configuration of odorant concentration measuring device 13] FIG. 4 is a diagram showing an example of the configuration of the odorant concentration measuring device 13.

[0044] The odorant concentration measuring device 13 shown in FIG. 4 includes an odorant extraction tank 13a, a dehumidifier 13b, an odor sensor cell 13c, an odor sensor head (hereinafter referred to as "odor sensor") 13d, and an odorant concentration calculating device 13f.

[0045] Inside odorant extraction tank 13a are overflow tray 13a-1 and raw water inlet pipe 13a-2. Raw water inlet pipe 13a-2 also contains heater 13a-3, which heats the raw water to a predetermined temperature, causing odorants in the raw water to evaporate together with water vapor. The evaporated water vapor and odorants, along with air taken in by air supply fan 13a-4 attached to odorant extraction tank 13a, are sent to dehumidifier 13b, where the water vapor is separated, and the dried air containing the odorants is sent to odor sensor cell 13c. Odor sensor cell 13c is fitted with odor sensor 13d, which reacts to odorants, and an output corresponding to the odorant concentration is sent to odorant concentration calculation device 13f.

[0046] The odorant concentration calculation device 13f has information on a conversion formula indicating the relationship between the output change dV / dt of the odor sensor 13d (the change over time (slope) of the sensor output V) and the odorant concentration for each of the various assumed odorants. From the various conversion formulas, the calculation device 13f selects a conversion formula according to the type of odorant indicated in the odorant information supplied from the odorant estimation device 12, and calculates the concentration of that odorant from the output change dV / dt of the odor sensor 13d based on this conversion formula. Concentration information indicating this concentration is supplied to the powdered activated carbon injection control device 200. Note that if the output change dV / dt of the odor sensor 13d is confirmed but the type of corresponding odorant cannot be obtained from the odorant information supplied from the odorant estimation device 12, the concentration may be calculated using the corresponding conversion formula using dimethylisoborneol as a hypothetical odorant.

[0047] Here, the relationship between the change in output of odor sensor 13d and the concentrations of various odorous substances will be described with reference to FIGS. 5A, 5B, and 5C.

[0048] [Relationship between output change of odor sensor 13d and concentration of various odorous substances] Fig. 5A is a graph showing the relationship between the output change dV / dt of the odor sensor 13d and the concentration of the odorant "dimethylisoborneol," and an example of a conversion formula. Fig. 5B is a graph showing the relationship between the output change dV / dt of the odor sensor 13d and the concentration of the odorant "geosmin," and an example of a conversion formula. Fig. 5C is a graph showing the relationship between the output change dV / dt of the odor sensor 13d and the concentration of the odorant "2,4-decadienal," and an example of a conversion formula.

[0049] The odor sensor outputs as voltage (mV) or frequency (Hz). As odorous substances adhere to the odor sensor 13d, the output V increases over time (t). The magnitude of the change in output dV (slope) per unit time dt (sec) is proportional to the odorous substance concentration. Furthermore, since the proportionality constant differs depending on the type of odorous substance, the proportionality coefficient k corresponding to each odorous substance is set in advance, and a conversion formula corresponding to the type of odorous substance indicated in the odorous substance information supplied from the odorous substance estimation device 12 can be selected to measure the odorous substance concentration in the raw water.

[0050] Examples of conversion formulas for dimethylisoborneol, geosmin, and 2,4-decadienal are shown below.

[0051] C 2-MIB = k 2-MIB × dV / dt + v (1)

[0052] C Geosmin = k Geosmin × dV / dt + v (2)

[0053] C D = k D × dV / dt + v (3)

[0054] where C: odorant concentration (ng / L), subscript 2-MIB: dimethylisoborneol, subscript Geosmin: geosmin, subscript D: 2,4-decadienal, k: proportionality coefficient, dV: output change (mV or Hz), dt: time change (sec).

[0055] By using the conversion formula corresponding to the type of odor substance estimated by the odor substance estimation device 12 from among the conversion formulas shown in equations (1) to (3), the concentration of the odor substance can be obtained from the output change dV / dt of the odor sensor 13d.

[0056] [Overview of the Functions of Devices 100, 200, and 300] Next, various functions of the treated water quality target setting device 100, powdered activated carbon injection control device 200, and flocculant injection control device 300 will be described.

[0057] As described above, the treated water quality target setting device 100 sets target values for various physical quantities that indicate the water quality of the water to be treated. Specifically, as target values for the concentrations of various odorants (target odorant concentrations), for example, target concentrations (target odorant concentrations) of the odorant "dimethylisoborneol," the odorant "geosmin," and the odorant "2,4-decadienal" are set. Furthermore, as target values for the soluble organic substance index value (target soluble organic substance index value), at least one of target values for ultraviolet absorbance, fluorescence intensity, and soluble organic carbon concentration (target ultraviolet absorbance, target fluorescence intensity, target soluble organic carbon concentration) is set. In addition, a target value for turbidity (target turbidity) and a target value for hydrogen ion concentration index (target hydrogen ion concentration index) are set.

[0058] As described above, the powdered activated carbon injection control device 200 controls the powdered activated carbon injection device 21, which injects powdered activated carbon into the water to be treated in the receiving well 20. This powdered activated carbon injection control device 200 takes in the data set by the treated water quality target setting device 100, and also takes in various data supplied from the algae detection and determination device 11, the odorous substance estimation device 12, the odorous substance concentration measurement device 13, the soluble organic substance indicator meter set 14, and the flow meter 15 as needed, as well as data supplied from the coagulant injection control device 300, and uses these data to control the injection rate of powdered activated carbon injected into the water to be treated in the receiving well 20.

[0059] As described above, the coagulant injection control device 300 controls the coagulant injection device 31 that injects a coagulant into the water to be treated in the coagulant mixing basin 30, and the oxidant injection device 32 that injects an oxidant. This coagulant injection control device 300 takes in data set by the treated water quality target setting device 100, as well as data supplied from the water quality meter set 10 and data supplied from the hydrogen ion concentration index measuring device 16, and uses these data to control the injection rate of the coagulant and the injection rate of the oxidant injected into the water to be treated in the coagulant mixing basin 30.

[0060] [Various functions of the powdered activated carbon injection control device 200] Various functions of the powdered activated carbon injection control device 200 of this embodiment will be described below.

[0061] The powdered activated carbon injection control device 200 of this embodiment has the function of calculating, using at least the concentration of odorants measured by the odorant concentration measuring device 13, a powdered activated carbon injection rate (hereinafter referred to as the "odorant-compatible powdered activated carbon injection rate") for adjusting the concentration of odorants contained in the water to be treated in the receiving well 20 to a target odorant concentration, and controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well 20 based on the odorant-compatible powdered activated carbon injection rate.

[0062] In addition, the powdered activated carbon injection control device 200 uses the soluble organic substance index value (at least one of ultraviolet absorbance, fluorescence intensity, and soluble organic carbon concentration) measured by the soluble organic substance index measurement set 14 to calculate the powdered activated carbon injection rate (hereinafter referred to as the "soluble organic substance-specific powdered activated carbon injection rate") required to bring the soluble organic substance residual rate in the water being treated in the receiving well 20 to a target residual rate, compares this soluble organic substance-specific powdered activated carbon injection rate with the odorous substance-specific powdered activated carbon injection rate, and controls the amount of powdered activated carbon to be injected into the water being treated in the receiving well 20 according to the larger powdered activated carbon injection rate.

[0063] Furthermore, the powdered activated carbon injection control device 200 has the function of controlling the odorant-specific powdered activated carbon injection rate to be greater than a predetermined reference value when the odorant concentration measured by the odorant concentration measuring device 13 is greater than the target odorant concentration, and of controlling the odorant-specific powdered activated carbon injection rate to be less than the predetermined reference value when the odorant concentration measured by the odorant concentration measuring device 13 is less than the target odorant concentration.

[0064] The powdered activated carbon injection control device 200 also has a function of calculating the odorant-specific powdered activated carbon injection rate so as to compensate for the influence of soluble organic substances that inhibit the adsorption of odorants by the powdered activated carbon.

[0065] In addition, the powdered activated carbon injection control device 200 has a function of calculating the powdered activated carbon injection rate corresponding to the soluble organic substances so as to compensate for the influence of the soluble organic substances that inhibit the adsorption of odorous substances by the powdered activated carbon when the powdered activated carbon injection process and the coagulant injection process are used in combination.

[0066] [Operation Overview] Next, an example of the operation of the powdered activated carbon injection control system of the first embodiment will be described with reference to the flowchart in Fig. 6A. However, the processing of each step described below does not necessarily have to be performed in the order shown in Fig. 6A, and the order of execution may be changed as appropriate.

[0067] In the treated water quality target setting device 100, various target values indicating the water quality of the water to be treated (target odorous substance concentration, target soluble organic substance index value (at least one of target ultraviolet absorbance, target fluorescent intensity, and target soluble organic carbon concentration), target turbidity, and target hydrogen ion concentration index) are set (S101). The data on the set target odorous substance concentration, target soluble organic substance index value, and target hydrogen ion concentration index are input into the powdered activated carbon injection control device 200, while the data on the set target turbidity is input into the coagulant injection control device 300.

[0068] Meanwhile, the water quality meter set 10 measures the water quality (turbidity, alkalinity, water temperature, and hydrogen ion concentration index) of the raw water. The measured water quality data is input to the coagulant injection control device 300. The algae detection and determination device 11 detects algae contained in the raw water and determines the type of algae. The odorant estimation device 12 estimates the type of odorant emitted by the algae from the type of algae. The odorant concentration measurement device 13 measures the concentration of odorant contained in the raw water for the estimated type of odorant. The soluble organic substance indicator meter set 14 measures at least one of the soluble organic substance indicator values of the raw water, such as ultraviolet absorbance, fluorescence intensity, and dissolved organic carbon concentration. The flow meter 15 measures the flow rate of the raw water (S102). These measured data are input to the powdered activated carbon injection control device 200.

[0069] The hydrogen ion concentration index measuring device 16 measures the hydrogen ion concentration index (pH value) of the mixed water in the flocculant mixing basin 30 (S103). The measured hydrogen ion concentration index data is input to the flocculant injection control device 300.

[0070] The coagulant injection control device 300 calculates a coagulant injection rate to achieve a target turbidity using the turbidity, alkalinity, water temperature, and hydrogen ion concentration index of the raw water measured by the water quality meter set 10 and the hydrogen ion concentration index measured by the hydrogen ion concentration index measuring device 16 (S104), and controls the coagulant injector 31 so that a coagulant is injected into the water to be treated in the coagulant mixing basin 30 according to the coagulant injection rate, and also controls the oxidant injector 32 so that an oxidant is injected (S105). Note that the processing of step S105 may be performed simultaneously with or after the processing of step S107 described below.

[0071] The powdered activated carbon injection control device 200 calculates the odorant-specific powdered activated carbon injection rate for achieving the target odorant concentration using the odorant concentration measured by the odorant concentration measuring device 13, and also calculates the soluble organic substance-specific powdered activated carbon injection rate for achieving the target soluble organic substance index value using the soluble organic substance index value measured by the soluble organic substance index meter set 14, and calculates the larger of this soluble organic substance-specific powdered activated carbon injection rate and the odorant-specific powdered activated carbon injection rate (S106), and controls the powdered activated carbon injection device 21 so that powdered activated carbon is injected into the water to be treated in the receiving well 20 in accordance with this powdered activated carbon injection rate (S107). In this case, the powdered activated carbon injection control device 200 can calculate the amount of powdered activated carbon to be injected per unit time, for example, from the calculated powdered activated carbon injection rate and the flow rate measured by the flow meter 15, and control the powdered activated carbon injection device 21 so that the amount of powdered activated carbon injected is injected into the water to be treated in the receiving well 20.

[0072] Thereafter, the processes from step S102 to step S107 are repeated.

[0073] [Examples of setting and calculation processes] Next, an example of the detailed operation of the setting process and calculation process related to the powdered activated carbon injection control system of this embodiment will be described with reference to the flowchart in Figure 6B. However, the process of each step described below does not necessarily have to be performed in the order shown in Figure 6B, and the order of the steps may be changed as appropriate.

[0074] In step S1, the treated water quality target setting device 100 sets various target values as target values for the tap water quality after water treatment.

[0075] Here, as examples of target odorant concentrations for various odorants, the target odorant concentrations C for "dimethylisoborneol," "geosmin," "2,4-decadienal," etc., which are assumed to be contained in raw water, are shown. 2-MIB ,C Geosmin ,C D ... are set, and the target ultraviolet absorbance UV is an example of the target soluble organic matter index value. D The target turbidity Tu D and target pH D is also set.

[0076] Set target odorant concentration C 2-MIB ,C Geosmin ,C D , target UV absorbance UV D , and target pH D The data of each of these is input to the powdered activated carbon injection control device 200, while the set target turbidity Tu D The data is input into the coagulant injection control device 300.

[0077] In the following explanation, to make the explanation easier to understand, a calculation example will be shown for "dimethylisoborneol" out of the various odorous substances "dimethylisoborneol," "geosmin," "2,4-decadienal," etc.

[0078] In step S2, a target odorant remaining rate, which is a target value of the odorant remaining rate, is calculated in the powdered activated carbon injection control device 200. Here, as an example, the target odorant remaining rate RC of dimethylisoborneol is calculated. 2-MIB An example where is calculated is shown below.

[0079] The powdered activated carbon injection control device 200 detects the target odorous substance concentration C of dimethylisoborneol set by the treated water quality target setting device 100. 2-MIB and the odorant concentration C of the raw water measured by the odorant concentration measuring device 13 R Therefore, the target odorous substance residual rate RC of dimethylisoborneol is 2-MIB is calculated using the following formula:

[0080] RC 2-MIB = C 2-MIB / C R ···(4)

[0081] In step S3, the powdered activated carbon injection control device 200 calculates an odorant-specific powdered activated carbon injection rate, which is the powdered activated carbon injection rate that achieves the target odorant residual rate calculated in step S2. Here, as an example, the odorant-specific powdered activated carbon injection rate I corresponding to dimethylisoborneol is calculated. car-D An example where is calculated is shown below.

[0082] The powdered activated carbon injection control device 200 adjusts the concentration of dimethylisoborneol to the target odorant concentration C 2-MIB Powdered activated carbon injection rate for odor substances I car-D is calculated using the following formula:

[0083] I car-D = f(RC 2-MIB ,E260 R ,DOC R ,FL R ) ···(5)

[0084] E260 in the above formula R is the ultraviolet absorbance of the raw water. ROne example of an index that represents this is the ultraviolet absorbance (abs / m) of raw water at a wavelength of 260 (nm).

[0085] The adsorption of odorous substances by powdered activated carbon is affected by the inhibition of adsorption by coexisting organic matter. Therefore, the powdered activated carbon injection rate I car-D When calculating , it is desirable to perform a correction process to compensate for this influence. This will be explained below with reference to FIGS.

[0086] FIG. 7 is a graph showing the results of a test conducted by the inventors when dimethylisoborneol or geosmin was added to raw water from a certain water purification plant and the same powdered activated carbon injection treatment was carried out.

[0087] The graph in Figure 7 shows the typical powdered activated carbon injection rate I car The graph shows the relationship between the amount of adsorption (mg / L) and the odorant residual rate RC (%) of each odorant. This graph shows that even when the same raw water and the same powdered activated carbon are used, the adsorption characteristics differ depending on the type of odorant.

[0088] Figure 8 is a graph showing the test results when dimethylisoborneol and various ratios of humic acid and fulvic acid were added to pure water and then powdered activated carbon was injected. Figure 9 is a graph showing the test results when geosmin and various ratios of humic acid and fulvic acid were added to pure water and then powdered activated carbon was injected.

[0089] 8 and 9 show the powdered activated carbon injection rate I car (mg / L) and dimethylisoborneol odorant residual rate RC 2-MIB (%) or Geosmin odorant residual rate RC Geosmin The graphs show a relationship with the TOC content (%). All test results are from a total addition concentration of approximately 3.0 mg / L, with rapid stirring in a jar tester at 150 rpm for 60 minutes. As can be seen from these graphs, the adsorption of odorous substances by powdered activated carbon is affected differently by the structure of the coexisting organic matter (humic acid / fulvic acid ratio).

[0090] Therefore, the odorant-specific powdered activated carbon injection rate I car-D In calculating this, the dissolved organic matter index (e.g., ultraviolet absorbance E260 R ), soluble organic carbon concentration DOC R , fluorescence intensity FL R It is desirable to take into consideration the ratio of etc. Furthermore, since the influence of coexisting organic matter differs depending on the target odorant, by including a correction coefficient for each of the multiple types of odorant in the function of equation (5), it becomes possible to calculate the appropriate powdered activated carbon injection rate corresponding to the odorant estimated by the odorant estimation device 12.

[0091] In step S4, the target soluble organic substance residual rate, which is a target value of the residual rate of soluble organic substances, is calculated in the powdered activated carbon injection control device 200. Here, the target ultraviolet absorbance residual rate RUV is calculated by using ultraviolet absorbance as an example of the soluble organic substance index value. T An example where is calculated is shown below.

[0092] The powdered activated carbon injection control device 200 controls the target ultraviolet absorbance UV D and the ultraviolet absorbance UV of the raw water measured by the ultraviolet spectrophotometer 14a. R Therefore, the target UV absorbance remaining rate RUV T is calculated using the following formula:

[0093] RUV T = UV D / UV R ···(6)

[0094] In step S5, the coagulant injection control device 300 calculates the target turbidity Tu D Coagulant injection rate to achieve I pacl is calculated.

[0095] The coagulant injection control device 300 controls the target turbidity Tu set by the treated water quality target setting device 100. Dand the raw water turbidity Tu measured by the turbidity meter 10a, alkalinity meter 10b, water temperature meter 10c, and hydrogen ion concentration index meter 10d in the water quality meter set 10. R , raw water alkalinity Alk R , water temperature T R , and hydrogen ion concentration exponent pH R , and the pH of the mixing basin measured by the pH measuring instrument 16 installed in the coagulant mixing basin 30. F Using this, the target turbidity Tu D Coagulant injection rate to achieve I pacl Calculate.

[0096] I pacl = f(Tu D ,Tu R ,Alk R ,T R ,pH R ,pH F ) ···(7)

[0097] In step S6, the coagulant injection control device 300 calculates the coagulant injection rate I pacl The coagulant injector 31 is controlled so that the coagulant is injected into the water to be treated in the coagulant mixing basin 30 in accordance with the above.

[0098] In step S7, the powdered activated carbon injection control device 200 calculates the residual rate of soluble organic matter after coagulation treatment, which is the residual rate of soluble organic matter remaining after coagulation treatment. Here, as an example, the residual rate of ultraviolet absorbance after coagulation treatment RUV pacl An example where is calculated is shown below.

[0099] The powdered activated carbon injection control device 200 controls the coagulant injection rate I pacl The residual rate of soluble organic matter remaining after coagulation treatment by UV absorbance after coagulation treatment was measured. pacl Calculate as follows.

[0100] The removal of soluble organic matter by coagulation treatment is also affected by the structure of the organic matter. Therefore, the residual UV absorbance (RUV) after coagulation treatment is paclWhen calculating , it is desirable to perform a correction process to compensate for the influence. This will be explained below with reference to FIG.

[0101] FIG. 10 shows the dissolved organic carbon concentration (DOC) of the raw water. R =2.5(mg / L), pH of miscible water F This graph shows the test results when a coagulant was added to the water to be treated, which had been adjusted to a pH of 6.5, and then the water was rapidly stirred at 150 rpm for 10 minutes, and then slowly stirred at 80 rpm for 60 minutes.

[0102] In this test, humic acid and fulvic acid were added as dissolved organic matter at different mixing ratios. pacl (mg / L) and residual UV absorbance (RUV) after coagulation treatment pacl The relationship between the residual UV absorbance after coagulation treatment (RUV) and the residual UV absorbance after coagulation treatment (RUV) is shown on the vertical axis. pacl is the ultraviolet absorbance after the coagulation treatment. pacl The ultraviolet absorbance of the raw water R The values shown are those divided by .

[0103] Figure 10 shows the results for 100% humic acid, a 50% humic acid / 50% fulvic acid mixture, and 100% fulvic acid, and it was found that the fulvic acid mixture ratio affects the performance of the coagulation treatment to remove dissolved organic matter.

[0104] Therefore, the powdered activated carbon injection control device 200 is configured to calculate the residual ultraviolet absorbance RUV after the coagulation treatment. pacl is calculated using the following equation using the relationship in FIG.

[0105] RUV pacl = α × I pacl + β (8)

[0106] β = f(pH F ,UV R ,DOC R ,FL R ) ···(9)

[0107] where I pacl is the coagulant injection rate (mg / L), α is the injection rate constant (-), and β is the I pacl =0 (mg / L).

[0108] β is the pH of the mixing pool F , ultraviolet absorbance UV R (abs / cm) (Here, for example, the ultraviolet absorbance E260 of the raw water at a wavelength of 260 (nm) R ), soluble organic carbon concentration DOC R (mg / L), and the fluorescence intensity of the raw water FL R (Here, for example, the fluorescence intensity at a fluorescence wavelength of 425 (nm) relative to an excitation wavelength of 345 (nm) is used for calculation.)

[0109] In step S8, the powdered activated carbon injection control device 200 calculates the residual rate of soluble organic substances after adsorption treatment, which is the rate of soluble organic substances remaining after adsorption treatment. Here, the residual rate of ultraviolet absorbance after adsorption treatment RUV is calculated using ultraviolet absorbance as an example of the soluble organic substance index value. car An example where is calculated is shown below.

[0110] After this adsorption treatment, the residual UV absorbance RUV car is the percentage of soluble organic matter remaining after adsorption treatment when powdered activated carbon treatment is performed alone, and is different from the percentage of soluble organic matter remaining after adsorption treatment when powdered activated carbon treatment is performed in combination with coagulation treatment. This will be explained below.

[0111] The ultraviolet absorbance after combined treatment with powdered activated carbon and coagulation treatment is shown in Figure 1. car / pacl After this combined treatment, the ultraviolet absorbance RUV car / pacl The residual UV absorbance rate (RUV) after adsorption treatment car , UV absorbance after aggregation treatment RUV pacl , and the combined treatment factor F DOM is defined as follows:

[0112] RUV car / pacl = F DOM × RUV car × RUV pacl ···(10)

[0113] F DOM is a coefficient that indicates the effect of combined treatment (combined treatment coefficient), and is the residual UV absorbance rate RUV after combined treatment car / pacl The residual UV transmittance RUV after adsorption treatment when adsorption treatment is performed alone car and residual UV transmittance RUV after coagulation treatment when coagulation treatment is performed alone pacl It is obtained by dividing by the product of and.

[0114] Here, the combined treatment coefficient F DOM The results of the inventors' tests on

[0115] FIG. 11 is a graph showing the test results when the powdered activated carbon treatment was performed by rapid stirring at 150 rpm for 60 minutes, the pH was adjusted to a predetermined value, a flocculant was added, and the treatment was rapidly stirred at 150 rpm for 10 minutes, and then slowly stirred at 80 rpm for 60 minutes.

[0116] As shown in Figure 11, the combined treatment coefficient F DOM varies greatly depending on the mixing ratio of humic acid and fulvic acid in the organic matter added. When there is a lot of humic acid, the residual ultraviolet absorbance RUV after combined treatment car / pacl The value obtained by multiplying the residual UV absorbance rate after adsorption treatment by the residual UV absorbance rate after coagulation treatment (RUV car ×RUV pacl ) is smaller than (F DOM <1), and there is an accelerating effect of combined treatment. On the other hand, as the proportion of fulvic acid increases, the residual ultraviolet absorbance (RUV) after combined treatment decreases. car / pacl The value obtained by multiplying the residual UV absorbance rate after adsorption treatment by the residual UV absorbance rate after coagulation treatment (RUV car ×RUV pacl ) is larger than (F DOM ≧1), indicating that the combined treatment had an inhibitory effect.

[0117] In Figure 11, the combined treatment coefficient F DOM and coagulant injection rate I pacl By approximating the relationship with the following equation, the coefficient f and exponent n that differ for each mixture ratio can be obtained.

[0118] F DOM = f × I pacl n ···(11)

[0119] Therefore, we investigated the relationship between the specific absorbance SUVA, defined by the following equation as an index that approximates the mixing ratio of humic acid and fulvic acid in the dissolved organic matter contained in raw water, and the coefficient f, and obtained the results shown in Figure 12.

[0120] SUVA = E260 R / DOC R (abs·L / m·mg) ···(12)

[0121] Here, E260 R is the ultraviolet absorbance (abs / m) of the raw water at a wavelength of 260 (nm), and DOC R is the dissolved organic carbon concentration in the raw water (mg / L).

[0122] The graph in Figure 12 shows the relationship between the specific absorbance SUVA (abs L / m mg) and the coefficient f. This graph shows that the coefficient f can be expressed as a function of the specific absorbance SUVA.

[0123] Therefore, in step S8, the powdered activated carbon injection control device 200 calculates the target ultraviolet absorbance remaining rate RUV by the following formula: T After combined treatment, the residual UV absorbance RUV car / pacl As the residual UV absorbance after adsorption treatment, RUV car Ask for.

[0124] RUV T = RUV car / pacl = F DOM × RUV car × RUV pacl···(13)

[0125] RUV car = RUV T / (F DOM × RUV pacl ) ···(14)

[0126] In step S9, the powdered activated carbon injection control device 200 calculates the soluble organic substance-specific powdered activated carbon injection rate, which is the powdered activated carbon injection rate that achieves the soluble organic substance remaining rate after the adsorption treatment calculated in step S8. Here, the soluble organic substance-specific powdered activated carbon injection rate I is calculated using ultraviolet absorbance as an example of the soluble organic substance index value. car-UV An example where is calculated is shown below.

[0127] The powdered activated carbon injection control device 200 is configured to control the soluble organic substance-compatible powdered activated carbon injection rate I car-UV is calculated using the following formula:

[0128] I car-UV = f(K UV ,RUV car ,E260 R ,DOC R ) ···(15)

[0129] where K UV is an adsorption constant determined by the performance of the powdered activated carbon and the properties of the substance to be adsorbed, and is a value that is determined and set in advance.

[0130] In step S10, the powdered activated carbon injection control device 200 calculates the odorant-specific powdered activated carbon injection rate I car-D and the soluble organic matter powder activated carbon injection rate I calculated in step S9. car-UV The larger one is the powdered activated carbon injection rate I car Adopted as.

[0131] Powdered activated carbon injection rate for soluble organic substances I car-UV is larger, in steps S11A and S12, the soluble organic matter compatible powdered activated carbon injection rate I car-UVis the powdered activated carbon injection rate I car This powdered activated carbon injection rate I car The powdered activated carbon injector 21 is controlled so that the powdered activated carbon is injected into the water to be treated in the receiving well 20 in accordance with the above.

[0132] On the other hand, the odor-resistant powder activated carbon injection rate I car-D is larger, in steps S11B and S12, the odorant-specific powdered activated carbon injection rate I car-D is the powdered activated carbon injection rate I car This powdered activated carbon injection rate I car The powdered activated carbon injector 21 is controlled so that the powdered activated carbon is injected into the water to be treated in the receiving well 20 in accordance with the above.

[0133] According to the first embodiment, the type of odorous substance to be removed by powdered activated carbon can be identified and the concentration of that odorous substance can be determined using the algae detection and determination device 11, the odorous substance estimation device 12, and the odorous substance concentration measurement device 13, so that the optimal powdered activated carbon injection rate for achieving the target concentration can be determined based on the concentration of the odorous substance in the powdered activated carbon injection control device 200. Furthermore, by setting concentration target values for various expected odorous substances in advance, it is possible to flexibly respond even when the algae living in the raw water change and the odorous substances generated change, and it is possible to determine the optimal injection rate of powdered activated carbon according to changes in the water quality of the raw water, which reduces unnecessary injection of powdered activated carbon and realizes economical water treatment control.

[0134] Furthermore, according to the first embodiment, by injecting powdered activated carbon while taking into consideration the combined effect of powdered activated carbon and coagulant on the removal of soluble organic substances and odorous substances, it is possible to significantly reduce the amount of powdered activated carbon that was previously required and to appropriately and precisely control the powdered activated carbon injection rate. As a result, it is possible to prevent the soluble organic substance concentration and odorous substance residual rate in the filtered water from exceeding the target due to insufficient injection of powdered activated carbon, and to prevent waste of chemical costs due to excessive injection.

[0135] In the first embodiment, the residual rate RUV of ultraviolet absorbance E260 at a wavelength of 260 (nm) was used as a representative index of soluble organic matter, but by using the soluble organic carbon concentration DOC or the fluorescence intensity FL at a fluorescence wavelength of 425 (nm) for an excitation wavelength of 345 (nm) in the calculation formula, it is possible to generally respond to variations in raw water and different water sources.

[0136] In the first embodiment, an example was shown in which the soluble organic substances in the raw water were monitored using three types of instruments: an ultraviolet absorptiometer 14a, a fluorescence intensity meter 14b, and a dissolved organic carbon concentration meter (DOC meter) 14c. However, if there is little fluctuation in the organic matter composition of the raw water in a single raw water system, one representative instrument may be used to determine the other indicators using conversion formulas. Below is an example of a conversion formula when an ultraviolet absorptiometer is used as the representative instrument.

[0137] DOC R = a × UV R × b ···(16)

[0138] FL R = c × UV R × d ···(17)

[0139] where: DOC R : Dissolved organic carbon concentration in raw water (mg / L) FL R : Fluorescence intensity of raw water (-) UV R : UV absorbance of raw water (abs / cm) a: Conversion coefficient between UV absorbance and dissolved organic carbon concentration b: Conversion constant between UV absorbance and dissolved organic carbon concentration c: Conversion coefficient of UV absorbance to fluorescence intensity d: UV absorbance-fluorescence intensity conversion constant By using this conversion formula, even when only one meter is installed, it is possible to obtain the same effect as when soluble organic matter in raw water is monitored using three types of meters.

[0140] <Second embodiment> Next, a second embodiment will be described, in which explanations of parts common to the first embodiment will be omitted and differences will be mainly described.

[0141] The configuration of the water treatment system is the same as that shown in Fig. 1. However, as will be explained below, the configuration relating to the odor sensor in the odorant concentration measuring device 13 is different.

[0142] Fig. 13 is a diagram showing an example of the configuration of an odorant concentration measuring device 13 in the second embodiment. In Fig. 13, elements common to those in Fig. 4 are given the same reference numerals.

[0143] In the first embodiment described above, the odor substance concentration measuring device 13 in Figure 4 is provided with one type of odor sensor, but in this second embodiment, multiple types of sensors are provided, for example, an odor sensor that reacts to mold odor substances generated from algae, and an odor sensor that does not react to mold odor substances but reacts to oily odors.

[0144] In the example of FIG. 13, the odorant concentration measuring device 13 is provided with a plurality of odor sensors 13d-1, 13d-2, and 13d-3.

[0145] Odor sensors 13d-1, 13d-2, and 13d-3 each have a different target substance to detect. For example, odor sensor 13d-1 is a sensor designed to selectively detect dimethylisoborneol, odor sensor 13d-2 is a sensor designed to selectively detect geosmin, and odor sensor 13d-3 is a sensor configured to selectively detect oily odors but not to react to mold-smelling substances.

[0146] According to the second embodiment, by installing a sensor optimally designed for the odorant to be detected, even if the type of odorant contained in the raw water changes, the optimal sensor is selected based on the estimation results by the odorant estimation device 12, making it possible to measure the concentration with high sensitivity. Furthermore, by installing at least one sensor that selectively detects the odor of oil among multiple sensors, it becomes possible to immediately issue an alarm in the event of an oil spill into the water source, and also to make it possible to urgently inject powdered activated carbon as necessary, thereby significantly improving the ability to respond to pollutants in the raw water.

[0147] <Third embodiment> Next, a third embodiment will be described. Here, the description of the parts common to the first embodiment will be omitted, and the description will focus on the parts that are different.

[0148] [composition] Fig. 14 is a diagram showing an example of the configuration of a water treatment system according to the third embodiment. In Fig. 14, elements common to those in Fig. 1 are denoted by the same reference numerals.

[0149] In the water treatment system of the third embodiment, the powdered activated carbon injection device is configured in two stages instead of one, with the first stage powdered activated carbon injection device 21a installed to inject powdered activated carbon into the receiving well 20, and the second stage powdered activated carbon injection device 21b installed to inject powdered activated carbon into the flocculant mixing basin 30. Another difference from the first embodiment is that the odorant concentration measuring device 13 is installed not in the piping 2 but in the piping 3 leading from the receiving well 20 to the flocculant mixing basin 30. Therefore, the odorant concentration measuring device 13 measures the concentration of odorants contained in the test water collected from the piping leading from the receiving well 20 to the flocculant mixing basin 30, i.e., the concentration of odorants contained in the treated water after the powdered activated carbon injection treatment. Accordingly, the functions and operations of the powdered activated carbon injection control device 200 differ in some respects from those of the first embodiment.

[0150] The powdered activated carbon injection control device 200 of the third embodiment uses the soluble organic substance index value (at least one of ultraviolet absorbance, fluorescence intensity, and soluble organic carbon concentration) measured by the soluble organic substance index measurement set 14 to calculate the soluble organic substance-specific powdered activated carbon injection rate required to bring the soluble organic substance residual rate in the water being treated in the receiving well 20 to a target residual rate, and controls the amount of powdered activated carbon to be injected into the water being treated in the receiving well 20 according to this soluble organic substance-specific powdered activated carbon injection rate, and also has the function of controlling the amount of powdered activated carbon to be injected into the water being treated in the coagulant mixing basin 30 according to the odorous substance-specific powdered activated carbon injection rate required to bring the concentration of odorous substances contained in the water being treated in the receiving well 20 to a target concentration.

[0151] Furthermore, the powdered activated carbon injection control device 200 of the third embodiment has a function of controlling the odorant-specific powdered activated carbon injection rate so that it is greater than a predetermined reference value when the odorant concentration measured by the odorant concentration measuring device 13 is greater than a target concentration, and on the other hand, controlling (feedback control) the odorant-specific powdered activated carbon injection rate so that it is less than the predetermined reference value when the odorant concentration measured by the odorant concentration measuring device 13 is less than the target concentration.

[0152] [Operation Overview] Next, an example of the operation of the powdered activated carbon injection control system of the third embodiment will be described with reference to the flowchart in Figure 15A. However, the processing of each step described below does not necessarily have to be performed in the order shown in Figure 15A, and the order of execution may be changed as appropriate. The following description will focus on the parts that are different from Figure 6A.

[0153] The process in step S101 is the same as the process described in FIG. 6A.

[0154] The process of step S102' differs from the process of step S102 described in FIG. 6A in that the concentration of odorous substances in the raw water is not measured.

[0155] In step S201, the odorant concentration measuring device 13 measures the concentration of odorants contained in the treated water after the powdered activated carbon injection treatment, for the types of odorants estimated by the odorant estimation device 12.

[0156] The processes in steps S104 and S105 are the same as those described in FIG. 6A.

[0157] The processes in steps S106' and S107' are different from the processes in steps S106 and S107 described with reference to FIG. 6A.

[0158] In step S106', the powdered activated carbon injection control device 200 calculates an odorant-specific powdered activated carbon injection rate for achieving a target odorant concentration using the odorant concentration measured by the odorant concentration measuring device 13, and also calculates a soluble organic substance-specific powdered activated carbon injection rate for achieving a target soluble organic substance index value using the soluble organic substance index value measured by the soluble organic substance index meter set 14, but the details of the process at this time are different from step S106 described in Fig. 6A. The details of this process will be described later in the flowchart of Fig. 15B.

[0159] In step S107', the powdered activated carbon injection control device 200 controls the amount of powdered activated carbon to be injected into the water to be treated in the receiving well 20 according to the calculated soluble organic substance-compatible powdered activated carbon injection rate, and also controls the amount of powdered activated carbon to be injected into the water to be treated in the coagulant mixing basin 30 according to the calculated odorous substance-compatible powdered activated carbon injection rate.

[0160] Thereafter, the processes from step S102' to step S107' are repeated.

[0161] [Examples of setting and calculation processes] Next, an example of the detailed operation of the setting process and calculation process related to the powdered activated carbon injection control system of this embodiment will be described with reference to the flowchart in Figure 15B. However, the process of each step described below does not necessarily have to be performed in the order shown in Figure 15B, and the order of execution may be changed as appropriate. The following description will focus on the differences from FIG. 6B.

[0162] The process in step S1 is the same as the process described in FIG. 6B.

[0163] The process of step S2 is the same as the process described in FIG. 6B, but the odorant concentration C R However, this differs from the process described in FIG. 6B in that it is the concentration of odorous substances contained in treated water after powdered activated carbon injection treatment, rather than the concentration of odorous substances contained in raw water.

[0164] The processes of steps S2 and S3' are different from the processes of steps S2 and S3 described in FIG. 6B, and are performed after the processes of steps S4 to S9, for example.

[0165] In step S9, the powdered activated carbon injection control device 200 determines the soluble organic substance-specific powdered activated carbon injection rate I car-UV In step S12a, the soluble organic substance-compatible powdered activated carbon injection rate I car-UV Next, in step S2, the powdered activated carbon injector 21a is controlled so that the powdered activated carbon is injected into the water to be treated in the receiving well 20 according to the target odorant concentration C of dimethylisoborneol set by the treated water quality target setting device 100. 2-MIB and the odorant concentration C of the raw water measured by the odorant concentration measuring device 13 R Therefore, the target odorous substance residual rate RC of dimethylisoborneol is 2-MIB is calculated using the following formula:

[0166] RC 2-MIB = C 2-MIB / C R ···(18)

[0167] Next, in step S3′, dimethylisoborneol is added to the target odorant concentration C 2-MIB Powdered activated carbon injection rate for odor substances I car-D is calculated using the following formula:

[0168] I car-D = f(RC 2-MIB ) ···(19)

[0169] Next, in step S12b, the odorant-specific powdered activated carbon injection rate C R In accordance with this, the powdered activated carbon injector 21b is controlled so that the powdered activated carbon is injected into the water to be treated in the flocculant mixing basin 30.

[0170] According to the third embodiment, the powdered activated carbon injection control device 200 controls the soluble organic substance-specific powdered activated carbon injection rate I car-UV In addition to controlling the powdered activated carbon injector 21a so that powdered activated carbon is injected into the water to be treated in the receiving well 20 according to the above, the concentration C of odorous substances contained in the treated water after the powdered activated carbon injection treatment is R Odor-specific powdered activated carbon injection rate I calculated using car-D Therefore, even if the amount of powdered activated carbon injected by the powdered activated carbon injection device 21a is insufficient, the powdered activated carbon can be made up for by the powdered activated carbon injection device 21b, which can compensate for the adsorption inhibition caused by coexisting organic matter, eliminate errors due to prediction of the inhibition effect in advance, and prevent over- or under-injection of powdered activated carbon.

[0171] As described above in detail, according to each embodiment, the injection rate of powdered activated carbon can be optimized.

[0172] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0173] 1...water treatment facility, 2, 3, 4...piping, 10...water quality meter set, 10a...turbidity meter, 10b...alkalinity meter, 10c...water thermometer, 10d...hydrogen ion concentration index meter, 11...algae detection and determination device, 11a...flow cell, 11b...lighting, 11c...camera, 11f...calculator, 11g...display device, 12...odor substance estimation device, 13...odor substance concentration measurement device, 13a...odor substance extraction tank, 13a-1...overflow tray, 13a-2...raw water inlet pipe, 13a-3...heater, 13a-4...air supply Fan, 13b...dehumidifier, 13c...odor sensor cell, 13d...odor sensor head (odor sensor), 13f...odor substance concentration calculation device, 16...hydrogen ion concentration index meter (pH meter), 20...receiving well, 21, 21a, 21b...powdered activated carbon injection device, 30...coagulant mixing basin, 30a...agitator, 31...coagulant injection device, 32...oxidant injection device, 40...coagulation and sedimentation basin, 100...treated water quality target setting device, 200...powdered activated carbon injection control device, 300...coagulant injection control device.

Claims

1. an algae detection and determination means for detecting algae contained in raw water and determining the type of the algae; an odor substance estimation means for estimating the type of odor substance emitted by the algae based on the type of algae determined by the algae detection and determination means; an odorant concentration measuring means for measuring the concentration of odorants contained in the raw water or treated water after powdered activated carbon injection treatment, targeting the type of odorant estimated by the odorant estimation means; a powdered activated carbon injection control means for calculating an odorant-specific powdered activated carbon injection rate for adjusting the odorant concentration contained in the water to be treated in the receiving well to a target concentration using at least the concentration of the odorant measured by the odorant concentration measurement means, and for controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well or the water to be treated in the coagulant mixing basin based on the odorant-specific powdered activated carbon injection rate; a soluble organic matter index measuring means for measuring at least one of ultraviolet absorbance, fluorescent intensity, and soluble organic carbon concentration of the raw water as a soluble organic matter index value; Equipped with The powdered activated carbon injection control means calculating a soluble organic matter-specific powdered activated carbon injection rate for adjusting the soluble organic matter residual rate of the water to a target residual rate using the soluble organic matter index value measured by the soluble organic matter index measuring means; the soluble organic substance-specific powdered activated carbon injection rate and the odorous substance-specific powdered activated carbon injection rate are compared, the larger of the two is set as the powdered activated carbon injection rate, and the amount of powdered activated carbon to be injected into the water to be treated in the receiving well is controlled according to the powdered activated carbon injection rate; Powdered activated carbon injection control system.

2. The odor substance estimation means includes: The apparatus has information indicating the relationship between various types of algae and the odorous substances produced by these algae, and estimates the type of odorous substance contained in the raw water from the type of algae determined by the algae detection and determination means based on the information.

10. The powdered activated carbon injection control system of claim 1.

3. The odorant concentration measuring means is The odor substance concentration measuring means has information indicating the relationship between the output change of the odor sensor and the odor substance concentration for each type of odor substance, and the concentration is determined from the output change measured by the odor sensor based on the information corresponding to the type of odor substance estimated by the odor substance estimation means.

3. The powdered activated carbon injection control system according to claim 1 or 2.

4. The odorant concentration measuring means is The system includes an odor sensor that reacts to mold-smelling substances generated from algae, and an odor sensor that does not react to the mold-smelling substances but reacts to oily odors.

4. The powdered activated carbon injection control system of claim 1.

5. The odorant concentration measuring means is measuring the concentration of odorous substances contained in the raw water; The powdered activated carbon injection control means When the concentration of the odorant measured by the odorant concentration measuring means is higher than a target concentration, the odorant-specific powdered activated carbon injection rate is controlled to be higher than a predetermined reference value, and when the concentration of the odorant measured by the odorant concentration measuring means is lower than the target concentration, the odorant-specific powdered activated carbon injection rate is controlled to be lower than a predetermined reference value.

5. The powdered activated carbon injection control system of claim 1.

6. The powdered activated carbon injection control means Calculating the odorant-specific powdered activated carbon injection rate so as to compensate for the influence of dissolved organic substances that inhibit the adsorption of odorants by the powdered activated carbon.

6. The powdered activated carbon injection control system of claim 1.

7. The powdered activated carbon injection control means Calculate the soluble organic substance-adapted powdered activated carbon injection rate so as to compensate for the influence of soluble organic substances that inhibit the adsorption of odorous substances by the powdered activated carbon when the powdered activated carbon injection treatment and the coagulant injection treatment are used in combination.

6. The powdered activated carbon injection control system of claim 1.

8. detecting algae contained in the raw water and determining the type of the algae by an algae detection and determination means; an odor substance estimation means for estimating the type of odor substance emitted by the algae from the determined type of algae; measuring the concentration of odorous substances contained in the raw water or the treated water after the powdered activated carbon injection treatment, for the type of odorous substance estimated by the odorous substance concentration measuring means; a powdered activated carbon injection control means for calculating an odorant-specific powdered activated carbon injection rate for adjusting the odorant concentration contained in the water to be treated in the receiving well to a target concentration using at least the measured odorant concentration, and controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well or the water to be treated in the coagulant mixing basin based on the odorant-specific powdered activated carbon injection rate; measuring at least one of ultraviolet absorbance, fluorescent intensity, and soluble organic carbon concentration of the raw water as a soluble organic matter index value using a soluble organic matter index measuring means; Including, Controlling the amount of powdered activated carbon injected a measurement result of at least one of the ultraviolet absorbance, the fluorescence intensity, and the soluble organic carbon concentration of the raw water as a soluble organic matter index value is taken in, and the soluble organic matter index value is used to calculate a soluble organic matter-specific powdered activated carbon injection rate for bringing the soluble organic matter residual rate of the water to be treated in the receiving well to a target residual rate; comparing the soluble organic substance-specific powdered activated carbon injection rate with the odorous substance-specific powdered activated carbon injection rate, determining the larger powdered activated carbon injection rate as the powdered activated carbon injection rate, and controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well according to the powdered activated carbon injection rate; Powdered activated carbon injection control method.

9. a powdered activated carbon injection control means for inputting the results of measuring the concentration of odorous substances contained in raw water or treated water after powdered activated carbon injection treatment, targeting types of odorous substances emitted by algae contained in the raw water, and calculating an odorous substance-specific powdered activated carbon injection rate using at least the odorous substance concentration to adjust the odorous substance concentration contained in the water to be treated in the receiving well to a target concentration, and controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well or the water to be treated in the coagulant mixing basin based on the odorous substance-specific powdered activated carbon injection rate; The powdered activated carbon injection control means a measurement result of at least one of the ultraviolet absorbance, the fluorescence intensity, and the soluble organic carbon concentration of the raw water as a soluble organic matter index value is taken in, and the soluble organic matter index value is used to calculate a soluble organic matter-specific powdered activated carbon injection rate for bringing the soluble organic matter residual rate of the water to be treated in the receiving well to a target residual rate; the soluble organic substance-specific powdered activated carbon injection rate and the odorous substance-specific powdered activated carbon injection rate are compared, the larger of the two is set as the powdered activated carbon injection rate, and the amount of powdered activated carbon to be injected into the water to be treated in the receiving well is controlled according to the powdered activated carbon injection rate; Powdered activated carbon injection control device.

10. The powdered activated carbon injection control means When the measured odorant concentration is greater than a target concentration, the odorant-specific powdered activated carbon injection rate is controlled to be greater than a predetermined reference value, and when the measured odorant concentration is less than the target concentration, the odorant-specific powdered activated carbon injection rate is controlled to be less than the predetermined reference value.

10. The powdered activated carbon injection control device of claim 9.

11. The powdered activated carbon injection control means Calculating the odorant-specific powdered activated carbon injection rate so as to compensate for the influence of dissolved organic substances that inhibit the adsorption of odorants by the powdered activated carbon. The powdered activated carbon injection control device according to claim 9 or 10.

12. The powdered activated carbon injection control means Calculate the soluble organic substance-adapted powdered activated carbon injection rate so as to compensate for the influence of soluble organic substances that inhibit the adsorption of odorous substances by the powdered activated carbon when the powdered activated carbon injection treatment and the coagulant injection treatment are used in combination. The powdered activated carbon injection control device according to claim 9 or 10.

13. On the computer, A function to take in the results of measuring the concentration of odorous substances contained in raw water or treated water after powdered activated carbon injection treatment, targeting the types of odorous substances emitted by algae contained in the raw water, and to calculate the odorous substance-specific powdered activated carbon injection rate using at least the odorous substance concentration to bring the concentration of odorous substances contained in the water in the receiving well to a target concentration; a function of controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well or the water to be treated in the coagulant mixing basin based on the odorous substance-specific powdered activated carbon injection rate; a function of measuring at least one of ultraviolet absorbance, fluorescence intensity, and dissolved organic carbon concentration of the raw water as a dissolved organic matter index value; A program for realizing the above, The function of controlling the injection amount of the powdered activated carbon is a measurement result of at least one of the ultraviolet absorbance, the fluorescence intensity, and the soluble organic carbon concentration of the raw water as a soluble organic matter index value is taken in, and the soluble organic matter index value is used to calculate a soluble organic matter-specific powdered activated carbon injection rate for bringing the soluble organic matter residual rate of the water to be treated in the receiving well to a target residual rate; comparing the soluble organic substance-specific powdered activated carbon injection rate with the odorous substance-specific powdered activated carbon injection rate, determining the larger powdered activated carbon injection rate as the powdered activated carbon injection rate, and controlling the amount of powdered activated carbon to be injected into the water to be treated in the receiving well according to the powdered activated carbon injection rate; program.

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