JP2005288309A - Water treatment method and water treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method and a water treatment system capable of performing injection of powdery activated carbon in proper quantities by measuring the concentration of a malodorous material in raw water and the concentration of coexisting soluble organic substances and determining the injection rate of powdery activated carbon necessary for removal of the malodorous material in consideration of influences of the coexisting soluble organic substances. <P>SOLUTION: The concentration of the malodorous material in the water to be treated and the concentration of the coexisting soluble organic substances are respectively measured by measuring devices 11, 13. In an arithmetic unit 7 for the injection of powdery activated carbon, coefficients which affect the residual rate of the malodorous material and the organic substances upon the injection of powdery activated carbon are respectively determined and, because the necessary injection rate of the powdery activated carbon is determined, the odor substances are effectively removed without being affected by the coexisting organic substances. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water treatment method and a water treatment system for injecting powdered activated carbon into water to be treated to remove soluble organic substances in the water to be treated.

  In recent years, the generation of algae and actinomycetes due to eutrophication of stagnant water areas such as dams, lakes, and reservoirs, which are tap water sources, and the generation of off-flavors due to proliferation have become a problem. There are many musty odors in tap water, and the causative substances are cyanobacteria, dimethylisoborneol derived from actinomycetes (hereinafter abbreviated as 2-MIB), geosmin, etc. In terms of water quality, both 2-MIB and geosmin are defined as 20 ng / L for powdered activated carbon treatment and 10 ng / L for permanent facilities such as granular activated carbon. However, in the revision of the tap water quality standard scheduled in 2004, 10 ng / L is scheduled to be adopted as a stricter regulation value even with the powdered activated carbon treatment.

  In water treatment plants, there are an increasing number of places where advanced treatment such as ozone treatment is introduced to remove off-flavors, but adsorption removal by powdered activated carbon is the mainstream in water treatment plants of medium scale or smaller.

  It is known that when mold odor substances are adsorbed and removed by powdered activated carbon, they may be affected by coexisting soluble organic substances, and the influence depends on the concentration and properties of the organic substances (for example, non-patent literature) 1).

  This soluble organic substance reacts with a chlorine agent that is injected for disinfection treatment, iron / manganese removal, and the like during the water purification process to produce trihalomethane. Since trihalomethane is a carcinogen, it is necessary to suppress its production.

  Powdered activated carbon is also injected to remove soluble organic substances that are precursors of trihalomethanes. Therefore, in order to estimate the optimum powder activated carbon injection rate for removing mold odor substances and soluble organic substances at the same time, the concentration of mold odor substances and soluble organic substances in raw water are measured at the same time. It is necessary to determine the powder activated carbon injection rate in consideration of the effect of soluble organic substances on odor removal.

  As a method for controlling the powder activated carbon injection rate, for example, a odorous substance to be removed, trihalomethane or a pesticide is detected by a special sensor and feedback control is performed (for example, see Patent Document 1), an odorous substance, an anion. There is a method of controlling the injection rate of powdered activated carbon and a flocculant based on the measurement results of the activator, trihalomethane, chromaticity and metal ion concentration (for example, see Patent Document 2).

  Such a conventional powder activated carbon injection control system will be described. In general, in a water purification facility, raw water pumped up from a water intake is led to a sand basin through a water conduit, where large impurities are removed. The raw water then enters the coagulation / sedimentation basin from the landing well. In the coagulation / sedimentation basin, the coagulant is injected at the inlet, and suspended substances such as clay, bacteria, and algae in the raw water are aggregated and separated as floc. Furthermore, the suspended matter remaining in the filter basin is removed.

  A water quality measuring instrument is connected to the water conduit, and the odor substance concentration is measured. The measured value enters the powdered activated carbon injection calculation device, and the powdered activated carbon injection rate is calculated from the odor substance concentration. In addition, a flow rate measuring device is also provided in the water conduit, and the raw water flow rate is measured. This measured value enters the powdered activated carbon injection device together with the powdered activated carbon injection calculation value, where the powdered activated carbon injection amount corresponding to the raw water flow rate is calculated, and the powdered activated carbon is injected into the sand basin.

In this example, an odor substance is described as an example of the substance measured by the water quality measuring instrument, but there are an anionic surfactant, trihalomethane, chromaticity, and metal ion concentration. In some cases, a water quality measuring instrument is attached to the inlet piping section of the subsequent agglomeration / sedimentation basin, the residual concentration of the substance to be treated is measured, and the powder activated carbon injection rate is feedback controlled.
Japanese Patent Laid-Open No. 5-10941 JP-A-8-309109 D.Cook, G. Newcombe and P. Sztajnbox, "The Application of Powdered Activated Carbon for MIB and Geosmin Removal: Predicting PAC Dose in Four Raw Waters,", Water Research, vol. 35, No. 5, pp. 1325- 1333 (2001)

  The conventional powder activated carbon injection control system described above has the following problems.

  In the conventional system, since the injection rate is determined based on the concentration of the substance to be treated by the powdered activated carbon, there may be a mutual influence when a plurality of substances to be treated coexist. In particular, the removal performance of odorous substances is greatly affected by the coexisting soluble organic substances, so if the powdered activated carbon injection rate is determined based on the treatment of odorous substances alone, the injection rate is insufficient. was there.

  In addition, when measuring the target substance after powdered activated carbon treatment and performing feedback control, the residence time from the powdered activated carbon injection point to the agglomeration / sedimentation basin usually takes about 15 to 60 minutes. It was not possible to cope with the sudden water quality change due to the above, and the powder activated carbon injection rate was excessive or insufficient.

  If the activated carbon powder injection rate is excessive, not only will the treatment cost increase due to the waste activated carbon powder being injected, but the increase in the injection rate of the flocculant injected in the coagulation / sedimentation basin and the processing cost due to the increased sludge treatment cost To increase. Moreover, when the powder activated carbon injection rate is insufficient, the water quality treatment target cannot be achieved.

  The object of the present invention is to measure the concentration of odorous substances in the raw water and the concentration of soluble organic substances that coexist, and determine the powder activated carbon injection rate necessary for the removal of odorous substances in consideration of the influence of coexisting soluble organic substances. Accordingly, an object of the present invention is to provide a water treatment method and a water treatment system that can perform powdered activated carbon injection without excess or deficiency.

  The water treatment method of the present invention is a water treatment method for injecting powdered activated carbon into the water to be treated to remove soluble organic substances in the water to be treated, which is an organic substance coexisting with the concentration of odorous substances in the water to be treated. Concentrations are measured respectively, and coefficients that affect the residual ratio of these odorous substances and organic substances with the powdered activated carbon injection are obtained based on the measured odorous substance concentration and organic substance concentration, respectively, and obtained in advance. The injection rate of the powdered activated carbon necessary to achieve the target removal rate of odorous substances is obtained as a function of each coefficient and residence time.

  In the method of the present invention, in measuring the concentration of the organic substance, the fluorescence intensity of the water to be treated may be measured, and the organic substance concentration may be obtained from the correlation between the fluorescence intensity and the organic substance concentration.

  In the water treatment method of the present invention, the concentration target value of the treated odor substance and the concentration target value of the coexisting organic substance are set, and the fluorescence intensity corresponding to the organic substance concentration target value is set as the processed fluorescence intensity target. Obtained from the correlation as a value, measure the fluorescence intensity of the water to be treated, and from the difference between the measured fluorescence intensity and the target value of the treatment fluorescence intensity, the first injection rate of powdered activated carbon necessary for organic substance removal is determined Obtaining and measuring the concentration of odorous substances in the treated water, obtaining the concentration of organic substances coexisting by correlation from the measured fluorescence intensity of the treated water, and injecting the powdered activated carbon of these odorous substances and organic substances Necessary to achieve the target removal rate of odorous substances determined in advance based on the measured odorous substance concentration and organic substance concentration, respectively. The second injection rate of the powdered activated carbon is obtained as a function of the coefficients and the residence time, and the maximum value among the first injection rate and the second injection rate is used as the powdered activated carbon injection rate for the water to be treated. You may decide.

  Further, in the method of the present invention, the concentration of the odorous substance and the fluorescence intensity in the treated water after the powdered activated carbon injection are measured, respectively, the concentration target value of the odorous substance after the treatment and the fluorescence intensity target value after the treatment, A difference between the measured value of the odorous substance of the treated water and the measured value of the fluorescence intensity may be obtained, and a correction value for the powder activated carbon injection rate may be obtained based on the larger value of these differences.

  The water treatment system of the present invention includes an odor substance concentration measuring device and an organic substance concentration measuring device for measuring the concentration of an odorous substance in the water to be treated and the concentration of the organic substance, and the concentration measurement value of these odorous substances and the organic substance. The concentration measurement values of these odorous substances and organic substances are input, and the coefficients that affect the residual ratio of these odorous substances and organic substances accompanying the powder activated carbon injection are determined based on the odorous substance concentration measurement values and the organic substance concentration measurement values. Coefficient calculation means for obtaining each, and injection rate calculation means for obtaining the injection rate of the powdered activated carbon necessary for achieving the target removal rate of odorous substances determined in advance as a function of the calculated coefficients and residence time. It is characterized by that.

  Further, in the system of the present invention, as an organic substance concentration measuring device, a fluorescence analyzer for measuring the fluorescence intensity of the water to be treated, and the concentration of odorous substances in the water to be treated, the fluorescence intensity and the organic Organic substance concentration calculating means for obtaining the organic substance concentration from the correlation with the substance concentration may be provided.

  In the water treatment system of the present invention, the concentration target value of the odorous substance of the treated water after the activated carbon injection treatment and the concentration target value of the coexisting organic substance are respectively set, and the equivalent organic substance concentration target value is set. Water quality target value setting means for obtaining the fluorescence intensity to be processed from the correlation as a processed fluorescence intensity target value, a fluorescence analyzer for measuring the fluorescence intensity of the treated water, and an odor for measuring the concentration of odorous substances in the treated water The first injection rate of powdered activated carbon necessary for organic substance removal is determined from the difference between the substance concentration measuring device and the fluorescence intensity measured by the fluorescence analyzer and the target fluorescence intensity after treatment, and the measured The first injection rate calculating means for obtaining the concentration of the coexisting organic substance from the fluorescence intensity of the water to be treated, and the odorous substance concentration measurement value and the organic substance concentration measurement value are respectively input. Coefficient calculating means for determining coefficients that affect the residual ratio of the odorous substance and organic substance with the powdered activated carbon injection based on the measured odorous substance concentration and organic substance concentration, respectively, Second injection rate calculation means for obtaining a second injection rate of the powdered activated carbon necessary for reducing the odorous substance to the target value of the processed odorous substance concentration as a function of the coefficients and residence time, and these injection rates It is good also as a structure provided with the injection | pouring rate determination means which determines the largest value as the powder activated carbon injection | pouring rate with respect to to-be-processed water among the 1st injection | pouring rate calculated | required by the calculating means and a 2nd injection | pouring rate.

  Further, in the system of the present invention, the odorous substance concentration measuring apparatus and the fluorescence analyzer for measuring the odorous substance concentration and the fluorescence intensity of the treated water after the powdered activated carbon injection, respectively, and the pretreated odorous substance after the treatment are measured. The difference between the concentration target value and the treated fluorescence intensity target value, and the measured odor substance concentration measured value and the fluorescence intensity measured value through the treated water guiding device are obtained, and the larger of these differences. Correction value calculation means for obtaining a correction value of the powdered activated carbon injection rate based on one of the values may be provided.

  According to the present invention, the concentration of organic substances coexisting with the concentration of odorous substances in the water to be treated is measured, respectively, and the coefficients that affect the residual ratio of these odorous substances and organic substances at the time of powder activated carbon injection are determined, Since the required injection rate of the powdered activated carbon is obtained, the odorous substance can be effectively removed without being affected by the coexisting organic substance.

  In addition, if the concentration of substances to be treated, such as the concentration of odorous substances in treated water after activated carbon injection treatment and soluble organic substances coexisting, is measured and feedback control is performed, it is possible to cope with changes in water quality characteristics, etc. Therefore, reliable powder activated carbon injection control can be performed.

  By these things, the processing cost by suppression of excessive powder activated carbon injection | pouring can be optimized, and the water quality deterioration of the treated water by the shortage of powder activated carbon injection | pouring quantity can be prevented.

  Hereinafter, an embodiment of a water treatment method and a water treatment system according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a water purification facility and a powdered activated carbon injection control system to which this embodiment is applied. In FIG. 1, 1 is a water intake, and the raw water pumped up from this water intake 1 is led to the sand basin 3 through the water conduit 2, and a large contaminant is removed here. Thereafter, the raw water enters the agglomeration / sedimentation basin 5 through the landing well 4 connected to the sedimentation basin 3. In the flocculation / sedimentation basin 5, a flocculant is injected at the inlet, and suspended substances such as clay, bacteria, and algae in the raw water are aggregated and separated as floc. Furthermore, the suspended substance remaining in the filter basin 6 is removed.

  A pretreatment device 10 is connected to the water conduit 2 via a water collection tube 9, and an odorous substance concentration measuring device 11 and a soluble organic substance concentration measuring device 13 are connected to the pretreatment device 10. Part of the raw water (treated water) flowing through the water conduit 2 is sampled by the water sampling pipe 9, and the odorous substance is passed through the pretreatment device 10 for removing impurities and suspended substances in the raw water. It is supplied to the concentration measuring device 11 and the soluble organic substance concentration measuring device 13.

  Reference numeral 7 denotes a powdered activated carbon injection arithmetic unit, to which the odorous substance concentration measurement value 12 measured by the odorous substance concentration measurement apparatus 11 and the soluble organic substance concentration measurement value 14 measured by the soluble organic substance concentration measurement apparatus 13 are respectively input. The A water quality target value input means 15 is connected to the powdered activated carbon injection arithmetic unit 7, and processing target values of the odor substance concentration and the soluble organic substance concentration are input here.

  In this powdered activated carbon injection arithmetic unit 7, the relationship between the odor substance concentration and the soluble organic substance concentration is compared with the preset target values for the odor substance concentration and the soluble organic substance to achieve each target value. The required powdered activated carbon injection rate is calculated.

  Further, a display device 16 is connected to the powdered activated carbon injection computing device 7, and an odor substance concentration measurement value 12, a soluble organic substance concentration measurement value 14, a water quality target value, and a powdered activated carbon injection rate calculation result are output. Is displayed.

  Further, a flow rate measuring device 17 is provided in the water conduit 2, and the raw water flow rate 18 is measured by the flow rate measuring device 17. 8 is a powdered activated carbon injection device, which inputs the powdered activated carbon injection rate 19 obtained by the powdered activated carbon injection arithmetic unit 7 and the raw water flow rate 18 measured by the flow rate measuring device 17, and powdered activated carbon injection according to the raw water flow rate 18. The amount is calculated and powdered activated carbon 20 is injected into the sand basin 3.

  Next, the operation of the present embodiment will be described.

  First, arithmetic expressions set in the powdered activated carbon injection arithmetic unit 7 will be described with reference to FIGS.

FIG. 2 shows the relationship between the coexisting soluble organic substance concentration and the odor substance removal rate. Here, as an odor substance, 2M-IB is taken as an example, and the soluble organic substance concentration is expressed using a soluble organic carbon concentration (hereinafter referred to as DOC). The 2-MIB removal rate on the vertical axis is calculated by equation (1).

  As shown in FIG. 2, as the DOC increases, the 2-MIB removal rate decreases. The effect increases as the 2-MIB concentration of raw water increases. Therefore, in order to estimate the powdered activated carbon injection rate required to achieve the 2-MIB treatment target, it is necessary to consider the relationship between the 2-MIB concentration of raw water and the concentration of soluble organic matter coexisting therewith.

Next, a method for calculating the powdered activated carbon injection rate necessary for 2-MIB removal will be described. FIG. 3 shows the influence of the coexisting organic substance concentration (DOC) on the relationship between the residence time and the 2-MIB residual rate when the powdered activated carbon injection rate is constant. FIG. 4 shows the relationship between the powder activated carbon injection rate and the 2-MIB residual rate when the residence time is constant, and the influence of DOC. Here, the 2-MIB remaining rate is calculated by the equation (2).

  In FIG. 3, the relationship between the 2-MIB remaining rate, the residence time, and the DOC is calculated by a relational expression such as the expression (3).

2-MIB residual ratio = 1-Mt _DOC × Mt _2-MIB × t ⁿ (3)
Here, t is a residence time and n is an exponential coefficient. Mt _DOC and Mt _{2 -MIB} are coefficients for considering the effects of DOC and 2-MIB, respectively, and are obtained by the following equations (4) and (5).

_{Mt DOC = a t1 × exp (} a t2 × DOC i) ··· (4)
Here, a _t1 and a _t2 are coefficients. DOC _i is a measured value of dissolved organic carbon concentration in raw water.

Mt _{2 -MIB} = b _t1 × C _{2 -MIBi} + b _t2 (5)
Here, b _t1 and b _t2 are coefficients. C _2-MIBi is a measured value of 2-MIB concentration of raw water.

  In FIG. 4, the relationship between the 2-MIB residual rate and the powdered activated carbon injection rate, and the raw water 2-MIB concentration and DOC are calculated by the following relational expression (6).

2-MIB remaining rate = exp (Mi _DOC × Mi _2-MIB × I) (6)
Here, I is the powder activated carbon injection rate. Mi _DOC and Mi _2-MIB are coefficients for considering the effects of DOC and 2-MIB, respectively, and are obtained by the following equations (7) and (8).

Mi _DOC = a _i1 × exp (a _i2 × DOC _i ) (7)
Here, a _i1 and a _i2 are coefficients. DOC _i is a measured value of dissolved organic carbon concentration in raw water.

Mi _2-MIB = b _i1 × C _2-MIBi + b _i2 (8)
Here, b _i1 and b _i2 are coefficients. C _2-MIBi is a measured value of 2-MIB concentration of raw water.

Therefore, the powder activated carbon injection rate I is a function of the coefficients Mi _DOC , Mi _{2 -MIB} and residence time t as shown in the following equation (9) from the relationship between the equations (3) and (6). Can be computed.

I = f (Mi _DOC , Mi _2-MIB , t) (9)
That is, the powdered activated carbon injection arithmetic unit 7 inputs the concentration measurement value DOC _i of the organic substance coexisting with the concentration measurement value C _2-MIBi of the odorous substance (2-MIB in this case) in the treated water (raw water), The coefficient calculation means calculates the coefficients Mi _2-MIB and Mi _DOC that affect the residual rate of these odorous substances and organic substances accompanying the powdered activated carbon injection into the measured odorous substance concentration measurement value C _2-MIBi. And the formula (4), (5), (7), and (8) based on the organic substance concentration DOC _i , respectively, and obtained from the relationship between the expressions (3) and (6), and the injection rate calculating means Thus, the odorous substance in the water to be treated is determined by using the relational expression shown in the equation (9), the injection rate I of the powdered activated carbon necessary to achieve the target removal rate obtained in advance by the equation (1). _Obtained as a function of the coefficients Mi _DOC , Mi _{2 -MIB} and residence time t.

  According to this embodiment, when removing the musty odor substance with powdered activated carbon, the powdered activated carbon injection computing device 7 takes into consideration the influence of the coexisting dissolved organic substance concentration, and the powdered activated carbon injection rate I (19) Since the activated carbon powder injection device 8 can be controlled based on the injection rate, it is possible to prevent deterioration of the treated water quality due to insufficient powder activated carbon injection, and economically by suppressing unnecessary powder activated carbon injection. Excellent powder activated carbon injection control support and injection control system can be realized.

  Next, the embodiment shown in FIG. 5 will be described. In addition, the same code | symbol is attached | subjected to the part same as FIG.

  In FIG. 5, raw water is led from the intake 1 to the sedimentation basin 3 through the water conduit 2, and the suspended solids are removed while passing from the landing well 4 through the coagulation / sedimentation basin 5 and the filtration basin 6. . A water sampling tube 9 is connected to the water conduit 2 and is supplied to the odorous substance concentration measuring device 11 and the fluorescence analyzer 21 via the pretreatment device 10. The odor substance concentration measuring device 11 measures the odor substance concentration, and the measured value 12 enters the powdered activated carbon injection arithmetic unit 7.

  The fluorescence analyzer 21 is used as an organic substance concentration measuring device. That is, the intensity of fluorescence having a wavelength of 425 nm emitted in response to excitation light having a wavelength of 345 nm is measured, and the measured value 22 enters the powdered activated carbon injection arithmetic unit 7. Since there is a correlation between the fluorescence intensity and the soluble organic carbon concentration (DOC), the DOC is estimated from the fluorescence intensity measurement value based on the correlation.

  A water quality target value input means 15 is connected to the powdered activated carbon injection arithmetic unit 7, and the target value of the odor substance concentration and the soluble organic substance concentration is input here. The powdered activated carbon injection arithmetic unit 7 compares the relationship between the odor substance concentration and the soluble organic substance concentration with the preset odor substance concentration and the treatment target value of the soluble organic substance to achieve each target value. The required powdered activated carbon injection rate is calculated. Further, a display device 16 is connected to the powdered activated carbon injection calculation device 7, and the odorous substance concentration measurement value 12, fluorescence intensity measurement value, soluble organic substance concentration estimated value, water quality target value, and powdered activated carbon injection rate calculation are calculated. The result is output and displayed.

On the other hand, the raw water flow rate is measured by the flow meter 17, and this measured value 18 enters the powdered activated carbon injection device 8 together with the powdered activated carbon injection calculation value 19. Here, the powdered activated carbon injection amount corresponding to this is calculated, and the powder Activated carbon 20 is injected into the sand basin 3.

  Next, the operation of this embodiment will be described.

  FIG. 6 shows the relationship between the fluorescence intensity measured by the fluorescence analyzer 21 and the soluble organic carbon concentration (DOC). As described above, since there is a correlation shown in FIG. 6 between the fluorescence intensity and the DOC, it is possible to estimate the DOC from the measured value by the following equation (10) by measuring the fluorescence intensity.

DOC _i = c _D1 × FL + c _D2 (10)
Here, c _D1 is a coefficient, c _D2 is a constant, and FL is fluorescence intensity. The DOC _i is estimated using this equation, and the odor substance concentration C _{2 -MIBi} measured by the odor substance concentration measuring device 11 is used to calculate the odor according to the above equations (3) to (9). The powdered activated carbon injection rate necessary to achieve the substance removal target can be calculated.

  According to this embodiment, the fluorescence analyzer 21 can measure the fluorescence intensity of raw water without contact with time delay, and can estimate the DOC from this fluorescence intensity. Thus, it is possible to prevent the deterioration of the treated water quality due to insufficient powdered activated carbon injection, and it is possible to realize a powdered activated carbon injection control support and an injection control system excellent in economic efficiency by suppressing unnecessary powdered activated carbon injection.

  Next, the embodiment shown in FIG. 7 will be described. The hardware configuration in this embodiment is the same as that shown in FIG. 5, but the means for calculating the powdered activated carbon injection rate is different. Below, the calculation procedure of powder activated carbon injection rate is demonstrated.

In FIG. 7, in step 30, the water quality target setting means 15 shown in FIG. 5 uses the treatment target concentrations of 2-MIB and geosmin (Ct ₂ -MIB, Ct _G ) as the odor component substance and the indicator of the soluble organic matter. As a target, the dissolved organic carbon concentration (DOC), potassium permanganate consumption (KMnO ₄ consumption) and trihalomethane production ability (THMFP) after powder activated carbon treatment (DOC _t , KMnO 4 _t , THMFP _t ) Set.

Here, there is a correlation between the DOC and the fluorescence intensity measured by the fluorescence analyzer 21 as shown in FIG. Further, it has been confirmed that there is a correlation between the fluorescence intensity, the KMnO ₄ consumption amount, and THMFP as shown in FIGS. 8 and 9, and using this relationship, in step 31, the water quality target value is obtained. Among them, the fluorescence intensity FL corresponding to DOC _t , KMnO 4 _t , and THMFP _t related to the organic substance concentration is calculated from the following expressions (11), (12), and (13).

FL _DOC = c _D3 × DOC _t + c _D4 (11)
FL _KMnO4 = c _K1 × KMnO ₄ consumption _t + c _K2 (12)
FL _THMFP = c _T1 × THMFP _t + c _T2 (13)
In step 32, FL _DOC , FL _KMnO4 , and FL _THMFP are compared, and the minimum fluorescence intensity is determined as the target value (FL _t ) of the treated water fluorescence intensity.

In step 34, in order to achieve the target of the soluble organic substance concentration from the relationship between the measured value FL _i (33) by the fluorescence analyzer 21, the target value FL _t of the post-treatment fluorescence intensity, and the activated carbon treatment time t. The required powdered activated carbon injection rate (first injection rate) I _O is calculated by the following equation (14).

Io = f (FL _i , FL _t , t) (14)
In step 35, the DOC _i of the raw water is estimated by the above equation (10) using the measured value FL _i by the fluorescence analyzer 21.

In step 37, odorant concentration in the raw water that is measured by the odorant concentration measuring device _{11 (Ci 2-MIB, Ci} G) (36) and the odorant concentration process target value _{(Ct 2-MIB, Ct G} ) and, from the relationship of solubility organic substance concentration of the coexisting (DOC _i), powdered activated carbon injection rate required to achieve the target processing by the above equation (9) (a second injection rate) I _2-MIB, and I _G Calculate.

In step 38, a first powdered activated carbon injection rate _IO required to achieve the soluble organic concentration target and a second powdered activated carbon injection rate required to achieve the odorous substance treatment target. I _{2 -MIB} and _IG are compared, and the maximum value is defined as the powder activated carbon injection rate I.

  According to the present embodiment, it is possible to control the powdered activated carbon injection device at the optimum powdered activated carbon injection rate to simultaneously achieve the treatment target of the odorous substance and the soluble organic substance. Generation of disinfection by-products such as trihalomethane can be prevented, and powder activated carbon injection control support and injection control system excellent in economic efficiency can be realized by preventing unnecessary powdered activated carbon injection.

  Next, the embodiment shown in FIG. 10 will be described.

  In FIG. 10, the raw water is led from the water intake 1 through the water conduit 2 to the sand basin 3 where large impurities are removed. Thereafter, suspended substances are removed while passing from the landing well 4 through the coagulation / sedimentation basin 5 and the filtration basin 6. A water collection pipe 9 is connected to the water conduit 2, and a part of the raw water of the pretreatment device 10 is collected to remove impurities and suspended substances in the raw water. The configuration up to this point is the same as in FIGS.

  In the configuration of FIG. 10, a three-way valve 25 is provided on the outlet side of the pretreatment device 10, and one inlet side thereof is connected to the outlet side of the pretreatment device. Further, the outlet side of the three-way valve 25 is connected to the odor substance concentration measuring device 11 and the fluorescence analyzer 21 so that raw water can be supplied thereto.

  Moreover, in this embodiment, the water sampling pipe 23 is connected to the outlet side piping of the sand basin 3 where the powdered activated carbon is injected, and the treated water after the powdered activated carbon injection processing collected here is pretreated. Guided to device 24. The pretreatment device 24 has a filtration function, and removes suspended substances such as the powdered activated carbon 20 injected from the powdered activated carbon injection device 8.

  The outlet side of the pretreatment device 24 is connected to the other inlet of the three-way valve 25, and the sample water treated by the pretreatment device 24 is guided to the three-way valve 25. The three-way valve 25 is set so as to periodically switch the flow path, and the raw water and the powdered activated carbon treatment water are alternatively switched every predetermined time, and the odorous substance concentration measuring device 11 and the fluorescence analyzer are switched. 21 is supplied. As for the switching cycle of the three-way valve 25, for example, the minimum analysis time of the odor substance concentration measuring device 11 and the fluorescence analyzer 21 is compared, and the larger value is set as the minimum switching cycle.

  The odorous substance concentration measuring device 11 measures the odorous substance concentration, and the measured value 12 enters the powdered activated carbon injection arithmetic unit 7. The fluorescence analyzer 21 measures the intensity of fluorescence having a wavelength of 425 nm, which is emitted in response to excitation light having a wavelength of 345 nm, and the measured value 22 enters the powdered activated carbon injection arithmetic unit 7.

  A water quality target value input means 15 is connected to the powdered activated carbon injection arithmetic unit 7, from which target values of odor substance concentration and soluble organic substance concentration are input. In the powdered activated carbon injection calculation device 7, the optimum powdered activated carbon injection rate is calculated using the odor substance concentration and the soluble organic substance concentration of raw water and treated water, and the treatment target value of the odor substance concentration and the soluble organic substance. Moreover, the display apparatus 16 is connected to the powdered activated carbon injection | pouring calculating apparatus 7, and the odorous substance density | concentration measured value 12, the fluorescence intensity measured value 22, the soluble organic substance density | concentration estimated value of raw | natural water and treated water, respectively. Water quality target value and powder activated carbon injection rate calculation result are output and displayed.

  On the other hand, the raw water flow rate is measured by the flow meter 17, and this measured value 18 enters the powdered activated carbon injection device 8 together with the powdered activated carbon injection calculation value 19, and the powdered activated carbon injection amount corresponding to this is calculated. It is injected into the sand basin 3.

  Next, the powder activated carbon injection rate calculation procedure in the powder activated carbon injection calculation device 7 will be described with reference to FIG.

In FIG. 11, the processing from step 30 to step 38 is the same as that in FIG. That is, in step 30, the water quality target setting means 16, after processing target concentration of 2-MIB and geosmin _{(Ct 2-MIB, Ct G} ) and, as an indicator of soluble organic substances, soluble organic carbon concentration (DOC) , The target concentration (DOC _t , KMnO _4t , THMFP _t ) after the powdered activated carbon treatment of potassium permanganate consumption (KMnO ₄ consumption) and trihalomethane production ability (THMFP) is set.

In step 31, the fluorescence intensity FL corresponding to DOC _t , KMnO _4t , and THMFP _t related to the organic substance concentration in the water quality target value is expressed by the equation (11) based on the correlation shown in FIGS. , (12) and (13).

In step 32, FL _DOC, compares the FL _KMnO4, FL _THMFP, to determine the minimum fluorescent intensity target value FL _t of treated water fluorescence intensity.

In step 34, the target value of the soluble organic substance concentration is achieved by the equation (14) using the measured value of the fluorescence intensity FL _{i of} the raw water, the target value FL _t of the post-treatment fluorescence intensity, and the value of the activated carbon treatment time t. The first powdered activated carbon injection rate _IO required for the calculation is calculated.

In step 35, the DOC _i of the raw water is estimated from the equation (10) using the raw water fluorescence intensity measurement value FL _i .

In step 37, odorant concentration in the raw water that is measured by the odorant concentration measuring device _{11 (Ci 2-MIB, Ci} G) and odorant concentration process after the target value _{(Ct 2-MIB, Ct G} ) and, coexist From the relationship of the dissolved organic substance concentration (DOC _i ), the second powdered activated carbon injection rate (I _{2 -MIB} , I _G ) necessary to achieve the treatment target is calculated by the equation (9).

In step 38, a first powdered activated carbon injection rate _IO required to achieve the soluble organic concentration target and a second powdered activated carbon injection rate required to achieve the odorous substance treatment target. (I _{2 -MIB} , I _G ) are compared, and the maximum value is defined as the basic injection rate I _bas of the powdered activated carbon.

Next, at step 39, a preset odorant concentration process target values are _{(Ct 2-MIB, Ct G} ) target values associated with and concentration of organic substances, DOC _t, KMnO4 _t, and THMFP _t, of the three-way valve 25 measured by switching, the powdered activated carbon treated water, 2-MIB concentration Co _2-MIB, compared geosmin concentration Co _G, and the measured value of fluorescence intensity FLo. As a result, if the concentration of treated water exceeds the target value in any one item, the powder activated carbon injection rate correction value for each water quality item is calculated according to the following formulas (15) to (19) depending on the difference. Calculate

ΔI _2−MIB = a × (Ct _2−MIB− Co _2−MIB ) (15)
ΔI _G = b × (Ct _G -Co _G ) (16)
ΔI _DOC = c × (Ct _DOC -Co _DOC ) (17)
ΔI _{KMnO 4} = d × (Ct _KMnO 4 _—Co KMnO ₄ ) (18)
ΔI _THMFP = e × (Ct _THMFP− Co _THMFP ) (19)
Here, a, b, c, and d are coefficients.

  As a result, for example, when the treated water concentration exceeds the target for one item, the correction value for that item is set as the powder activated carbon injection rate correction value ΔI. Further, when the concentration of treated water in a plurality of items exceeds the target value, the maximum correction value among the corresponding items is adopted as ΔI. In addition, the tolerance between the treated water concentration and the target concentration in each water quality item is determined in advance, and if the treated water concentration is lower than the target concentration in all the water quality items, it is corrected to reduce the powder activated carbon basic injection rate. The value ΔI is determined.

  Finally, in step 40, the powdered activated carbon injection rate I is determined by the equation (20).

I = _Ibas ± ΔI (20)
According to the present embodiment, since the powder activated carbon injection rate can be determined by measuring the odor substance concentration and the fluorescence intensity of the raw water, the powder activated carbon injection rate can be increased or decreased without a time delay even for sudden fluctuations in water quality. In addition to preventing deterioration of treated water quality due to insufficient injection rate, it is possible to prevent an increase in processing cost due to excessive injection. In addition, since it has the function of feedback control to correct the powder activated carbon injection rate by measuring the odorous substance concentration and fluorescence intensity after powdered activated carbon treatment, more accurate powder activated carbon injection control becomes possible. In addition to preventing water quality accidents due to odorous substances and generation of disinfection by-products such as trihalomethanes, it is possible to realize a powdered activated carbon injection control support and an injection control system that are excellent in economy by preventing unnecessary powdered activated carbon injection.

It is a system configuration figure showing one embodiment of a water treatment system by the present invention. It is a characteristic figure explaining the relationship between the odorous substance removal rate and organic substance density | concentration in one Embodiment same as the above. It is a characteristic view explaining the relationship between the odorous substance residual rate and residence time in one embodiment same as the above. It is a characteristic figure explaining the relationship between the odorous substance residual rate and injection | pouring rate in one Embodiment same as the above. It is a system block diagram which shows other embodiment of this invention. It is a characteristic view explaining the correlation between the fluorescence intensity and the organic substance concentration used in the embodiment. It is a flowchart explaining the calculation processing procedure of the powdered activated carbon injection rate of other embodiment. It is a characteristic view explaining the correlation of the fluorescence intensity used for embodiment same as the above and KMnO4. It is a characteristic view explaining the correlation between the fluorescence intensity and THMFP used in the same embodiment. It is a system configuration figure showing other embodiments of the present invention. It is a flowchart explaining the calculation processing procedure of the powdered activated carbon injection rate of other embodiment same as the above.

Explanation of symbols

7 Powdered activated carbon injection computing device 8 Powdered activated carbon injection device 11 Odor substance concentration measuring device 13 Organic substance concentration measuring device 15 Water quality target value setting means 21 Fluorescence analyzer

Claims (8)

A water treatment method for injecting powdered activated carbon into water to be treated and removing soluble organic substances in the water to be treated,
Measure the concentration of odorous substances in the water to be treated and the concentration of coexisting organic substances,
Coefficients that affect the residual ratio of these odorous substances and organic substances with the powdered activated carbon injection are determined based on the measured odorous substance concentration and organic substance concentration, respectively.
A water treatment method, characterized in that an injection rate of the powdered activated carbon necessary to achieve a target removal rate of odorous substances determined in advance is determined as a function of the coefficients and residence time.   2. The water treatment method according to claim 1, wherein in measuring the concentration of the organic substance, the fluorescence intensity of the water to be treated is measured, and the concentration of the organic substance is obtained from the correlation between the fluorescence intensity and the concentration of the organic substance. . A water treatment method for injecting powdered activated carbon into water to be treated and removing soluble organic substances in the water to be treated,
Set the target concentration of odorous substances after treatment and the target concentration of coexisting organic substances,
The fluorescence intensity corresponding to the organic substance concentration target value is determined from the correlation as the processed fluorescence intensity target value,
The fluorescence intensity of the water to be treated is measured, and the first injection rate of powdered activated carbon necessary for organic substance removal is determined from the measured fluorescence intensity, the post-treatment fluorescence intensity target value, and the activated carbon treatment time,
While measuring the concentration of odorous substances in the treated water, obtain the concentration of organic substances coexisting by correlation from the measured fluorescence intensity of the treated water,
Coefficients that affect the residual ratio of these odorous substances and organic substances with the powdered activated carbon injection are determined based on the measured odorous substance concentration and organic substance concentration, respectively.
Determining a second injection rate of the powdered activated carbon necessary to achieve the target removal rate of odorous substance determined in advance as a function of the coefficients and residence time;
A water treatment method characterized in that the maximum value among the first injection rate and the second injection rate is determined as the powdered activated carbon injection rate for the water to be treated.   The concentration of the odorous substance and the fluorescence intensity in the treated water after powdered activated carbon injection are measured, respectively. The concentration target value of the odorous substance after treatment and the target value of the fluorescence intensity after treatment, and the concentration of the odorous substance in the treated water 4. The water treatment method according to claim 3, wherein a difference between the measured value and the measured value of the fluorescence intensity is obtained, and a correction value for the powder activated carbon injection rate is obtained based on the larger value of these differences. A water treatment system for injecting powdered activated carbon into the water to be treated to remove soluble organic substances in the water to be treated,
An odor substance concentration measuring device and an organic substance concentration measuring device for measuring the concentration of odorous substances in the water to be treated and the concentration of organic substances coexisting with each other;
The odorous substance concentration measurement value and the organic substance concentration measurement value are respectively input, and the odorous substance concentration measurement is performed to determine a coefficient that affects the residual ratio of the odorous substance and the organic substance accompanying the powdered activated carbon injection. Coefficient calculating means for obtaining the value and the measured value of organic substance concentration, respectively,
An injection rate calculating means for determining the injection rate of the powdered activated carbon necessary to achieve the target removal rate of the odorous substance determined in advance as a function of the calculated coefficients and residence time;
A water treatment system comprising: As an organic substance concentration measuring device,
A fluorescence analyzer that measures the fluorescence intensity of the water to be treated;
Concentration of odorous substance in the water to be treated Based on the measurement value of the fluorescence analyzer, an organic substance concentration calculating means for obtaining the organic substance concentration from the correlation between the fluorescence intensity and the organic substance concentration,
The water treatment system according to claim 5, wherein the water treatment system is provided. A water treatment system for injecting powdered activated carbon into the water to be treated to remove soluble organic substances in the water to be treated,
Set the target concentration of odorous substances and the target concentration of coexisting organic substances after activated carbon injection treatment, and set the fluorescence intensity corresponding to the set organic substance concentration target value after processing. Water quality target value setting means to obtain from the correlation as,
A fluorescence analyzer for measuring the fluorescence intensity of the water to be treated;
An odor substance concentration measuring device for measuring the concentration of the odor substance in the treated water;
A first injection rate of powdered activated carbon necessary for organic substance removal is obtained from the fluorescence intensity measured by the fluorescence analyzer, the post-treatment fluorescence intensity target value, and the activated carbon treatment time, and the measured water to be treated is obtained. A first injection rate calculating means for determining the concentration of the coexisting organic substance from the fluorescence intensity;
The concentration measurement value of the odorous substance and the concentration measurement value of the organic substance are respectively input, and the coefficient that affects the residual rate of the odorous substance and the organic substance accompanying the powdered activated carbon injection is determined as the measured odorous substance. Coefficient calculation means for obtaining each based on the substance concentration and the organic substance concentration,
A second injection rate calculating means for determining a second injection rate of the powdered activated carbon necessary for achieving the target removal rate of the odorous substance determined in advance as a function of the coefficients and residence time;
And an injection rate determining means for determining a maximum value among the first injection rate and the second injection rate obtained by the injection rate calculating means as the powdered activated carbon injection rate for the water to be treated. Water treatment system. A treated water guide device that causes the odorous substance concentration measuring device and the fluorescence analyzer to measure the odorous substance concentration and fluorescence intensity of the treated water after the powdered activated carbon injection,
Difference between the target concentration value of the processed odorous substance and the target fluorescence intensity value after processing, and the measured odorous substance concentration measured value and fluorescent intensity measured value through the treated water guide device The water treatment system according to claim 7, further comprising: a correction value calculation unit that calculates the correction value of the powdered activated carbon injection rate based on a larger value of these differences.

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