KR101494083B1 - Method for determining residual ozone decay kinetic constant in ozone water treatment system - Google Patents

Abstract

The present invention is to provide a method for determining reliable ozone decomposition rate constants [D ₀ ] and K _D by measuring ozone concentration at two or more points in an ozone water treatment system including an ozone contact tank.
There has been a problem that not only a cost and a complicated method are required but also the reliability is low in order to obtain the ozone decomposition rate constant in the conventional ozone contact tank. However, in the present invention, although the ozone concentration is measured at arbitrary several points in the ozone contact tank, it is possible to easily and reliably obtain the reliable ozone decomposition rate constant, and thereby to simulate the ADR model very close to the actual ozone contact tank have. Through the ADR model simulation, and easily control the CT value desired in the ozone water treatment system, and even C. parvum oocyst deactivation and bromate generation control can be implemented with high reliability.

Description

TECHNICAL FIELD The present invention relates to a method for determining an ozone decomposition rate constant in an ozone water treatment system,

The present invention relates to a method for obtaining ozone decomposition rate constants [D ₀ ] and K _D in an ozone water treatment system including an ozone contact tank, and a method for controlling ozone doses using the same.

Ozone is a substance that has a stronger oxidizing potential than oxidants used in water treatment, such as chlorine or chloramine. Especially, ozone has a higher bactericidal power against microorganisms such as C. parvum oocyst than chlorine - based disinfectants, and in recent years, it has been widely used in water treatment plants in the United States.

Generally, the ozone water treatment process installed in a water purification plant generates ozone by discharging a high voltage to oxygen gas, dissolves generated ozone into the treatment water flowing into the ozone contact tank, and accumulates trace pollutants and microorganisms Oxidative decomposition step. At this time, the ozone is dissolved in the treated water and decomposed into oxygen and water in the ozone contact tank. The rate of ozone decomposition in this way is influenced by various factors. For example, the decomposition rate of ozone is influenced by various factors such as water temperature, pollutant concentration, pH, alkalinity, and heavy metal concentration. Considering such decomposition characteristics, the residence time in the ozone contact tank Design for 15 to 30 minutes. Here, the residence time of the ozone contact tank means the time during which the treated water flows in the ozone contact tank and is the same as the time when ozone decomposition occurs in the ozone contact tank. This is the time required for the treatment water to flow into the ozone contact tank .

The disinfection process of ozone, that is, the water treatment process, determines the disinfecting ability based on the value of CT (ozone concentration x contact time), and in particular, C. parvum Control of the deactivation rate of the oocyst is achieved by controlling the CT value. The CT can be determined by integrating the residual ozone concentration during the total residence time in the graph of the residual ozone concentration versus residence time, i.e., the ability to disinfect treated water passing through the ozone contact tank. Therefore, it can be seen that the CT value increases as the amount of ozone supplied to the treated water increases and the contact time of the treated water increases. As the CT value increases, the disinfection ability increases and C. parvum increasing the deactivation rate of the oocyst but increasing the amount of ozone to inject for this purpose the residual ozone is excessively contained to be processed discharged from crude ozone contact to kill the microorganism that is used in the post-treatment process, or volatilized into the air to the human body It can cause harmful problems. Furthermore, when ozone is used in raw water rich in Br ^-, there is a problem that a substance suspected of being carcinogenic to bromate (BrO ₃ ^- ) is produced as a disinfection by-product, and the amount of bromate increases as the CT value increases have. Therefore, C. parvum it is important to determine and control the appropriate CT value to prevent excessive production of bromate while effectively performing inactivation of the oocyst .

However, the determination and control of CT values is very difficult for experienced ozone contactors. This is because it is not possible to accurately grasp the concentrations of the treated water ozone in the actual ozone contact tank at all points and to estimate the residual ozone concentration with respect to the residence time in real time since the decomposition rate of the ozone is influenced by various variables It is very hard work.

As a method for predicting and controlling the CT value, a reaction rate model has been proposed that can account for ozone decomposition reflecting the hydraulic characteristics of an ozone contact tank. Recently, this reaction rate model can be simulated using computer-based software, typically OCM software. The OCM software can automatically perform simulations such as graphs of residual ozone concentration simply by entering the ozone decomposition model equation and entering parameters related to the ozone decomposition rate constant.

On the other hand, CSTR (Continuous Stirred Tank Reactor) model has conventionally been used as the reaction velocity model. This is modeled as an ozone contact tank composed of several successive stirred batch reactors, idealized to be composed of cells having a plurality of uniform volumes. This CSTR model has advantages such that it is easy to obtain the parameters to be used, i.e., the ozone decomposition rate constant, and that the simulation is simple. However, since the actual ozone contact volume is different from each other in the cell volume, the treated water exhibits a non-ideal flow rather than an ideal CSTR, and the K _R value as the second-order rate constant is not reflected. There is a problem that ozone decomposition can not be predicted with high reliability.

Under these circumstances, the present inventors more fully reflect the hydraulic characteristics of the ozone contact tank, which exhibits non-idealities such as horizontal flow cereals, and the ADR model (Axial Dispersion Reactor Model) It was confirmed that reliable CT values can be predicted and controlled through simulation that reflects the model equation. Furthermore, in determining the three parameters (K _R , [D ₀ ] and K _D ) necessary to simulate the ADR model, K _R value is fixed as a constant and not large in importance, by identifying the remaining available ozone decomposition rate constant of [D _0], and can reliably obtain the K _D value, the present invention has been completed.

The present invention measures the ozone concentration at two or more points in an ozone water treatment system including an ozone contact tank, and estimates the initial ozone concentration reduction amount ([D ₀ ]), which is reliable ozone decomposition rate constants To obtain a decomposition rate constant (K _D ).

In order to solve the above problems, the present invention provides a method for determining an ozone decomposition rate constant [D ₀ ] and K _D comprising the steps of:

1) an inlet through which treated water flows;

An ozone input unit installed at the inlet to supply ozone to the treated water;

An ozone contact tank connected to the inlet and including a passage through which the treated water flows and forms a cereal;

Two or more ozone sensors provided at an arbitrary distance ( _Li ) of the passage channels in the ozone contact tank;

A discharge port through which the treated water passing through the ozone contact tank is discharged through the passage channel; And

Using an ozone water treatment system including a central processing system for analyzing the ozone concentration measured through the ozone sensor,

The ozone concentration of the inlet [O _{3] 0,} and the ozone concentration in the i-th through the ozone sensor distance L _i [O _3] measuring a _i, respectively; And

2) obtaining an ozone decomposition rate constant [D ₀ ] and a K _D , in which the value of m is the minimum value in the equation represented by the following equation (1);

[Equation 1]

Where m is the difference between the actual ozone concentration ([O ₃ ] _i ) at x = L _i corresponding to the i-th ozone sensor in Equation 1 and the ozone concentration ([O ₃ ] the square _{([O 3] - [O} 3] i) represents the sum of the ^two,

Where E is the dispersion coefficient, U is the flow rate of the treated water, [O ₃ ] is the ozone concentration, and K _R is the second order rate constant with reduced ozone requirement. In the case of post-ozone treatment (total ozone->coagulation->precipitation->filtration-> post-ozone) in the water treatment process, this value is a constant determined constantly.

The present invention uses the ADR model (Axial Dispersion Reactor Model), which is the most suitable model for the ozone contact tank in which the treated water exhibits a non-ideal flow of horizontal currents and cereals, and simplifies the ozone decomposition rate constants There is a feature that can be obtained efficiently. Specifically, it is possible to simulate and determine only two [D ₀ ] and K _D out of the total three ozone decomposition rate constants (K _R , [D ₀ ] and K _D ) required in the ADR model, The CT can be predicted with high reliability and the optimal CT can be easily controlled.

Hereinafter, the present invention will be described in detail.

As shown in FIG. 1 according to an embodiment of the present invention, the method for determining the ozone decomposition rate constant of the present invention can be performed using an ozone water treatment system.

As shown in FIG. 2, the ozone contact tank, which is a main constituent of the ozone water treatment system according to the present invention, may be formed so as to allow the treated water flowing through the inlet port to flow out through the outlet port after passing through the passage channel.

The ozone water treatment system of the present invention including the ozone contact tank formed as described above is characterized in that it comprises an ozone injection unit installed at the inlet, an ozone sensor installed in the passage water passage, and a center Processing system may be further included.

The ozone input unit is provided on the inlet side and feeds ozone into the raw water before the water is introduced into the ozone contact tank. The supplied ozone may be supplied from an ozone supply device and an ozone storage tank provided outside.

In one preferred embodiment of the present invention, the ozone input unit may be a venturi pipe for ozone injection, in which case a part of the treated water may be introduced into the venturi pipe. Ozone is injected into a part of the treatment water flowing into the venturi tube due to the phenomenon that the pressure in the neck portion of the venturi tube is lowered and the gaseous ozone is dissolved and contained in a part of the treatment water flowing in the venturi tube . Then, a part of the treated water containing ozone may be introduced into the ozone contact vessel through the inlet after combining with the remaining treated water. Then, the treated water containing ozone can be treated in contact with, i.e., reacted with, ozone while flowing through the passage channel in the ozone contact tank for a predetermined contact time.

The ozone input unit may be a venturi as described above, but may be a bubble diffuser for ozone injection, and the ozone input unit is not particularly limited.

The ozone contact tank includes a passage through which the process water can flow while forming a cereal.

In an embodiment of the present invention, the ozone contact vessel may be provided with several partition walls in the form of a labyrinth so that the flow channel of the treatment water is changed to cereal flow, horizontal flow, or the like. These partition walls are connected to the left and right inner walls and the upper and lower inner walls of the ozone contact tank body, and the space separated by the partition walls constitutes a cell. The treated water flows vertically or horizontally along the cells separated by these partitions and can form various types of flows. The passage channel may be formed as a set of cells that are space in which the process water flows, that is, a space separated into inner walls.

FIG. 2 is a schematic view showing an example of the ozone contact tank and the passage passage in which the partition wall is provided on the inner wall of the ozone contact tank to form a passage water passage. In this case, .

Of the cells separated by the barrier ribs, the first cell (the upper part of the passage channel) is connected to the inlet to supply the treated water for the first time, and the last cell (the end of the passage channel) And is the area where the disassembled treated water is discharged.

The shape of the ozone contact tank and the passage passage described above are not particularly limited, and include all kinds of passing water channels and ozone contact vessels which are formed and flowable with cereals generally known in the art.

At least two ozone sensors may be installed in the passage through the ozone contact tank. The ozone sensor is a sensor capable of detecting the concentration of ozone in the treated water, and is not particularly limited.

The number of the ozone sensors is not particularly limited. However, the ozone decomposition rate constant is determined and the simulation result is concurrent with the reliability. To 5 is preferable. Most preferably, three ozone sensors may be installed.

The ozone sensor can be installed at any point in the passage waterway, that is, at any arbitrary distance L _i . The distance L _i is a distance in the water channel from the upper portion of the passage through which the inlet is connected to the point where the i-th sensor is installed, that is, the distance that the process water travels from the upper portion of the passage passage to the point where the i- , And the unit is m (meters).

Preferably, the last of the ozone sensors may be located at the distal end of the passageway that is connected to the outlet. The distance at which the ozone sensor is installed corresponds to 80% to 100% of L, which is the length of the passage, and preferably 80% to 90% of the length L of the passage. Thus, the final sensor is installed at the distal end of the passage passage, so that the concentration of ozone in the final treated water discharged from the discharge port can be detected.

A central processing system for receiving and analyzing the ozone concentration data measured through the ozone sensor includes a display unit for recording and displaying an ozone amount calculation so as to control and monitor the ozone concentration of the ozone input amount and the inlet ozone concentration; The ADR model algorithm according to Equation (1), which is a model prediction equation capable of quantitatively estimating and predicting the disinfection effect in consideration of the chemical decomposition rate of ozone, is installed. The treatment water flow rate at the inlet, the treatment water ozone concentration at the inlet, A numerical operation unit for quantitative analysis and simulation according to the ADR model by receiving the ozone concentration ([O ₃ ] _i ) data by the ozone sensor through the ozone sensor in the water pH and temperature and the passing water; And a model prediction control unit capable of automatically calculating an ozone input amount. Specifically, the numerical operation unit can more easily perform numerical computation and simulation using the modified OCM software.

Since the OCM software is a program that is commonly used by ordinary engineers in the industry for ozone concentration simulation, a person skilled in the art can appropriately apply the numerical computation and the simulation. Further details of the modified OCM software have already been described by the inventor's paper [Kim, D., Hasan, S., Tang, G., Marinas, BJ, Couillard, L., Shukairy, ) Simulaneous simulation of pathogen inactivation and bromate formation in full scale ozone contactors. Journal AWWA 99 (8), 77-91, which is incorporated herein by reference.

The optimum ozone decomposition rate constants [D ₀ ] and K _D in the ADR model in the ozone contact tank can be obtained through the numerical calculator.

In the ozone water treatment system configured as described above, the reason why the model predictive control is applied by simulating by the ADR model, which is the disinfection model equation, which will be described later, and the optimum ozone decomposition rate constant, In most of the water purification plants that use this severe surface water as the inflow source of the water purification plant, the demand level of the substance to be removed may be changed according to the variation of the water quality and the quantity. In the case of ozone, , It is possible to calculate the deactivation of the substance to be removed by substituting it into the ADR model that reflects the system and the reaction rate theory of the real system because it shows a complex flow in the ozone contact tank. This is because the amount of ozone to be injected can be calculated.

In the present invention, the ozone decomposition rate constants [D ₀ ] and K _D applied to the ADR model equation can be obtained by using the above-described ozone water treatment system. Hereinafter, this method will be described in more detail.

The present invention can measure or determine the ozone concentration ([O ₃ ] ₀ , mg / ℓ) of the treated water flowing into the ozone contact vessel through the amount of ozone injected into the treated water through the ozone input unit using the above-described ozone water treatment system . Furthermore, the ozone concentration [O ₃ ] _i (mg / l) can be measured at any distance ( _Li ) of the passage through which each ozone sensor is located, through two or more ozone sensors installed in the passage channel.

[Equation 1]

Wherein, x is a concept corresponding to the length of the dimensionless distance, that is, the passage channels L, E is the dispersion coefficient (m ² / sec), U is the flow velocity (m / sec) of the treated water, [ O ₃ ] corresponds to the ozone concentration (mg / l).

Further, the three ozone decomposition rate constants K _R (l / mg / min), [D ₀ ] (mg / l) and K _D (min ^-1 ) are the second order rate constant, the initial instantaneous ozone demand, and the ozone decomposition primary rate constant, respectively. In particular, the present invention is characterized in that the value of K _R is a constant determined constantly. Therefore, the [D ₀ ] and K _D values can be calculated to simulate an ADR model that is almost identical to the actual model.

The dispersion number (d) must be determined by performing a tracer test by creating a sampling port between two points of the passage in the ozone contact tank. This process does not require repetition if it is performed only once, and it is also possible to apply existing experimental values to the new ozone contact group if similar conditions are met. The Tracer test measures the concentration of F ^- in the upper part of the passage by injecting NaF, which is harmless to the human body, and sampling the sample at the downstream point in time. After plotting the concentration as non-dimensional, the differential equation corresponding to Equation 1, which is the ADR model equation, is solved using a numerical analysis to find the dispersion number fitted to the most experimental value.

In the present invention, the above Tracer test confirmed that the ADR model matched the ozone contact group mathematically disclosed by the present invention, more satisfactorily than the conventional CSTR model. Further, the appropriate dispersion number (d) Was 0.03. The dispersion coefficient (E) of the equation (1) can be determined through the dispersion number (d) obtained as described above, and can be calculated by the equation d = E / UL.

The next step is to determine the ozone decomposition rate constants [D ₀ ] and K _D by measuring ozone concentrations [O ₃ ] ₀ and [O ₃ ] _i at the top and at any point of the passage, to be.

The [O ₃ ] ₀ and [O ₃ ] _i are multiplied by various values [D ₀ ] and K _D , and the values obtained through the modeling of Equation (1) are compared by a trial and error method , Then the best fit [D ₀ ] and K _D values are obtained. The above equation can be solved using various numerical analysis tools. A typical method is Finite Element Method. The most suitable values [D ₀ ] and K _D are [D ₀ ] and K _D values when the sum of the difference between the experimental value and the predicted value by modeling is the smallest.

이 가장 작은 값이다(여기서 i는 통과수로 내에 설치된 첫 번째 센서(i=1)부터 i번째 센서까지의 모든 센서를 나타냄).In other words,

(Where i represents all the sensors from the first sensor (i = 1) to the i-th sensor installed in the pass-through channel).

Specifically, if being the ozone sensor fitting 3 in a number of passes, when the m is, the equation ₁ x = L 1 in the graph in one of the last ozone sensor of which is installed at the terminal of the passage channel ([O ₃ ] - [O ₃ ] ₁ ) ² obtained by squaring the difference between the ozone concentration ([O ₃ ]) and the corresponding ozone concentration [O ₃ ] ₁ in the first sensor, L ₂ il ozone concentration ([O _3]) and a corresponding two ozone concentration in the second sensor for [O _3] by squaring the difference between the value of _{2 ([O 3] - [} O 3] 2) when the ^second and, ozone concentration when in the graph _{x = L 3 ([O 3} ]) and its corresponding square the three difference values of the ozone concentration [O _{3] 3} of the second sensor for _{([O 3] - [O} 3] ₃ ) ² .

In the present invention, going by changing the above formula [D _0] and K _D values, it can be determined with the minimum value of m [D _0] and K _D values. An example of the graph according to the above formula is shown in Figs. 6 and 7. Fig.

At this time, in the process of finding the minimum value of the above equation, the initial [D ₀ ] and K _D values can be obtained through the MC-SFR system (Multi-Channel Stopped-Flow Reactor). The MC-SFR system can automatically derive the ozone decomposition rate constant for a batch reactor. Briefly, the MC-SFR system comprises six tubular reactors with different reaction times, and the flow in each tubular reactor can be isolated during the reaction by a solenoid valve on either side of the reactor. The reacted ozone aqueous solution from each of the tubular reactors is mixed and then passed through a spectrophotometer together with the indigo reagent and analyzed to obtain the ozone decomposition rate constant for the batch reactor.

The specific contents of such MC-SFR system have already been described by the present inventor's paper [Kim, D., Fortner, J. D. and Kim, J.-H. (2006) A multi-channel stopped-flow reactor for measuring ozone decay rate: Instrument development and application. ozone science and engineering 29, 121-129., which is incorporated herein by reference.

However, the ozone decomposition rate constant obtained by the MC-SFR system is a suitable constant for a batch reactor, and can be applied to a plug model of a kind, but it is difficult to use it as a suitable constant in the ADR model of the present invention. Therefore, [D ₀ ] and K _D are used as initial guess values in the process of finding the minimum value of the above equation.

The second-order rate constant, K _{R, which} is the reduced ozone requirement of the ozone decomposition rate constant, is a very difficult constant to obtain because it is associated with a very rapid decrease in ozone requirement just prior to ozone injection. This constant can only be obtained if expensive equipment is installed on site and can not be immediately obtained through the ozone water treatment system of the present invention and the ozone sensor included therein. However, in the embodiment of the present invention, since the sensitivity of the K _R to the simulation result through the ADR model is insignificant through the sensitivity analysis, it can be treated as a constant constantly determined value Respectively. This allows the subject to the ozone concentration ([O _{3] 0} and [O _{3] i)} measured at each point compared to the number of ADR model simulation results, the station with the [D _0], and special expensive and the K _D value There is a feature that you can get it easily and quickly without the need for equipment.

Preferably, K _R is an _integer from 1 to 15 l / mg / min, and most preferably 13 l / mg / min.

The step of measuring the ozone decomposition rate constants [D ₀ ] and K _D by measuring the ozone concentrations [O ₃ ] ₀ and [O ₃ ] _i is performed through the central processing system in the ozone water treatment system . The numerical operation unit of the central processing system receives the above-mentioned real-time ozone concentration data and the like and compares the results with a plurality of ADR model simulation results, and conversely, the [D ₀ ] and K _D values can be obtained.

The distance L to the passage in the ozone contact tank is theoretically not limited, but may be, for example, 10 to 200 m, but is not limited thereto, for proper decomposition and disinfection of ozone.

Through the above process, reliable ozone decomposition rate constants [D ₀ ] and K _D that can be simulated according to the ADR model, which is somewhat difficult to implement but which can actually implement the actual ozone contact set, can be obtained.

In another aspect, the present invention provides a method of controlling the amount of ozone in the ozone water treatment system and calculating the ozone decomposition rate constant determined by the method of [D _0], and CT (ozone concentration × contact time) through the K _D value.

In this case, the value of CT (ozone concentration × contact time), and can be simulated in the ADR model according to Equation 1 through the ozone decomposition rate constant [D _0] and K _D obtained by the above method, ozone appears here And the concentration value is obtained by integrating up to the total contact time in the ozone contact tank. The total contact time in the ozone contact tank means the residence time of the treated water, which means the time from the moment the treated water flows into the passage through the inlet to the moment the treated water is finally discharged through the outlet, 1 < / RTI > These CT values are typically representative values indicating the ability to disinfect by the ozone contact bath.

The CT value can be easily obtained by appropriately simulating the ADR model by obtaining the above-described ozone decomposition rate constants [D ₀ ] and K _D , and those skilled in the art can easily understand it.

In the present invention, the ozone decomposition rate constants [D ₀ ] and K _D are determined through the numerical calculator, and the ADR model is simulated to calculate the CT value, and then the model predictive controller It is possible to automatically calculate the amount of ozone to be reached. More specifically, the model prediction control unit calculates an error of the CT value by subtracting a predetermined CT value set in advance from the calculated CT value, and calculates a treatment water concentration (C) capable of correcting the error of the calculated CT value And the ozone contact time (t) is multiplied by the calculated concentration (C) to obtain an ozone input amount. In the equation (1), [D ₀ ] and K _D are applied equally to the ozone contact tank as long as the inflow water quality is kept constant. Therefore, the ozone input concentration value ([O ₃ ] ₀ ) Can be calculated. It was confirmed that, in one embodiment of the present invention, the ozone decomposition rate constant determined according to the ozone input concentration value ([O ₃ ] ₀ ) is highly reliable even at the other flow rate Q.

Further, the present invention relates to a method for producing C. parvum the deactivation performance of the oocyst can be predicted. Through the ADR model predictive control method based on the numerical calculation described above, the C. parvum oocyst , that is, when CT is known, the deactivation rate of the microorganisms to be removed even if only the ozone decomposition rate constant value according to the water quality of the ozone contact inflow treatment water Can be accurately evaluated.

Specifically, when the desired sterilization rate is 2 log (99% inactivation ratio), a necessary CT value can be calculated according to Equation (2), which is an ADR model relating to the inactivation of C. parvum oocyst , The amount of ozone supplied can be adjusted to meet the CT value of C. parvum the deactivation of the oocyst can be easily and reliably controlled.

&Quot; (2) "

In the above equation, x, E, U, and [O ₃ ] are the same as in Equation 1, where N is the number density of the microorganisms and K _N is the inactivated secondary rate constant.

Further, the present invention can predict bromate production. This is because the C. parvum oocyst. The CT value according to the upper limit of bromate generation can be calculated according to the following equation (3), and the amount of ozone injected can be adjusted according to the desired CT value through the simulation. It is possible to control the generation of bromate easily and reliably.

&Quot; (3) "

Same as that of the above formula, x, E, U, [ O 3] is a formula (1) described above, and, [BrO _3] is bromo and formate concentration, k _BrO3 is a bromate generating first order rate constant.

There has been a problem that not only a cost and a complicated method are required but also the reliability is low in order to obtain the ozone decomposition rate constant in the conventional ozone contact tank. However, in the present invention, although the ozone concentration is measured at arbitrary several points in the ozone contact tank, it is possible to easily and reliably obtain the reliable ozone decomposition rate constant, and thereby to simulate the ADR model very close to the actual ozone contact tank have. Through the ADR model simulation, it is possible to easily control the desired CT value in the ozone water treatment system,C. parvum oocystAnd control of bromate generation can be realized with high reliability.

1 is a configuration diagram of an ozone water treatment system according to an embodiment of the present invention.
2 is a schematic diagram of an ozone contact tank according to an embodiment of the present invention.
3 is a schematic diagram of an MC-SFR system according to an embodiment of the present invention.
4 is a graph showing the tracer test results of the ADR model and the CSTR model in the ozone contact tank with the flow rate Q = 158,000 m ³ / day.
5 is a graph comparing the ozone concentration according to the K _R value varying between 0 and 15 / / mg / min at pH 8.0 and 25 캜 with experimental values.
6 is a graph showing the relationship between (a) the ADR model equation and the ozone concentration value measured by the ozone sensor, and (b) the initial input ozone concentration [O ₃ ] ₀ = 1.2 mg / l, the flow rate Q = 3,000 m ³ / And (b) the sum of squared residuals according to the finite element method with respect to [D ₀ ] and K _D.
7 is a graph showing the relationship between (a) the ADR model equation and the ozone concentration measured by the ozone sensor, and (b) the initial input ozone concentration [O ₃ ] ₀ = 0.85 mg / l, the flow rate Q = 1,760 m ³ / And (b) the sum of squared residuals according to the finite element method with respect to [D ₀ ] and K _D.
FIG. 8 is a graph showing a result of simulating an ADR model according to a change in flow rate when [O ₃ ] ₀ = 1.2 mg / liter.
9 is a graph showing a simulation result of an ADR model according to a change in flow rate when [O ₃ ] ₀ = 0.85 mg / l.
10 is a graph comparing the simulation results of the CSTR model and the ADR model when [O ₃ ] ₀ = 1.2 mg / l and [O ₃ ] ₀ = 0.85 mg / l.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited thereto.

Example  1: ozone in the ozone water treatment system Contact tank

A full scale ozone contact tank was designed, which was capable of treating the treated water by 350,000 m ³ / day and designed for a hydraulic retention time of 15.4 minutes. The data for each cell constituting the ozone contact tank and the flow direction of the treated water are shown in Table 1, and a schematic diagram of the ozone contact tank is shown in Fig. Ozone was injected at a concentration of 0.5 mg / l to 2.0 mg / l, which was injected into the treated water using a side-stream venturi injector (SVI). The ozone contact tank had a total length of 9.0 m and an inner diameter of 0.65 m. The sand-filtered treated water was put into the ozone contact tank.

Cell number first second third fourth Fifth sixth Seventh Eighth Volume (m ³ ) 87 87 459 164 164 164 164 362 Width (m) 3.5 3.5 18.2 14.4 14.4 14.4 14.4 14.4 Depth (m) 4.2 4.2 4.2 1.9 1.9 1.9 1.9 4.2 Height (m) 6 6 6 6 6 6 6 6 Flow direction ↑ ↓ ↑ ↓ ↔ ↔ ↔ ↔ ↔ ↔

Example  2: MC - SFR  Measurement of rate constant of ozone decomposition using system

In order to derive an experimental ozone decomposition rate constant value, it was derived through the MC-SFR system (Multi-Channel Stopped-Flow Reactor) shown in Fig. 3 below. The ozone decomposition rate constants thus obtained are close to constants for the batch reactor model and can not be used directly in the ADR model according to the present invention.

The treated water samples were prepared by sand filtration of water obtained from Paldang Dam on April 1, This was injected into the system, and the ozone decomposition rate constant was measured by combining the first-order differential equation and the measured ozone concentration data. Specifically, by regression analysis, the ln ([O _3]) for the measured ozone concentration linearly, was obtained [D _0] and K _D. Furthermore, K _R was able to determine the difference between the experimental value and the calculated ozone concentration according to the least squares method.

Furthermore, the MC-SFR system comprises six tubular reactors with different reaction times, and the flow in each tubular reactor is isolated during the reaction by a solenoid valve on either side of the reactor. The reacted ozone aqueous solution from each tubular reactor was mixed and analyzed with an Indigo reagent through a spectrophotometer to obtain the ozone decomposition rate constant for the batch reactor according to the above principle.

A total of 9 experiments were performed according to the three temperatures (5, 15 and 25 ° C respectively) and three pH values (6.0, 7.0 and 8.0, respectively), and the resulting ozone decomposition rate constants are shown in Table 2 below .

Temperature pH 6.0 pH 7.0 pH 8.0 K _D
1 / min D ₀
mg / l K _R
ℓ / mg / min K _D
1 / min D ₀
mg / l K _R
ℓ / mg / min K _D
1 / min D ₀
mg / l K _R
ℓ / mg / min 5 ℃ 0.024 0.16 0.971 0.038 0.10 1.918 0.047 0.17 1.439 15 ℃ 0.034 0.24 1.501 0.065 0.38 2.139 0.073 0.59 1.915 25 ℃ 0.054 0.48 2.238 0.112 0.68 2.572 0.152 0.84 9.000

Example  3: ozone with horizontal currents Contact  Analysis of hydraulic characteristics

In order to investigate the hydraulic characteristics of the ozone contact tank of Example 1, a tracer test was performed.

Tracer test was performed by injecting NaF which is harmless to the human body at the upper part of the passage channel, and the concentration of F ^- was measured by sampling the sample at the downstream point in time. After plotting these concentrations as non-dimensional, the differential equations corresponding to each model equation were solved using numerical analysis and fitted with experimental values.

The model equation is compared with the ADR model equation according to Equation 1 of the present invention mentioned above and the CSTR model equation conventionally used. The CSTR model equation is as follows.

Where E is the normalized concentration < RTI ID = 0.0 >

The results of the tracer test are shown in FIG. From the results of the Tracer test, it can be seen that the ozone contact group having the horizontal flow of the present invention is much closer to the ADR model than the CSTR model. Specifically, the ADR model is best when the dispersion number (d) value is 0.03 It was confirmed that they were matched.

The dispersion coefficient (E) of Equation (1) can be determined through the dispersion number (d) obtained as described above.

Example  4: ADR  In the model K _R ( Reduced ozone requirement Secondary rate constant ) Influence and determination of value

As mentioned earlier, the K _R value is a very difficult constant to obtain because it relates to a very rapid decrease in ozone demand that occurs immediately before ozone injection. However, if a uniform K _R value can be determined, more flexible and flexible simulation and control is possible.

First, to determine the K _R value, the experimental [D ₀ ] and K _D values measured at pH 8.0 and 25 ° C of Example 2 above, while varying the K _R in the range of 0-15 l / mg / min And compared with experimental data (ozone concentration over time).

The results are shown in Fig.

According to the result graph, the ozone concentration tended to decrease more rapidly as the K _R value increased. Furthermore, it was confirmed that when the K _R value was 13 ℓ / mg / min, the ozone concentration rapidly dropped from the first stage of ozone decomposition and the trend was in good agreement with the experimental data. Therefore, the desired K _R value for the batch reactor was determined to be 13 l / mg / min.

Furthermore, we analyzed the meaning of K _R in the ADR model, not the model for the batch reactor. This was done through sensitivity analysis.

Specifically, with the modified K _R value obtained in the second embodiment and the obtained K _R = 13 L / mg / min using the modified OCM software in which the ADR model formula and algorithm are input, Depending on the temperature (5, 15 and 25 ° C respectively) and the three pH values (6.0, 7.0 and 8.0 respectively), the CT value, ozone concentration, C. parvum deactivation of oocyst , and bromate generation were simulated. The results are shown in Table 3 below.

Temperature pH 6.0 pH 7.0 pH 8.0 experimental k _R k _R = 13 l / mg / min experimental k _R k _R = 13 l / mg / min experimental k _R k _R = 13 l / mg / min CT
(min · mgO ₃ / l) 5 ℃ 17.7 17.6 16.5 16.5 14.8 14.7 15 ℃ 15.4 15.3 11.0 11.0 8.5 8.4 25 ℃ 10.8 10.7 6.1 6.0 3.9 3.9 Ozone concentration
(mgO ₃ / l) 5 ℃ 0.92 0.92 0.77 0.77 0.64 0.65 15 ℃ 0.74 0.74 0.41 0.42 0.29 0.30 25 ℃ 0.44 0.44 0.15 0.15 0.07 0.07 C. parvum oocyst inactivation (log) 5 ℃ 1.01 1.01 0.95 0.95 0.85 0.85 15 ℃ 2.07 2.06 1.53 1.52 1.21 1.20 25 ℃ 3.36 3.34 2.01 2.01 1.62 1.62 Bromate generation
(Ug BrO < ₃ > ^- / l) 5 ℃ 1.94 1.94 2.66 2.66 2.93 2.93 15 ℃ 1.80 1.80 2.50 2.50 2.67 2.66 25 ℃ 1.92 1.92 1.98 1.98 2.30 2.30

Table 3 as the results shown in Example 2 CT values of the experimental data obtained through the K _R of the concentration of ozone, C. parvum Comparison of the results of simulated oocyst inactivation and bromate generation with that of uniformly determined K _R = 13 ℓ / mg / min reveals no significant difference, and therefore K _R needs to be strictly determined It is confirmed that the simulation can be performed reliably without the need for the simulation.

We further analyzed the sensitivity of K _R values through modified OCM software at pH 8.0 and 15 ° C. In the case of ozone input concentration [O ₃ ] ₀ = 1.5 mg / ℓ and flow rate Q = 150,000 m ³ / day, the experimental K _R value under the condition is 1.915 ℓ / mg / min. .

These experimental K _R values and the K _R values varied in the range of 0.600 to 13 L / mg / min are shown in Table 4 below.

k _R
ℓ / mg / min CT
min · mgO ₃ / ℓ %
Difference O ₃
mg / l %
Difference C. parvum oocyst inactivation (log) %
Difference BrO ₃ ^-
mg / l %
Difference 0.600 8.88 4.08 0.27 -6.31 1.25 3.11 2.71 1.43 0.900 8.70 1.89 0.28 -3.61 1.23 1.37 2.69 0.67 1.200 8.62 0.94 0.29 -1.91 1.22 0.66 2.68 0.33 1.500 8.57 0.42 0.29 -0.87 1.21 0.29 2.67 0.15 1.915 8.54 0.00 0.29 0.00 1.21 0.00 2.67 0.00 3.000 8.54 0.00 0.29 1.06 1.20 -0.36 2.66 -0.17 6.000 8.46 -0.92 0.30 1.95 1.20 -0.66 2.66 -0.32 9.000 8.45 -1.05 0.30 2.25 1.20 -0.76 2.66 -0.37 13,000 8.44 -1.14 0.30 2.43 1.20 -0.84 2.66 -0.40

As can be seen from the above results, the difference of the results obtained between experimentally obtained K _R = 1.915 ℓ / mg / min and uniformly determined K _R = 13 ℓ / mg / min was -1.14% _{), 2.43% (O 3)} , -0.84% (C. parvum oocyst ) and -0.40% (BrO ₃ ^- ), respectively.

As a result, through the above sensitivity analysis, the K _R has little effect on the simulation result through the ADR model, so it can be uniformly treated as a constant determined as a constant value, and the value is 13 L / mg / min was appropriate.

Example  5: Ozone In contact group  About ADR  Through the model, the ozone decomposition rate constant [ D ₀ ] And K _D Wanted

Using only the two ozone decomposition rate constants [D ₀ ] and K _{D in} Equation 1, which is an ADR model equation, using K _R = 13 ℓ / mg / min determined in Example 4, Simulation was performed.

Specifically, an ozone sensor was installed at three points in the ozone contact tank shown in Fig. 2, and the real-time ozone concentration obtained through the comparison was compared with the simulation curve of Equation 1 using the trial and error method while fitting. At this time, the initial guess values of [D ₀ ] and K _D for the simulation were the values of the ozone decomposition rate constants for the batch reactor using the MC-SFR system obtained in Example 2. [

Here, the finite element method was used to determine the final [D ₀ ] and K _D. The most suitable values [D ₀ ] and K _D are [D ₀ ] and K _D values when the sum of the difference between the experimental value and the predicted value by modeling is the smallest.

이 가장 작은 값이다(여기서 i는 유입구와 연결되는 통과수로의 상부를 0으로 놓고, i번째 센서까지의 모든 센서를 나타낸다). In other words,

Is the smallest value (where i represents zero for all of the sensors up to the i-th sensor, with the top of the pass waterway connected to the inlet port set to zero).

Fitting between the ozone concentration obtained through the above-described ozone sensor and the ADR model equation was performed in the case of the initial input ozone concentration [O ₃ ] ₀ = 1.2 mg / l, the flow rate Q = 3,000 m ³ / hr and the temperature 21 ° C , And the results are shown in Fig. 6, it can be seen that the value of m becomes minimum when K _D and [D ₀ ] are 0.12 min ^-1 and 0.4 mg / l, respectively, whereby the ozone decomposition rate constant [D ₀ ] and K _D was determined.

Fitting was carried out in the same manner also in the case of the initial input ozone concentration [O ₃ ] ₀ = 0.85 mg / l, the flow rate Q = 1,760 m ³ / hr and the temperature of 21 ° C, and the results are shown in FIG. 7, it can be seen that the value of m is minimized when K _D and [D ₀ ] are 0.102 min ^-1 and 0.02 mg / l, respectively, whereby ozone decomposition rate constants [D ₀ ] and K _D was determined.

Also, when [O ₃ ] ₀ = 1.2 mg / ℓ and [O ₃ ] ₀ = 0.85 mg / ℓ, the values of [D ₀ ] and K _D are applied as they are, The model was simulated. The simulation results are shown in Figs. 8 and 9, respectively.

As a result, it can be seen that the ozone decomposition rate constant is in good agreement with the measured ozone concentration in the actual sensor even if the flow rate is changed. That is, if the ozone decomposition rate constant is determined with respect to the initial injection concentration value [O ₃ ] ₀ , the simulation using the ozone decomposition rate constant can be highly reliable even if the flow rate fluctuates.

Example  6: Ozone In contact group  About ADR  Model and CSTR  Comparison of models

Through the tracer test of Example 3, it was confirmed that the ADR model is much more reliable than the CSTR model for the ozone contact tank of the present invention. More specifically, the differences between the K _D values and the CT values of the ozone decomposition primary rate constant were examined through comparison between these two simulations.

First, in the case of [O ₃ ] ₀ = 1.2 mg / l, the K _D value obtained through the conventional CSTR model is 0.142 min ^-1, but the corrected OCM software equipped with the ADR model formula in Example 4 The K _D value was 0.12 min ^-1 . Both of them showed a significant difference of about 16%. Furthermore, in the case of the CT value, the CT value obtained from the CSTR model simulation is 5.23 mg · min / ℓ, whereas the CT value obtained from the ADR model simulation is 6.53 mg · min / ℓ, which is about 20% I could.

Next, in the case of [O ₃ ] ₀ = 0.85 mg / l, the same comparison as above was carried out. If the K _D value, CSTR model and model ADR each of 0.0912 min ^-1 and 0.102 min ^{- 1} showed a difference of about 12%, and even if the CT value, CSTR model and model ADR each of 9.06 mg · min / ℓ And 8.11 mg · min / ℓ, respectively.

A comparison graph is shown in Fig.

In conclusion, in the case of the ozone contact tank of the present invention having a horizontal flow cereal, using the ADR model simulation is a means for enabling more reliable model control, and furthermore, since the conventional CSTR model records a significant error therebetween, And it was confirmed that the accuracy was significantly lowered.

Claims (6)

An inlet through which treated water flows;
An ozone input unit installed at the inlet to supply ozone to the treated water;
An ozone contact tank connected to the inlet and including a passage through which the treated water flows and forms a cereal;
Two or more ozone sensors provided at an arbitrary distance ( _Li ) of the passage channels in the ozone contact tank;
A discharge port through which the treated water passing through the ozone contact tank is discharged through the passage channel; And
A method for determining ozone rate decomposition constants [D ₀ ] and K _D by an ozone water treatment system including a central processing system for analyzing ozone concentration measured through the ozone sensor,
1) measuring the ozone concentration [O ₃ ] _i at the distance L _i by the ozone sensor; And
2) the central processing system, the ozone concentration in the inlet [O _{3] 0,} and the measured [O _3] by using a _i, to ozone degradation rate constant indicating the value of the equation m minimum value represented by the equation (1) [ D _0] and a method comprising the step of obtaining the K _D, the ozone decomposition rate constant to obtain a [D _0] and K _D:
[Equation 1]

Where m is the difference between the actual ozone concentration ([O ₃ ] _i ) at x = L _i corresponding to the i-th ozone sensor in Equation 1 and the ozone concentration ([O ₃ ] the square _{([O 3] - [O} 3] i) represents the sum of the ^two,
Wherein O is the dispersion coefficient, U is the flow rate of the treated water, [O ₃ ] is the ozone concentration, and K _R is a constant that is constantly determined as a secondary rate constant with reduced ozone demand.
The method of claim 1, wherein the initial estimated values of the ozone decomposition rate constant [D ₀ ] and K _D are experimental values obtained through an MC-SFR system.
The method of claim 1, wherein K _R is from 1 to 15 l / mg / min. < / RTI >
The method according to claim 1, wherein the ozone concentration [O ₃ ] ₀ of the inlet is 0.5 mg / l to 2.0 mg / l.
2. The method of claim 1, wherein the length of the passage channel is 10 to 200 m.
Claim 1 to claim 5 further comprising: measuring the concentration of ozone according to any one of items, comprising: a step of obtaining an ozone decomposition rate constant, via the central processing system to the calculated ozone decomposition rate constant [D _0] and K _D Calculating a value of CT (ozone concentration x contact time), and controlling an ozone input amount of the ozone water treatment system using the calculated CT value.

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