KR20180104413A - Oxygen control system for activated sludge process using harmony search algorithm - Google Patents

Abstract

An oxygen supply amount control system according to an embodiment of the present invention is an oxygen supply amount control system in an activated sludge process including a blower for supplying oxygen. The system comprises: a bioreactor into which sewage is introduced and oxidation, nitrification, and denitrification of organic matters occurs; an analyzing device for extracting an appropriate dissolved oxygen concentration using at least one data selected from a group consisting of an influent flow rate detected in the bioreactor, chemical oxygen demand (COD), dissolved oxygen (DO), water temperature and suspended solids (SS), and harmony search algorithm; and a control device for controlling the blower according to an appropriate dissolved oxygen concentration extracted from the analyzer.

Description

TECHNICAL FIELD The present invention relates to an oxygen supply control system for an activated sludge process using a harmonic search algorithm,

The present invention relates to an oxygen supply amount control system in an activated sludge process, and more particularly, to an oxygen supply amount control system in an activated sludge process using a harmony search algorithm in a wastewater treatment facility.

In the treatment of sewage, factory wastewater and livestock manure, an activated sludge process which treats organic substances in waste water and nutrients such as nitrogen and phosphorus by using aerobic microorganisms such as bacteria is widely used. A large amount of oxygen is required to remove organic substances and nutrients using the activated sludge process.

The amount of oxygen supplied varies depending on the activated sludge process, but is generally in the range of 1.0 to 2.0 kgO2 / kg BOD removal.

Oxygen supply for removing organics and nutrients has been used in the past to supply oxygen of high purity by using a pure oxygen generator, but it is rarely used recently due to high maintenance cost.

Therefore, most of the oxygen required for the activated sludge process is a method in which oxygen (about 21%) contained in the air is supplied in the form of dissolved oxygen (dissolved oxygen), which can be used as a metabolic reaction by microorganisms in water using a blower .

In order to remove organic matter and nutrients from aquatic organisms, dissolved oxygen is required. For this purpose, equipment such as a blower is required and the blower consumes a large amount of electric energy.

About 54 ~ 60% of the total power energy consumption required for sewage treatment facility operation is used for air supply (Aeration). In addition, according to the Ministry of Environment data in 2013, it is known that about 3% of the total power consumption of the country is used to operate water and sewage facilities.

Korea is the seventh largest producer of greenhouse gases, and the government is planning to reduce greenhouse gas emissions by about 37% by 2020.

For this reason, when the amount of energy used to supply the air for the activated sludge process in the wastewater treatment facility is reduced, there is an enormous economic benefit and a reduction effect of carbon dioxide, which is a greenhouse gas, can be expected.

The saturated oxygen saturation concentration in water changes with water temperature, and when the water temperature is lower, it becomes possible to maintain a high dissolved oxygen concentration even with a smaller amount of oxygen (at 10 ° C, saturated oxygen concentration is higher than 30 ° C 1.5 fold increase).

In the case of sewage treatment facilities which do not control the volume of air in the activated sludge process, the dissolved oxygen concentration in the bioreactor (aeration tank) is maintained as high as 4 ~ 6mg / L on average during the winter or when the influent water load decreases, In spring and autumn, where the influent load is relatively increased, it is often operated relatively low at 1 to 4 mg / L.

Typically, the optimal dissolved oxygen concentration required for organic material oxidation and nitrification is known to be about 2.0 mg / L (Biological Wastewater Treatment, Second Edition, Carlos D. Filipe, C. Leslie Grady, p.

However, excessive oxygen supply in the activated sludge process is a general phenomenon in domestic and overseas wastewater treatment facilities, and it is known that only a few cases where a proper oxygen supply control system is applied,

This is because the flow rate and the pollutant concentration flowing into the wastewater treatment facility change instantaneously, so that when the automated air amount control system is not used, the excessive amount of air must be injected at all times to enable operation without degrading the efficiency of the activated sludge process .

Various studies have been carried out on the method of appropriately injecting the oxygen supply amount necessary for the oxidation and nitrification of organic materials in the activated sludge process, but there are not many cases in which many effects have been obtained by practical use.

This is because the optimal oxygen demand for the activated sludge process is constantly changing in accordance with the water temperature, the concentration of the organic substance in the inflow water, and the condition of the bioreactor, and the control method of the blower in connection with the operation condition is not appropriate, management is difficult.

Various methods are used for controlling the oxygen supply amount for the operation of the activated sludge process, and it can be mainly divided into on-off control and blowing variable control. On-off control is a method that is used for a fan that can not control the oxygen supply rate variably.

In the case of variable control of air flow rate, it is possible to control the air flow rate variably by using a turbo blower installed in most domestic sewage treatment facilities. However, the optimum dissolved oxygen concentration for determining the air flow rate in many wastewater treatment facilities is not determined through experiments, It is often the case that the blowing amount is operated at about 90% or more of the maximum air flow rate without keeping the dissolved oxygen concentration at a high level of 2 to 5 mg / L.

Oxygen uptake rate (OUR) should be determined experimentally to determine the oxygen supply of the original activated sludge process. However, OUR experiments are rarely carried out because of problems such as time and site conditions.

In addition, even if the OUR test is performed, the influent wastewater changes dynamically. Therefore, it is not suitable to determine the blowing amount of the blower by only one or two measurements per day.

Korean Patent Publication No. 10-2007-0049751 (published May 15, 2007)

It is an object of the present invention to provide an oxygen supply amount control system capable of controlling an appropriate amount of oxygen supply required for organic matter removal and nitrification / denitrification in an activated sludge process.

The oxygen supply amount control system according to an embodiment of the present invention is an oxygen supply amount control system in an activated sludge process including an air blower for supplying oxygen. The oxygen supply amount control system includes a bioreactor in which wastewater flows into the bioreactor, An analyzing device for extracting an appropriate dissolved oxygen concentration of an activated sludge process using at least one or more data selected from the group consisting of chemical oxygen demand (COD), dissolved oxygen concentration (DO), water temperature and suspended solids concentration (SS) And a controller for controlling the blower in accordance with the optimum dissolved oxygen concentration extracted from the analyzer.

Here, the analyzing apparatus includes a database storing at least one data selected from the group including inflow flow rate, treated water chemical oxygen demand (COD), dissolved oxygen concentration (DO), water temperature and suspended solids concentration (SS) can do.

Here, the analyzer may include an operation unit for calculating an appropriate dissolved oxygen concentration using a harmony search algorithm.

The operation unit applies the data stored in the database to the activated sludge model to calculate total chemical oxygen demand (TCOD) information, total nitrogen information, average suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air), and biochemical oxygen demand (BOD).

Here, the operation unit can extract the optimum dissolved oxygen concentration satisfying the expression (6) in the expression (1).

[Equation 1]

&Quot; (2) "

&Quot; (3) "

&Quot; (4) "

&Quot; (5) "

&Quot; (6) "

And wherein, BOD _cal, TCOD _cal, TN _cal is processed can biochemical oxygen demand (BOD), total COD (TCOD), the total nitrogen concentration (TN) of the calculation in the arithmetic unit using the activated sludge model,

The BOD _guideline , the TCOD _guideline , and the TN _guideline are the design quality standards for BOD, TCOD, and TN effluent,

DO _cal is the calculated dissolved oxygen concentration, Air _cal is the calculated blower air mass, MLSS _cal is the calculated mean suspended solids concentration,

DO _min , DO _max are the maximum and minimum dissolved oxygen concentrations, Air _min and Air _max are the minimum and maximum blower volumes, MLSS _min and MLSS _max are the minimum and maximum average suspended particulate concentrations.

Here, the controller may perform proportional integral derivative control according to the input optimum dissolved oxygen concentration.

Here, the analysis apparatus may include a filtering unit for removing noise of data input from the bioreactor.

Here, the bioreactor may include a chemical oxygen demand (COD) meter, an influent flow meter, a suspended solids meter, a dissolved oxygen meter, and a thermometer.

The oxygen supply amount control method according to an embodiment of the present invention is a method of controlling the oxygen supply amount in an activated sludge process including a blower for satisfying an appropriate oxygen concentration realized by an oxygen supply amount control system, The method of claim 1, wherein the analyzing apparatus comprises at least one selected from the group consisting of inflow flow rate measured in the biological reactor, chemical oxygen demand (COD), dissolved oxygen concentration (DO), water temperature and suspended solids concentration (SS) The activated sludge model was applied to the above data to calculate total chemical oxygen demand (TCOD) information, total nitrogen concentration (TN) information, mean suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air) and biochemical oxygen demand (TOD) information, an average suspended solids concentration (MLSS), a dissolved oxygen concentration (DO), an amount of dissolved oxygen (DO) Extracting an optimum dissolved oxygen concentration satisfying Equation (1) and Equation (6) below, which is an objective function of the air and the biochemical oxygen demand (BOD) Calculating a required air blowing amount, and the control device controlling the blower in accordance with the required air blowing amount.

[Equation 1]

&Quot; (2) "

&Quot; (3) "

&Quot; (4) "

&Quot; (5) "

&Quot; (6) "

And wherein, BOD _cal, TCOD _cal, TN _cal is processed can biochemical oxygen demand (BOD), total COD (TCOD), the total nitrogen concentration (TN) of the calculation in the arithmetic unit using the activated sludge model,

The BOD _guideline , the TCOD _guideline , and the TN _guideline are the design quality standards for BOD, TCOD, and TN effluent,

DO _cal is the calculated dissolved oxygen concentration, Air _cal is the calculated blower air mass, MLSS _cal is the calculated mean suspended solids concentration,

DO _min , DO _max are the maximum and minimum dissolved oxygen concentrations, Air _min and Air _max are the minimum and maximum blower volumes, MLSS _min and MLSS _max are the minimum and maximum average suspended particulate concentrations.

If the objective function is not satisfied at the step of extracting the optimum dissolved oxygen concentration, the total chemical oxygen demand (TCOD) information, the total nitrogen concentration (TN) information, the average suspended solids concentration (MLSS) ), The blower air amount (Air), and the biochemical oxygen demand (BOD) are repeated to extract the optimum dissolved oxygen concentration satisfying the objective function.

According to the oxygen supply amount control system according to the embodiment of the present invention, energy consumption due to operation of the blower can be reduced by suppressing excessive oxygen supply in the water treatment facility.

In the activated sludge process anoxic tank, the nitrogen removal efficiency can be improved by minimizing the influence of the transport sludge dissolved oxygen.

In addition, cost and time can be saved in comparison with the existing OUR analysis method for the proper oxygen concentration analysis.

1 is a schematic view of an activated sludge process according to the present invention.
2 is a functional block diagram of a system for controlling the amount of oxygen supplied in an activated sludge process in accordance with an embodiment of the present invention.
3 is a detailed block diagram of a bioreactor according to an embodiment of the present invention.
4 is a detailed block diagram of an analysis apparatus according to an embodiment of the present invention.
5 is a chart for performing an activated sludge model according to an embodiment of the present invention.
6 is a flowchart illustrating a process of performing a general harmony search algorithm.
7 is a simulation result of a proper dissolved oxygen control of an actual sewage treatment facility bioreactor using the oxygen supply amount control system according to the embodiment of the present invention.
8 is a flowchart of a method of controlling the oxygen supply amount according to the embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It will be possible. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

The suffix "module "," block ", and "part" for components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, the oxygen supply amount control system in the activated sludge process according to the present invention will be described.

In this regard, Figure 1 is a schematic diagram of an activated sludge process according to the present invention.

Activated sludge is a sludge composed of naturally occurring mixed microorganisms involved in the treatment of sewage and wastewater. It differs from conventional sludge in that it has the ability to ingest and degrade organic and inorganic materials.

Aerobic bacteria group and mixed anaerobic bacteria group, and fungi and cyanobacteria coexist. Aerobic bacteria and fungi oxidize organic matter in water in the presence of dissolved oxygen to produce inorganic substances such as water, carbon gas and ammonia.

The thermophilic anaerobic bacteria group oxidizes or reduces the organic substances to produce organic acids and carbon dioxide gas. The anaerobic bacteria such as denitrifying bacteria take nitric acid breath and take oxygen from nitric acid and nitrite contained in sewage and wastewater and produce nitrogen gas. And simultaneously oxidizes and decomposes organic matter.

As such, activated sludge coexists with heterotrophic bacteria that acquire the basic energy needed to survive by oxidizing and reducing organic matter, and autotrophic bacteria that produce energy by oxidizing minerals.

The activated sludge process refers to the process of purifying wastewater through the process of coagulation while repeating aeration and precipitation. The precipitate formed in this process is activated sludge.

As shown in FIG. 1, the treated water flows into the first sedimentation tank, and some of the sludge contained in the treated water flowing into the first sedimentation tank is filtered and separated into the digestion tank.

The bioreactor is a tank which is the center of the activated sludge process. When the first settling tank treated water flows into the bioreactor, it is mixed with the activated sludge and oxygen is supplied to oxidize the organic and inorganic substances contained in the treated water. Dissolved oxygen is a very important factor to promote the oxidation of organic matter and minerals in bioreactors.

The sediment produced in the bioreactor causes sedimentation in the second sedimentation tank, some of the sludge that is filtered in the second sedimentation tank is filtered by surplus sludge, and some of the sludge is supplied to the bioreactor by the return sludge, .

2 is a functional block diagram of a system for controlling the amount of oxygen supplied in an activated sludge process in accordance with an embodiment of the present invention.

As shown in FIG. 2, the system for controlling the oxygen supply amount in the activated sludge process according to the embodiment of the present invention includes a bioreactor 100 in which treated water flows into the activated sludge reaction, (200) for extracting an appropriate dissolved oxygen concentration using at least one data selected from the group consisting of a flow rate, a chemical oxygen demand (COD), a dissolved oxygen (DO), a water temperature and a suspended solids concentration (SS) And a control device 300 for controlling the blower according to an appropriate dissolved oxygen concentration extracted from the analyzer 200.

3 is a detailed block diagram of a bioreactor according to an embodiment of the present invention.

The bioreactor 100 is a tank for decomposing organic and inorganic substances by microorganisms, as described above. 3, the bioreactor according to an embodiment of the present invention includes a blower 110 for supplying oxygen, a chemical oxygen demand meter 120, an influent flow meter 130, a suspended solids meter 140, An oxygen system 150 and a thermometer 160.

The chemical oxygen demand measuring system 120 is an apparatus for measuring the amount of oxygen consumed in oxidizing and decomposing pollutants such as organic substances contained in treated water by oxidizing agents.

Organics, nitrites, ferrous salts, sulfides, etc. contained in water consume oxygen dissolved in water. When these substances are contained in a lot, oxygen in water disappears and becomes contaminated water. When an aqueous solution of potassium permanganate or potassium dichromate is added to water containing such an organic substance as an oxidizing agent, the organic substance is oxidized. The amount of oxygen corresponding to the amount of oxidizing agent written at this time is referred to as the COD value and expressed in ppm or mg / l.

The chemical oxygen demand meter 120 according to an embodiment of the present invention may be UV254, but is not necessarily limited thereto. UV254 is a device for indirectly measuring COD, which is a chemical oxygen demand, by using the absorbance of ultraviolet ray having a wavelength of 254 nm.

The inflow flow meter 130 is a device for measuring in real time the amount of the sedimentation treatment water flowing into the bioreactor 100. By measuring the flow rate of the incoming sedimentation treatment water, it can be used to calculate the mass balance equation of the bioreactor activated sludge model.

The suspended solids meter 140 is an apparatus called an SS meter, which measures the amount of suspended solids (SS) in the treated water.

The dissolved oxygen system 150 is a machine for measuring the amount of oxygen dissolved in water. The automatic measurement of dissolved oxygen has a diaphragm oxygen electrode method. It is a principle to detect dissolved oxygen by measuring the signal of oxygen diffusing in the solution through the diaphragm by placing an electrode coated with a permeable film such as polyethylene in electrolyte solution. The dissolved oxygen system 150 has an electronic and polarographic detection system.

The thermometer 160 measures the water temperature of the treated water. Generally, the dissolved oxygen concentration of the bioreactor 100 is maintained as 4 to 6 mg / l during the winter and when the load is decreased, and is kept as low as 1 to 4 mg / l during the rise of the water temperature or the inflow load There are many cases.

4 is a detailed block diagram of an analysis apparatus according to an embodiment of the present invention.

As shown in FIG. 4, the analysis apparatus 200 according to an embodiment of the present invention includes an influent flow rate, a chemical oxygen demand (COD), a dissolved oxygen concentration (DO), a water temperature, and a suspended solids concentration (SS) A database 210 for storing at least one or more data selected from the group consisting of the selected oxygen concentration data, and an operation unit 220 for calculating an appropriate dissolved oxygen concentration using a harmony search algorithm. The analyzer 200 further includes a filtering unit 230 for removing noise of data input from the bioreactor.

As shown in FIG. 3, information measured in various measuring instruments included in the biological reaction tank 100 is stored in the database 210 after the noise is removed from the filtering unit 230. The information stored in the database 210 is measurement information measured in real time and extracts an appropriate dissolved oxygen concentration using the measurement information stored in the database 210. [

The operation unit 220 calculates the optimum dissolved oxygen concentration using a harmony search algorithm. To apply the harmony search algorithm, the operation unit 220 applies the data stored in the database 210 to the activated sludge model to calculate the chemical oxygen of the total activated sludge process water Total Chemical Oxygen Demand (TCOD) information, total nitrogen information and average suspended solids concentration (MLSS) are calculated first.

The activated sludge model is a mathematical model for calculating BOD, TSS, TN, and MLSS in activated sludge process water.

5 is a chart for performing an activated sludge model according to an embodiment of the present invention.

The activation sludge model shown in FIG. 5 leads to an expression related to the dissolved and particulate COD (TCOD) and total nitrogen concentration (TN) of the activated sludge process.

Equation 1 and Equation 2 below are for total chemical oxygen demand (TCOD) information and total nitrogen concentration (TN) information, respectively.

[Equation 1]

TCOD = S _s + S _i + X _s + X _bh + X _ba + X _I + X _p

&Quot; (2) "

S = S + _na + _nh TN S S + _ni + _{nd nd} + X X _ni

Here, S _s is the concentration of biodegradable substrate (Readily biodegradable substrate, mg / L)

S _i is the concentration of inert organic solvent (mg / L),

X _s is the biodegradable particulate organic matter (mg / L),

X _i is the inert particulate organic matter (mg / L),

X _bh is the heterotrophic biomass (mg / L, assume zero in the raw wastewater),

X _ba is the autotrophic biomass (mg / L, assumed zero in the raw wastewater),

X _p is inert particulate products (mg / L, assume zero in the raw wastewater),

S _nd is a soluble biodegradable organic nitrogen,

S _ni is a soluble nonbiodegradable organic nitrogen,

X _nd is particulate biodegradable organic nitrogen,

X _ni is particulate nonbiodegradable organic nitrogen.

FIG via a state variable, _{S s, S i, X s} , X i, X bh, X ba, X p, S nd, S ni, X nd, X ni calculated using the activated sludge model illustrated in Figure 5 The total chemical oxygen demand (TCOD) information and the total nitrogen concentration (TN) information, which are synthetic parameters, are expressed by Equations (1) and (2).

In the activated sludge model shown in FIG. 5, the dissolved oxygen concentration required through the change in the total chemical oxygen demand and the total nitrogen concentration is calculated using the table in FIG.

The mean suspended solids concentration (MLSS) is calculated by the following equation (3).

&Quot; (3) "

MLSS = (X _s + X _I + X _bh + X _ba + X _p ) x f _ss

Here, f _ss is a coefficient for switching the COD to SS.

Using the result obtained through the activated sludge model and the measurement information stored in the database 210, the operation unit 220 calculates the optimum dissolved oxygen concentration using the harmony search algorithm.

6 is a flowchart illustrating a process of performing a general harmony search algorithm.

The Harmony Search algorithm is an example of a meta-heuristic optimization algorithm that imitates improvisation in music by default and starts from a randomly generated solution set and leads to an optimal solution through local search and reverse search. In other words, when various musical instruments make a harmonic of a sound, the various sounds from each musical instrument produce a harmonic, and there may be harmonic chords or dissonance in each harmonic. Through the practice, each dissonance gradually disappears, and there will be the most beautiful chord (global optimum) among the chords (local optimum) that can be used as a chord, and it can be constituted through repetitive practice. The harmonic search algorithm is a technique to set the optimum harmonic that is found through the exercise process (iterative calculation) to the optimal solution to find.

The parameters of the harmonic search algorithm are HM (Harmony Memory), HMCR (Harmony Memory Considering Rate), PAR (Pitch Adjusting Rate) and BW (bandwidth).

In the present invention, in order to find the minimum dissolved oxygen concentration satisfying BOD, COD and TN concentrations of the activated sludge process effluent, which is an objective function at the time of influent sewage load and water temperature change, HMS is set to be in the range of 1,000 to 1,200, HMCR in the range of 0.8 to 1.0 , PAR 0.05-0.2 and BW can be set to 0, and the set parameters can be adjusted within the ranges shown according to the concentration of the inflow organic material and nitrogen.

The proposed parameter range is the value for finding the global optimum in the earliest time of the minimum dissolved oxygen concentration. These parameters are values obtained empirically through field experiments, and operations are performed according to the procedure shown in FIG. 6 using these values. These calculations are performed by using a computer program. After starting HMM, HMM, PAR, and BW values are evaluated after evaluating the initial fitness. Here, the BW value is used without changing to a constant. This process is repeated until the dissolved oxygen concentration satisfying the water quality criterion of the effluent water as the objective function is found, and it is usually repeated 100 times to 500 times.

In order to evaluate the optimum dissolved oxygen concentration of the activated sludge process in the oxygen supply amount control system according to the embodiment of the present invention, the objective function of the harmony search algorithm as shown in the following equations (4) to (9) is utilized.

&Quot; (4) "

&Quot; (5) "

&Quot; (6) "

&Quot; (7) "

&Quot; (8) "

&Quot; (9) "

(BOD), total chemical oxygen demand (TCOD), and total nitrogen concentration (TN) of the treated water calculated by the operation unit are BOD _cal , TCOD _cal and TN _cal ,

The BOD _guideline , the TCOD _guideline , and the TN _guideline are the design quality standards for BOD, TCOD, and TN effluent,

DO _cal is the calculated dissolved oxygen concentration, Air _cal is the calculated blower air mass, MLSS _cal is the calculated mean suspended solids concentration,

DO _min , DO _max are the maximum and minimum dissolved oxygen concentrations, Air _min and Air _max are the minimum and maximum blower volumes, MLSS _min and MLSS _max are the minimum and maximum average suspended particulate concentrations.

Also, the biochemical oxygen demand, BOD, can be calculated through the dissolved oxygen concentration.

The minimum and maximum blowing amount of the blower can be determined by checking the specifications of the blower 110 installed in the biological reactor 100. For the minimum and maximum average suspended solids concentrations of ₂ 0 A method and SBR formulations main process (process mainstream) for 2000 ~ 3000mg / L, MBR method is 8000 ~ 12000mg / L.

The minimum and maximum dissolved oxygen concentrations may be between 0.5 and 3.0 mg / L, depending on the sewage treatment method employed.

In order to determine the optimum dissolved oxygen concentration in the oxygen supply amount control system according to the embodiment of the present invention, the harmony search algorithm described above is used. The operation unit 220 of the present invention finds the optimal dissolved oxygen concentration by repeating the harmony search algorithm 100 to 500 times.

In summary, in most cases, it is intended to efficiently deliver the target oxygen supply amount, whereas the present invention is characterized in finding the target optimum dissolved oxygen concentration.

That is, as described above, the oxygen concentration is feedback-controlled through OUR (oxygen uptake rate) or discharged water quality measurement. In contrast, the present invention utilizes the existing technology to find the target dissolved oxygen concentration There is a difference in achieving.

It is one of the characteristics of the present invention that the optimum oxygen concentration is determined to achieve the goal of the optimization of the amount of air in the activated sludge process.

In this way, the process of controlling the blower air volume using the optimization algorithm, which is the harmony search algorithm applied according to the embodiment of the present invention, can be performed as shown in FIG.

Once air volume control is initiated, the operator sets the influent water quality, treated water quality, pump control capacity range, and MLSS operating conditions in the controller and collects flow, COD, TN and water temperature information from the instrument.

Using the collected information, the target dissolved oxygen concentration is determined using a harmony search algorithm, and the value is set as a set-point value of the air flow rate control device.

The process up to this point allows the driver to set the dissolved oxygen target on a daily or weekly basis. This reduces the operator burden because the target dissolved oxygen concentration is not set in real time and can be less sensitive to instrument error for automatic control.

This is because the optimum dissolved oxygen concentration in the activated sludge process changes in units of time, but the optimal dissolved oxygen range is within 0.2-0.5 mg / L. That is, since the optimum dissolved oxygen concentration changes when the inflow water amount or the water temperature change occurs, it is not necessary to set the target dissolved oxygen concentration setting in units of time.

Generally, the influent sewage concentration changes by time, but the reason is that it is not necessary to set the optimum dissolved oxygen concentration per unit of time since the biological treatment method has a hydraulic retention time and a solids retention time of several hours to several days. Of course, it is possible to save more energy than setting the target dissolved oxygen concentration in units of time, but there may not be much difference from the practical point of view.

The analyzer 200 transmits the optimum dissolved oxygen concentration to the controller 300 that controls the blower 110 when the optimal dissolved oxygen concentration calculated through the calculator 220 of the analyzer 200 is determined.

The control device 300 controls the blower 110 by performing proportional integral derivative control according to the input optimum dissolved oxygen concentration.

FIG. 7 is a simulation program screen and simulation results for determining the optimum dissolved oxygen of an actual sewage treatment facility bioreactor using the oxygen supply amount control system according to the embodiment of the present invention.

The sewage treatment facility shown in FIG. 7 is a medium-scale sewage treatment facility having a daily average inflow amount of 110,000 m ³ / day, and is operated by the A ₂ O method and the MLE method. The sludge treatment facility consists of concentration, digestion, and dehydration processes, and treats the untreated water into the geyser. The sewage treatment facility shown in FIG. 7 is operated by a PLC (programmable logic controller), and the blower can be automatically controlled in a central control room.

By using the activated sludge model and the harmony search algorithm according to the embodiment of the present invention, an actual sewage treatment facility is configured to control the optimum dissolved oxygen concentration of the activated sludge bioreactor once an hour.

Item Total volume of ventilation in the activated sludge process (capacity 110,000 m ³ / day)
unit April to June (before control) July to September (after control) m ³ / min
m ³ / h m ³ / min m ³ / h Average 514.9 30,896 429.3 25,756 maximum 528.9 31,736 438.5 26,310 at least 472.9 28,372 408.5 24,507

According to Table 1, as a result of controlling the volume of air to the actual sewage treatment facility, it can be confirmed that the average amount of air flow was reduced by 16.7% in July ~ September 2016 compared with April ~ June 2016.

(Unit: mg / L) Item BOD TSS T-N T-P unit In May August In May August In May August In May August Average 1.1 1.1 0.8 1.6 9.5 7.8 0.22 0.15 maximum 1.6 1.5 1.7 8.7 10.8 9.2 0.30 0.43 at least 0.8 0.8 0.3 0.3 6.2 6.9 0.12 0.08

* Design water quality: BOD 5 mg / L, TSS 15 mg / L, T? N 15 mg / L, TP 0.5 mg / L

According to Table 2, after the average wind volume has been reduced by about 16.7%, the quality of the treated water is below the design quality. The TSS of treated water increased slightly compared with May, but the average was 1.6mg / L, which is very good, and T-N and T-P showed improved treatment quality. This is because simultaneous denitrification rate improvement in the aerobic tank and reduction of dissolved oxygen in the transport sludge reduced the effect of dissolved oxygen in the anoxic tank.

As a result, according to the oxygen supply amount control system according to the embodiment of the present invention, the air blowing amount of the blower was reduced by 16.7% on the average during the three months of the blowing amount control, and the amount of power was reduced by 8.1% .

Air volume was reduced, but the quality of treated water was somewhat improved. This means that proper airflow control can help improve not only energy efficiency but also water quality.

8 is a flowchart of a method of controlling the oxygen supply amount according to the embodiment of the present invention.

The oxygen supply amount control method according to another aspect of the present invention is a method for controlling an oxygen supply amount in an activated sludge process including a blower for supplying oxygen, which is implemented by an oxygen supply amount control system, (S100), the analyzer calculates at least one of the flow rate of the treated water measured in the biological reactor, the chemical oxygen demand (COD), the dissolved oxygen concentration (DO), the water temperature and the suspended solids concentration The activated sludge model is applied to one or more data to determine total chemical oxygen demand (TCOD) information, total nitrogen concentration (TN), mean suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air), and biochemical oxygen demand (BOD) (S200), the analyzer calculates the total chemical oxygen demand (TCOD) information, the total nitrogen concentration (TN) information, the average suspended solids concentration (MLSS), the dissolved oxygen concentration (DO) (Step S300) of extracting an appropriate dissolved oxygen concentration satisfying the formula (9) in the above-mentioned equation (4), which is an objective function of the dissolved oxygen concentration (Air) and the biochemical oxygen demand (BOD) (S400) of calculating the required blowing amount according to the concentration, and the control device includes a step (S500) of controlling the blower according to the required blowing amount.

Explanations of the configuration and contents overlapping with those of the foregoing embodiment, particularly the description of the objective function for Equations (4) to (9), are omitted.

The step S100 of inputting the objective function set value receives the target water quality range according to the water quality standards of the biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total nitrogen concentration (TN) of the treated water. In addition, the minimum and maximum blowing amount of the blower can be determined by checking the specification of the blower 110 installed in the biological reaction tank 100. The minimum and maximum mean suspended solids concentrations may be 2000 to 3000 mg / L for the mainstream process, A ₂ 0 process and SBR process, and 8000 to 12000 mg / L for MBR process.

The minimum and maximum dissolved oxygen concentrations may be between 0.5 and 3.0 mg / L, depending on the sewage treatment method employed.

Wherein the analyzer is operative to determine at least one of at least one data selected from the group consisting of influent flow rate of treated water measured in the biological reactor, COD (chemical oxygen demand), dissolved oxygen concentration (DO), water temperature and suspended solids concentration The sludge model was applied to calculate total chemical oxygen demand (TCOD) information, total nitrogen concentration (TN) information, mean suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air) and biochemical oxygen demand (BOD) In operation S200, measurement information measured in real time by the measurement data is stored in a database, and total chemical oxygen demand (TCOD) information, total nitrogen concentration (TN) information for applying the measurement function to the objective function, The average suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air) and biochemical oxygen demand (BOD) are calculated by applying the activated sludge model.

The analyzer is configured to measure the total chemical oxygen demand (TCOD) information, the total nitrogen concentration (TN) information, the mean suspended solids concentration (MLSS), the dissolved oxygen concentration (DO), the blower air volume (Air), and the biochemical oxygen demand The step S300 of extracting the optimum dissolved oxygen concentration satisfying the above-described objective functions (Equation 4) to (Equation 9) includes the total chemical oxygen demand (TCOD) information calculated through the activated sludge model, (TN) information, average suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air), and biochemical oxygen demand (BOD) are used as the objective function of the harmony search algorithm. 9] is satisfied, the appropriate dissolved oxygen concentration is extracted, and the necessary blowing amount according to the optimum dissolved oxygen concentration is calculated (S400), and the blower is controlled according to the required blowing amount (S500).

If the objective function is not satisfied, the activated sludge model is applied to calculate the total chemical oxygen demand (TCOD) information, total nitrogen concentration (TN) information, mean suspended solids concentration (MLSS), dissolved oxygen concentration (DO) ) And the biochemical oxygen demand (BOD) are repeated to extract the optimum dissolved oxygen concentration satisfying the objective function.

In addition, by controlling the blower in accordance with the optimum dissolved oxygen concentration, when the dissolved oxygen concentration of the treated water reaches the appropriate dissolved oxygen concentration, the total chemical amount for the application of the objective function using the activated sludge model (TOD) information, total suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air), and biochemical oxygen demand (BOD) Dissolved oxygen concentration is extracted. By repeating this process, a method of controlling the blower by extracting the optimized optimum dissolved oxygen concentration can be implemented.

100 bioreactor
110 blower
120 Chemical oxygen demand meter
130 Inflow Flow Meter
140 Floating Material Meter
150 dissolved oxygen meter
160 Thermometers
200 Analyzer
210 Database
220 operation unit
230 filtering unit
300 control device

Claims (10)

An oxygen supply amount control system in an activated sludge process including an oxygen-
A bioreactor into which sewage is introduced to cause organic matter oxidation, nitrification and denitrification;
(COD), dissolved oxygen concentration (DO), water temperature and suspended solids concentration (SS) of the treated water detected in the biological reaction tank and using the at least one data selected from the group consisting of the appropriate dissolved An analyzer for extracting oxygen concentration; And
And a control device for controlling the blower in accordance with an appropriate dissolved oxygen concentration extracted from the analyzer. The method according to claim 1,
The analysis apparatus includes a database storing at least one data selected from the group including inflow flow rate of treated water, chemical oxygen demand (COD), dissolved oxygen concentration (DO), water temperature and suspended solids concentration (SS) And the oxygen supply amount control system. 3. The method of claim 2,
Wherein the analyzer comprises an operation unit for calculating an appropriate dissolved oxygen concentration using a harmony search algorithm. The method of claim 3,
The operation unit applies the data stored in the database to the activated sludge model to calculate total chemical oxygen demand (TCOD) information, total nitrogen information, average suspended solids concentration (MLSS), dissolved oxygen concentration (DO ), A blower air amount (Air), and a biochemical oxygen demand (BOD). 5. The method of claim 4,
Wherein the operation unit extracts an optimum dissolved oxygen concentration satisfying the following formula (1) using the harmony search algorithm and the activated sludge model.
[Equation 1]

&Quot; (2) "

&Quot; (3) "

&Quot; (4) "

&Quot; (5) "

&Quot; (6) "

And wherein, BOD _cal, TCOD _cal, TN _cal is processed can biochemical oxygen demand (BOD), total COD (TCOD), the total nitrogen concentration (TN) of the calculation in the arithmetic unit using the activated sludge model,
The BOD _guideline , the TCOD _guideline , and the TN _guideline are the design quality standards for BOD, TCOD, and TN effluent,
DO _cal is the calculated dissolved oxygen concentration, Air _cal is the calculated blower air mass, MLSS _cal is the calculated mean suspended solids concentration,
DO _min , DO _max are the maximum and minimum dissolved oxygen concentrations, Air _min and Air _max are the minimum and maximum blower volumes, MLSS _min and MLSS _max are the minimum and maximum mean suspended solids concentrations, respectively. The method according to claim 1,
Wherein the control device performs proportional integral derivative control according to the input optimum dissolved oxygen concentration. The method according to claim 1,
Wherein the analysis device further comprises a filtering unit for removing noise of data inputted from the biological reaction tank. The method according to claim 1,
Wherein the bioreactor includes a chemical oxygen demand (COD) meter, an influent flow meter, a suspended solids meter, a dissolved oxygen meter, and a thermometer. A method for controlling an oxygen supply amount in an activated sludge process including an oxygen-fed blower implemented by the oxygen supply amount control system of claim 1,
(a) receiving an objective function set value by an analyzing apparatus;
(b) at least one selected from the group consisting of an influent flow rate of the treated water measured in the biological reactor, a chemical oxygen demand (COD), a dissolved oxygen concentration (DO), a water temperature and a suspended solids concentration (SS) The data were applied to the activated sludge model to determine total chemical oxygen demand (TCOD) information, total nitrogen concentration (TN), mean suspended solids concentration (MLSS), dissolved oxygen concentration (DO), blower air volume (Air) and biochemical oxygen demand );
(c) The analyzer is configured to measure the total chemical oxygen demand (TCOD) information, the total nitrogen concentration (TN) information, the mean suspended solids concentration (MLSS), the dissolved oxygen concentration (DO), the blower air volume (Air) BOD) extracting an optimum dissolved oxygen concentration that satisfies the following formula (1), which is an objective function, using Equation (6), using the harmony search algorithm and the activated sludge model;
(d) the controller calculates a required blowing amount according to the optimum dissolved oxygen concentration; And
(e) The control device controls the blower in accordance with the required blowing amount.
[Equation 1]

&Quot; (2) "

&Quot; (3) "

&Quot; (4) "

&Quot; (5) "

&Quot; (6) "

And wherein, BOD _cal, TCOD _cal, TN _cal is processed can biochemical oxygen demand (BOD), total COD (TCOD), the total nitrogen concentration (TN) of the calculation in the arithmetic unit using the activated sludge model,
The BOD _guideline , the TCOD _guideline , and the TN _guideline are the design quality standards for BOD, TCOD, and TN effluent,
DO _cal is the calculated dissolved oxygen concentration, Air _cal is the calculated blower air mass, MLSS _cal is the calculated mean suspended solids concentration,
DO _min , DO _max are the maximum and minimum dissolved oxygen concentrations, Air _min and Air _max are the minimum and maximum blower volumes, MLSS _min and MLSS _max are the minimum and maximum mean suspended solids concentrations, respectively. 10. The method of claim 9,
Wherein if the objective function is not satisfied in the step (c), the optimal dissolved oxygen concentration satisfying the objective function of the step (c) is extracted by repeating the step (b).

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