KR102239139B1 - water treatment method and apparatus for sequencing bath reactor using specific oxygen uptake rate of microbial - Google Patents

Abstract

A water treatment method for a sequencing bath reactor using specific oxygen uptake rate of microorganisms, and a water treatment apparatus for a sequencing bath reactor using the same. More specifically, the present invention relates to water treatment method for a sequencing bath reactor using specific oxygen uptake rate of microorganisms, and a water treatment apparatus for a sequencing bath reactor using the same, which can suppress the proliferation of filamentous bacteria and control the supply of excessive oxygen through an immediate and active response by quantifying and using the specific oxygen uptake rate of microorganisms, and predicting the state and processing efficiency of the microorganisms.

Description

A batch-type water treatment method using the non-oxygen consumption rate of microorganisms and a batch-type water treatment apparatus using the same

The present invention relates to a batch-type water treatment method using the non-oxygen consumption rate of microorganisms and a batch-type water treatment apparatus using the same, and more particularly, to quantify the specific oxygen uptake rate of microorganisms and use it to determine the state of the microorganisms and The present invention relates to a batch type water treatment method capable of controlling the growth of filamentous bacteria and controlling excessive oxygen supply through an immediate and active response by predicting treatment efficiency, and a batch type water treatment apparatus using the same.

Environmental pollution, especially water pollution, is emerging as a very serious problem due to rapid industrial development, population growth, and urban concentration. Moreover, as the inflow of nitrogen and phosphorus, which are nutrients seriously emerging as one of the main pollutants of rivers and lakes, increases, the water quality of water sources such as lakes and rivers is rapidly deteriorating due to drought and abnormal temperature. These problems destroy the aquatic ecosystem, reduce the utilization value of water resources, and cause economic and social problems in many ways.

Sewage and wastewater flowing into the sewage treatment plant typically contain organic matter (BOD), total nitrogen (T-N), and total phosphorus (T-P) as representative pollutants, and other substances such as heavy metals, E. coli, and oil. In order to treat the main pollutants such as organic matter, nitrogen, and phosphorus, activated sludge method including anaerobic, oxygen-free and aerobic processes has been used for a long time.

As a type of activated sludge method for treating pollutants, a Sequencing Bath Reactor (SBR) treatment method in which organic matter, nitrogen, and phosphorus are treated while repeating aeration and non-aeration conditions in one reactor is widely used. As such a batch type water treatment system, Korean Patent Registration No. 10-0873416 and Korean Utility Model Registration No. 20-0361460 are disclosed.

The batch type treatment method is a method of converting the spatial concept of the conventional activated sludge method into a time concept by applying a measuring equipment and an automatic control system, and treating it by repetitive processes of inflow, reaction, precipitation, and discharge in a single reaction tank. This process is performed by an automatic control device. Since the treatment process is carried out in one reaction tank, the operation is simple and the treatment efficiency is high. Nitrogen and phosphorus along with organic matter can be removed by microorganisms in the process of repeating the aeration and non-aeration processes in the reaction tank.

Bacteria, which play the most important role among microorganisms contained in activated sludge, can be divided into floc-forming bacteria and dispersion-proliferating bacteria according to the floc formation standard in which microorganisms and various substances are mixed. It can be divided into bacillus, spiralum, and filamentos bacterium.

Bacteria mainly involved in the removal of organic matter among pollutants are heterothrophic, circular-shaped cocci and short rod-shaped bacillus.

And bacteria mainly involved in nitrogen removal are autothrophic bacteria such as Nitrosomonas and Nitrobacter, which nitrify ammonia nitrogen, and Pseudomonas, which is a Gram-negative bacteria that converts nitrified nitrate into nitrogen gas. Pseudomonas), Bacillus (Bacillus) and other heterotrophic bacteria. Bacteria involved in such denitrification are aerobic anaerobic bacteria that metabolize using dissolved oxygen under aerobic conditions, but live by using bound oxygen such as _{NO -3} and NO _{-2 in anoxic condition.}

In addition, the bacteria involved in phosphorus removal are the same as heterothrophic bacteria involved in the removal of organic matter, but in particular polyphosphate accumulating organisms (PAO) such as Acinetobacter are repeated in aerobic and anaerobic conditions. It is removed by inducing excessive intake of phosphorus by exposing it. PAO releases phosphorus under anaerobic conditions and stores excess phosphorus in the cells of microorganisms under aerobic conditions. At this time, it decomposes PHB to synthesize ATP, and at this time, excessive amounts of phosphate (PO ₄ -P, soluble phosphate) are synthesized from the solution. ) Is synthesized into Poly-P after Phosphorus uptake and stored in cells.

In the process of removing contaminated substances by using microorganisms as described above, microorganisms that occur and proliferate in activated sludge are so diverse that only bacteria, which play an important role in removing contaminants, cannot be separated and proliferated. Filamentos bacterium, which partially proliferate in this proliferation process, are multicellular bacteria of a peculiar form in which cells are connected in a filament shape, and when excessive proliferation worsens the sedimentation of microbial flocs, resulting in a mixture of microbial sludge and treated water. In the sedimentation process for the separation of the mixed solution of, it does not precipitate or it takes a long time for precipitation. If bulking occurs due to the proliferation of such excessive filamentous bacteria, sludge sedimentation is poor and sludge is not condensed, so sludge is lost to the effluent water, exceeding the discharged water quality standard, and the moisture content of the sludge increases, causing sludge dewatering problems, etc. It is necessary to accurately understand the factors that affect the growth of filamentous bacteria and the factors that affect the growth of filamentous bacteria, as it causes an important problem that is directly related to the treatment efficiency.

The causes of the growth of Filamentos bacterium in sewage treatment facilities are very diverse. Representative causes can be attributed to low load of organic matter (F/M ratio), low DO concentration, corruption of raw water, deficiency of nutrients (N,P), and low pH. The mechanism by which these filamentous fungi grow can be explained by the A/V (Area/Volume) value. Bacteria take in nutrients through cells. Therefore, the larger the surface area compared to the cell volume, the faster the bacterial metabolism activity is. There are spherical, rod-shaped, spiral, and filamentous bodies in the form of cells, and among them, the filamentous bodies have the largest A/V (Area/Volume) value. In general, contaminants are removed by spherical and rod-shaped bacteria, but if a low load of organic matter (F/M ratio) persists, spherical or rod-shaped bacteria decrease and the filamentous body with the largest A/V (Area/Volume) value The amount increases even more. The state in which these filamentous bodies have become extremely large is bulking.

It is very important for a facility that treats sewage and wastewater using microorganisms to understand the state of microorganisms and manage them stably at all times. However, it is very difficult to determine the state of the bacteria that are not visible, and there is no suitable identification method available in the field.

In most conventional water treatment facilities, the condition of microorganisms is indirectly predicted by estimating the state of microorganisms with the empirical thoughts and judgments of the manager, or by microscopic observation or analyzing the water quality of the effluent. Due to the deterioration of the condition, the discharge exceeds the discharge standards, causing serious legal and economic damage to the business operator, as well as the mental and physical damage to the manager. This phenomenon is very difficult to cope with for new managers or less experienced managers.

1. Republic of Korea Patent Registration No. 10-0873416: Sewage treatment apparatus and method using activated sludge in a continuous batch reactor 2. Republic of Korea Utility Model No. 20-0361460: Continuous batch type sewage treatment system

The present invention deviates from the conventional method of predicting the growth state of microorganisms by relying on empirical observations of an operator in a treatment facility that treats sewage or wastewater using microorganisms, the dissolved oxygen amount and suspended matter concentration directly involved in the metabolism of microorganisms. Batch water treatment that can accurately predict the condition and treatment efficiency of microorganisms after several hours or a day by calculating the specific oxygen uptake rate using the value and then quantifying it to check the current state of the microorganism in real time on site. An object thereof is to provide a method and a batch type water treatment apparatus using the same.

In addition, the present invention is a batch type water treatment method capable of effectively controlling the supply of excessive oxygen and inhibiting the growth of filamentous bacteria through an immediate and active response by predicting the state and treatment efficiency of the microorganisms based on the non-oxygen consumption rate of the microorganisms. Another object is to provide a batch type water treatment apparatus using this.

The batch-type water treatment method using the non-oxygen consumption rate of microorganisms of the present invention for achieving the above object comprises: an inlet step of introducing water to be treated into a selection tank; An intermittent aeration step in which aeration and non-aeration are alternately repeated by intermittently supplying air into the bioreactor in communication with the selection tank; A sludge sedimentation step of allowing the sludge in the bioreactor to settle by standing for a certain period of time after the intermittent aeration; After the sedimentation step, the supernatant water discharge step of discharging the supernatant water in the bioreactor is included, and the intermittent aeration step determines the state of microorganisms based on the non-oxygen consumption rate of the microorganisms, and returns the sludge to the selection tank and in the bioreactor. Control aeration.

The non-oxygen consumption rate is calculated by the following calculation formula.

Formula: Non-oxygen consumption rate (mg/g·hr) = oxygen consumption rate/microbial amount

(The oxygen consumption rate (mg/l·hr) is the amount of dissolved oxygen (mg/l) that is reduced per hour in the activated sludge in the bioreactor, and the amount of microorganisms is the concentration of suspended matter in the activated sludge in the bioreactor (g/l). to be)

In addition, the oxygen consumption rate is calculated from data obtained from a section in which the amount of dissolved oxygen is decreased during non-aeration during the intermittent aeration step.

In the intermittent aeration step, when the non-oxygen consumption rate is less than or equal to a set value, the sludge is returned from the bioreactor to the selection tank.

In addition, in the intermittent aeration step, when the non-oxygen consumption rate is less than or equal to a set value, the amount of dissolved oxygen in the activated sludge in the bioreactor is reduced by adjusting the amount of aeration in the bioreactor.

When the non-oxygen consumption rate is less than the set value, the amount of dissolved oxygen is reduced to 1.0 mg/L or less to reduce energy required during aeration in the intermittent aeration step.

The set value is 1.2 to 3.0 mg/g·hr.

And the batch type water treatment apparatus using the non-oxygen consumption rate of microorganisms of the present invention for achieving the above object includes: a selection tank in which water to be treated is introduced and an agitator is installed; A bioreactor formed in communication with the selection tank and in which the water to be treated in the selection tank flows through a lower portion; Sludge transfer means for transferring the sludge of the bioreactor to the selection tank or to the sludge tank; Aeration means for aeration by supplying air to the bioreactor; A decanter for discharging the supernatant water from the bioreactor to the outside; A control panel for sequentially performing intermittent aeration, sludge settling, and supernatant discharge in the bioreactor by controlling the operation of the aeration means and the decanter; A dissolved oxygen meter installed in the bioreactor to measure the amount of dissolved oxygen in the activated sludge in the bioreactor; A suspended solids concentration measuring device installed in the bioreactor to measure the concentration of suspended solids in the activated sludge in the bioreactor; And a non-oxygen consumption rate monitoring unit for calculating the non-oxygen consumption rate of microorganisms based on the amount of dissolved oxygen measured by the dissolved oxygen meter and the suspended material concentration measured by the floating material concentration meter, and the control panel includes the non-oxygen consumption rate. The microbial state is determined by the non-oxygen consumption rate calculated through the monitoring unit, and the sludge is transferred to the selection tank and aeration in the bioreactor is controlled.

The decanter is supported by a guide rail installed inside the bioreactor to be installed in a lower part of the main body so that when the lower part of the main body is immersed in supernatant water, supernatant water can flow into the main body. The buoyancy of the main body is controlled by controlling the amount of supernatant water inlet pipe, supernatant water discharge pipe connected to the lower part of the main body so that supernatant water flowing into the main body can be discharged to the outside, and supernatant water flowing into the main body. It is provided with a buoyancy control means for changing.

As described above, the present invention measures the dissolved oxygen amount and the suspended matter concentration in real time, calculates the specific oxygen uptake rate of the microorganism based on the dissolved oxygen amount value and the suspended matter concentration value, and uses this to determine the state and treatment of microorganisms. The efficiency can be predicted. Therefore, it is possible to suppress the proliferation of filamentous bacteria and control the supply of excessive oxygen through an immediate and active response.

Accordingly, using the numerical non-oxygen consumption rate, it is possible to inhibit the growth of filamentous bacteria that occur in the process of microbial growth and numerically confirm the decomposition stage of contaminants. The power energy can be saved together with the improvement of the sedimentation properties of

In addition, since the non-oxygen consumption rate, which is calculated numerically and accumulated in real time, is used, even a driver with little experience in microbial treatment can easily manage microbes and operate treatment facilities.

1 is a block diagram schematically showing a batch type water treatment apparatus according to an example of the present invention,
2 is a graph showing the ideal oxygen consumption rate of microorganisms,
3 is a graph showing the change in the amount of dissolved oxygen in activated sludge over time in the intermittent aeration step in the bioreactor,
4 is a graph showing the amount of dissolved oxygen that can be reduced when the non-oxygen consumption rate is less than a certain value,
5 is a graph showing the daily calculation of the SVI (Sludge Volume Index) value that can confirm the sedimentation of sludge,
6 is a block diagram schematically showing a main part of a batch type water treatment apparatus according to another example of the present invention.

Hereinafter, a batch-type water treatment method using the non-oxygen consumption rate of microorganisms and a batch-type water treatment apparatus using the same according to a preferred embodiment of the present invention will be described.

Referring to Figure 1, the batch type water treatment apparatus according to an example of the present invention is formed to be in communication with the selection tank 20 in which the water to be treated is introduced and the stirrer 21 is installed, and the selection tank 20 The bioreactor 30 in which the water to be treated is introduced through the lower portion, the sludge transfer means for returning the sludge of the bioreactor 30 to the selection tank 20 or to the sludge tank 40, and the bioreactor ( The bioreactor 30 by controlling the operation of the aeration means for supplying air to 30) and aeration, the decanter 91 for discharging the supernatant water from the bioreactor 30 to the outside, and the aeration means and the decanter 91 The control panel 50 sequentially proceeds intermittent aeration, sludge sedimentation, and supernatant discharge in the bioreactor 30, and a dissolved oxygen meter 61 installed in the bioreactor 30 to measure the amount of dissolved oxygen in the activated sludge in the bioreactor 30, and , A suspended solids concentration meter 65 installed in the bioreactor 30 to measure the concentration of suspended solids in activated sludge in the bioreactor 30, and the dissolved oxygen amount and suspended solids concentration meter 65 measured by the dissolved oxygen meter 61 And a non-oxygen consumption rate monitoring unit 70 for calculating the non-oxygen consumption rate of microorganisms by the suspended solid concentration measured in.

A storage tank 10 may be further provided to introduce the water to be treated into the selection tank 20. The storage tank 10 serves to homogenize water quality by storing a certain amount of water to be treated introduced from the outside. A stirrer 11 may be installed in the storage tank 10 to homogenize the water quality. The operation of the stirrer 11 is controlled by the control unit 50.

The water to be treated that has stayed in the storage tank 10 for a certain period of time is transferred to and introduced into the selection tank 20 by the operation of the pump 13 installed in the storage tank 10. The pump 13 installed inside the storage tank 10 is controlled by the control panel 50. The water to be treated may be sewage or wastewater. In addition, the water to be treated may be filthy water or heavy water.

The selection tank 20 and the bioreactor 30 are formed adjacent to each other. The present invention has a configuration in which one reaction space is divided into two spaces by a partition wall 25 by improving the conventional technology consisting of one reaction space. The selection tank 20 is located in front of the partition wall 25 with respect to the partition wall 25, and the bioreactor 30 is located at the rear of the partition wall 25. The lower end of the partition wall 25 is formed to be spaced apart from the floor. Therefore, the lower portion of the selection tank 20 and the lower portion of the bioreactor 30 have a structure in communication.

By dividing one space into a selection tank (20) and a bioreactor (30) in this way, it is resistant to rapid changes in the flow rate and concentration of wastewater, inflow of toxic substances, and shock load, and suppresses the growth of filamentous bacteria for stable treatment. While maintaining efficiency, it has the advantage of minimizing the installation area.

The water to be treated flowing from the storage tank 10 is mixed with the sludge returned from the bioreactor 30 and the selection tank 20. A stirrer 21 is installed in the selection tank 20 to mix the water to be treated and the sludge. The operation of the stirrer 21 is controlled by the control panel 50. Since the selection tank 20 does not undergo aeration, the amount of dissolved oxygen is 0.0 to 0.2 mg/ℓ, and the anaerobic and oxygen-free conditions are achieved.

The water to be treated mixed with the sludge in the selection tank 20 is naturally transferred to the bioreactor 30 through the lower portion of the partition wall 25.

An aeration means is provided to supply air to the bioreactor 30. The illustrated aeration means comprises a blower 81 and an air diffuser 83 that is connected to the blower 81 and installed inside the bioreactor 30. The operation of the blower 81 is controlled by the control panel 50.

A sludge transfer means is provided to return the sludge settled in the bioreactor 30 to the selection tank 20 or to the sludge tank 40.

A pump 31 installed inside the bioreactor 30 as a sludge transfer means, a three-way valve 35 installed in the sludge discharge pipe 33 connected to the pump 31, and a three-way valve 35 And a conveying pipe 37 extending to the selection tank 20 and a discharge pipe 39 connected to the three-way valve 35 and extending to the sludge tank 40. The operation of the pump 31 and the three-way valve 35 is controlled by the control panel 50.

The sludge discharged through the discharge pipe 39 is introduced into the sludge tank 40. The sludge tank 40 provides a function of temporarily storing the sludge discharged from the bioreactor 30 in order to dewater or carry the sludge to the outside.

The decanter 91 serves to discharge supernatant water from the bioreactor 30 to the outside. The decanter 91 may apply a conventional floating decanter capable of floating on the water surface. The decanter 91 is preferably a structure capable of stably discharging even if the sedimentation of the sludge temporarily deteriorates due to a change in water temperature of the water to be treated, a temporary decrease in the activity of microorganisms, a toxic substance, a change in concentration, an amount of dissolved oxygen, etc.

When the pump 93 connected to the decanter 91 is operated, supernatant water is sucked into the decanter 91 and discharged to the outside. A flow meter 95 may be installed in a discharge pipe connected to the pump 93 in order to measure the flow rate of supernatant water discharged to the outside by the pump 93. The operation of the pump 95 is controlled by the control panel 50.

In the above-described bioreactor 30, aeration, sludge settling, and supernatant discharge are alternately repeated. For example, after intermittently aeration is performed on the water to be treated flowing from the selection tank 20, the sludge is allowed to settle for a certain period of time, and the process of discharging the supernatant water to the outside after the sludge has settled is repeated to treat the water to be treated. . Therefore, in the bioreactor 30, an intermittent aeration step, a sludge settling step, and a supernatant discharge step are sequentially performed to form one cycle.

The cycle operation of the bioreactor 30 may be operated 5 times a day with 4.8 hours as 1 cycle as an example. And one cycle can be operated with 2.8 hours of intermittent aeration stage, 1 hour of sludge settling stage, and 1 hour of supernatant water discharge stage. In the intermittent aeration step, aeration and non-aeration are alternately repeated. Aeration and non-aeration can be carried out automatically with a set amount of dissolved oxygen. In addition, aeration and non-aeration can be performed automatically or manually by a set time. Aeration and non-aeration can be repeated 4 to 12 times. The aeration time is about 5 to 15 minutes, and the non-aeration time can be operated in a maximum of less than 15 minutes.

As aeration and non-aeration are repeated in the intermittent aeration step, the inside of the bioreactor 30 is alternately aerated and anaerobic, thereby removing organic matter, nitrogen, and phosphorus.

When the intermittent aeration step is finished and the sludge settling step is started, the sludge is settled on the bottom of the bioreactor 30. And when the sludge sedimentation step ends and the supernatant discharge step begins, the supernatant water of the bioreactor 30 is discharged to the outside through the decanter 91, and the sludge settled in the lower part is transferred to the sludge tank 40 through the sludge transfer means. do. When the supernatant discharge is completed, the water to be treated flows back from the storage tank 10 to the selection tank 20, and the intermittent aeration step, the sludge settling step, and the supernatant discharge step are repeated in the bioreactor 30.

The control panel 50 is composed of a microcomputer and various driving circuits. The control panel 50 controls the operation of the aeration means and the decanter 91 to sequentially perform intermittent aeration, sludge sedimentation, and supernatant discharge in the bioreactor 20. In addition, the control panel 50 determines the microbial state according to the non-oxygen consumption rate calculated through the non-oxygen consumption rate monitoring unit 70, and returns the sludge from the bioreactor 30 to the selection tank 20, and Control the aeration inside (30).

The dissolved oxygen meter 61 is installed in the bioreactor 30. The dissolved oxygen analyzer 61 measures the amount of dissolved oxygen (DO) in the activated sludge in the bioreactor.

The suspended solids concentration meter 65 is installed in the bioreactor 30. The suspended solid concentration meter 65 measures the concentration of a mixed liquor suspended solid (MLSS) in activated sludge in the bioreactor 30. The concentration of the suspended matter is used in the same meaning as the concentration of the microorganism.

The non-oxygen consumption rate monitoring unit 70 calculates the non-oxygen consumption rate based on the dissolved oxygen amount measured by the dissolved oxygen meter 61 and the suspended solid concentration value measured by the suspended solid concentration meter 65. The non-oxygen consumption rate monitoring unit 70 can calculate the non-oxygen consumption rate by software having a function and an operation function. The non-oxygen consumption rate monitoring unit 70 is installed inside the control panel 50 and sends the calculated non-oxygen consumption rate to the control panel.

In order to calculate the specific oxygen uptake rate (SOUR), the oxygen consumption rate must first be calculated. Oxygen Uptake Rate (OUR: Oxygen Uptake Rate) is the decreasing amount of dissolved oxygen divided by time.

Oxygen consumption rate (OUR) represents the consumption rate of oxygen consumed in the process of biodegrading organic matter by microorganisms. Oxygen consumption rate changes depending on the health status of microorganisms directly involved in decomposition, load of organic matter, and toxic substances.

The most ideal oxygen consumption rate (OUR) is shown in the graph of FIG. 2. 2 shows the oxygen consumption rate (OUR) consumed step by step in the process of decomposing organic matter by microorganisms. Step 1 is a process in which microorganisms decompose organic matter in a state where dissolved oxygen is sufficient. In the first step, microorganisms ingest the most easily degradable rbCOD (readily biodegradable COD) first, and then decompose sbCOD (slowly biodegradable COD), and at this time, the oxygen consumption rate (OUR) is the highest. Subsequently, in the second step, the microorganism consumes oxygen for the nitrification reaction of the nitrogen compound, and in the third step, as the colloidal or particulate COD (particulate COD) is gradually decomposed, the oxygen consumption rate (OUR) is lowered. And when the decomposition of all organic matter is completed, in step 4, the microorganism maintains the endogenous growth stage, which stops metabolic activity.

In the literature, the oxygen consumption rate (OUR) ranges from 50 to 35 mg/ℓ·hr when decomposing rbCOD, 35 to 20 mg/ℓ·hr when decomposing sbCOD, and 20 to 4 mg/ℓ·hr when decomposing nitrogen compounds. It is reported that the endogenous growth stage has been reached below hr.

As such, the oxygen consumption rate is a value that allows the decomposition state of organic matter to be known, but does not include a relationship with the amount of microorganisms (Volume, g/L), so it is difficult to predict the state of microorganisms only by the oxygen consumption rate. However, the non-oxygen consumption rate reflects the amount of microorganisms actually operated in the treatment facility (Volume, g/L) so that the state of the microorganisms can be predicted, so it can be usefully used in the treatment facility.

In the present invention, the state of microorganisms that cannot be visually identified is expressed numerically using the concept of non-oxygen consumption rate, so that the state of microorganisms can be checked in real time at a processing site.

In the present invention, the non-oxygen consumption rate can be calculated by the following calculation formula.

Non-oxygen consumption rate (mg/g·hr) = oxygen consumption rate/microbial amount

In the above calculation formula, the oxygen consumption rate (mg/ℓ·hr) is the amount of dissolved oxygen (mg/ℓ) that is reduced per hour in the activated sludge in the bioreactor. And the amount of microorganisms is the concentration of suspended matter in the activated sludge in the bioreactor (g/ℓ).

The oxygen consumption rate (OUR) is first calculated through the amount of dissolved oxygen measured using the dissolved oxygen meter 61, and the calculated oxygen consumption rate is divided by the amount of microorganisms as in the above calculation formula to quantify the non-oxygen consumption rate. .

3 shows the change in the amount of dissolved oxygen in the activated sludge in the intermittent aeration step in the bioreactor 30. In the graph of FIG. 3, section'R' is a section in which the amount of dissolved oxygen increases in an aerated state, and section'S' is a section in which the amount of dissolved oxygen is decreased in a non-aerated state.

In order to calculate an accurate value when calculating the oxygen consumption rate, only a specific range of data can be used among the measured values of the amount of dissolved oxygen continuously measured. For example, only the data of section S where the amount of dissolved oxygen decreases can be used to calculate the oxygen consumption rate. The R section of the graph is a section in which microorganisms directly consume oxygen and at the same time supply oxygen by aeration, so the supply of oxygen is greater than the consumption amount, so the concentration of dissolved oxygen gradually increases. Therefore, the R section data is not used to calculate the oxygen consumption rate (OUR).

The non-oxygen consumption rate monitoring unit 70 calculates the oxygen consumption rate by extracting only the S section data. The calculated oxygen consumption rate is divided by the suspended solid concentration value measured through the suspended solid concentration meter 65, and finally the non-oxygen consumption rate (SOUR) is calculated. And the control panel 50 operates the sludge pump 31 to control the growth of filamentous bacteria according to the calculated non-oxygen consumption rate, returns the sludge to the selection tank 20, and reduces the amount of air by controlling the blower. Shut off air supply.

Hereinafter, a batch-type water treatment method using the non-oxygen consumption rate of microorganisms will be described step by step.

1. Treatment target water inflow stage

First, the water to be treated is introduced into the selection tank 20. The water to be treated is temporarily stored in the storage tank 10 and then flows into the selection tank 20.

The water to be treated flowing into the selection tank 20 is mixed with the sludge returned from the bioreactor 30 and naturally flows into the bioreactor 30. Since air is not supplied to the selection tank 20, an anaerobic or oxygen-free condition of about 0.0 to 0.2 mg/ℓ of dissolved oxygen is achieved.

2. Intermittent aeration phase

Next, an intermittent aeration step of alternately repeating aeration and non-aeration by intermittently supplying air into the bioreactor 30 is performed.

Intermittent aeration may be repeated 5 times a day, and the intermittent aeration time per each may be 2.8 hours.

As aeration and non-aeration are repeated in the intermittent aeration step, the inside of the bioreactor 30 is alternately aerated and anaerobic, thereby removing organic matter, nitrogen, and phosphorus. That is, in the aerobic state in which aeration occurs, excessive intake of phosphorus by microorganisms and oxidation in which ammonia nitrogen is converted into nitrate nitrogen occur. And in the anaerobic state of non-aeration, nitrogen is removed as nitrate nitrogen is reduced to nitrogen gas by microorganisms involved in denitrification. In this way, by alternately repeating aeration and non-aeration in the intermittent aeration step, it is possible to effectively remove nitrogen and phosphorus by inducing excessive phosphorus intake, nitrification, and denitrification.

In the intermittent aeration step, the concentration of dissolved oxygen in the bioreactor 30 is preferably 0.2 to 2.5 mg/ℓ so that nitrification and denitrification can occur simultaneously with removal of phosphorus.

In the intermittent aeration step, the dissolved oxygen amount and the suspended matter concentration are measured in real time, and the non-oxygen consumption rate monitoring unit 70 calculates the non-oxygen consumption rate of the microorganisms based on the measured dissolved oxygen amount and the suspended matter concentration. Based on the calculated non-oxygen consumption rate, the control panel 50 determines the microbial state and controls the conveyance of the sludge to the selection tank 20 and aeration in the bioreactor 30.

In the intermittent aeration step, when the amount of dissolved oxygen is changed as shown in FIG. 3, the non-oxygen consumption rate monitoring unit calculates the non-oxygen consumption rate by extracting only the data obtained in the S section in which the amount of dissolved oxygen is decreased.

If the calculated non-oxygen consumption rate is less than or equal to the set value, the control panel 50 operates the sludge transfer means to return the sludge from the bioreactor 30 to the selection tank 20. At this time, the set value may be 1.2 to 3.0 mg/g·hr. When the non-oxygen consumption rate is 1.2 to 3.0 mg/g·hr or less, it can be predicted that the microorganisms decompose all organic matter and enter the endogenous growth stage where microbial activity is stopped.

When the non-oxygen consumption rate is 1.2 to 3.0 mg/g·hr or less, the sludge pump 31 is operated to return the sludge from the bioreactor 30 to the selection tank 20. The sludge can be returned at a rate of about 20 to 50% (v/v). The returned sludge is mixed with the water to be treated by the agitator 21 of the selection tank 20. As described above, when the non-oxygen consumption rate is 1.2 to 3.0 mg/g·hr or less, the sludge is returned to the selection tank 20, thereby bringing the microorganisms into contact with a high load environment with a high organic matter concentration to dominate the spherical and rod-shaped bacteria and grow filamentous fungi. By suppressing silver, the bulking phenomenon can be prevented in advance.

Filamentos bacterium bacteria of a peculiar form that are connected in a thread shape are excessively proliferated to deteriorate the sedimentation of microbial flocs, so that sedimentation does not occur during the sludge sedimentation process, or it takes a long time for sedimentation. When such a bulking phenomenon occurs, sludge is lost to the discharged water, which exceeds the discharged water quality standard and increases the moisture content of the sludge, which makes it difficult to dewater the sludge. The present invention also provides a technique for controlling the bulking of sludge and maintaining the SVI (Sludge Volume Index) value in the range of 50 to 150.

The occurrence of bulking is as follows.

Contaminants are generally removed by spherical and rod-shaped bacteria, but relatively low organic substance load (F/M ratio) occurs in the stage where most of the organic substances are decomposed, which causes spherical or rod-shaped bacteria to become active. The growth of filamentous fungi that easily absorbs organic matter becomes weaker and stronger. This phenomenon can be explained by the A/V (Area/Volume) value. Filamentous fungi have a small volume of cells compared to spherical or rod-shaped bacteria, but their length is long in the form of a thread, so the total surface area is large, so it is very advantageous for absorption of organic matter. In particular, under low load of organic matter, it absorbs and proliferates more easily than spherical or rod-shaped bacteria.

Minimizing the exposure of microorganisms to such low load conditions can inhibit the growth of filamentous fungi. Therefore, the low load condition in which most of the organic matter is decomposed is confirmed by the non-oxygen consumption rate (SOUR) value, and the sludge is returned to the selection tank with the highest organic matter concentration. Accordingly, it is possible to inhibit the proliferation of filamentous bacteria by preventing the microorganisms in the bioreactor from being exposed to the environment under low load of organic matter.

On the other hand, if the calculated non-oxygen consumption rate is less than or equal to the set value, the amount of dissolved oxygen in the activated sludge in the bioreactor 30 may be reduced by adjusting the amount of aeration in the bioreactor 30. When the non-oxygen consumption rate is 1.2 to 3.0 mg/g·hr or less, microbial activity is stopped, so there is no need to supply excess air. Therefore, when the non-oxygen consumption rate is 1.2 to 3.0 mg/g·hr or less, aeration is stopped or the amount of aeration is reduced to reduce the amount of dissolved oxygen to 1.0 mg/l or less. Since the amount of oxygen consumed in the endogenous growth stage in which most of the organic substances are decomposed is very small, the amount of oxygen supplied can be actively reduced, thereby reducing unnecessary operation time of the blower. Accordingly, energy required during aeration in the intermittent aeration step can be reduced. For example, as shown in the graph of FIG. 4, since the amount of dissolved oxygen by the area corresponding to SA can be reduced, the power consumed for the corresponding blower operation can be reduced.

As described above, the present invention predicts the state of microorganisms by using the non-oxygen consumption rate to improve sedimentation of sludge and save energy, as well as numerically confirm the overall state of microorganisms and the decomposition step of organic matter, and measure data. By accumulating management, microbial treatment facilities that are difficult to operate and maintain can be operated stably and efficiently.

3. Sludge sedimentation stage

After the intermittent aeration is over, it is allowed to stand for a certain period of time and the sludge settling step of sedimenting the sludge in the bioreactor 30 is performed. The sludge settling step may be repeated 5 times a day, and the sludge settling time per each cycle may be 1 hour.

When the sludge sedimentation step starts, sludge is settled and accumulated in the lower layer of the bioreactor 30, and supernatant water is located in the upper layer of the bioreactor 30.

4. Supernatant water discharge stage

Next, the supernatant water is discharged to the outside through the decanter 91. When the pump 93 is operated under the control of the control panel 50, supernatant water is discharged to the outside through the decanter 91 floating on the water surface.

And the sludge settled in the lower layer of the bioreactor 30 at the same time as the supernatant water is discharged or after the supernatant water is discharged is transferred to the sludge tank 40 through the sludge transfer means.

When the supernatant discharge is completed, the water to be treated is re-introduced from the storage tank 10 to the selection tank 20, and the intermittent aeration step, the sludge settling step, and the supernatant water discharge step are repeated in the bioreactor 30.

(Experimental example)

In order to determine the non-oxygen consumption rate (SOUR) of sewage according to the present invention, an experiment was conducted at the site where 1,000 tons of sewage mixed with urban sewage and wastewater per day were treated by a batch method.

A dissolved oxygen meter and a suspended solids concentration meter were installed in the bioreactor of the treatment facility to measure dissolved oxygen (mg/ℓ) and suspended solids concentration (g/ℓ) in real time. The bioreactor was operated for 1 cycle in the order of intermittent aeration → sludge settling → supernatant water discharge, and operated 5 times a day with 4.8 hours as 1 cycle. And each cycle was operated with 2.8 hours of intermittent aeration step, 1 hour of sludge settling step, and 1 hour of supernatant water discharge step.

The oxygen consumption rate (mg/ℓ·hr) was first calculated from the value of the dissolved oxygen measured during intermittent aeration, and then the non-oxygen consumption rate (mg/g·hr) was calculated by reflecting the amount of microorganisms. As for the oxygen consumption rate, only data in the range of 2.5~1.0mg/ℓ in which the amount of dissolved oxygen decreases with time were selected and used. Since the accuracy of the dissolved oxygen analyzer is significantly lowered in the range of less than 1.0 mg/ℓ of dissolved oxygen, data for the range of less than 1.0 mg/ℓ of dissolved oxygen was not used.

The oxygen consumption rate (OUR) and the non-oxygen consumption rate (SOUR) were calculated by dividing into sections 1 to 4 for each decomposition step, and the results are shown in Table 1 below.

Item division unit Section 1 Section 2 Section 3 Section 4 One OUR mg/ℓ·hr 24.00 12.94 7.38 3.06 2 Suspended solids concentration g/ℓ 2.5 2.4 2.5 2.5 3 SOUR mg/g hr 9.6 5.4 3.0 1.2 division rbCOD decomposition section sbCOD decomposition section Nitrification section Endogenous field section Classification of metabolic activities Organic matter decomposition section Organic matter decomposition section Nitrogen compounds
Decomposition section Dormant period Oxygen supply condition Maximum amount of oxygen required Need an appropriate amount of oxygen Need an appropriate amount of oxygen Minimum amount of oxygen required Oxygen demand Maintains up to 2.5mg/ℓ Up to 2.5mg/ℓ
maintain Maintains up to 2.5mg/ℓ Up to 1.0mg/ℓ
maintain

Referring to the results of Table 1, the oxygen consumption rate (OUR) was 3.06 ~ 24.0mg/ℓ·hr, and the non-oxygen consumption rate (SOUR) calculated by reflecting the amount of microorganisms was 1.20 ~ 9.60mg/g·hr. Appeared.

In detail, when 0 to 75 minutes elapsed after the sewage was introduced, the non-oxygen consumption rate value was 9.60 to 5.40 mg/g·hr, and in this range, most of the organic substances are decomposed. And after 75 to 90 minutes, the non-oxygen consumption rate value was 5.40 to 3.00 mg/g·hr, and nitrification takes place within this range. And after 90 to 160 minutes, the non-oxygen consumption rate value is 3.00 to 1.20 mg/g·hr, and it can be confirmed numerically that the endogenous growth stage proceeds within the range.

The non-oxygen consumption rate does not represent the same non-oxygen consumption rate value in all treatment facilities due to various variables such as the composition and amount of organic matter contained in the wastewater, nitrogen concentration, and operating oxygen concentration in the treatment facility. However, since the non-oxygen consumption rate value is calculated by the amount of dissolved oxygen and the concentration of microorganisms to indicate the state of the microorganism, it can be used in all water treatment facilities by quantifying and standardizing the non-oxygen consumption rate.

The treatment facility was operated for 30 days to check the sludge sedimentation. From 1 to 15 days, the intermittent aeration step was performed by repeating aeration and non-aeration without using the non-oxygen consumption rate. And for 16 to 30 days, when the non-oxygen consumption rate is less than 1.2mg/g·hr, aeration is stopped or the amount of aeration is reduced to reduce the amount of dissolved oxygen to less than 1.0mg/L, while 30% (v/v) of the sludge in the bioreactor. ) Was transported to the selection tank and operated.

The SVI (Sludge Volume Index) value for confirming the sedimentation of the sludge was calculated daily and shown in FIG. 5.

Referring to FIG. 5, it was confirmed that the sedimentation property of sludge was greatly improved by controlling the amount of sludge conveyance and aeration according to the degree of non-oxygen consumption. The SVI value before using the non-oxygen consumption rate value was 110-120, but after using the non-oxygen consumption rate value, the SVI value gradually decreased and decreased to 40-60. Therefore, it can be confirmed that the sedimentation properties of the sludge have been greatly improved.

Typically, when the SVI (Sludge Volume Index) value is 150 or higher, bulking occurs due to the growth of filamentous bacteria. The present invention automatically operates the sludge pump 31 in the control panel when it is predicted to have entered the endogenous growth stage by the non-oxygen consumption rate calculated in the non-oxygen consumption rate monitoring unit 70 to select the sludge tank 20 As it can be transferred to, microbial sludge can be brought into contact with a high load environment to suppress the growth of filamentous bacteria.

Meanwhile, FIG. 6 shows a connection between a selection tank and a bioreactor applied to a batch water treatment apparatus according to another example of the present invention.

Referring to FIG. 6, a connection passage for connecting the lower portion of the selection tank 20 and the lower portion of the bioreactor 30 is provided.

In order to provide a connection passage, a channel portion 100 coupled to the lower end of the partition wall 25 is provided. The channel unit 100 is formed in a U-shape that is opened toward the bottom, and the front and rear surfaces are open.

Inside the channel unit 100, a plurality of diaphragms 101 and 103 are arranged vertically and alternately. For example, the first diaphragm 101 is installed on the floor, and the second diaphragm 103 is installed on the upper plate of the channel portion 100. In this way, since a plurality of the first and second diaphragms 101 and 103 are arranged vertically and alternately, the speed of the water to be treated flowing along the connection passage can be reduced. Accordingly, since the water to be treated slowly flows into the lower portion of the bioreactor, it can act as a buffer for rapid changes in flow rate and concentration, inflow of toxic substances, and impact load. In addition, since it is possible to sufficiently shorten the contact time of microbial sludge returned from the bioreactor to the selection tank in the endogenous growth stage and organic matter, it is possible to dominate the spherical and rod-shaped bacteria in the high load environment with the highest concentration of organic matter and effectively inhibit the growth of filamentous bacteria have.

7 to 10 illustrate a decanter applied to a batch type water treatment apparatus according to another example of the present invention.

7 to 10, the decanter is supported by a guide rail 110 installed inside the bioreactor 30, the main body 120 that can be moved up and down according to the water level, and the lower part of the main body 120 is When submerged, the supernatant water inlet pipe 140 installed at the lower part of the main body 120 so that supernatant water can be introduced into the main body 120, and the main body so that supernatant water flowing into the main body 120 can be discharged to the outside. Buoyancy control means for changing the buoyancy of the main body 120 by adjusting the amount of supernatant water flowing into the body 120 through the supernatant water discharge pipe 145 connected to the lower part of the 120) and the supernatant water inlet pipe 140 It is equipped with.

Inside the bioreactor 30, a pair of guide rails 110 are installed side by side. The guide rail 110 is formed to be long vertically. A lower part of the guide rail 110 is provided with a lowering limit panel 115 that limits the lowering range of the main body 120.

The main body 120 is installed so as to be supported by the guide rail 110 so that it can be lifted up and down according to the water level.

The main body 120 is provided with a weight portion 121 that is empty inside and through which supernatant water is introduced and discharged, and a buoyancy body 125 installed in the weight portion 121 and generating buoyancy.

The weight portion 121 includes a conical lower body 122 and a cylindrical upper body 124 protruding from the center of the lower body 122. A support bracket 117 coupled to the guide rail 110 is provided on the lower body 122 of the weight part 121. The weight unit 121 is capable of sliding up and down along the guide rail 110. A traction ring 119 is installed on the upper body 124 of the weight portion 121.

The buoyancy body 125 is installed around the upper body 124 of the weight portion 121. The interior of the buoyancy body 125 is divided into a plurality of spaces by a plurality of partition walls 127.

The upper water inlet pipe 140 is installed under the weight portion 121. An automatic valve for opening and closing the flow path may be installed in the upper water inlet pipe 140. When the lower part of the main body 120 is immersed in the supernatant water, supernatant water flows into the inside of the weight unit 122 through the supernatant water inlet pipe 140. One or more of the upper water inlet pipe 140 may be installed under the weight unit 121. In addition, in order to prevent foreign substances from flowing into the weight unit 121 in the intermittent aeration step and to keep the flow of the supernatant water flowing in the supernatant water discharge step evenly, the spherical sealing ball is the flow path of the supernatant water inlet pipe 140. Can be installed on. In this case, it is preferable that the specific gravity of the sealing ball is greater than that of water. For example, the specific gravity of the sealing ball may be 1.05 to 1.15.

The supernatant water discharge pipe 145 is installed under the weight part 121. For example, it is installed at the lowest position of the lower body 122 of the weight part 121. The supernatant water introduced into the weight unit 121 through the supernatant water inlet pipe 140 is discharged to the outside through the supernatant water discharge pipe 145.

The supernatant water discharge pipe 145 is connected to the discharge pipe 150. Although not shown, the discharge pipe 150 is connected to the supernatant water discharge pipe 145 and extends to the outside of the bioreactor 30.

The buoyancy control means serves to change the buoyancy of the main body 120 by adjusting the amount of supernatant water flowing into the body 120 through the supernatant water inlet pipe 140.

The buoyancy control means is, for example, installed inside the weight unit 121 and extends out of the water surface of the bioreactor 30 by being connected to the ventilation pipe 160 and the lower portion extending to the outside of the weight unit 121 An air discharge valve (not shown) is provided on the connection hose 165 to open and close the flow path of the connection hose 165.

The upper part of the ventilation pipe 160 is located adjacent to the ceiling of the weight part 121. In addition, the lower portion of the ventilation pipe 160 passes through the lower portion of the weight portion 121.

The connection hose 165 is connected to the lower end of the ventilation pipe 160 exposed to the outside of the weight unit 121. The connection hose 165 is connected to the ventilation pipe 160 and extends outside the water surface of the bioreactor 30. An air discharge valve is installed at the end of the connecting hose 165 extending out of the water surface. When the air discharge valve is opened, air inside the weight unit 121 may be discharged to the outside.

The above-described main body 120 is supported by the guide rail 110 and floats on the water surface of the bioreactor 30. At this time, since the lower part of the main body 120 is immersed in the supernatant water to a certain depth, the supernatant water flows into the inside of the weight unit 121 through the supernatant water inlet pipe 140. Since the supernatant water can flow into the weight unit 121 only in a certain amount by the air pressure inside the weight unit 121, the supernatant water maintains a constant water level inside the weight unit 121. The supernatant water introduced into the weight unit 121 is discharged to the outside through the supernatant water discharge pipe 145 in a natural flow manner. Unlike this, of course, it can be forcibly pumped and discharged using a pump. As much as the amount of supernatant water discharged through the supernatant water discharge pipe 145, the supernatant water flows into the inside of the weight unit 121 through the supernatant water inlet pipe 140.

The air pressure inside the weight unit 121 can be adjusted by opening and closing the air discharge valve installed in the connection hose 165. When the air discharge valve is opened, air inside the weight unit 121 is discharged to the outside, and as the air pressure inside the weight unit 121 is lowered, supernatant water is further introduced into the inside of the weight unit 121. As the supernatant water further flows into the inside of the weight unit 121, the weight of the weight unit 121 increases, and accordingly, the buoyancy of the body 120 decreases, and the weight unit 121 is applied to the supernatant water of the bioreactor 30. Deeper immersion. In addition, when air is injected into the weight unit 121 through the connection hose 165 after opening the public discharge valve, the internal air pressure of the weight unit 121 increases, and accordingly, the supernatant water of the weight unit 121 As the amount that can be introduced into the interior decreases, the buoyancy of the main body 120 increases.

In this way, the buoyancy of the main body can be easily adjusted through the buoyancy control means.

In the above, the present invention has been described with reference to an exemplary embodiment, but this is only exemplary, and those of ordinary skill in the art will appreciate that various modifications and equivalent embodiments are possible therefrom. Therefore, the true scope of protection of the present invention should be determined only by the appended claims.

20: selection tank 21: stirrer
30: bioreactor 50: control panel
61: dissolved oxygen meter 65: suspended solids meter
70: non-oxygen consumption rate monitoring unit

Claims (9)

An inflow step of introducing water to be treated into the selection tank;
An intermittent aeration step in which aeration and non-aeration are alternately repeated by intermittently supplying air into the bioreactor in communication with the selection tank;
A sludge sedimentation step of allowing the sludge in the bioreactor to settle by standing for a certain period of time after the intermittent aeration;
Including; a supernatant water discharge step of discharging supernatant water in the bioreactor after the sedimentation step,
In the intermittent aeration step, the state of the microorganism is determined by the non-oxygen consumption rate of the microorganism, and the sludge is returned to the selection tank and aeration in the bioreactor is controlled,
In the intermittent aeration step, if the non-oxygen consumption rate is less than or equal to a set value, the sludge is returned from the bioreactor to the selection tank. The batch water treatment method according to claim 1, wherein the non-oxygen consumption rate is calculated by the following calculation formula.
Formula: Non-oxygen consumption rate (mg/g·hr) = oxygen consumption rate/microbial amount
(The oxygen consumption rate (mg/l·hr) is the amount of dissolved oxygen (mg/l) that is reduced per hour in the activated sludge in the bioreactor, and the amount of microorganisms is the concentration of suspended matter in the activated sludge in the bioreactor (g/l). to be) The batch water treatment method according to claim 2, wherein the oxygen consumption rate is calculated from data obtained from a section in which the amount of dissolved oxygen is decreased during non-aeration during the intermittent aeration step. delete The non-oxygen of microorganisms according to claim 1, wherein in the intermittent aeration step, when the non-oxygen consumption rate is less than or equal to a set value, the amount of dissolved oxygen in the activated sludge in the bioreactor is reduced by adjusting the amount of aeration in the bioreactor. Batch water treatment method using consumption rate. The method of claim 5, wherein when the non-oxygen consumption rate is less than the set value, the amount of dissolved oxygen is reduced to 1.0 mg/L or less to reduce energy required for aeration in the intermittent aeration step. Batch water treatment method using non-oxygen consumption rate. The batch water treatment method according to claim 1 or 5, wherein the set value is 1.2 to 3.0 mg/g·hr. delete A selection tank in which water to be treated is introduced and an agitator is installed;
A bioreactor formed in communication with the selection tank and in which the water to be treated in the selection tank flows through a lower portion;
Sludge transfer means for transferring the sludge of the bioreactor to the selection tank or to the sludge tank;
Aeration means for aeration by supplying air to the bioreactor;
A decanter for discharging the supernatant water from the bioreactor to the outside;
A control panel for sequentially performing intermittent aeration, sludge sedimentation, and supernatant discharge in the bioreactor by controlling the operation of the aeration means and the decanter;
A dissolved oxygen meter installed in the bioreactor to measure the amount of dissolved oxygen in the activated sludge in the bioreactor;
A suspended solids concentration measuring device installed in the bioreactor to measure the concentration of suspended solids in the activated sludge in the bioreactor;
And a non-oxygen consumption rate monitoring unit for calculating the non-oxygen consumption rate of microorganisms based on the amount of dissolved oxygen measured by the dissolved oxygen meter and the suspended solid concentration measured by the suspended solid concentration meter, and
The control panel determines the state of microorganisms based on the non-oxygen consumption rate calculated through the non-oxygen consumption rate monitoring unit, and controls the transport of the sludge to the selection tank and aeration in the bioreactor,
The control panel controls the aeration means to intermittently supply air into the bioreactor to perform intermittent aeration in which aeration and non-aeration are alternately repeated, and when the non-oxygen consumption rate is less than a set value during the intermittent aeration, the bioreactor To return the sludge to the selection tank at,
The decanter is supported by a guide rail installed inside the bioreactor to be installed in a lower part of the main body so that when the lower part of the main body is immersed in supernatant water, supernatant water can flow into the main body. A supernatant water inlet pipe, a spherical sealing ball having a specific gravity of 1.05 to 1.15 and installed in the flow path of the supernatant water inlet pipe, and supernatant water connected to the lower part of the main body so that supernatant water flowing into the main body can be discharged to the outside. A discharge pipe and a buoyancy control means for changing the buoyancy of the body by adjusting the amount of supernatant water flowing into the interior of the body,
The main body includes a weight unit in which the supernatant water inlet pipe and the supernatant water discharge pipe are installed so that supernatant water is introduced and discharged, and the inside is empty, and a buoyant body installed in the weight unit and generating buoyancy,
The buoyancy control means is installed inside the weight part, the lower part extends to the outside of the weight part, and the upper part is a vent pipe positioned adjacent to the ceiling of the weight part, and a connection hose connected to the vent pipe to extend out of the water surface of the bioreactor. And, an air discharge valve installed at an end of the connection hose extending out of the water surface of the bioreactor to open and close the flow path of the connection hose.

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