JP2011016076A - Method and apparatus of treating organic waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of treating organic waste water and an apparatus thereof by which an activated sludge treatment can be performed by suppressing bulking.SOLUTION: In the method of treating organic waste water, an activated sludge tank 3 which treats waste water containing organic material by an activated sludge method and a final settling tank 4 which settles sludge contained in treated water passing through the activated sludge tank 3 are disposed, and supernatant water of the final settling tank 4 is discharged and, at the same time, the sludge pulled out of the bottom part of the final settling tank 4 is returned to an inlet part of the activated sludge tank 3. The active sludge tank 3 is divided into a plurality of tanks; a selector tank 10a into which an organic waste water and return sludge are caused to flow is disposed on the inlet part, and a method having an organic material concentration adjusting process of determining a control value of the concentration of the organic material in the selector tank 10a based on a value of SVI which is determined beforehand by a bulking characteristic of the sludge and permits the discharge and adjusting the concentration of the organic material in the selector tank 10a based on the control value is adopted.

Description

  The present invention relates to an organic wastewater treatment method and treatment equipment.

  The activated sludge method is known as a method for treating wastewater containing organic matter such as industrial wastewater, livestock wastewater, sewage and human waste (organic wastewater). The activated sludge method is a method of biologically treating organic wastewater using microorganisms such as bacteria and protozoa. In the treatment facility using this method, organic wastewater is mixed with sludge in an activated sludge tank and aerated, and sludge contained in the treated water is precipitated in the next settling tank, and the supernatant water is discharged while sedimented. Part of the sludge is returned to the activated sludge tank as return sludge, and the remainder is discharged as excess sludge.

In the activated sludge method, the swelling phenomenon of sludge called bulking is a problem. Bulking is a phenomenon in which filamentous bacteria with low sedimentation grow and lighten sludge. When this bulking occurs, the sedimentation in the sedimentation tank deteriorates and the sludge is discharged together with the supernatant water. Sufficient sludge cannot be secured and processing capacity deteriorates.
In SVI (Sludge Volume Index) indicating sludge settling, generally, bulking occurs and the value at which the treatment system breaks down is 200 mL / g or more, and a value capable of normal treatment is 50 to 150 mL / g, which is an indication of the operation of the processing equipment.

Conventionally, in order to suppress this bulking, various countermeasures described in Patent Documents 1 to 8 below have been taken.
Patent Documents 1 and 2 disclose a technique of adding a bulking inhibitor that attacks and destroys bacteria that cause bulking. Patent Documents 3 and 4 disclose a method of adding a floc forming agent that promotes floc formation. Patent Document 5 discloses a technique in which a mixer for mechanically cutting filamentous bacteria is provided in a treatment system. Patent Documents 6 and 7 disclose a method of adding a sludge settling agent that increases the settling property of sludge. Patent Document 8 discloses a method of adding saponin and Bacillus bacteria.

Japanese Patent No. 4212422 JP 2006-305552 A JP 2005-177715 A JP 2007-686 A JP 2007-216203 A JP 2007-105596 A JP 2007-111666 A JP 2006-231209 A

  However, in the method of adding a drug or a bacterium as described above, although there is an effect on a specific bacterium, if the addition amount is wrong, the balance of the microorganism is broken, and there is a possibility that the processing ability of activated sludge is deteriorated. Moreover, in the method using a mixer, not only filamentous bacteria but also floc-forming bacteria are broken, and there is a risk that the treatment capacity of activated sludge will also deteriorate.

  While such measures are taken, a tank referred to as a selector is provided at the inlet of the activated sludge tank, and drainage and return sludge are allowed to flow into the selector tank to bring the activated sludge into contact with high-concentration organic matter. There is a technique for suppressing the growth of filamentous bacteria having a small sedimentation property by predominating the growth of floc-forming bacteria having a large sedimentation property. According to this method, bulking can be suppressed without adding chemicals and bacteria as described above, and without providing a mixer, and the concern about deterioration of processing capability can be solved.

  However, although this method of providing a selector tank has been empirically recognized as being effective for countermeasures against bulking, the operation management value of the selector tank, for example, the size of the selector tank, the appropriate COD ( Chemical Oxygen Demand (Chemical Oxygen Demand) Since the concentration was unknown, there was no choice but to operate while adjusting the inflow (return ratio) of the return sludge to the inflow of wastewater by trial and error, and a selector tank was provided. However, sludge bulking often occurred without the suppression of filamentous bacterial growth.

  This invention is made | formed in view of the said situation, and it aims at provision of the processing method and processing equipment of the organic waste_water | drain which suppresses bulking and enables the stable activated sludge process.

The inventors of the present application have conducted extensive experiments to solve the above problems, and as a result, found that the organic substance (COD) concentration value in the selector tank is correlated with the SVI value in the processing system. I came up with it.
That is, in order to solve the above problems, the present invention has an activated sludge tank that treats wastewater containing organic substances by an activated sludge method, and a sedimentation tank that precipitates sludge contained in treated water that has passed through the activated sludge tank. And draining the supernatant water of the settling tank and returning the sludge extracted from the bottom of the settling tank to the inlet of the activated sludge tank, wherein the activated sludge tank includes a plurality of activated sludge tanks. The inlet portion has a selector tank into which the drainage and the returned sludge to be returned flow, and is a sludge volume index that is predetermined by the bulking characteristics of the sludge and can be discharged. A method is adopted in which a control value of the organic substance concentration in the selector tank is determined based on the value, and an organic substance concentration adjusting step of adjusting the organic substance concentration in the selector tank is adjusted based on the control value.
By adopting this method, in the present invention, it is possible to control the SVI value of the processing system to be equal to or lower than the SVI value at which bulking occurs by adjusting the organic substance concentration in the selector tank.

In the present invention, the activated sludge tank has a denitrification tank that performs anaerobic treatment with denitrifying bacteria in the previous stage, and a nitrification tank that performs aerobic treatment with nitrifying bacteria in the subsequent stage. The method of constructing the entrance of the nitrogen tank is adopted.
By adopting this method, in the present invention, the inlet portion of the denitrification tank is configured as a selector tank, and the organic substance concentration in the selector tank is adjusted.

Further, in the present invention, the organic matter concentration adjusting step employs a method of controlling the concentration of organic matter in the selector tank by controlling at least one of the inflow amount of the waste water and the inflow amount of the return sludge. To do.
By adopting this method, in the present invention, the organic substance concentration in the selector tank is adjusted by controlling the flow rate of the waste water and the return sludge flowing into the selector tank, that is, the return ratio.

In the present invention, a part of the nitrification water is returned from the nitrification tank to the denitrification tank. In the organic matter concentration adjusting step, the inflow amount of the waste water, the inflow amount of the return sludge, and the denitrification tank are returned. A method of controlling at least one of flowing a part of the nitrification water returned to the nitriding tank into the selector tank to adjust the concentration of organic matter in the selector tank is adopted.
By adopting this method, in the present invention, the organic matter concentration in the selector tank is adjusted using waste water and return sludge flowing into the selector tank, and further nitrification water.

In the present invention, the waste water is potato starch waste water, and the organic substance concentration adjusting step adjusts the organic substance concentration in the selector tank to 1,000 mg / L or more in terms of COD _Cr concentration. adopt.
By adopting this method, the present invention, the treatment facility potato starch wastewater, organic matter concentration of the selector tank, by the 1,000 mg / L or more COD _Cr concentration, it size of precipitated in the selector tank Priority can be given to the growth of floc-forming bacteria, and bulking can be prevented.

  Further, in the present invention, there is an activated sludge tank for treating wastewater containing organic substances by an activated sludge method, and a settling tank for precipitating sludge contained in treated water that has passed through the activated sludge tank. It is an organic wastewater treatment facility for discharging clear water and returning the sludge extracted from the bottom of the settling tank to the entrance of the activated sludge tank, wherein the activated sludge tank is partitioned into a plurality of tanks, The inlet tank has a selector tank into which the drainage and the returned sludge to be returned flow in, and the selector tank is based on a sludge volume index value that is predetermined by the bulking characteristics of the sludge and can be discharged. A configuration is adopted in which a control value of the organic matter concentration is determined and an organic matter concentration adjusting device is provided for adjusting the concentration of the organic matter in the selector tank based on the control value.

According to the present invention, it has an activated sludge tank for treating wastewater containing organic substances by an activated sludge method, and a settling tank for precipitating sludge contained in treated water that has passed through the activated sludge tank, and the supernatant water of the settling tank The organic sludge is discharged from the bottom of the settling tank and returned to the inlet of the activated sludge tank, wherein the activated sludge tank is divided into a plurality of tanks, and the inlet The unit has a selector tank into which the drainage and the returned sludge to be returned flow in, and is based on the value of the sludge volume index that is predetermined by the bulking characteristics of the sludge and can be discharged, in the selector tank. By adopting a method of determining an organic substance concentration control value and having an organic substance concentration adjusting step of adjusting the organic substance concentration in the selector tank based on the control value, the selector tank can be adjusted. Adjusting the concentration of organic substances, the value of SVI processing system, it is possible to control the following values bulking occurs SVI.
Therefore, in the present invention, the organic substance is preferentially adsorbed on microorganisms (floc-forming bacteria) in the activated sludge by appropriately maintaining the organic substance concentration in the selector tank while monitoring the SVI value of the treatment system. The growth of filamentous bacteria can be suppressed. For this reason, the sedimentation property of sludge is ensured and the stable activated sludge process is attained.

It is a schematic block diagram which shows the processing equipment of the organic waste_water | drain in embodiment of this invention. It is a principal part block diagram of the processing equipment of the organic waste_water | drain in embodiment of this invention. It is a figure which shows the driving | operation performance data of the processing equipment of the organic waste_water | drain in embodiment of this invention. It is a figure which shows the relationship between the value of the organic substance density | concentration in the selector tank in embodiment of this invention, and the value of SVI in a processing system.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an organic wastewater treatment facility in an embodiment of the present invention.
The organic wastewater treatment facility 1 is a facility for treating wastewater containing organic matter such as industrial wastewater, livestock sewage, sewage, human waste, etc. The treatment facility 1 of this embodiment is starch wastewater discharged from a potato starch manufacturing plant. Is the processing target.

  As shown in FIG. 1, the organic wastewater treatment facility 1 includes an anaerobic treatment device 2 that performs anaerobic treatment of organic wastewater using anaerobic microorganisms, and an organic wastewater that has passed through the anaerobic treatment device 2. An activated sludge tank 3 to be treated by the activated sludge method and a final sedimentation tank (sedimentation tank) 4 for precipitating sludge contained in treated water that has passed through the activated sludge tank are configured.

  The anaerobic treatment apparatus 2 is configured to have sludge containing anaerobic microorganisms such as acid-producing bacteria and methane-producing bacteria, and the organic wastewater sent by a pump or the like is reduced by this sludge. Conversion to methane gas, that is, methane fermentation, is performed by steps such as molecularization → organic acid generation → methane generation. The methane gas obtained by the anaerobic treatment apparatus 2 is recovered as clean energy, that is, as a valuable material, and further recovered as electric energy by a gas turbine or the like. In this embodiment, an IC reactor is used as the anaerobic treatment device 2.

In this embodiment, the concentration of organic matter before the organic waste water to be processed in the anaerobic treatment apparatus 2 _{(COD Cr} concentration) is about 10,000~20,000mg / L. The anaerobic treatment apparatus 2 has a performance of treating 70 to 80% of organic substances contained in organic waste water, and contains waste organic substances (COD _Cr concentration of about 2,000 to 3,000 mg / L organic matter). Wastewater) is sent to the activated sludge tank 3 through the organic wastewater supply line 15. The organic waste water supply line 15 includes a pressure feeding means (not shown) such as a pump, a flow rate control device for controlling the flow rate of the organic waste water, and piping.

  The activated sludge tank 3 of this embodiment is a tank that treats organic wastewater using a so-called nitrification / denitrification circulation modified activated sludge method. The activated sludge tank 3 has a denitrification tank 10 that performs anaerobic treatment with denitrifying bacteria in the previous stage and a nitrification tank 11 that performs aerobic treatment with nitrifying bacteria in the subsequent stage to constitute a circulation treatment system. In the activated sludge tank 3, the effluent from the anaerobic treatment apparatus 2 is treated in the denitrification tank 10, then this is treated in the nitrification tank 11, and the treated water is again removed through the nitrification liquid circulation line 12. By treating with, it is comprised so that a nitrogen compound may be removed from organic waste water. The nitrification liquid circulation line 12 includes a pressure feeding means (not shown) such as a pump, a flow rate control device for controlling the flow rate of the nitrification liquid, and piping.

  Specifically, the activated sludge tank 3 converts the organic nitrogen into ammonium ions by the action of denitrifying bacteria in the denitrification tank 10 and then oxidizes ammonium ions to nitrite ions or nitrate ions by the action of nitrifying bacteria in the nitrification tank 11 (nitrification). Then, the nitrification solution is returned to the denitrification tank 10 again, and in the denitrification tank 11, nitrite ions or nitrate ions are reduced to nitrous oxide or nitrogen gas by the action of denitrifying bacteria, and the gas is released to the outside. It is designed to remove nitrogen compounds from organic wastewater. In addition, it is good to supply oxygen or air continuously to the nitrification tank 11 with a blower etc. (not shown), and to perform nitrification reaction by nitrifying bacteria continuously.

  Further, the treatment system of the present embodiment is configured to send a part of the organic wastewater to the activated sludge tank 3 without the anaerobic treatment device 2. That is, a bypass line 15 a is provided for bypassing the anaerobic treatment device 2 and sending organic wastewater directly to the activated sludge tank 3. The bypass line 15a includes a pumping means (not shown) such as a pump, a flow rate control device for controlling the flow rate of organic waste water, and piping. By sending a part of the organic wastewater to the activated sludge tank 3 by omitting the anaerobic treatment device 2 via the bypass line 15a, the amount of organic matter introduced into the activated sludge tank 3 is increased. Thereby, reaction of nitrification denitrification processing can be accelerated | stimulated and the nitrogen concentration of a processed material can be reduced favorably.

  The treated water that has passed through the activated sludge tank 3 is introduced into the final sedimentation basin 4 and separated into solid and liquid, and the supernatant water is discharged into the river as treated water. On the other hand, a part of the sludge settled in the final sedimentation tank 4 is returned to the inlet portion of the activated sludge tank 3 through the return sludge line 13. Further, in order to keep the activated sludge concentration at a predetermined concentration, the sludge proliferation is extracted as excess sludge by the return sludge line 13, dehydrated and disposed of. In addition, you may return the separation liquid at the time of sludge dehydration to the entrance part of the activated sludge tank 3. FIG. The return sludge line 13 includes a pumping means (not shown) such as a pump, a flow rate control device for controlling the flow rate of the return sludge, and piping.

Next, with reference to FIG. 2, the principal part structure of the processing equipment 1 of this embodiment is demonstrated in detail.
FIG. 2 is a configuration diagram of a main part of an organic wastewater treatment facility in the embodiment of the present invention.
The activated sludge tank 3 includes a denitrification tank 10 (indicated by dot ground areas (1) to (7) in FIG. 2) divided into seven tanks, and a nitrification tank 11 (white background area (in FIG. 1) to (16)). The total volume of the activated sludge tank 3 is about 7,600 m ³ , each volume of the denitrification tanks (1) to (3) is about 120 m ³ , and each volume of the denitrification tank (4) to the nitrification tank (16) is about 360 m ^3. It has become.

  The organic waste water consists of treated water that has passed through the anaerobic treatment device 2 and further bypass water that bypasses the anaerobic treatment device 2, and flows into the denitrification tank (1) that constitutes the inlet of the denitrification tank 10. Similarly, the return sludge from the final sedimentation basin 4 also flows into the denitrification tank (1). The nitrification liquid from the nitrification tank (16) flows into the denitrification tank (4).

The denitrification tank (1) has a role as a selector (hereinafter, the denitrification tank (1) is referred to as a selector tank 10a). The selector tank 10a is a tank in which activated sludge is brought into contact with a high-concentration organic substance, and is generally effective in giving priority to the growth of floc-forming bacteria having a large sedimentation property. On the other hand, when the organic substance concentration in the selector tank 10a is low, the growth of filamentous bacteria having a low sedimentation priority is given priority and the activated sludge bulges (bulking), resulting in a decrease in sedimentation.
Hereinafter, the correlation between the organic substance concentration and the bulking in the selector tank 10a will be described with reference to the data shown in FIGS.

FIG. 3 shows operation result data of the treatment facility 1, and changes in the activated sludge concentration (MLSS (Mixed Liquor Suspend Solids)) value (shown by rhombus plots) and SV ₃₀ (sludge sedimentation property) during a certain operation period. Index of the sludge (volume% of sludge left for 30 minutes in a 1 L graduated cylinder)) (shown by square plot).
As shown in FIG. 3, MLSS was maintained at 3,000 to 4,000 mg / L throughout the operation period, but SV ₃₀ increased from October 7 and was about 80 after October 18. % Or more and the sludge has a very low sedimentation property. That is, it can be seen that the processing system normally operated from September 28 to October 17, but after October 18, the processing system failed and was not operating normally.

Figure 4 shows the values of concentration of organic substances in the selector tank 10a of the processing system collapse before and processing system after the collapse (COD _Cr concentration) and the values of SVI in the processing system. Also, in the figure, the COD _Cr concentration in the selector tank 10a before failure of the processing system is indicated by a rhombus plot, and the COD _Cr concentration in the selector tank 10a after failure of the processing system is indicated by a square plot.
It should be noted that the pre-processing system failure and the post-processing system failure are defined with the boundary of the SVI value at which bulking generally occurs, in this embodiment, the value of 200 mL / g.

As shown in FIG. 4, but correlation between the value of the SVI in value as the processing system of the COD _Cr concentration in the selector tank 10a of the processing system after the collapse (October 18, after in FIG. 3) is not observed, treatment system it is recognized that in a correlation with the value of SVI and the value and the processing system of the _{COD Cr} concentration in the selector tank 10a of the bankrupt before (September 28 to October 17 in FIG. 3). More specifically, as indicated by the straight line in the figure, in the pretreatment system collapse, there is a trend towards bulking (collapse) the value of COD _Cr concentration of the selector tank 10a becomes higher values of SVI as lower, also, the value of the _{COD Cr} concentration value larger the SVI selector tank 10a tends away from bulking low.

Processing equipment 1 of the present embodiment is provided with a fifth control unit (organic matter concentration adjusting device) for preventing the bulking defining the optimum operation control value (lower limit of COD _Cr concentration in the selector tank 10a) using the above characteristics ( (See FIG. 2). The control device 5 comprises a computer system that adjusts the _CODCr concentration in the selector tank 10a based on a predetermined control value determined from the above characteristics. Specifically, the control device 5 according to the present embodiment controls the inflow amount of organic waste water through the organic waste water supply line 15 (including the bypass line 15a as necessary) and the inflow amount of return sludge through the return sludge line 13. Thus, the _CODCr concentration in the selector tank 10a is adjusted.

_{COD Cr} concentration A in the selector tank 10a (mg / L) is represented by the following formula (a).
A = A _in × Q _in / (Q _in + Q _re ) (a)
In the formula (a), the inflow amount per unit time of the organic waste water flowing into the selector tank 10a is Q _in (L / h), the COD _Cr concentration is A _in (mg / L), and the selector tank 10a. Q _re (L / h) represents the amount of inflow per unit time of the return sludge flowing in. Note that the amount of biodegradable organic matter contained in the returned sludge is small, so the COD _Cr concentration of the returned sludge does not need to be considered (considered when the COD _Cr concentration of the activated sludge treated water is high).

The control device 5 controls the _CODCr concentration in the selector tank 10a by controlling at least one of the inflow amount of organic wastewater and the inflow amount of return sludge using the above formula. For example, if the inflow amount of organic waste water is constant, the inflow amount of return sludge is controlled to adjust the _CODCr concentration in the selector tank 10a. In the processing equipment 1 of the present embodiment, since the starch waste water discharged from the potato starch manufacturing plant processed, the lower limit of the COD _Cr concentration in the selector tank 10a from the operation record data shown in FIG. 4 (control value) It is preferably set to 1,000 mg / L and controlled to a value of 1,000 mg / L or more.

Therefore, according to the above-described embodiment, the activated sludge tank 3 for treating the wastewater containing organic substances by the activated sludge method and the final sedimentation tank 4 for precipitating the sludge contained in the treated water that has passed through the activated sludge tank 3 are provided. The waste water is discharged from the bottom of the final sedimentation basin 4 and the sludge extracted from the bottom of the final sedimentation basin 4 is returned to the inlet of the activated sludge tank 3. Based on the SVI value that is divided into a plurality of tanks and has a selector tank 10a into which the organic waste water and the return sludge flow into the inlet, and is predetermined by the bulking characteristics of the sludge and can be discharged. By adopting a method of determining an organic substance concentration control value in the selector tank 10a and having an organic substance concentration adjusting step of adjusting the organic substance concentration in the selector tank 10a based on the control value, Adjusting the concentration of organic substances in 10a, it is possible to control the value of SVI processing system to below the value of the bulking occurs SVI.
Therefore, in the present embodiment, organic substances are preferentially taken into microorganisms (floc-forming bacteria) in the activated sludge by appropriately maintaining the organic substance concentration in the selector tank 10a while monitoring the SVI value of the treatment system. And the growth of filamentous bacteria can be suppressed. For this reason, the sedimentation property of sludge is ensured and the stable activated sludge process is attained.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, it has been described that the control device 5 adjusts the _CODCr concentration in the selector tank 10a by controlling at least one of the inflow amount of organic wastewater and the inflow amount of return sludge. Is not limited to the above configuration, for example, a part of the nitrification liquid returned to the denitrification tank (4) is diverted and introduced into the selector tank 10a, and the inflow amount is controlled to The structure which adjusts a COD _Cr density | concentration may be sufficient. Further, when the _CODCr concentration in the selector tank 10a is low, the flow rate from the bypass line 15a may be controlled and adjusted.

  DESCRIPTION OF SYMBOLS 1 ... Processing equipment, 3 ... Activated sludge tank, 4 ... Final sedimentation tank (sedimentation tank), 5 ... Control apparatus (organic substance concentration control apparatus), 10 ... Denitrification tank, 10a ... Selector tank, 11 ... Nitrification tank

Claims (10)

An activated sludge tank for treating wastewater containing organic substances by an activated sludge method; and a settling tank for precipitating sludge contained in treated water that has passed through the activated sludge tank, and discharging the supernatant water of the settling tank and the settling An organic wastewater treatment method for returning the sludge extracted from the bottom of the tank to the inlet of the activated sludge tank,
The activated sludge tank is partitioned into a plurality of tanks, and the inlet portion has a selector tank into which the drainage and the returned sludge to be returned flow.
Based on the value of the sludge volume index that is predetermined by the bulking characteristics of the sludge and can be discharged, the control value of the concentration of organic matter in the selector tank is determined,
An organic wastewater treatment method comprising: an organic matter concentration adjusting step of adjusting an organic matter concentration in the selector tank based on the control value. The activated sludge tank has a denitrification tank that performs anaerobic treatment with denitrifying bacteria in the previous stage, and a nitrification tank that performs aerobic treatment with nitrifying bacteria in the subsequent stage,
The method for treating organic waste water according to claim 1, wherein the selector tank constitutes an inlet portion of the denitrification tank.   3. The organic matter concentration adjusting step controls the concentration of organic matter in the selector tank by controlling at least one of the inflow amount of the waste water and the inflow amount of the return sludge. The organic wastewater treatment method as described. A part of the nitrification water is returned from the nitrification tank to the denitrification tank,
In the organic matter concentration adjusting step, the organic matter in the selector tank is controlled by controlling at least one of the inflow amount of the waste water, the inflow amount of the return sludge, and the inflow amount of the nitrification water returned to the selector tank. The method for treating organic waste water according to claim 1, wherein the concentration of the organic waste water is adjusted. The waste water is potato starch waste water,
In the organic material concentration adjusting step, a concentration of organic matter in the selector tank, the organic waste water according to claim 1, characterized in that the adjusted COD _Cr concentration than 1,000 mg / L Processing method. An activated sludge tank for treating wastewater containing organic substances by an activated sludge method; and a settling tank for precipitating sludge contained in treated water that has passed through the activated sludge tank, and discharging the supernatant water of the settling tank and the settling An organic wastewater treatment facility for returning the sludge extracted from the bottom of the tank to the inlet of the activated sludge tank,
The activated sludge tank is partitioned into a plurality of tanks, and the inlet portion has a selector tank into which the drainage and the returned sludge to be returned flow.
Based on the value of the sludge volume index that is predetermined by the bulking characteristics of the sludge and can be discharged, the control value of the concentration of organic matter in the selector tank is determined,
An organic wastewater treatment facility comprising an organic matter concentration adjusting device for adjusting an organic matter concentration in the selector tank based on the control value. The activated sludge tank has a denitrification tank that performs anaerobic treatment with denitrifying bacteria in the previous stage, and a nitrification tank that performs aerobic treatment with nitrifying bacteria in the subsequent stage,
The organic wastewater treatment facility according to claim 6, wherein the selector tank constitutes an inlet portion of the denitrification tank.   The organic substance concentration adjusting device controls at least one of the inflow amount of the waste water and the inflow amount of the return sludge to adjust the concentration of the organic substance in the selector tank. The organic wastewater treatment facility described. A part of the nitrification water is returned from the nitrification tank to the denitrification tank,
The organic matter concentration adjusting device controls at least one of the inflow amount of the waste water, the inflow amount of the return sludge, and the inflow amount of the nitrification water to be returned to the selector tank, and the organic matter in the selector tank The organic waste water treatment facility according to claim 6 or 7, wherein the concentration of the organic waste water is adjusted. The waste water is potato starch waste water,
The organic material concentration regulating device, the concentration of organic matter in the selector tank, the organic waste water according to any one of claims 6-9, characterized in that to adjust more than 1,000 mg / L at COD _Cr concentration Processing equipment.

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