JP6437794B2 - Waste water treatment apparatus and waste water treatment method - Google Patents

Description

  The present invention relates to a technology of a wastewater treatment apparatus and a wastewater treatment method for biologically treating wastewater containing organic matter and the like.

  As a method for biologically treating wastewater containing organic substances, an activated sludge method using an aggregate of microorganisms called floc (biological sludge) has been used. However, the activated sludge method may have a problem that when the floc is separated from the treated water in the sedimentation basin, the surface area of the sedimentation basin must be very large because the sedimentation speed of the floc is slow. The treatment rate of the activated sludge method depends on the sludge concentration in the tank, and the treatment rate can be increased by increasing the sludge concentration. For example, when the concentration of the substance to be treated such as sewage is low In order to increase the treatment amount, the flow rate increases, and it may become more difficult to separate the floc and the treated water in the sedimentation basin.

  In anaerobic biological treatment, it is common to use aggregates (granular biological sludge) in which microorganisms called granules are densely aggregated and granulated. Granules have a very fast sedimentation rate, and microorganisms gather densely, so that the sludge concentration in the treatment tank can be increased and high-speed wastewater treatment can be realized. However, the anaerobic biological treatment has problems such as the fact that the wastewater species to be treated is limited compared to the aerobic treatment (activated sludge method) and that the treated water temperature needs to be maintained at 30 to 35 ° C. May have. In addition, when the anaerobic biological treatment alone is poor in the quality of the treated water, it may be necessary to separately perform an aerobic treatment such as an activated sludge method when discharged into a river or the like.

  In recent years, treatment has been carried out using a semi-batch treatment device that allows wastewater to flow into the reaction tank intermittently, and the sedimentation time of biological sludge is shortened, so that it is not limited to anaerobic biological sludge. It has been clarified that a biological sludge (hereinafter sometimes referred to as granule) can be formed (see, for example, Patent Documents 1 to 4).

  As described above, high-speed treatment can be achieved by granulating biological sludge, but when using a semi-batch treatment device for large-scale wastewater treatment facilities such as sewage treatment, a huge wastewater storage tank May have to be installed. However, for example, in a sewage treatment plant, it is difficult to provide a huge drainage storage tank.

  Therefore, it is equipped with a continuous biological treatment device that treats wastewater by continuously flowing it in, and a semi-batch biological treatment device that generates aerobic granules, and aerobic granules are continuously fed from the semi-batch biological treatment device. A treatment apparatus that granulates biological sludge in a continuous biological treatment apparatus by supplying it to the biological treatment apparatus has been proposed (see, for example, Patent Document 5). According to the apparatus of Patent Document 5, the sedimentation basin and the reaction tank can be miniaturized, the space for the wastewater treatment facility can be saved, and the equipment cost can be greatly reduced.

International Publication No. 2004/024638 JP 2008-212878 A Japanese Patent No. 4975541 Japanese Patent No. 4804888 JP 2007-136367 A

  By the way, in the apparatus of Patent Document 5, it is necessary to stably form granules in a semi-batch type biological treatment apparatus in order to achieve high-speed treatment of waste water, but the granules can be stably formed. For example, the concentration of organic substances in the wastewater flowing into the semi-batch biological treatment apparatus is preferably about 200 to 1000 mg BOD / L, for example. However, the organic substance concentration contained in the wastewater (raw water) to be treated is often lower than the above numerical range. For example, the organic matter concentration of normal sewage is often relatively low at about 50 to 200 mg BOD / L. Even when such waste water to be treated (raw water) is supplied to a semi-batch biological treatment apparatus, it may be difficult to form a stable granule.

  Even when the organic matter concentration in the wastewater to be treated (raw water) is high, for example, industrial wastewater such as food industry and chemical industry wastewater is necessary for biological treatment of organic matter such as nitrogen and phosphorus in the wastewater. There may be a shortage of nutrients. Even when such waste water to be treated (raw water) is supplied to a semi-batch biological treatment apparatus, it is difficult to form a stable granule.

  Then, this invention aims at providing the waste water treatment apparatus and waste water treatment method which make it possible to form a granule stably in a semibatch type biological treatment apparatus, and to supply to a continuous biological treatment apparatus. To do.

The wastewater treatment apparatus of the present invention is a continuous biological treatment apparatus that biologically treats wastewater that flows continuously, a solid-liquid separation apparatus that separates biological sludge from treated water discharged from the continuous biological treatment apparatus, Semi-batch organism that forms granules by intermittently introducing the desorbed water obtained from at least one of concentration, digestion and dehydration of excess sludge discharged from the solid-liquid separator. A treatment apparatus, a desorption water supply means for intermittently supplying the desorption water to the semi-batch biological treatment apparatus, and granules discharged from the semi-batch biological treatment apparatus are supplied to the continuous biological treatment apparatus. Granule sludge supply means.

  Moreover, it is preferable that the waste water treatment apparatus further includes waste water supply means for supplying a part of the waste water flowing into the continuous biological treatment apparatus to the semi-batch biological treatment apparatus.

  Moreover, the waste water treatment apparatus of the present invention preferably includes treated water supply means for supplying treated water discharged from the continuous biological treatment apparatus to the semi-batch biological treatment apparatus.

Further, in the waste water treatment apparatus, it is preferable that the biological sludge discharged from the pre Symbol solid-liquid separator comprises a biological sludge return means to return to the continuous biological treatment device.

  The wastewater treatment apparatus includes a sludge treatment system that performs at least one of concentration, digestion, and dehydration of surplus sludge to generate desorption water, and the desorption water supply means includes the sludge treatment system. It is preferable to intermittently supply discharged water to the semi-batch biological treatment apparatus.

Moreover, the wastewater treatment method of the present invention includes a continuous biological treatment step for biologically treating wastewater that flows continuously, and a solid-liquid separation step for separating biological sludge from treated water discharged from the continuous biological treatment step. , Semi-batch to form granules by performing biological treatment by intermittently introducing desorbed water obtained from at least one of concentration, digestion and dehydration of excess sludge discharged from the solid-liquid separation step Biological biological treatment step, desorbed water supply step for intermittently supplying the desorbed water to the semi-batch biological treatment step, and granule discharged from the semi-batch biological treatment step to the continuous biological treatment step And a granule sludge supply step to supply.

  The waste water treatment method preferably includes a waste water supply step of supplying a part of the waste water flowing into the continuous biological treatment step to the semi-batch biological treatment step.

  The waste water treatment method preferably includes a treated water supply step of supplying treated water discharged from the continuous biological treatment step to the semi-batch biological treatment step.

Further, in the wastewater treatment method, preferably comprises a biological sludge discharged from the pre Symbol solid-liquid separation step as the biological sludge return Engineering for returning the continuous biological treatment process.

  Further, in the wastewater treatment method, a sludge treatment step is performed in which at least any one of concentration, digestion, and dehydration of surplus sludge is performed to generate desorption water. In the desorption water supply step, the sludge treatment step includes It is preferable to intermittently supply discharged water to the semi-batch biological treatment process.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to form a granule stably with a semibatch type biological treatment apparatus, and to supply to a continuous biological treatment apparatus.

It is a schematic diagram which shows an example of a structure of the waste water treatment apparatus which concerns on this embodiment. It is a schematic diagram which shows an example of a structure of the semibatch type | formula biological treatment apparatus used by this embodiment. It is a schematic diagram which shows another example of a structure of the waste water treatment apparatus which concerns on this embodiment.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic diagram illustrating an example of a configuration of a wastewater treatment apparatus according to the present embodiment. A wastewater treatment apparatus 1 shown in FIG. 1 includes a continuous biological treatment apparatus 10, a semi-batch biological treatment apparatus 12, a solid-liquid separation apparatus 14, and a sludge treatment system 16. The sludge treatment system 16 shown in FIG. 1 includes a sludge concentrating device 18, a sludge digesting device 20, and a sludge dewatering device 22.

  The wastewater treatment apparatus 1 shown in FIG. 1 includes wastewater inflow lines 24a and 24b, treated water discharge lines 26a and 26b, sludge return line 28, sludge discharge line 30, desorbed water supply line 32, concentrated sludge discharge line 34, and digested sludge discharge. A line 36, a dewatered cake discharge line 38, and a granule sludge supply line 40 are provided.

  The drainage inflow line 24 a is connected to the drainage inlet of the continuous biological treatment apparatus 10. One end of the drainage inflow line 24 b is connected to the drainage outlet of the continuous biological treatment apparatus 10, and the other end is connected to the drainage inlet of the solid-liquid separator 14. The treated water discharge line 26 a is connected to the treated water outlet of the solid-liquid separator 14. One end of the sludge return line 28 is connected to the sludge outlet of the solid-liquid separator 14, and the other end is connected to the drainage inflow line 24a. One end of the sludge discharge line 30 is connected to the sludge return line 28, and the other end is connected to the sludge inlet of the sludge concentrator 18. One end of the desorbed water supply line 32 is connected to the desorbed water inlet of the semi-batch biological treatment apparatus 12, and the other end is connected to each desorbed water outlet of the sludge concentrator 18, sludge digester 20, and sludge dewaterer 22. . One end of the concentrated sludge discharge line 34 is connected to the sludge outlet of the sludge concentrator 18, and the other end is connected to the sludge inlet of the sludge digester 20. One end of the digested sludge discharge line 36 is connected to the sludge outlet of the sludge digester 20, and the other end is connected to the sludge inlet of the sludge dewaterer 22. The dewatered cake discharge line 38 is connected to the sludge outlet of the sludge dewatering device 22. One end of the biological sludge supply line 40 is connected to the sludge outlet of the semi-batch biological treatment apparatus 12, and the other end is connected to the sludge return line 28. One end of the treated water discharge line 26b is connected to the treated water outlet of the semi-batch biological treatment apparatus 12, and the other end is connected to the treated water discharge line 26a.

  FIG. 2 is a schematic diagram showing an example of the configuration of the semi-batch biological treatment apparatus used in the present embodiment. In the semi-batch biological treatment apparatus 12 shown in FIG. 2, as will be described later, (1) inflow of desorbed water, (2) biological treatment of substances to be treated such as organic matter, phosphorus, nitrogen, and (3) sedimentation of biological sludge (4) Granules are formed by repeating the four steps of discharging the treated water. The semi-batch biological treatment apparatus 12 shown in FIG. 2 includes an aerobic reaction tank 42, a desorbed water inflow pump 44, a treated water side electromagnetic valve 46, a stirring device 48, and an air pump in and around the aerobic reaction tank 42. 50, an air diffuser 52, a sludge discharge pump 54, and the like are arranged.

  In this embodiment, the desorbed water supply line 32 and the desorbed water inflow pump 44 installed in the desorbed water supply line 32 function as a desorbed water supply apparatus that intermittently supplies the desorbed water to the semi-batch biological treatment apparatus 12. To do. In this embodiment, intermittent supply of desorbed water is performed by operating / stopping the desorbed water inflow pump 44. For example, an electromagnetic valve or the like may be installed in the desorbed water supply line 32 and the valve may be opened and closed. good. The desorbed water is water obtained by concentrating, digesting or dehydrating excess sludge as will be described later. In this embodiment, the surplus sludge introduced into the sludge treatment step for obtaining desorbed water is intended for sludge discharged from the continuous biological treatment apparatus, but is not limited thereto, for example, When a solid-liquid separator that removes solids in the wastewater is installed in the previous stage of the continuous biological treatment equipment, and excess sludge is discharged from the previous solid-liquid separator (when so-called raw sludge is discharged), The raw sludge may be mixed with surplus sludge introduced into the sludge treatment system.

  In the present embodiment, the granule sludge supply line 40 and the sludge discharge pump 54 installed in the granule sludge supply line 40 function as a biological sludge supply apparatus that supplies the granular sludge to the continuous biological treatment apparatus 10. In addition, you may install a valve | bulb etc. in the biological sludge supply line 40 suitably.

  The air diffuser 52 is connected to the air pump 50, and the air supplied from the air pump 50 is supplied into the tank through the air diffuser 52. The agitator 48 is for agitating the liquid in the tank, and includes, for example, a motor, a stirring blade, a shaft connecting the motor and the stirring blade, and the like.

  The continuous biological treatment apparatus 10 of the present embodiment is an aerobic reaction tank in which wastewater to be treated (hereinafter sometimes referred to as raw water) is continuously supplied into the tank, and the raw water is biologically treated. Although not shown, the continuous biological treatment apparatus 10 shown in FIG. 1 includes, for example, a stirring device, an air pump, an air diffuser connected to the air pump, and the liquid in the tank is stirred by the stirring device. It is comprised so that the air supplied from an air pump may be supplied in a tank through a diffuser.

  The sludge concentrating device 18 of this embodiment is a device for concentrating excess sludge. Here, the concentration of surplus sludge by the sludge concentrating device 18 used in the present embodiment is to condense the surplus sludge and to perform the subsequent digestion and dehydration operations efficiently, the water content of the surplus sludge in the previous stage. It aims at lowering. By the concentration step, it becomes possible to reduce the moisture content of the sludge discharged from the continuous biological treatment step from 99% or more to about 96 to 98%. In addition, in the process of concentrating excess sludge, it is generally considered that the excess sludge is eluted from the excess sludge by an anaerobic digestion reaction or the like. That is, it is considered that the desorbed water obtained by concentrating the excess sludge contains organic substances derived from the excess sludge, nitrogen, phosphorus, etc. eluted by an anaerobic digestion reaction or the like. As the sludge concentrating device 18 of the present embodiment, a known concentrating device can be used, and examples thereof include a gravity concentrator, a belt concentrator, a centrifugal concentrator, and an elliptical plate concentrator.

  The sludge digestion apparatus 20 of this embodiment is an apparatus for digesting excess sludge. Here, digestion of excess sludge by the sludge digester 20 used in the present embodiment means that the excess sludge is hydrolyzed and digested by the action of anaerobic microorganisms (acid-producing bacteria, methane fermentation bacteria, etc.), and excess sludge is obtained. This is a process that reduces the amount of sludge by converting part of the organic matter into gaseous substances such as methane and carbon dioxide. Particularly, in the case of a system in which the digestion tank has two stages, the biological reaction is performed in the primary tank, and the solid-liquid separation is performed in the secondary tank, the desorbed water is discharged from the secondary tank. In the sludge digestion process, in addition to undecomposed organic substances, the nitrogen component in the sludge elutes ammonia, which is the final product, and the phosphorus discharged from the sludge in an anaerobic state elutes in the form of phosphoric acid. In other words, the desorbed water obtained by digestion contains digested surplus sludge-derived organic matter, nitrogen, phosphorus, and the like. The sludge digester 20 of the present embodiment can use a known digester, and examples thereof include an anaerobic tank. An aerobic digestion method may also be used.

  The sludge dewatering device 22 of this embodiment is a device for dewatering excess sludge. Here, the dewatering of biological sludge by the sludge dewatering device 22 used in the present embodiment is to dehydrate concentrated sludge or digested sludge having a moisture content of about 96 to 98% to a moisture content of about 80%, It is a process of reducing the sludge capacity by converting a liquid material into a so-called cake shape. In the dehydration process, a flocculant may be added to perform the dehydration process more efficiently. The desorbed water obtained by dewatering excess sludge contains organic substances, nitrogen, phosphorus, and the like generated through the concentration and / or digestion steps. Further, in the dehydration process, the microorganisms in the sludge are physically destroyed, so that components such as organic matter, nitrogen, and phosphorus are eluted into water and are contained in the desorbed water. As the sludge dewatering device 22 of the present embodiment, a known dewatering device can be used. For example, a screw press dewatering device, a belt press dewatering device, a centrifugal dewatering device, a vacuum dewatering device, a filter press dewatering device, a multiple disk. Examples include a dehydrator.

  The solid-liquid separation device 14 of this embodiment is a separation device for separating water containing biological sludge into biological sludge and treated water. Examples of the solid-liquid separation device 14 include separation devices such as sedimentation separation, pressurized flotation, filtration, and membrane separation.

  An example of operation | movement of the waste water treatment equipment 1 of this embodiment is demonstrated.

  Examples of the wastewater (raw water) to be treated in this embodiment include food processing factory wastewater, chemical factory wastewater, semiconductor factory wastewater, machine factory wastewater, sewage, human waste, river water, and the like. Further, the wastewater generally contains biodegradable organic substances. In addition, when the biologically indegradable organic substance is contained in the waste water, it is desirable to remove by performing physicochemical treatment such as flotation separation, agglomeration pressure flotation device, and an adsorption device in advance.

  First, the wastewater to be treated is continuously supplied to the continuous biological treatment apparatus 10 through the wastewater inflow line 24a. In the continuous biological treatment apparatus 10, wastewater is biologically treated with biological sludge under aerobic conditions. The biological sludge treated water (treated water containing biological sludge) treated by the continuous biological treatment device 10 is supplied to the solid-liquid separation device 14 through the drainage inflow line 24b. In the solid-liquid separator 14, the biological sludge treated water is solid-liquid separated into treated water and biological sludge. The treated water passes through the treated water discharge line 26a and is discharged out of the system. A part of the biological sludge discharged from the solid-liquid separator 14 is supplied from the sludge return line 28 to the continuous biological treatment apparatus 10 through the wastewater inflow line 24a, and is also discharged from the solid-liquid separator 14. A part of is supplied to the sludge treatment system 16 from the sludge discharge line 30 as surplus sludge.

  In the sludge treatment system 16 of the present embodiment, the biological sludge discharged from the solid-liquid separator 14 is introduced from the sludge discharge line 30 to the sludge concentrator 18 to concentrate the biological sludge. The excess sludge (concentrated sludge) concentrated by the sludge concentrating device 18 is supplied from the concentrated sludge discharge line 34 to the sludge digester 20. In the sludge digester 20, the concentrated sludge is digested and the volume of sludge is reduced. Excess sludge (digested sludge) discharged from the sludge digester 20 is introduced from the digested sludge discharge line 36 to the sludge dewatering device 22. In the sludge dewatering device 22, the digested sludge is dehydrated, and a dehydrated cake having a low water content is obtained. The obtained dehydrated cake is discharged from the dehydrated cake discharge line 38. The dehydrated cake is sent to an incineration facility.

  In the sludge concentrating device 18, the sludge digesting device 20, and the sludge dewatering device 22, the desorbed water separated from the excess sludge in each tank is generated. As described above, these desorbed water contains organic substances derived from surplus sludge and the like eluted by an anaerobic digestion reaction, nitrogen, phosphorus and other substances, and the desorbed water containing the substances is supplied to the desorbed water. The semi-batch biological treatment apparatus 12 is intermittently introduced from the line 32.

  In the semi-batch biological treatment apparatus 12, as described above, the steps of (1) inflow of desorbed water, (2) biological treatment of the treatment target substance, (3) sedimentation of biological sludge, and (4) discharge of treated water are performed. Repeatedly. Hereinafter, description will be made based on the semi-batch biological treatment apparatus 12 shown in FIG.

<(1) Inflow of desorbed water>
First, the desorbed water inflow pump 44 is operated and introduced into the semi-batch biological treatment apparatus 12 until the aforementioned desorbed water reaches a predetermined amount. Meanwhile, the air pump 50 and the stirring device 48 are stopped, and the treated water side electromagnetic valve 46 is closed. After the desorbed water is introduced to a predetermined amount, the desorbed water inflow pump 44 is stopped.

<(2) Biological treatment of target substances>
The air pump 50 is operated, air is introduced from the air diffuser 52, and the supply of air into the semi-batch biological treatment device 12 is started. As the desorbed water is stirred, biological treatment of the desorbed water is started. Then, after the predetermined time has elapsed, the operation of the air pump 50 is stopped to stop the supply of air, and the stirring device 48 is stopped to stop the biological treatment.

<(3) Sedimentation of biological sludge>
Stirring and air supply are stopped, and the biological sludge in the semi-batch biological treatment apparatus 12 is allowed to settle for a predetermined time. Thereby, in the semibatch type biological treatment apparatus 12, it isolate | separates into biological sludge and treated water.

<(4) Discharge of treated water>
When the treated water side electromagnetic valve 46 is opened, the treated water in the semi-batch biological treatment apparatus 12 is discharged from the treated water discharge line 26b. After a predetermined time has elapsed, the treated water side electromagnetic valve 46 is closed.

  By repeating the steps (1) to (4) above, granules are formed in the semi-batch biological treatment apparatus 12. Then, the sludge discharge pump 54 is operated, and the granules formed in the semi-batch biological treatment apparatus 12 are supplied from the granule sludge supply line 40 to the continuous biological treatment apparatus 10. In addition, the extraction of the granule from the semi-batch type biological treatment apparatus 12 may be performed in the (3) biological sludge sedimentation step, (2) the biological treatment step of the substance to be treated, or ( 4) You may carry out at the process water discharge process. Here, the granule formed by the semi-batch biological treatment apparatus 12 is sludge that has been self-granulated. For example, the average particle diameter of sludge is 0.2 mm or more, or SVI5 that is a sedimentation index. Is biological sludge of 80 mL / g or less.

  In the present embodiment, whether or not granules are formed is determined by measuring SVI, which is a sedimentation index of sludge, for example. Specifically, the SVI value is periodically measured by a sludge settling test in the semi-batch treatment device 12, and the value of SVI5 calculated from the volume ratio after settling for 5 minutes is equal to or less than a predetermined value (for example, 80 mL / g or less), it can be determined that granules have been formed. Alternatively, the particle size distribution of the sludge in the semi-batch processing device 12 is measured, and when the average particle size becomes a predetermined value or more (for example, 0.2 mm or more), it is determined that granules are formed. (It can be determined that the lower the SVI value, the larger the average particle size, the better the granular sludge). Thereafter, the sludge discharge pump 54 is operated, and the granules formed in the semi-batch type biological treatment apparatus 12 are supplied from the granule sludge supply line 40 to the continuous biological treatment apparatus 10. Further, for example, it may be confirmed in advance by a preliminary experiment how many cycles the above steps (1) to (4) are repeated to form granules. That is, in the actual treatment process, it is determined that granules are formed at the stage where the above steps (1) to (4) are repeated up to the number of cycles confirmed in the preliminary experiment, and then the sludge discharge pump 54 is operated. The granule formed by the semi-batch biological treatment apparatus 12 may be supplied from the granule sludge supply line 40 to the continuous biological treatment apparatus 10.

  In general, biological sludge repeats a state in which organic substances, nitrogen, and phosphorus, which are target substances to be treated, are in a high state (immediately after the inflow process, a satiety state) and a state in which these concentrations are low (the end of the biological treatment process, starvation state) Through experience, it is believed that granulation of biological sludge proceeds. That is, for stable granule formation, the semi-batch biological treatment apparatus 12 can stably supply organic substances, nitrogen, or phosphorus (a certain amount or more) as a treatment target substance before the biological treatment is started. It becomes important. As described above, the desorbed water discharged from the sludge treatment system 16 of the present embodiment includes organic matter, nitrogen, phosphorus, etc. derived from excess sludge eluted by the anaerobic digestion reaction. 12 can be supplied with a certain amount or more of organic matter, nitrogen, phosphorus or the like. In the sludge treatment system 16 of the present embodiment, depending on the operating conditions and treatment method, for example, the BOD concentration is 200 to 2000 mgBOD / L, the total nitrogen concentration is about 200 to 2000 mgN / L, and the phosphorus concentration is 20 to 200 mgP / L. It is possible to discharge a certain amount of desorbed water.

  By the way, since organic matter etc. are contained also in the raw | natural water supplied to the continuous biological treatment apparatus 10, it is also considered that raw water is supplied to the semi-batch biological treatment apparatus 12 to form granules. However, when only raw water is used, concentration fluctuations of organic substances, nitrogen, phosphorus, etc. are likely to occur, so that a certain amount or more of the above substances cannot always be supplied to the semi-batch biological treatment apparatus 12, and the source of the raw water In some cases, the concentration of organic matter, nitrogen, phosphorus, or the like is extremely low, which makes it difficult to stably supply a certain amount or more of the substance to the semi-batch biological treatment apparatus 12. Therefore, when the desorbed water discharged from the sludge treatment system 16 is supplied to the semi-batch biological treatment device 12, compared with the case where only the raw water is supplied to the semi-batch biological treatment device 12, organic matter, nitrogen or phosphorus Can be stably supplied (a certain amount or more), so that stable granule formation is possible. In other words, by supplying the desorbed water discharged from the sludge treatment system 16 to the semi-batch biological treatment device 12, the concentration of organic matter, nitrogen and phosphorus in the wastewater (raw water) flowing into the continuous biological treatment device 10 Regardless of their concentration fluctuations, organic substances, nitrogen, phosphorus, and the like can be stably supplied to the semi-batch biological treatment apparatus 12, so that stable granule formation is possible.

  In addition, if the BOD concentration, nitrogen concentration or phosphorus concentration of the desorption water supplied to the semi-batch biological treatment device 12 is too high (for example, the BOD concentration is 1000 mgBOD / L or more, the nitrogen concentration is 1000 mgBOD / L or more, or the phosphorus concentration 100 mg P / L or more), since the semi-batch biological treatment device 12 may not be sufficiently biologically treated, the biological sludge treated water discharged from the continuous biological treatment device 10 is used as the semi-batch biological treatment device 12. It is preferable to provide a sludge treated water supply line for supplying to the water. Thereby, it becomes possible to dilute the desorption water supplied to the semi-batch biological treatment apparatus 12 as appropriate. Although the sludge treated water supply line is not shown, for example, one end of the sludge treated water supply line is connected to one end of the drainage inflow line 24b, and the other end is connected to the semi-batch biological treatment tank or the desorbed water supply line 32.

  The organic matter concentration of the desorbed water supplied to the semi-batch biological treatment device 12 is higher than the organic matter concentration of the waste water (raw water) supplied to the continuous biological treatment device 10 in that it stably forms granules. For example, the BOD concentration is preferably 100 mgBOD / L or more, and more preferably 200 mgBOD / L or more. In addition, the nitrogen concentration of the desorption water supplied to the semi-batch biological treatment apparatus 12 is more stable than the nitrogen concentration of the waste water (raw water) supplied to the continuous biological treatment apparatus 10 in that it stably forms granules. The concentration is preferably high, and for example, the concentration of TN (total nitrogen concentration) is preferably 20 mgN / L or more, and more preferably 40 mgN / L or more. In addition, the phosphorus concentration of the desorption water supplied to the semi-batch biological treatment apparatus 12 is more stable than the phosphorus concentration of the wastewater (raw water) supplied to the continuous biological treatment apparatus 10 in that it stably forms granules. A high concentration is preferable, for example, 5 mgP / L or more is preferable, and 10 mgP / L or more is more preferable.

  Below, the modification etc. of this embodiment are demonstrated.

  In the wastewater treatment apparatus 1 shown in FIG. 1, the granules formed by the semi-batch biological treatment apparatus 12 are supplied to the continuous biological treatment apparatus 10 through the sludge return line 28. If it supplies to the apparatus 10, it will not be limited to the said form. For example, the granule sludge supply line 40 may be directly connected to the continuous biological treatment apparatus 10, and the granules formed by the semi-batch biological treatment apparatus 12 may be supplied to the continuous biological treatment apparatus 10, or the biological The sludge supply line 40 is connected to the solid-liquid separator 14, the granules formed in the semi-batch biological treatment device 12 are supplied to the solid-liquid separator 14, and the continuous biological organism is fed from the solid separator through the sludge return line 28. You may supply to the processing apparatus 10. FIG.

  In the wastewater treatment apparatus 1 shown in FIG. 1, the treated water discharged from the semi-batch biological treatment apparatus 12 is discharged out of the system through the treated water discharge line 26, but is not limited to this form. For example, the treated water discharged from the semi-batch biological treatment device 12 may be supplied to the continuous biological treatment device 10 or may be supplied to the solid-liquid separation device 14.

  In the semi-batch type biological treatment apparatus 12 shown in FIG. 1, the form of performing biological treatment under aerobic conditions has been described as an example. There are no particular restrictions on alternating air operation. However, since the growth rate of biological sludge is increased by including aerobic conditions, it is desirable to include aerobic conditions from the viewpoint of granule formation rate. In granule formation, it is desirable to properly control the settling time and the wastewater inflow rate per batch. The settling time to stop the stirring (including stirring by aeration) and set the sludge is calculated from the distance from the water surface to the sludge discharge part and the settling speed of the sludge, for example, between 4 minutes / m and 15 minutes / m Is preferably set at 5 minutes / m to 10 minutes / m. Further, the drainage inflow rate (ratio of influent water to the effective volume during reaction) is preferably in the range of 20% to 80%, for example, and more preferably in the range of 40% to 60%. As sludge repeatedly experiences a state in which the concentration of organic matter, which is the treatment target substance, is very high (immediately after the inflow process, a satiety state) and a state in which the organic matter concentration is very low (the end of the biological treatment process, starvation state), Since granulation is considered to progress, the drainage inflow rate should be as high as possible from the viewpoint of granule formation. On the other hand, the higher the drainage inflow rate, the more the inflow pump Capacity increases and costs increase. Therefore, the drainage inflow rate is preferably in the range of 40% or more and 60% or less in terms of granule formation and cost reduction.

  The semi-batch biological treatment apparatus 12 is preferably operated, for example, in a range where the sludge concentration in the tank is 2000 to 20000 mg / L. When the sludge concentration increases above a predetermined concentration, it is desirable to extract biological sludge from the tank. In order to maintain the soundness (sedimentation, activity, etc.) of biological sludge, it is desirable to maintain an appropriate sludge load, preferably in the range of 0.05 to 0.60 kg BOD / MLSS / day, more preferably It is desirable to draw biological sludge out of the tank so that it is kept in the range of 0.1 to 0.5 kg BOD / MLSS / day.

  The pH in the semi-batch biological treatment apparatus 12 is preferably adjusted to a range of 6 to 9 suitable for general biological treatment, and more preferably adjusted to a range of 6.5 to 7.5. When the pH value is out of the above range, it is preferable to adjust the pH using an acid or an alkali. When the pH adjustment is performed in the semi-batch biological treatment apparatus 12, the pH adjustment is performed in a state where the semi-batch biological treatment apparatus 12 is stirred rather than in a state where the semi-batch biological treatment apparatus 12 is not stirred. It is desirable to do. The dissolved oxygen (DO) in the semi-batch biological treatment apparatus 12 is preferably 0.5 mg / L or more, more preferably 1 mg / L or more, which is suitable for general biological treatment.

  The semi-batch biological treatment device 12 includes a device that simultaneously performs inflow of desorbed water and discharge of treated water. That is, an apparatus that repeats the three steps of (1) inflow of desorbed water / discharge of treated water, (2) biological treatment of the substance to be treated, and (3) sedimentation of biological sludge is also a semi-batch biological treatment apparatus of this embodiment. 12.

  In the continuous biological treatment apparatus 10 shown in FIG. 1, an example has been described in which biological treatment is performed by a standard activated sludge method using organic matter or the like as a treatment target. However, the present invention is not limited to this, and for example, A2O (Anaerobic- Nutrient removal systems (systems with anaerobic and anaerobic tanks) such as Anoxic Process (ANOX) and AO (Anaerobic-Oxic Process), systems such as oxidation ditch method, step inflow type multi-stage activated sludge method, etc. It may be an apparatus that performs processing. Moreover, the apparatus which performs biological treatment in presence of carriers, such as a polyurethane, a plastics, resin, may be sufficient.

  The continuous biological treatment apparatus 10 is preferably operated, for example, in a range where the sludge concentration in the tank is 2000 to 20000 mg / L. In order to maintain the soundness (sedimentation, activity, etc.) of biological sludge, the sludge load is preferably in the range of 0.05 to 0.6 kg BOD / MLSS / day, and 0.1 to 0.5 kg BOD. More preferably, the range is / MLSS / day.

  The pH in the continuous biological treatment apparatus 10 is preferably adjusted to a range of 6 to 9 suitable for general biological treatment, and more preferably adjusted to a range of 6.5 to 7.5. In addition, the dissolved oxygen (DO) in the continuous biological treatment apparatus 10 is preferably 0.5 mg / L or more, more preferably 1 mg / L or more, which is suitable for general biological treatment.

  The sludge treatment system 16 shown in FIG. 1 includes a sludge concentrator 18 that concentrates biological sludge, a sludge digester 20 that digests biological sludge, and a sludge dewaterer 22 that dehydrates biological sludge. It does not restrict | limit, What is necessary is just to provide at least any one among the sludge concentrating device 18, the sludge digesting device 20, and the sludge dewatering device 22. In this embodiment, at least any one of the desorbed water obtained from the sludge concentrating device 18, the desorbed water obtained from the sludge digesting device 20, and the desorbed water obtained from the sludge dewatering device 22 is used as the desorbed water supply line. The semi-batch biological treatment device 12 may be supplied from 32, but from the viewpoint of introducing dewatered water having a higher organic concentration into the semi-batch biological treatment device 12, the sludge treatment system includes the sludge digester 20 and the sludge. A dehydrator 22 is preferably included. As a result, it is possible to stably supply desorbed water that is eluted by the sludge digester 20 and contains organic substances, nitrogen, and phosphorus at high concentrations.

  In the sludge concentrating device 18 used in this embodiment, although depending on the operating conditions of the device, for example, it is possible to concentrate the solid matter concentration of the biological sludge to 2 to 4%, and the water content of the biological sludge is 96. It can be ˜98%. Further, in the sludge concentrating device 18 used in the present embodiment, depending on the operating conditions of the device, for example, the BOD concentration in the desorbed water is 200 mg BOD / L or more, the total nitrogen concentration is 200 mg N / L or more, and the phosphorus concentration is It is possible to make it 10 mgP / L or more.

  In the sludge digesting apparatus 20 used in the present embodiment, although it depends on the operating conditions of the apparatus, for example, it is possible to reduce the surplus sludge amount to about 60% before the treatment. Moreover, in the sludge digestion apparatus 20 used in the present embodiment, depending on the operation conditions of the apparatus, for example, the BOD concentration in the desorption water is 200 mg BOD / L or more, the total nitrogen concentration is 200 mg N / L or more, and the phosphorus concentration is It is possible to make it 10 mgP / L or more.

  In the sludge dewatering device 22 used in the present embodiment, although depending on the operating conditions of the device, for example, the water content of biological sludge (dehydrated cake) can be dehydrated in the range of 75 to 85%.

  In the waste water treatment apparatus 1 illustrated in FIG. 1, the embodiment including the solid-liquid separation device 14 has been described as an example, but the solid-liquid separation device 14 is not necessarily provided. However, the wastewater treatment apparatus 1 is a solid-liquid separation that separates biological sludge from the biological sludge treated water discharged from the continuous biological treatment apparatus 10 in terms of improving the wastewater treatment efficiency by circulating granules. It is preferable to provide a sludge return line 28 for returning the biological sludge discharged from the apparatus 14 and the solid-liquid separator 14 to the continuous biological treatment apparatus 10. When the solid-liquid separator 14 is not installed, for example, the biological sludge treated water discharged from the continuous biological treatment apparatus 10 may be discharged out of the system as it is, or the biological sludge treated water is used as biological sludge. Separation water may be obtained by supplying it to the treatment system 16 or, as described above, the biological sludge treatment water is intermittently supplied to the semi-batch biological treatment device 12 for the purpose of diluting the desorption water. May be.

  Moreover, in the waste water treatment apparatus 1 of this embodiment, you may install the solid-liquid separation apparatus 14 in the front | former stage of the continuous biological treatment apparatus 10. FIG. That is, waste water (raw water) to be treated is separated from raw water into biological sludge and water (drainage) by the solid-liquid separation device 14 before being introduced into the continuous biological treatment apparatus 10. When the solid-liquid separation device 14 is installed in the previous stage of the continuous biological treatment apparatus 10, it is desirable to supply the biological sludge separated by the previous solid-liquid separation apparatus 14 to the sludge treatment system 16 to obtain desorbed water. When the biological sludge separated by the solid-liquid separation device 14 in the previous stage is not supplied to the sludge treatment system 16, the biological sludge treated water discharged from the continuous biological treatment device 10 is supplied to the sludge treatment system 16 as biological sludge. Thus, desorbed water may be obtained. Note that the waste water separated by the solid-liquid separation device 14 in the previous stage is introduced into the continuous biological treatment device 10 or the like.

  Moreover, in the waste water treatment apparatus 1 shown in FIG. 1, although the form provided with the sludge treatment system 16 was demonstrated to the example, the sludge treatment installed in the separate waste water treatment apparatus for the desorption water supplied to the semi-batch type biological treatment apparatus 12 If it can be secured from the system, it is not always necessary to install the sludge treatment system 16 in the wastewater treatment apparatus 1 of the present embodiment. However, a sludge treatment system 16 is provided from the viewpoint that surplus biological sludge generated from the wastewater treatment apparatus 1 can be treated and that the desorbed water can be stably supplied to the semi-batch biological treatment apparatus 12. It is preferable to supply the semi-batch biological treatment apparatus 12 with the desorbed water obtained from the sludge treatment system 16. In addition, when the waste water treatment apparatus 1 of this embodiment is not provided with the sludge treatment system 16, for example, the sludge treatment system installed in another waste water treatment apparatus and the semi-batch type biological treatment apparatus 12 of this embodiment The desorption water supply line 32 may be installed between the two, and the desorption water obtained from the sludge treatment system installed in another wastewater treatment apparatus may be supplied to the semi-batch biological treatment apparatus 12. Further, the intermittent supply of the desorption water is performed by the desorption water inflow pump 44 provided in the desorption water supply line 32 as described above.

  FIG. 3 is a schematic diagram illustrating another example of the configuration of the waste water treatment apparatus according to the present embodiment. In the waste water treatment apparatus 2 of FIG. 3, the same components as those of the waste water treatment apparatus 1 shown in FIG. The waste water treatment apparatus 2 shown in FIG. 3 includes a waste water inflow line 24 c that supplies a part of waste water (raw water) flowing into the continuous biological treatment apparatus 10 to the semi-batch biological treatment apparatus 12. One end of the drainage inflow line 24 c is connected to the drainage inflow line 24 a, and the other end is connected to the desorption water supply line 32.

  In the wastewater treatment apparatus 2 shown in FIG. 3, a part of the raw water passing through the drainage inflow line 24a is mixed with the desorption water flowing through the drainage inflow line 24c and flowing through the desorption water supply line 32, and the mixed liquid is semi-batch biological treatment. It is supplied intermittently to the device 12. In this way, by supplying a part of the raw water to the semi-batch biological treatment device 12, it becomes possible to adjust the organic matter, nitrogen, and phosphorus concentrations in the desorbed water, and the semi-batch biological treatment device 12 is more stable. Granule formation is possible. Moreover, since stable granule formation enables stable supply of granules to the continuous biological treatment apparatus 10, it is possible to increase the wastewater treatment speed.

  1, 2 Wastewater treatment equipment, 10 Continuous biological treatment equipment, 12 Semi-batch biological treatment equipment, 14 Solid-liquid separation equipment, 16 Sludge treatment system, 18 Sludge concentration equipment, 20 Sludge digestion equipment, 22 Sludge dewatering equipment, 24a, 24b, 24c Wastewater inflow line, 26a, 26b Treated water discharge line, 28 Sludge return line, 30 Sludge discharge line, 32 Desorbed water supply line, 34 Concentrated sludge discharge line, 36 Digested sludge discharge line, 38 Dehydrated cake discharge line, 40 Granule sludge supply line, 42 Aerobic reaction tank, 44 Desorption water inflow pump, 46 Treated water side solenoid valve, 48 Stirrer, 50 Air pump, 52 Air diffuser, 54 Sludge discharge pump.

Claims (10)

A continuous biological treatment device for biological treatment of wastewater that flows continuously;
A solid-liquid separation device for separating biological sludge from treated water discharged from the continuous biological treatment device;
Semi-batch type in which granules are formed by intermittently introducing the desorbed water obtained from at least one of concentration, digestion and dehydration of surplus sludge discharged from the solid-liquid separator. A biological treatment device;
Desorption water supply means for intermittently supplying the desorption water to the semi-batch biological treatment apparatus;
A wastewater treatment apparatus comprising: granule sludge supply means for supplying granules discharged from the semi-batch biological treatment apparatus to the continuous biological treatment apparatus.   The waste water treatment apparatus according to claim 1, further comprising waste water supply means for supplying a part of the waste water flowing into the continuous biological treatment apparatus to the semi-batch biological treatment apparatus.   The wastewater treatment apparatus according to claim 1, further comprising a treated water supply unit configured to supply treated water discharged from the continuous biological treatment apparatus to the semi-batch biological treatment apparatus. Wastewater treatment device according to any one of claims 1 to 3, characterized in that the biological sludge discharged from the pre Symbol solid-liquid separator comprises a biological sludge return means to return to the continuous biological treatment device . A sludge treatment system that performs at least one of the concentration, digestion and dehydration of surplus sludge and generates desorbed water;
The drainage according to any one of claims 1 to 4, wherein the desorbed water supply means intermittently supplies desorbed water discharged from the sludge treatment system to the semi-batch type biological treatment apparatus. Processing equipment. A continuous biological treatment process for biologically treating continuously flowing waste water;
A solid-liquid separation step for separating biological sludge from the treated water discharged from the continuous biological treatment step;
Semi-batch type in which granules are formed by performing biological treatment by intermittently introducing desorbed water obtained from at least any one of concentration, digestion and dehydration of excess sludge discharged from the solid-liquid separation step. Biological treatment process;
A desorbed water supply step of intermittently supplying the desorbed water to the semi-batch biological treatment step;
A wastewater treatment method comprising: a granule sludge supply step for supplying granules discharged from the semi-batch biological treatment step to the continuous biological treatment step.   The wastewater treatment method according to claim 6, further comprising a wastewater supply step of supplying a part of the wastewater flowing into the continuous biological treatment step to the semi-batch biological treatment step.   The wastewater treatment method according to claim 6 or 7, further comprising a treated water supply step of supplying treated water discharged from the continuous biological treatment step to the semi-batch biological treatment step. Waste water treatment method according to any one of claims 6-8, characterized in that it comprises a biological sludge discharged from the pre Symbol solid-liquid separation step as the biological sludge return Engineering for returning the continuous biological treatment process .   A sludge treatment step for producing at least one of concentration, digestion and dehydration of surplus sludge to produce desorption water; and in the desorption water supply step, the desorption water discharged from the sludge treatment step The wastewater treatment method according to any one of claims 6 to 9, wherein the wastewater treatment method is intermittently supplied to the batch biological treatment process.

Images