JP3836564B2 - Wastewater treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wastewater treatment apparatus, and more particularly, to a wastewater treatment apparatus suitable for wastewater treatment by an aerobic filter bed method mainly intended for removal of BOD and SS.
[0002]
[Prior art]
Conventionally, in a relatively small-scale sewage treatment facility, a filter bed type biological treatment apparatus is often used because of easy maintenance. The aerobic filter bed is also a filter bed type treatment device that is easy to maintain and has an advantage that the treated water quality is good because it has a filtration function.
[0003]
4 and 5 show the structure of a conventional general aerobic filter bed. FIG. 4 shows a single-bed type, and FIG. 5 shows a two-bed (layer) type. The single-bed type aerobic filter bed shown in FIG. 4 is one in which a filter medium 2 such as anthracite is filled in the lower part of the treatment tank 1 and an air diffuser 3 is provided below the filter medium 2. In such a single-bed aerobic filter bed, the filling height of the filter medium 2 is limited to about 2 m in consideration of cleaning of the filter medium 2, and the upper part of the treatment tank 1 cannot be effectively used. .
[0004]
What improved this point is a two-bed type aerobic filter bed shown in FIG. 5, in which a plastic contact material 4 having a large porosity is filled above the filter medium 2 filled in the lower part of the treatment tank 1. Yes. This two-bed type aerobic filter bed can hold more organisms in the same installation area as the single-bed type aerobic filter bed by allowing the plastic contact material 4 to hold the organisms. Efficiency can be improved.
[0005]
[Problems to be solved by the invention]
On the other hand, in recent years, even in small-scale wastewater treatment facilities, cases where nitrogen removal is required are increasing, and nitrogen removal by an anaerobic aerobic filter is being performed. In such a case, conventionally, in order to promote nitrification, there are many examples to cope with by reducing the amount of treated water in the aerobic filter bed, and the water flow rate has been set to about 10 to 20 m ³ / m ² / day. . Therefore, compared with the aerobic filter bed for BOD removal, about twice the facility capacity was required.
[0006]
However, recent studies have shown that the reaction efficiency decreases significantly when the water flow rate of the aerobic filter is lowered. In order to maintain high reaction efficiency in the aerobic filter bed, it is preferable to set the water flow rate as fast as possible, and in particular, it is considered that a water flow rate of 5 times to 10 times the conventional one is necessary. However, when such a high-speed treatment is attempted with a conventional aerobic filter bed, the filter bed (filter material filling portion) is blocked in a short time, and the filtration resistance rapidly increases. Therefore, it is necessary to frequently wash the filter medium, and stable treatment and treatment over time cannot be performed.
[0007]
Then, this invention aims at providing the waste water treatment equipment which can improve the reaction efficiency in an aerobic filter bed, making a water flow speed into the speed corresponding to a filter material filling part.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the wastewater treatment apparatus of the present invention is a two-layer wastewater treatment apparatus in which a plastic contact material having a large porosity is filled in the upper part of the treatment tank and a filter medium is filled in the lower part. the filling unit, a partition wall for partitioning the filling portion to the descending portion and the rising portion of the for-treatment water is provided, you vertically movably formed to follow the variations in the water level in the tank the upper edge of the partition wall In addition, the present invention is characterized in that stirring means for circulating the water to be treated to the ascending part and the descending part is provided.
[0009]
Further, in the wastewater treatment apparatus of the present invention, the partition wall is formed of a cylindrical draft tube, the upper portion of the draft tube has a bellows structure that can be expanded and contracted, and the opening is formed at the height of the water surface in the tank. the combined it fitted with a float vertically moving in the, also characterized in that from the bottom of the filter material filling unit and a processing water circulation means for circulating the treated water in the contact material filling unit.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view of an aerobic filter bed showing an embodiment of the waste water treatment apparatus of the present invention. This waste water treatment apparatus is provided with a contact material filling portion 12 filled with a plastic contact material having a large porosity at the upper portion of the treatment tank 11, and anthracite, quartz sand, lightweight aggregate, etc. at the lower portion of the treatment tank 11. A filter medium filling part 13 filled with a filter medium is provided, a cylindrical partition wall (draft tube) 14 is installed in the contact material filling part 12, and an outer peripheral part of the draft tube 14 is connected to the rising part 12a of the water to be treated. The peripheral side is the falling portion 12b of the water to be treated. At the bottom of the rising portion 12a of the water to be treated is an aeration device that serves as an agitating means for raising the water to be treated by the air lift effect and also serves as an aeration means for maintaining the contact material filling portion 12 in an aerobic manner. 15 is provided.
[0011]
The filter medium in the filter medium filling unit 13 is supported by a support layer 17 having an air diffuser 16, and a treated water outflow path 19 is provided below the support layer 17 via a water collection nozzle 18. Is provided with a treated water inflow path 20. Further, the treated water outflow path 19 is provided with a treated water circulation path 21 for circulating a part of the treated water to the upper part of the tank by the pump P.
[0012]
The upper portion of the draft tube 14 has a bellows structure 14a that can be expanded and contracted, and a float 22 for moving the opening 14b up and down in accordance with the water surface height in the tank. Is installed.
[0013]
In the contact material filling part 12 in the wastewater treatment apparatus formed as described above, an air lift effect is generated in the water to be treated on the outer periphery of the draft tube by the bubbles generated by the air diffused from the air diffuser 15. Thereby, in the contact material filling part 12, after the treated water on the outer periphery of the draft tube rises up the rising part 12a, it flows into the draft tube 14 from the opening part 14b at the upper end of the draft tube, and descends part 12b on the inner periphery of the draft tube A circulating flow descending is formed. In this way, by forming a circulation flow in the water to be treated in the contact material filling unit 12, the flow rate of the water to be treated that comes into contact with the contact material can be increased. While maintaining the speed corresponding to the filter medium filled in the filling portion 13, only the water flow speed in the contact material portion can be increased. Therefore, the reaction efficiency in the contact material filling part 12 can be significantly improved while maintaining the filtering capacity in the filter material filling part 13 at the same level as before.
[0014]
In addition, the flow direction of the circulating flow may be reversed, and as shown in FIG. 2, by installing an air diffuser 15 below the draft tube 14 and forming the inside of the draft tube 14 so that bubbles rise, The outer peripheral part of the draft tube 14 can be a descending part of the water to be treated, and the inner peripheral side can be an ascending part of the water to be treated.
[0015]
Further, as described above, the opening 14b at the upper end of the draft tube is formed so as to be movable up and down following the fluctuation of the water surface height in the tank, so that the water surface height is changed by the fluctuation of the filtration resistance of the filter medium filling part 13. Even if fluctuates, a predetermined circulating flow can be formed in a stable state. In particular, by expanding and contracting the upper end of the draft tube 14 with the bellows structure 14a and the float 22 as a stretchable structure, a reliable operation can be expected with a simple configuration. In addition, this telescopic structure of the upper end of the draft tube can be replaced with a bellows structure, and the draft tube can be a slide-type double tube. You can also Furthermore, the vertical movement of the opening may be performed by detecting the water surface height and using hydraulic pressure or electric drive.
[0016]
The partition for partitioning the ascending and descending portions of the water to be treated is not limited to the draft tube, and can be formed in an appropriate shape according to the shape of the treatment tank 11, for example, the treatment tank When 11 is a square shape, a partition may be provided at a corner, and a plurality of circulation flow channels may be formed in the tank. Further, a mechanical stirring device such as a screw can be used as the stirring means for generating the circulating flow.
[0017]
In addition, by circulating a part of the treated water extracted from the lower part of the filter medium filling unit 13 through the treated water circulation path 21 to the contact material filling unit 12 at the upper part of the tank, the water flow rate in the filter medium filling unit 13 is increased. Therefore, the reaction efficiency of the filter medium filling part 13 can also be improved. In addition, what is necessary is just to perform the circulation of this treated water as needed, and may perform the aeration to the filter-medium filling part 13 from the aeration apparatus 16 as needed. The compressor C connected to both the air diffusers 15 and 16 can be shared by providing an appropriate valve in the air piping, but can also be installed separately and independently.
[0018]
The plastic contact material having a large porosity used in the present invention is made of polyethylene, polypropylene, hard vinyl chloride or the like in a predetermined shape, for example, a wave shape, a ball shape, a net shape, a loop shape, a pipe shape, etc., and 90% or more. A generally known waste water treatment contact material can be used.
[0019]
FIG. 3 shows an example in which the wastewater treatment apparatus of the present invention is used in a wastewater treatment facility that also removes nitrogen, and the wastewater treatment apparatus formed in the same manner as described above is mainly an aerobic filter bed for performing nitrification treatment. It is an example used as.
[0020]
In this wastewater treatment facility, the raw water tank 31, the washing drainage tank 32, the anaerobic filter bed 33, the pressurized flotation separator 34, the aerobic filter bed 35, and the treated water tank 36 are arranged in this order from the upstream side of the treated raw water flow. The aerobic filter bed 35 has the same structure as the treatment tank shown in FIG.
[0021]
The inflowing sewage flows into the raw water tank 31 after being subjected to sedimentation and screen treatment, and is further sent to the anaerobic filter bed 33 in a state of being mixed with the washing wastewater of the aerobic filter bed 35 in the washing drainage tank 32. The anaerobic filter bed 33 is fed with the raw water from the washing drain 32 and the nitrification liquid circulating through the path 37 from the aerobic filter bed 35. Anaerobic decomposition is performed.
[0022]
The water (anaerobic treated water) treated in the anaerobic filter bed 33 is sent to the pressurized flotation separator 34 including sludge that leaks, and mixed with the pressurized air-dissolved water supplied from the path 38. Flow into. Suspended components in water adhere to the fine bubbles generated from the pressurized air-dissolved water, and the apparent specific gravity is reduced, separated as floating sludge (floss) at the upper part of the tank, and scraped by the scraper 39 and routed. 40 is sent to the sludge storage tank 41.
[0023]
Further, a part of the water treated by the pressurized levitation separator 34 is withdrawn into the passage 42 on the outlet side, pressurized by the pump P, and mixed with the compressed air supplied from the compressor C in the mixing tank 43. Then, it is supplied and mixed into the anaerobic treated water from the path 38 as pressurized air dissolved water.
[0024]
In this way, the water treated by the pressurized flotation separator 34 (flotation treated water) has a higher removal rate of suspended components compared to the normal precipitation treatment, so the inflow load of the aerobic filter bed 35 can be reduced, In the levitation process, components that easily float, such as hair, oil, and scum, can be removed almost completely, so that the contact material blockage and scum generation on the aerobic filter bed 35 are reduced.
[0025]
The water that has been floated by the pressurized floatation separator 34 is sent to the aerobic filter bed 35 via the treated water inflow path 20. In the aerobic filter bed 35, the aerobic treatment is efficiently performed by the circulation flow by the draft tube 14 installed in the contact material filling unit 12, BOD is removed and nitrification is performed, and further, the lower filter material filling unit 13 is aerobic. After the filtration process is performed together with the process, it flows out from the treated water outflow path 19. A part of this treated water circulates to the contact material filling unit 12 through the treated water circulation path 21 and also circulates to the anaerobic filter bed 33 via the path 37. The remaining treated water is sent to the treated water tank 36, and then appropriately sterilized and discharged to a river or the like.
[0026]
In addition, a washing drainage outflow portion 44 for extracting washing drainage is provided above the filter medium filling portion 13 of the aerobic filter bed 35, and the filtering media washing water flows out of the washing drainage via the wedge wire screen 45. It is extracted by the part 44 and returned to the washing drainage tank 32 together with the generated sludge. In this case, the extraction of the washing waste water, by carrying out through the wedge wire screen 45, it is possible to perform good has filter material washing efficiency while preventing the outflow of the filter material. Thus, sludge generated by washing the filter medium is returned to the washing drainage tank 32 together with the washing drainage, and after being reduced by the anaerobic filter bed 33, it is treated by the pressurized flotation separator 34. It is possible to unify the locations and increase the concentration. In addition, this washing waste water outflow part 44 can be used as a nitrification liquid circulation path instead of the path 37.
[0027]
In this way, the flotation process sent to the aerobic filter bed 35 is provided in the previous stage of the aerobic filter bed 35 by installing the pressurized flotation separation device 34 having a higher removal rate of suspended components than in the normal precipitation process. Since the amount of suspended components in water is reduced and the inflow load into the aerobic filter bed 35 is reduced, the capacity of the aerobic filter bed 35 can be reduced. In addition, when the SS concentration is 2000 to 3000 mg / l or less, the levitation treatment of the pressurized levitation separator 34 is not affected by the raw water concentration, so that stable treatment is possible. Furthermore, even if sludge leaks from the anaerobic filter bed 33, it is processed by the pressurized flotation separator 34. Therefore, the sludge leaked from the anaerobic filter bed 33 does not flow into the aerobic filter bed 35 and is aerobic. The processability of the filter bed 35 is not affected.
[0028]
Therefore, an efficient nitrification treatment can be performed by forming a circulating flow as described above in the contact material filling portion 12 in the aerobic filter bed 35, and a pressurized flotation separation device 34 is provided in the front stage of the aerobic filter bed 35. By providing, the BOD and SS load of the aerobic filter bed 35 can be reduced, the nitrification reaction efficiency can be further improved, and the burden on the filter medium filling unit 13 can be reduced. The filtration process can be continued for a long time in a stable state.
[0029]
【The invention's effect】
As described above, according to the wastewater treatment apparatus of the present invention, the reaction efficiency in the aerobic filter bed can be improved without increasing the burden on the filter medium, and the BOD treatment and nitrification treatment can be stabilized for a long time. Can continue.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a wastewater treatment apparatus of the present invention.
FIG. 2 is a cross-sectional view of a main part showing another embodiment.
FIG. 3 is a system diagram showing an example of waste water treatment equipment to which the waste water treatment apparatus of the present invention is applied.
FIG. 4 is a cross-sectional view showing an example of a conventional single-bed aerobic filter bed.
FIG. 5 is a cross-sectional view showing an example of a conventional two-bed aerobic filter bed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Processing tank, 12 ... Contact material filling part, 13 ... Filter material filling part, 14 ... Draft tube, 15, 16 ... Air diffuser, 17 ... Support layer, 18 ... Water collection nozzle, 19 ... Treatment water outflow path, 20 Treatment water inflow path, 21 ... treated water circulation path, 22 ... float, 31 ... raw water tank, 32 ... washing drainage tank, 33 ... anaerobic filter bed, 34 ... pressurized flotation separator, 35 ... aerobic filter bed, 36 ... treated water tank, 41 ... sludge storage tank

Claims (3)

In a two-layer wastewater treatment apparatus in which a plastic contact material having a large porosity is filled in the upper portion of the treatment tank and a filter material is filled in the lower portion, the filling portion is connected to the rising portion of the water to be treated in the contact material filling portion. partition walls separating the moving-down portion is provided, the rewritable formed so as to be vertically movable to follow the variation of the water level in the tank the upper edge of the partition wall, the circulation the to the falling portion and rising portion of the water to be treated A wastewater treatment apparatus characterized in that a stirring means is provided. The partition wall is formed of a cylindrical draft tube, and the upper portion of the draft tube has a bellows structure that can be expanded and contracted, and a float that moves the opening up and down in accordance with the water surface height in the tank is attached to the opening. The waste water treatment apparatus according to claim 1. The waste water treatment apparatus according to claim 1 or 2, further comprising a treated water circulation means for circulating treated water from a lower part of the filter medium filling unit to the contact material filling unit.

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