JPH07290085A - Treatment of waste water and device therefor - Google Patents

Abstract

PURPOSE:To improve the quality of treated water in accordance with the inflow of waste water such as sewage, reduce the power cost for the aeration in treating activated sludge and the output of sludge and make the device compact. CONSTITUTION:A high-speed filter 10 and a biological treating device 12 are organically combined. When the inflow of the waste water is less than the allowable capacity of the biological treating device 12, the waste water is filtered by the high-speed filter 10 at the rate of <=400m/day, and the whole amt. of the treated water is sent to the biological treating device 12. When the inflow of waste water is more than the allowable capacity of the device 12, a flocculant is added to the waste water, the waste water is filtered by the filter 10 at the rate of 400-1000m/day, the filtered water in the amt. corresponding to the allowable capacity is sent to the treating device 12, and the remaining filtered water is discharged outside the system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method and apparatus thereof, and more particularly to a wastewater treatment method for efficiently purifying a large amount of wastewater such as sewage according to the amount and quality of the inflowing wastewater. And its device.

[0002]

2. Description of the Related Art Conventionally, as a wastewater treatment method for purifying wastewater such as sewage and discharging it into rivers and lakes, the solid components in the wastewater are first allowed to spontaneously settle in a sedimentation tank, and then activated sludge treatment equipment is used to remove microorganisms. The method of biological treatment is generally used. In addition, the activated sludge in the treated water that has undergone biological treatment is settled in the final settling tank, the supernatant water is discharged, and part of the settled activated sludge is extracted as excess sludge, and the remaining activated sludge is the activated sludge treatment device. Is circulated to. In addition, in order to remove fine solid components, there is also proposed a device in which a filtration device filled with a filler is first provided in the latter stage of the settling tank (Japanese Patent Laid-Open No. Hei 4).
171007). In this way, by purifying wastewater such as sewage, the treated water that satisfies the standard water quality has been released, contributing to the improvement of water quality in public water areas.

However, due to the increase in concentration of sewage pollution due to the recent urbanization and improvement of lifestyle, and the increase in the temporal fluctuation of the inflowing wastewater amount flowing into the wastewater treatment equipment, the aeration power cost in the activated sludge treatment increases. However, there are problems such as sludge treatment due to an increase in the amount of sludge generated. In addition, when treated water is discharged into closed water areas such as rivers and lakes, it is necessary to reduce nutrient salts (nitrogen component, phosphorus component) in order to comply with total BOD regulation and prevent eutrophication. In the case of a combined sewer system where rainwater joins, it is an important issue to establish a treatment technology when the amount of inflowing wastewater that flows into the wastewater treatment equipment is temporarily increased in the case of rain.

Further, in the urban area where the site of the device is restricted due to overcrowding, when solving the above-mentioned problems and problems,
Correspondence within the current premises is required.

[0005]

In order to solve the above-mentioned problems and problems, in the case of a conventional wastewater treatment apparatus which is initially composed of a sedimentation tank and activated sludge treatment, solids in the wastewater sent to activated sludge treatment It is necessary to remove the components in the first settling tank in as short a time as possible, but the processing capacity in the first settling tank is limited, and it is necessary to increase the capacity of the first settling tank to increase the removal capacity. . However, it is practically impossible to add more in urban areas where the site of the equipment is restricted, and there is a drawback that the conventional wastewater treatment equipment cannot deal with problems and problems.

On the other hand, in the case of the wastewater treatment apparatus of Japanese Patent Laid-Open No. 4-171007, which is provided with a filtration device in the latter stage of the first settling tank, although the removal rate of solid components can be increased and the load on activated sludge treatment can be reduced, It is easy for the filling material to become clogged,
There is a drawback in that the flow of water must be stopped and backwashing of the packing material must be carried out frequently, and as a result, the treatment efficiency for the site area cannot be improved.

Further, when considering biological treatment by a modified activated sludge circulation method such as denitrification and dephosphorization in an activated sludge treatment device, an appropriate amount of BOD is required as a nutrient source for microorganisms. For example, in order to remove phosphorus by excessively ingesting it to the microorganism, a BOD component of 20 times or more the phosphorus concentration is required, and in order to smoothly perform the denitrification reaction that reduces nitrate ion to nitrogen, It is necessary to leave about 3 times the BOD component as the amount of nitrogen. Therefore, the first settling basin or the filtration device must be able to efficiently remove the solid components in the wastewater, and yet the biological treatment device must be supplied with an appropriate amount of BOD components. However, since the conventional wastewater treatment equipment cannot perform such control, it has a drawback that nutrient salts (nitrogen component, phosphorus component) are not sufficiently removed to prevent eutrophication.

[0008] In addition, in a combined sewage treatment plant, in rainy weather,
In particular, when wastewater that exceeds the treatment capacity of the activated sludge treatment device temporarily flows in due to heavy rainfall, solid components must be separated from the excess influent and discharged. Solid components should be removed as much as possible. However, conventional wastewater treatment equipment has a limited treatment capacity for temporarily increasing the amount of inflowing wastewater, and since the treatment technology to cope with the increase in water is not established, it can be discharged without sufficient purification treatment. Inevitably, it has the drawback of deteriorating the water quality of public water bodies.

The present invention has been made in view of the above circumstances, and it is possible to improve the quality of treated water according to the inflow amount and quality of wastewater such as sewage, and the aeration power in activated sludge treatment. It is an object of the present invention to provide a wastewater treatment method and an apparatus thereof which can reduce the cost and the amount of generated sludge and can further reduce the size of the apparatus.

[0010]

In order to solve the above-mentioned problems, the present invention relates to a wastewater treatment method for purifying wastewater such as sewage. A high-speed filtration step of filtering with a floating filter medium layer formed of a large number of mesh-like cylindrical filter medium having a smaller specific gravity than the drainage provided in the filtration tank, and filtered water filtered in the high-speed filtration step is anaerobic. An anaerobic tank for treatment, a denitrification tank for anoxic treatment, and a nitrification tank for aerobic treatment are brought into contact with microorganisms in activated sludge to remove organic components, nitrogen components, and phosphorus components in the filtered water by biological treatment. And a biological treatment step.

[0011]

According to the present invention, the high-speed filtration step and the biological treatment step are organically combined so that the solid component in the wastewater can be removed at a high removal rate in the high-speed filtration step. Can be reduced. This allows
The quality of the treated water after the biological treatment process can be improved, and the aeration power can be reduced because the amount of air required for the decomposition of organic substances in the biological treatment process can be reduced, and the amount of excess sludge can be reduced. it can. Further, since the carrier in which nitrifying bacteria are entrapped and fixed is added to the nitrification tank in the biological treatment process in addition to the activated sludge, the time required for the nitrification reaction can be shortened.

When the amount of inflowing wastewater that flows in is less than the treatment allowable amount of the biological treatment process, the filtration speed of the high-speed filtration process is 400 m / day or less, and the entire amount of the filtered water is sent to the biological treatment process. When the amount of inflowing wastewater is equal to or more than the treatment allowable amount of the biological treatment process, a coagulant is added to the wastewater to filter at a filtration speed of 400 m / day to 1000 m / day in the high-speed filtration process, and the treatment of the filtered water is performed. The permissible amount was sent to the biological treatment process, and the remaining filtered water was discharged to the outside of the system. That is, in the filtration tank of the high-speed filtration process, a large number of filter media (porosity of 80%) having a mesh-like cylindrical body having a smaller specific gravity than the drainage
As described above, since the thickness of the wire forming the mesh is 1 to 5 mm, preferably 2 to 4 mm), the levitation filter material layer is formed. Therefore, almost all-layer filtration can be performed and water resistance can be extremely reduced. . Therefore, even when the solid component concentration in the waste water is high, the high-speed filtration process can be performed at a filtration speed of up to 1000 m / day, and the filtration duration time can be extended. As a characteristic of this filter medium, when the filtration speed is 400 m / day or less, a sludge accumulation layer is formed on the floating filter medium layer without adding a coagulant, so that solid components should be removed at a high removal rate. You can Also, the filtration rate is 4
In the case of 00 m / day to 1000 m / day, the sludge deposition layer is not formed because the water flow is fast, so the coagulant is added to the waste water in advance and filtered, whereby the flocculated large flocs collide with the flotation filter medium layer. Can be captured by
Even if the filtration rate is increased, the solid component can be removed at a high removal rate. Thereby, the solid component can be efficiently removed according to the inflow amount of the waste water and the water quality. Therefore, in particular, in the case of combined sewerage, not only when the inflowing wastewater is less than the treatment capacity of the biological treatment process, such as during fine weather, but also when the inflowing wastewater amount is the processing permission of the biological treatment process due to a temporary increase in water during rainy weather. Even if the capacity is exceeded, treated water with good water quality can be discharged.

Further, a coagulant is added and the filtration rate is 4
When it is set to 00 m / day or less, the solid component is removed by both the action of forming the sludge deposition layer and the collision capture, so that an extremely high removal rate can be obtained. Therefore, when the amount of inflowing wastewater is equal to or greater than the treatment allowable amount of the biological treatment process, the high-speed filtration process is performed in parallel after adding the coagulant to the wastewater, and the filtration rate is set to 4
When the filtered water filtered at 00 m / day to 1000 m / day is sent to the biological treatment process and the filtered water filtered at 400 m / day or less is directly discharged to the outside of the system, the quality of the discharged water discharged to the outside of the system is further improved. be able to.

When a coagulant is added to waste water,
To prevent eutrophication, some of the wastewater was supplied directly to the biological treatment process via the bypass route without going through the high-speed filtration process to maintain the organic substances, which are the nutrient sources of microorganisms, at a predetermined concentration or higher. It is possible to sufficiently remove the nutrient salts (nitrogen component, phosphorus component). In addition, since a detection means for detecting the inflowing wastewater amount is provided and whether the coagulant is added from the coagulant adding means is controlled according to the detected inflowing wastewater amount, it is possible to automatically control the addition of the coagulant. You can

[0015]

The preferred embodiments of the wastewater treatment method and apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a flow for explaining a first embodiment of the wastewater treatment equipment of the present invention. The wastewater treatment device of the present invention is mainly composed of a high-speed filtration device 10 (high-speed filtration process), a biological treatment device 12 (high-speed filtration process), and a precipitation device 14. Further, although FIG. 1 shows one series of wastewater treatment devices for ease of explanation, it is also possible to provide multiple series of wastewater treatment devices in parallel.

As shown in FIG. 1, wastewater such as sewage flows into a raw water tank 20 through a raw water inflow pipe 18. A coagulant tank 22 that stores a coagulant solution is provided near the raw water tank 20, and the coagulant in the coagulant tank 22 is added to the raw water tank 22 through a coagulant addition pipe 24. The coagulant addition pipe 24 has an addition valve 26.
Is connected to a flow meter 28 provided in the raw water inflow pipe 18 via a signal cable. As a result, when the amount of inflowing waste water exceeds a predetermined amount, the addition valve 26 opens and a predetermined amount of the coagulant is added to the raw water tank 20. As the coagulant, an inorganic coagulant such as sulfuric acid band, polyaluminum chloride, ferric chloride or the like, or a polymer coagulant such as anionic, nonionic or cationic polymer is used. Further, the supply pipe 30 extending from the bottom of the raw water tank 20 is branched into two by a three-way valve 32, and one filtration pipe 34 is connected to the bottom of the filtration tank 38 of the high-speed filtration device 10 via a raw water valve 36, and the other. The bypass pipe 40 is connected to the inlet of the biological treatment apparatus 12 via a bypass valve 42. The raw water valve 36 is in an open state during the filtering operation, and is closed in the case of washing the floating filter medium layer 37, which will be described later, to stop the supply of the waste water to the high-speed filtration device 10. Further, the bypass valve 42 is opened as needed, and a part of the waste water is directly supplied to the biological treatment device 12. As a result, it is possible to maintain the organic substance, which is a nutrient source for microorganisms in the activated sludge added to the biological treatment device 12, at a predetermined concentration or higher.

The filter pipe 34 is branched near the inlet of the filter tank 38 and is connected to a cleaning drain pipe 44 for discharging the cleaning drainage when cleaning the filter medium to the outside of the filter tank 38. A washing and draining valve 46 is provided in the middle of the washing and draining pipe 44, and is closed when performing a filtering operation by the high-speed filtering device 10. Next, the structure of the high-speed filtration device 10 will be described with reference to FIG.
Has a quadrangular shape at the top and a quadrangular pyramid shape at the bottom. An upper screen 48 and a lower screen 50 formed in a mesh structure are arranged across the filtration tank 38 at the upper end and the bottom of the filtration tank 38. The opening of the upper screen 48 may be such that the filter medium does not pass through, and the opening of the lower screen 50 may be such that large contaminants in the drainage can be removed. Further, under the upper screen 48, a large number of mesh-like cylindrical filter media 52, 52 having a smaller specific gravity than the drainage are suspended in the drainage so as to occupy about 1/2 of the volume of the filter tank 38. Then, the floating filter material layer 37 is formed. In addition, the floating filter material layer 37
An air jet pipe 56 having a plurality of jet nozzles 54, 54 ... Is provided below the lower screen 50, and jets air into the drainage in the filtration tank 38 to generate a swirling flow, thereby forming a filter medium. By rotating 52, the filter medium 5
The solid component attached to 2 can be efficiently washed in a short time. In addition, at the bottom of the filtration tank 38,
A dispersion plate 58 that disperses the wastewater that has flowed into the filter tank 38 is provided. As a result, the drainage flowing from the raw water tank 20 to the bottom of the filtration tank 38 is dispersed by the dispersion plate 58 throughout the filtration tank 38 and becomes an upward flow to rise in the filtration tank 38. Further, above the upper screen 48 in the filtration tank 38, a trough 60 for overflowing the filtered water filtered by the floating filter material layer 37 is provided, and the filtered water overflowing the trough 60 is passed through the biological treatment pipe 62. And biological treatment equipment 12
Water is sent to the anaerobic tank 64 (see FIG. 1).

Next, referring to FIG. 3, an example of the filter medium 52 used in the present invention will be described. The filter medium 52 is made of polypropylene or the like having a light specific gravity and corrosion resistance, and an average diameter (D) of about 20 mm. Is formed into a mesh-like cylindrical body, and both ends 52A and 52B are opened. Also, the mesh 52
As C, a polypropylene wire rod 52D having a thickness of 1 to 5 mm, preferably 2 to 4 mm is used. The filter medium 52 has an apparent specific gravity of about 0.9, a porosity of about 90%, and a specific surface area of about 300 m ² / filter medium m ³ . By forming the floating filter medium layer 37 in the filter tank 38 using the filter medium 52 formed in this way, it is possible to perform substantially all-layer filtration and extremely reduce water resistance. Therefore, even when the solid component concentration in the waste water is high, the high-speed filtration process can be performed at a filtration speed of up to 1000 m / day, and the filtration duration time can be extended.

Further, as shown in FIG. 1, the biological treatment pipe 6
2 is connected to a discharge pipe 68 via a distributor 66 on the way. Then, the biological treatment device 12
By distributing the amount of the filtered water sent to the discharge pipe 68 and the amount of the filtered water sent to the discharge pipe 68 at a predetermined ratio, a part of the filtered water can be discharged directly to a river or the like. Next, the biological treatment device 12 will be described. The biological treatment device 12 includes an anaerobic tank 64, a denitrification tank 70, and a nitrification tank 72. Then, the anaerobic tank 64, the denitrification tank 70, the nitrification tank 72
Activated sludge containing microorganisms such as nitrifying bacteria, denitrifying bacteria, and phosphorus accumulating bacteria is added to. In addition to the activated sludge, a carrier in which nitrifying bacteria are entrapped and fixed in a polymeric material having a side length of about 3 mm is added to the nitrification tank 72, whereby the time required for nitrification can be shortened. In addition, in the anaerobic tank 64 and the denitrification tank 7
A stirring device 73 is provided in each of 0, and the biological treatment reaction is performed in an anaerobic state in the filtered water sent from the high-speed filtering device 10 by slow stirring. On the other hand, an aeration device 74 is provided in the nitrification tank 72, and the biological treatment reaction is performed in an anaerobic state. Then, the filtered water filtered by the high-speed filtration device 10 is anaerobic tank 64, denitrification tank 70, nitrification tank 7
The nitrogen component in the filtered water is removed by passing the nitrification solution in a certain amount in the order of 2 and circulating it in the denitrification tank 70. Further, when the filtered water is passed through the anaerobic tank 64, the denitrification tank 70, and the nitrification tank 72 in this order, the activated sludge takes in the organic matter in the anaerobic state in the anaerobic tank 64 (the state in which dissolved oxygen and oxidized nitrogen do not exist), The phosphorus accumulated in the activated sludge is released. Then, in the aerobic condition of the nitrification tank 72, the activated sludge takes up phosphorus again, and since the intake exceeds the release,
As a result, the phosphorus component in the filtered water is removed.

The treated water treated by the biological treatment device 12 is sent to the settling device 14. In the settling device 14, the activated sludge entrained in the treated water is subjected to solid-liquid separation by settling, and the treated water in the supernatant portion is discharged to a river or the like through the treated water pipe 76. In addition, a part of the settled activated sludge is sent to the sludge treatment process (not shown) as excess sludge by the sludge discharge pipe 78, and the remaining activated sludge is circulated to the anaerobic tank 64 through the sludge circulation pipe 80.

Next, a method of treating wastewater such as sewage with the wastewater treatment apparatus of the present invention configured as described above will be described. The drainage flowing into the raw water tank 20 through the raw water inflow pipe 18 is a flow meter 28 provided in the middle of the raw water inflow pipe 18.
The inflowing wastewater amount is detected by. When the detected inflow drainage amount is equal to or more than the predetermined amount, the addition valve 26 is opened and the predetermined amount of the coagulant is added from the coagulant tank 22 to the raw water tank 20. That is, when the raw water flow rate less than the treatment allowable amount in the biological treatment apparatus 12 is detected by the flow meter 28, a signal to close the addition valve 26 is sent from the flow meter 28 to add the coagulant to the waste water. I don't know. On the other hand, if the amount of inflowing wastewater in the biological treatment device 12 exceeds the allowable treatment amount,
8 is detected, the flow meter 28 adds the addition valve 2
A signal is sent to open 6 and a certain amount of flocculant is added to the wastewater. Next, the waste water of the raw water tank 20 is supplied to the supply pipe 30,
It is supplied to the bottom of the filtration tank 38 of the high-speed filtration device 10 through the filtration pipe 34. At this time, the raw water valve 36 is in the open state, and the bypass valve 42 is opened as necessary as described above. The waste water supplied to the filtration tank 38 is filtered by the filtration tank 3
The solid component in the waste water is filtered by the floating filter material layer 37 as it rises in the inside of 8 as an upward flow. The filtered water filtered by the floating filter material layer 37 overflows into the trough 60 and is sent to the anaerobic tank 64 of the biological treatment device 12 through the biological treatment pipe 62 and the distribution device 66. At this time, when the amount of filtered water sent to the biological treatment device 12 is equal to or more than the treatment allowable amount of the biological treatment device 12,
A part of the filtered water is distributed to the discharge pipe 68 by the distributor 66. Next, in the biological treatment apparatus 12, the filtered water sequentially flows through the anaerobic tank 64, the denitrification tank 70, and the nitrification tank 72, so that the biological treatment reaction removes nitrogen components, phosphorus components, and organic substances from the filtered water. Then, the treated water treated by the biological treatment device 12 is sent to the settling device 14, and after the activated sludge is settled and separated by the settling device 14, it is discharged to a river or the like.

According to the present invention, the high-speed filtration device 10 and the biological treatment device 12 are organically combined to form the high-speed filtration device 10.
Since the solid component in the waste water can be removed at a high removal rate, the load on the biological treatment device 12 can be reduced. As a result, the quality of the treated water at the outlet of the biological treatment device 12 can be improved, and the amount of air required for decomposing the organic matter in the biological treatment device 12 can be reduced, so that the aeration power can be reduced, and the amount of excess sludge can be further reduced. Can be reduced. In addition, the biological treatment device 1
Since the carrier in which the nitrifying bacteria are entrapped and fixed is added to the nitrification tank 72 of No. 2 separately from the activated sludge, the time required for the nitrification reaction can be shortened.

By the way, in terms of the relationship between the amount of inflowing wastewater and the amount of treated water, the biological treatment apparatus 12 generally has a treatment allowable amount which is about twice as much as the amount of inflowing raw water in fine weather (when there is no increase in water due to rainwater). However, even if the daily precipitation is less than 50 mm, the amount of raw water inflow is two to three times the treatment allowable amount, and the daily precipitation is 50
When it is up to 100 mm, it reaches 3 to 5 times the processing allowance.
Therefore, in the case of the combined sewer system, if the inflowing wastewater amount exceeds the treatment allowable amount of the biological treatment device 12 due to a temporary increase in water in the case of rain, it is only filtered by the high-speed filtration device 10 and directly discharged to a river or the like. I don't get. By the way, the daily precipitation varies greatly depending on the region, but in Sapporo and Sendai, the number of days with a daily precipitation of 10 to 50 mm is 30 days a year, and the daily precipitation is 5 days.
The number of days of 0 to 100 mm is about 6 days per year, and considering snowmelt water, the number of days that must be discharged without being treated by the biological treatment device 12 is about 7 days per year. Also, in Tokyo, Nagoya, and Osaka, the number of days with a daily rainfall of 10 to 50 mm is about 30 days a year, which is the same as in Sapporo and Sendai, but the daily rainfall is 5 days.
The number of days of 0 to 100 mm is slightly increased to 10 to 15 days per year. In the case of Kagoshima, the number of days with daily precipitation of 10 to 50 mm is similar, but the number of days with daily precipitation of 50 to 100 mm is extremely high, about 35 days per year, and the number of days of direct release is 40 days or more per year. Sometimes it becomes.

As described above, in the case of the combined sewer system, it is necessary to discharge the water directly to a river or the like without performing biological treatment due to a temporary increase in water in rainy weather, and solid components in the discharged water to be discharged directly can be generated. Must be removed as long as possible. Therefore, according to the present invention, when the inflowing wastewater amount is less than or equal to the treatment allowable amount of the biological treatment device 14, the filtration speed of the high-speed filtering device 10 is filtered at 400 m / day or less without adding a coagulant, The whole amount of the filtered water is sent to the biological treatment device 12, and when the inflowing wastewater amount is equal to or more than the treatment allowable amount of the biological treatment device 12, a coagulant is added to the wastewater and the high-speed filtration device 10 is added.
At a filtration speed of 400 m / day to 1000 m / day,
The distribution device 66 sends the treated amount of the filtered water to the biological treatment device 12, and the remaining filtered water is directly discharged from the discharge pipe 68 to a river or the like. As a result, without adding additional wastewater treatment equipment, that is, with the site area of the equipment as it is, the optimal treatment conditions are selected according to the regional and seasonal daily precipitation levels, and the solid components in the wastewater are selected. Since it can be removed at a high removal rate, good water quality can be obtained for both the treated water after the biological treatment device 12 and the discharged water that is directly discharged after the high-speed filtration device 10.

Here, referring to FIGS. 4, 5 and 6, the mechanism of capturing solid components in the wastewater depending on whether or not the additive is added to the wastewater and the difference in the filtration speed in the high-speed filtration device 10 will be described. FIG. 4 shows a filtration speed of 400 m /
It is a figure which shows the capture mechanism at the time of day or less. The solid component 82 when the flocculant is not added is small in shape and is removed by a trapping mechanism that sediments and deposits on the upper surface of the filter medium 52 to form a sludge deposition layer 84. That is, a speed difference is generated due to the contraction phenomenon of the drainage that passes through the mesh, and a vortex is generated. By this vortex,
A local stagnation area is generated above the wire 52D forming the mesh,
The solid component 82 in the drainage is in the sludge accumulation layer 8 in this local retention area.
4 is formed. Since this local retention area occurs over the entire area of the floating filter material layer 37, the solid component 82 can be removed at a high removal rate.

FIG. 5 shows that a coagulant was added and a filtration rate of 400
It is a figure which shows the capture mechanism in the case of m / day or less. When the flocculant is added, the solid component 82 forms flocs and becomes large. Since the filtration speed is low, the solid component 82 is settled and deposited on the upper surface of the filter medium 52 to form a sludge accumulation layer 84, and the solid component 82 collides with the filter medium 52 to form a sludge adhesion layer 86. Both mechanisms are performed. Since the trapping mechanism that forms the sludge deposit layer 86 by collision with the trapping mechanism that forms the sludge deposit layer 84 occurs over the entire area of the floating filter material layer 37, the solid component 82 can be removed at a higher removal rate.

FIG. 6 shows a filtration rate of 400 with the addition of a flocculant.
It is a figure which shows the capture mechanism in the case of -1000 m / day. When the flocculant is added, the solid component 82 forms flocs and becomes large. Since the filtration rate is high, the solid component 82
The trapping mechanism that forms the sludge deposit layer 84 on the upper surface of the filter medium 52 is not performed, but only the trapping mechanism that forms the sludge adhering layer 86 is performed. Since the trapping mechanism that forms the sludge adhering layer 86 occurs over the entire area of the floating filter material layer 37, the solid component 8
2 can be removed with a high removal rate. Comparing the removal rates of the solid components 82 under the above-mentioned filtration conditions, the highest rate was obtained when a flocculant was added and the filtration speed was 400 m / day or less, and then the flocculation agent was added and the filtration speed was 400-
In the case of 1000 m / day, the filtration speed was 400 m / day or less without adding a coagulant.

Further, the wire rod 52 forming the mesh of the filter medium 52
The thickness of D is in the range of 1 to 5 mm, preferably 2 to 4 mm
Since it is within the range, the sludge accumulation layer 84 is easily formed and the sludge adhesion layer 86 is easily formed. That is, the thickness of the wire material 52D for stably forming the locally-slow retention area in the upper portion of the wire material 52D forming the mesh of the filter material 52 is 1 mm or more, preferably 2 mm or more. In addition, a solid component 82 that has been made larger by adding a flocculant
The diameter of the wire 52D for making the sludge adhering layer 86 efficiently collide with the filter material is best to be slightly thinner than the thickness of the solid component 82. And the solid component 8 which has been enlarged
The thickness of 2 is about 80% in the range of 3 to 5 mm, and the remaining 20% is 3 mm or less. From this, when the coagulant is added, the solid component 82 should be removed when the thickness of the wire 52D of the filter medium 52 is 5 mm or less, preferably 4 mm or less.

Next, an actual example of the treatment method of the present invention using the wastewater treatment apparatus of the present invention will be described while comparing with the conventional wastewater treatment apparatus which is initially composed of a settling tank and an activated sludge treatment apparatus. In this example, the floating filter medium layer 37 of the high-speed filtration device 10 had a height of 2 m and a cross-sectional area of 3 m ² . First, a case where the inflowing wastewater amount detected by the flow meter 28 is equal to or less than the treatment allowable amount (1Q) of the biological treatment device 12 will be described.
In this case, the flocculating agent is not added to the raw water tank 20, the filtration speed in the high-speed filtration device 10 is filtered at 400 m / day or less, and the whole amount of the filtered water is sent to the biological treatment device 12 to perform biological treatment. It was At this time, the filter medium 52 was washed twice a day.

As a result, the removal rate of solid components in the high-speed filtration device 10 was about 60% as SS (suspended solid matter), and
The OD is about 40%, and the quality of the filtered water at the outlet of the high-speed filtration device 10 is 60 ppm for SS and 80-9 for BOD.
0 ppm, ammoniacal nitrogen was 25 ppm, and phosphorus concentration was 3 ppm. In addition, the quality of the treated water after biological treatment of the filtered water filtered by the high-speed filtration device 10 by the biological treatment device 12 is 5 ppm or less for SS and 5 ppm or less for BOD,
Ammonia nitrogen is 5ppm or less, phosphorus concentration is 1ppm
It is below, by filtering with the high-speed filtration device 10,
The load on the biological treatment device 12 is reduced, and the biological treatment device 12 is reduced.
It was possible to carry out biological treatment in a very efficient manner.

On the other hand, the removal rate of the solid component in the first settling tank of the conventional wastewater treatment equipment is about 40% as SS, B
The OD was about 30%. Also, filtration speed 400m
The retention time of the waste water in the filtration tank 38 of the high-speed filtration device 10 at less than 1 day / day was about 15 minutes, whereas the retention time of the waste water in the conventional first settling tank required 2 hours. From this, the present invention was able to shorten the filtration time to 1/8 of that of the prior art and further improve the quality of filtered water. This means that the high-speed filtration device 10 can reduce the site area of the device to about 1/8 as compared with the first settling tank.

Next, a case will be described in which the amount of inflowing waste water detected by the flow meter 28 is about twice (2Q) the allowable treatment amount of the biological treatment apparatus 12. In this case, the effluent of the raw water tank 20 contains a cationic polymer coagulant of 1.0 to 2.0 m.
g / l is added, and the filtration speed in the high-speed filtration device 10 is 600
The treated water was treated at a rate of m / day, and the filtered water exceeding the treatment allowable amount of the biological treatment apparatus 12 was made to flow through the discharge pipe 68 by the distributor 66 to be discharged directly. At this time, the filter medium 52 was washed three times a day.

As a result, the removal rate of the solid component 82 in the high speed filtration device 10 is 85 to 90% as SS and about 60% as BOD, and the quality of the filtered water at the outlet of the high speed filtration device 10 is SS. 40-50 ppm, BOD 55-65
ppm, ammoniacal nitrogen 25 ppm, phosphorus concentration 3
It was ppm. In this case, the BOD concentration at the inlet of the biological treatment device 12 is insufficient with respect to the nitrogen concentration. Therefore, the bypass valve 42 is opened by a predetermined amount and the bypass pipe 4 is opened.
The anaerobic tank 64 of the biological treatment equipment 12
And the BOD concentration was adjusted to 80 to 90 ppm.

Next, a case will be described in which the amount of inflowing wastewater detected by the flow meter 28 is about three times (3Q) the allowable treatment amount of the biological treatment apparatus 12. In this case, the effluent of the raw water tank 20 contains a cationic polymer coagulant of 1.0 to 2.0 m.
g / l is added, and the filtration speed in the high-speed filtration device 10 is 900
The treated water was treated at a rate of m / day, and the filtered water exceeding the treatment allowable amount of the biological treatment apparatus 12 was made to flow through the discharge pipe 68 by the distributor 66 to be discharged directly. At this time, the filter medium 52 was washed 6 times a day.

As a result, the removal rate of solid components in the high-speed filtration device 10 was about 80% as SS and about 50 as BOD.
%, And the quality of the filtered water at the outlet of the high-speed filtration device 10 is
SS is 45 to 55 ppm, BOD is 60 to 75 ppm,
Ammoniacal nitrogen was 20 ppm and phosphorus concentration was 2 ppm. The quality of the treated water after the biological treatment of the filtered water filtered by the high-speed filtration device 10 by the biological treatment device 12 is S
S was 5 ppm or less, BOD was 5 ppm or less, ammoniacal nitrogen was 5 ppm or less, and phosphorus concentration was 1 ppm.

The retention time of the waste water in the filtration tank 38 of the high-speed filtration device 10 when the filtration speed is 900 m / day is about 6
It was a minute. From this, the present invention was able to shorten the filtration time to 1/20 as compared with the conventional case (residence time was 2 hours), and was able to improve the quality of filtered water. Also in this case, the BOD concentration at the inlet of the biological treatment device 12 is insufficient with respect to the nitrogen concentration. Therefore, the bypass valve 42 was opened by a predetermined amount and a part of the wastewater was supplied to the anaerobic tank 64 of the biological treatment apparatus 12 through the bypass pipe 40, and the BOD concentration was adjusted to 80 to 90 ppm.

As described above, according to the wastewater treatment apparatus of the present invention, the high-speed filtration apparatus 1 is selected according to the amount of inflowing wastewater and the water quality.
Since the optimum treatment condition such as the filtration condition at 0 or the discharge amount directly discharged can be selected, even if the inflowing wastewater amount exceeds the treatment allowable amount of the biological treatment device 12, the load on the biological treatment device 12 is reduced. It is possible to reduce and efficiently perform biological treatment, and it is possible to directly discharge discharged water having good water quality to a river or the like by simply filtering the wastewater exceeding the treatment allowable amount with the high-speed filtration device 10. In particular,
The wastewater treatment device of the present invention is optimal for the case of a combined sewer system, and not only when the inflowing drainage water during fine weather is less than the treatment allowable amount of the biological treatment device 12, but also when the inflowing drainage water amount is temporarily increased during rainy weather. It is possible to deal with the case where the treatment allowable amount of the biological treatment device 12 is exceeded. When a coagulant is added and the filtration speed is 400 m / day or less, the solid component 82 is removed by both the formation mechanism of the sludge accumulation layer 84 and the sludge adhering layer 86, so that an extremely high removal rate is achieved. Obtainable. When adding a coagulant to the wastewater, a part of the wastewater is supplied to the inlet of the biological treatment apparatus 12 through the bypass pipe 40 so that the organic matter, which is a nutrient source of microorganisms, is maintained at a predetermined concentration or higher. Therefore, nutrient salts (nitrogen component, phosphorus component) can be sufficiently removed to prevent eutrophication.

Therefore, even if there is an inflowing wastewater amount exceeding the treatment allowable amount of the biological treatment apparatus 12, it is possible to obtain good water quality just by filtering with the high-speed filtering apparatus 10 by appropriately adding the coagulant and the filtration rate. Therefore, even if a part of the filtered water is discharged to the river without being treated by the biological treatment device 12, the water quality in the public water area is not deteriorated. Next, according to FIG. 7, the second of the wastewater treatment method and its apparatus of the present invention
An example will be described.

In the second embodiment, two series of high speed filtration devices 10 are provided in parallel, and two series (A system and B system) of high speed filtration devices 10A, 1 are provided according to the inflowing drainage amount measured by the flow meter 28.
OB is used properly. As shown in FIG. 7, the waste water flows from the raw water inflow pipe 18 into the raw water tank 20 through the flow meter 28, and then flows from the raw water tank 20 to the drainage distributor 90. In the drainage distributor 90, the flowmeter 2
The waste water is distributed to the two series (A system and B system) of the high-speed filtration devices 10A and 10B based on the signal indicating the inflowing waste water amount from 8. Further, a distribution device 66 is provided in the B system biological treatment pipe 62 to join the B system filtered water to the A system biological treatment pipe 62, or to directly discharge it to a river or the like via a discharge pipe 68. To do. The BO of the biological treatment device 14
When the D concentration is low, a part of the waste water is supplied to the anaerobic tank 64 of the biological treatment device 12 via the bypass pipe 40, as in the first embodiment.

Next, the operating method in the second embodiment will be described. (1) The amount of inflowing wastewater is the treatment allowable amount (1
In the case of about half (Q) of Q), all the wastewater is sent to the high-speed filtration device 10A of system A and treated at a filtration speed of 400 m / day or less without adding a coagulant, and the entire amount of the filtered water is biological. It is sent to the processing device 12 for biological treatment. At this time, the distribution device 66 prevents the filtered water of system A from flowing to system B. (2) When the inflowing wastewater amount is about the same as the treatment allowable amount of the biological treatment device 12 (1Q), 2 of A and B of the high-speed filtration device 10
A system is used to perform filtration without adding a coagulant at a filtration rate of 400 m / day or less, and the distribution device 66 sends the entire amount of the filtered water of two systems A and B to the biological treatment device 12 for biological treatment. (3) When the amount of inflowing wastewater is about 1.5 times (1.5Q) as the treatment allowable amount of the biological treatment device 12 and exceeds the treatment allowable amount, the distribution device 66 causes the biological treatment pipes 62 of the two systems A and B to be provided. 10A of high-speed filtration device of system A by blocking the communication of
The filtered water filtered in (1) is sent to the biological treatment device 12, and the filtered water filtered by the B-system high-speed filtering device 10B is directly discharged through the discharge pipe 68. In this state,
A coagulant is added to the inflowing wastewater in the raw water tank 20, and the wastewater distribution device 90 sends a wastewater amount (1Q) corresponding to the treatment allowable amount of the biological treatment device 12 to the high-speed filtration device 10A of system A to filter the water. Processing at 800m / day,
Then, water is sent to the biological treatment device 12. In addition, the remaining wastewater with the coagulant added in the raw water tank 20 (0.5Q)
Is a high-speed filtration device 1 of the B system by the drainage distribution device 90.
Sent to 0B and treated at a filtration speed of 400 m / day or less,
Then, the water is discharged through the discharge pipe 68. In this way, by selectively using the two systems of A and B of the high speed filtration device 10, the high speed filtration device (B
Since the filtration conditions of the (system) can be selected so that the removal rate of the solid component 82 is extremely high, the water quality of the discharged water to be discharged can be improved. In this case, the removal rate of the solid component 82 in the B-system high-speed filtration device 10B is 95.
%, An extremely high removal rate was obtained. (4) The amount of inflowing wastewater is 2 which is the allowable treatment amount of the biological treatment device 12.
When it becomes about twice (2Q) and exceeds the allowable processing range, the distribution device 66 interrupts the communication between the two systems A and B of the biological treatment pipes 62, and the system A high-speed filtration device 10A.
The filtered water filtered in (1) is sent to the biological treatment device 12, and the filtered water filtered by the B-system high-speed filtering device 10B is directly discharged through the discharge pipe 68. In this state, a coagulant is added to the inflowing wastewater in the raw water tank 20, and the biological treatment device 12 is supplied by the wastewater distributor 90.
The amount of waste water (1Q) corresponding to the treatment allowable amount of is sent to the high-speed filtration device 10A of system A, and the filtration speed is 800 to 1000 m.
/ Day, and then water is sent to the biological treatment device 12.
The remaining wastewater (1Q) to which the coagulant has been added in the raw water tank 20 is sent to the high-speed filtration device 10B of system B by the drainage distribution device 90, and the filtration speed is 800 to 1000 m /
It is treated in the day and then discharged through the discharge pipe 68.

As described above, according to the second embodiment of the present invention, the two high-speed filtration devices 10 are provided in parallel, so that the quality of the discharged water directly discharged to a river or the like is prevented from deteriorating. It is possible to select fine filtering conditions according to the conditions. Especially in a heavy rain area, the solid component in the inflowing wastewater tends to increase at the beginning of the rainfall, so by performing the operation of (3), the filtration speed in the high-speed filtration device 10B of the B system for direct discharge is slowed down. Therefore, it is possible to consider that the removal rate of the fixed component 82 is high. In addition, the amount of inflow drainage increases as time elapses from the beginning of the descent,
Since the solid component 82 and the BOD concentration in the waste water also drastically decrease, even if the operation of (3) is changed to the operation of (4), the quality of the discharged water is hardly deteriorated and the influence on the natural environment is small.

Next, a brief description will be given of the method of cleaning the filter medium in the first and second embodiments. When the water resistance of the floating filter material layer 37 of the high-speed filtration device 10 reaches a predetermined value, the supply of drainage is stopped and the filter material 52 is washed. Cleaning
First, the raw water valve 36 is closed to stop the drainage from being supplied to the high-speed filtration device 10, and the cleaning drainage valve 46 is opened to drain the drainage in the filtration tank 38, so that the water surface in the filtration tank 38 is aired. The filter medium 52 is lowered to a position where it does not come into contact with the upper screen 48 during cleaning. After that, wash drain valve 46
Close. The waste water remaining in the filtration tank 38 is used as washing water for the filter medium 52, and air is ejected from the central air nozzle 54 provided in the air ejection pipe 56 for about 5 minutes to raise the filter medium 52 in the central portion of the floating filter medium layer 37 upward. Then, the filter media 52 on the left and right parts are swirled downward, and by the air blown at this time, the filter media 5 is swirled.
The solid component 82 captured by 2 is peeled off.

Next, in order to prevent the reattachment of the peeled solid component 82, while the air is ejected from all the air nozzles 54 provided in the air ejection pipe 56, the cleaning drain valve 46 is opened to remove the separated solid component 82. The cleaning drainage which is the drainage contained is discharged to the outside of the filtration tank 38 through the cleaning drainage pipe 44 (the drainage time is about 1 to 2 minutes). Next, the ejection of air from the air ejection pipe 56 is stopped, the cleaning drain valve 46 is closed, and the cleaning is completed.

[0044]

According to the wastewater treatment method and apparatus of the present invention, the high-speed filtration step and the biological treatment step are organically combined so that the solid component in the wastewater can be removed at a high removal rate in the high-speed filtration step. Therefore, the load in the biological treatment process can be reduced. As a result, the quality of the treated water after the biological treatment process can be improved, and the amount of air required for decomposing organic substances in the biological treatment process can be reduced, which can reduce aeration power and further generate an excess sludge amount. Can be reduced. Further, since the carrier in which nitrifying bacteria are entrapped and fixed is added to the nitrification tank in the biological treatment process in addition to the activated sludge, the time required for the nitrification reaction can be shortened.

Further, in the high-speed filtration process, it is possible to select the optimum treatment conditions such as the filtration condition or the direct discharge amount according to the inflow amount of the waste water and the water quality, so that the treatment allowable amount of the biological treatment process is exceeded. Even if there is an inflow of wastewater, the load on the biological treatment process can be reduced and efficient biological treatment can be performed, and wastewater that exceeds the treatment allowable amount can be discharged with good water quality simply by filtering it in the high-speed filtration process. Water can be discharged directly. Therefore, in particular, in the case of combined sewerage, not only when the inflowing wastewater is less than the treatment capacity of the biological treatment process, such as during fine weather, but also when the inflowing wastewater amount is the processing permission of the biological treatment process due to a temporary increase in water during rainy weather. It is possible to cope even when the capacity is exceeded.

When a coagulant is added to waste water,
A part of the wastewater was supplied to the biological treatment process via a bypass route to maintain the organic substances, which are the nutrient sources of microorganisms, at a predetermined concentration or higher, so that nutrient salts (nitrogen component, phosphorus component) were prevented to prevent eutrophication. ) Can be sufficiently removed.
Further, the wastewater treatment equipment of the present invention can significantly reduce the treatment time for the amount of inflowing wastewater compared with the conventional wastewater treatment equipment which firstly combined the settling tank and the activated sludge treatment, and further improve the quality of filtered water. it can. As a result, the wastewater treatment equipment of the present invention can have a greater treatment capacity per site area than the conventional wastewater treatment equipment. Therefore,
The device can be made compact.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a flow of a first embodiment of a wastewater treatment apparatus of the present invention.

FIG. 2 is an explanatory diagram illustrating the structure of a high-speed filtration device.

FIG. 3 is a side view illustrating an example of a filter medium used in the present invention.

FIG. 4 shows a filtration speed of a high-speed filtration device of 400 m /
Explanatory diagram explaining the capture mechanism of solid components in wastewater when performed on a daily basis and when no additive is added

FIG. 5 shows the filtration speed of the high-speed filtration device of 400 m /
Explanatory diagram explaining the capture mechanism of solid components in wastewater when the additive is added on a daily basis

FIG. 6 shows the filtration speed of the high-speed filtration device of 400 to 1;
Explanatory diagram for explaining the trapping mechanism of the solid component in the waste water when the additive is added at 000 m / day

FIG. 7 is a configuration diagram showing a flow of a second embodiment of the wastewater treatment equipment of the present invention.

[Explanation of symbols]

 10 ... High-speed filtration device 12 ... Biological treatment device 14 ... Precipitation device 18 ... Raw water inflow pipe 20 ... Raw water tank 22 ... Flocculant tank 28 ... Flow meter 36 ... Raw water valve 37 ... Filter medium floating layer 38 ... Filtration tank 40 ... Bypass pipe 42 ... Bypass valve 44 ... Washing drainage pipe 48 ... Upper screen 50 ... Lower screen 52 ... Filter material 56 ... Air ejection pipe 58 ... Dispersion plate 60 ... Trough 62 ... Biotreatment pipe 64 ... Anaerobic tank 66 ... Distributor 68 ... Discharge pipe 70 … Denitrification tank 72… Digestion tank 74… Aeration device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Kojima Inventor Masayuki Kojima 1-1-14, Uchikanda, Chiyoda-ku, Tokyo Inside Hirit Plant Construction Co., Ltd. (72) Inventor, Hitoshi Kawajiri 1 Uchikanda, Chiyoda-ku, Tokyo 1-14 No. 1 in Hiratsugi Plant Construction Co., Ltd. (72) Inventor Hirofumi Yamamoto 1-1-14 Kanda, Uchida, Chiyoda-ku, Tokyo In Hirtichi Plant Construction Co., Ltd. (72) Inventor Kazuhiko Noto Tokyo 1-14-14 Kanda, Chiyoda-ku, Tokyo Inside Hiratsugi Plant Construction Co., Ltd. (72) Inventor Naomichi Mori 1-14-114, Kanda, Chiyoda-ku, Tokyo

Claims (9)

[Claims] 1. A wastewater treatment method for purifying wastewater such as sewage, wherein the wastewater that has flowed in an upward flow into the filter tank is provided in the filter tank and has a mesh shape with a specific gravity smaller than that of the wastewater. A high-speed filtration step of filtering with a floating filter material layer formed by a large number of cylindrical filter media, the filtered water filtered in the high-speed filtration step is an anaerobic tank for anaerobic treatment, a denitrification tank for anoxic treatment, and aerobic A biological treatment step of removing organic matter components, nitrogen components and phosphorus components in the filtered water by biological treatment by bringing the microorganisms in the activated sludge into contact with each other in a nitrification tank for treatment. 2. The filter medium having a meshed cylindrical shape has a porosity of 80.
% Or more, and the thickness of the wire forming the mesh is 1 to
The wastewater treatment method according to claim 1, wherein the wastewater treatment method is within a range of 5 mm, preferably within a range of 2 to 4 mm. 3. The wastewater treatment method according to claim 1, wherein a carrier in which nitrifying bacteria are entrapped and fixed is added to the nitrification tank in addition to the activated sludge. 4. When the inflowing wastewater amount of the wastewater is less than the treatment allowable amount of the biological treatment step, the filtration rate in the high-speed filtration step is filtered at 400 m / day or less, and the whole amount of the filtered water is passed to the biological treatment step. When the amount of wastewater that flows into the high-speed filtration step is more than the treatment allowable amount of the biological treatment step, a coagulant is added to the wastewater to increase the filtration rate of the high-speed filtration step from 400 m / day to 1000 m / day.
2. The waste water treatment method according to claim 1, wherein the filtration is carried out on a daily basis, and the treatment allowable amount of the filtered water is sent to the biological treatment step, and the remaining filtered water is discharged out of the system. 5. When the inflowing wastewater amount of the wastewater is equal to or more than the treatment allowable amount of the biological treatment process, a high-speed filtration process is performed in parallel after adding a coagulant to the wastewater, and the filtration speed is increased in one of the high-speed filtration processes. It is characterized by filtering at 400 m / day to 1000 m / day and sending the filtered water to the biological treatment step, and at the other high-speed filtering step, filtering at a filtration speed of 400 m / day or less and discharging the filtered water out of the system. The wastewater treatment method according to claim 1. 6. When a coagulant is added to the wastewater, a part of the wastewater is directly supplied to a biological treatment step without passing through a high-speed filtration step to maintain an organic substance as a nutrient source of microorganisms at a predetermined concentration or more. The wastewater treatment method according to claim 4 or 5, wherein 7. Whether or not a coagulant to be added to the wastewater is added,
The wastewater treatment method according to claim 4, 5 or 6, wherein the control is performed based on the flow rate of the wastewater flowing into the high-speed filtration step. 8. A wastewater treatment device for purifying wastewater such as sewage, wherein the wastewater that has flowed into the filtration tank in an upward flow is provided in the filtration tank and has a mesh shape with a smaller specific gravity than the wastewater. A high-speed filtration device for filtering with a floating filter material layer formed of a large number of cylindrical filter media, and filtered water filtered by the high-speed filtration device, an anaerobic tank for performing anaerobic treatment, a denitrification tank for performing anoxic treatment, and aerobic A biological treatment device that removes organic components, nitrogen components, and phosphorus components in the filtered water by biological treatment by bringing the microorganisms in the activated sludge into contact with each other in a nitrification tank that performs the treatment, and the drainage provided in the preceding stage of the high-speed filtration device. A coagulant addition means capable of adding a coagulant, a bypass path for bypassing the high-speed filtration device to directly supply the wastewater to the inlet of the biological treatment device, an opening / closing means for opening / closing the bypass path, the high speed A discharge route for discharging the filtered water filtered by a filtration device directly to the outside of the system without passing through the biological treatment device; and a distribution means for distributing the filtered water to the biological treatment device and the discharge route. A wastewater treatment device characterized in that 9. A detecting means for detecting the inflowing and outflowing amount of the wastewater is provided, and whether or not the coagulant is added from the coagulant adding means is controlled according to the magnitude of the inflowing and discharging water amount. Wastewater treatment equipment.