JP2608520B2 - Purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purification apparatus for treating domestic wastewater and human wastewater, and more particularly to a purification apparatus having a simple structure, a high operation rate, extremely easy maintenance, and a BOD and nitrogen treatment. The present invention relates to a purification device having extremely excellent removal performance.

[0002]

2. Description of the Related Art In so-called closed water areas such as lakes and inland seas, the progress of eutrophication is remarkable due to the inflow of various nutrients.

[0003] Eutrophication is a phenomenon in which nutrients such as nitrogen and phosphorus in wastewater increase, and algae and aqueous plants that perform photosynthesis using the nutrients grow abnormally.

[0004] In particular, regarding nitrogen compounds in water,
Except for the excrement of aquatic organisms, most of the water flowed in by human activities, and the effects of domestic wastewater and human effluent discharge water are extremely large.

[0005] Therefore, various purification devices having a denitrification function have been proposed for purifying household wastewater and human wastewater.

However, the conventional processing method has a drawback that the processing amount is reduced, the processing capacity is not increased, and if the processing amount is to be increased, the capacity of the processing tank must be increased, and the compactness is lacking. .

In order to solve such a problem, the present applicants have already disclosed Japanese Utility Model Application No. 1-145782 (Japanese Utility Model Application Laid-Open No.
No. 83697), in a purification apparatus having an anaerobic filter bed tank, a biofilm filtration tank, and a treated water tank, the ratio of the amount returned to the biofilm filtration tank and the anaerobic filter bed tank to the amount of raw water inflow was determined. A purifying apparatus has been proposed in which each is set to a predetermined value and the processing capacity of denitrification is extremely excellent, and as a result, the apparatus can be made compact.

[0008]

However, even in such an apparatus having extremely excellent performance, there is no point that there is no point to be improved at all, and it is desired to further improve the inconvenience that can be predicted. ing. That is, this apparatus is provided with an anaerobic filter bed tank, which may be clogged at the filter bed portion due to the filter medium being filled in the tank, and once clogged. And to remove this, the utilization rate will decrease,
Also, the sludge attached to the filter medium during cleaning is difficult to pull out,
A problem that maintenance is not easy may occur. Further, there is a problem such as an increase in cost due to a complicated structure using a filter medium.

The present invention has been made in view of such circumstances, and has as its object a simple structure, a high operation rate, and extremely easy maintenance.
In addition, it is an object of the present invention to propose a purifying apparatus having extremely excellent BOD and nitrogen removal capabilities.

[0010]

Means for Solving the Problems In order to achieve the above object, the inventors of the present invention have conducted intensive studies and found that the conventionally known anaerobic filter bed tank and biofilm filtration tank are known. In the filtration process having, a sedimentation separation tank with a simple structure is installed instead of the anaerobic filter bed tank, a part of the treated water is circulated to the sedimentation separation tank, and this circulation ratio is specified within a certain value range. Then, in addition to the new effect derived from the structure of the sedimentation separation tank, it was found that the same nitrification and denitrification effects as those provided with an anaerobic filter bed tank were obtained.
This has led to the present invention.

That is, the present invention is a purification apparatus having a sedimentation separation tank, a biofilm filtration tank filled with a granular porous carrier, and a treatment water tank, wherein the sedimentation separation tank is formed by being separated from raw water. The apparatus is provided with a chamber structure sufficient to store sludge, and the apparatus is one of the treated water in the treated water tank, which is processed through the sedimentation separation tank, the biofilm filtration tank, and the treated water tank sequentially, and does not contain sludge. Is provided with a treated water circulating device for carrying out biological nitrification and denitrification while returning and circulating the wastewater to the sedimentation / separation tank. ~ 5.

[0012]

The purifying apparatus of the present invention comprises a sedimentation separation tank, a biofilm filtration tank filled with a granular porous carrier, and a treatment water tank, and a part of the treatment water tank is circulated to the sedimentation separation tank at a predetermined ratio. By performing biological nitrification and denitrification,
Since the BOD removal performance and the denitrification treatment capacity are extremely excellent, and the simple structure with a sedimentation separation tank,
There are few troubles during operation and maintenance is very easy.

[0013]

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a longitudinal sectional view schematically showing the configuration of the purification device of the present invention.

As shown in FIG. 1, the purification apparatus of the present invention comprises a peak cut tank C, a sedimentation separation tank D, a backwash drain tank R,
It has a biofilm filtration tank B, a treatment water tank H, and a disinfection tank S.

The peak cut tank C is provided with an aeration type screen 4 including an inflow port 3, from which raw water (sewage) to be treated is introduced, and a pump 5 provided in the tank. Raw water (sewage) introduced by
Can be appropriately supplied to the sedimentation separation tank D in the subsequent step. That is, the peak cut tank C has a buffer-like function, and plays a role of adjusting the fluctuation of the flow rate.

The sedimentation / separation tank D connected to the peak cut tank C has a first sedimentation / separation tank D1 as shown in the figure.
(Hereinafter, simply referred to as sedimentation / separation tank D1) and a second chamber for sedimentation / separation tank D2 (hereinafter, simply referred to as sedimentation / separation tank D2), which are connected in series. Various configurations are conceivable as a two-row series configuration, and among them, the configuration shown in FIG. 1 is particularly preferable.

That is, as shown in FIG.
1 and D2 are communicated by an opening 8 provided at a predetermined water level position of the partition wall 7, and both tanks have a predetermined effective capacity. And such a sedimentation separation tank D
1 and D2 are provided with a chamber structure sufficient to store sludge separated and generated from raw water, and sedimentation separation tanks D1 and D2 are used for separation of suspended matter in inflowing sewage and storage of separated sludge. However, in the present invention, by circulating a part of the treated water to the sedimentation separation tank D as described later, extremely excellent denitrification and BOD removal effects can be obtained. The "chamber structure sufficient to store the sludge separated and generated from the raw water" is simply a tank shape for storing the liquid, as shown in FIG. Refers to a chamber structure that does not contain a carrier that is a filler for the formation of. In order to exert the functions of these sedimentation separation tanks, it is preferable to adopt a structure in which short-circuiting of inflowed sewage is unlikely to occur, or a structure in which sedimentation and separation can be performed effectively and the separated sludge is not disturbed and mixed.

A backwash drainage tank R is connected to the sedimentation separation tanks D1 and D2. The backwash drain tank R is mainly provided with a pump 9 for adjusting the excess amount of backwash wastewater returned in the reverse direction from the biofilm filtration tank B in the next step by a so-called backwash operation.
It has. That is, an excessive amount of backwash wastewater is returned to the peak cut tank C via the return pipe 31 as shown in the figure.

A biofilm filtration tank B is connected to such a backwash drain tank R. The biofilm filtration tank B is used to nitrify the ammonia nitrogen remaining in the wastewater into nitrite nitrogen by nitrite bacteria, further nitrify nitrite nitrogen into nitrate nitrogen, and remove pollutants from microorganisms. It is intended to perform microbial treatment and phosphate adsorption, biological adsorption of iron ions and the like utilizing the decomposition action of, and physical filtration, and various configurations are conceivable as the configuration of the treatment tank. Is preferable.

That is, as shown in the drawing, an aeration / backwash pipe 37 directly connected to the aeration blower 35 is provided near the bottom of the biofilm filtration tank B, and a framed portion 37a near the bottom is often provided. Holes are provided.

A support plate 39 is provided near the upper part of the frame portion 37 a of the aeration / backwash pipe 37, and a large number of carriers 43 made of granular porous ceramic to which aerobic microorganisms are adhered. Filled with biofilm filtration layer 45
Is formed.

As the granular porous ceramic, for example, it is preferable to use porous granular foam glass. Examples of the material of the porous granular foam glass include silica glass, soda coal glass, aluminoborosilicate glass, borosilicate glass, aluminosilicate glass, and lead glass.
Although it can be appropriately changed as needed, inexpensive soda-lime glass is desirable from an economic viewpoint. In addition, using a special composition glass impregnated with metals such as iron,
It is also possible to increase the removal rate of specific components such as phosphorus.

The foam glass used is granular, and
It has a high degree of porosity. The particle size of the foam glass is, for example, 0.2 to 20 mm, preferably 4 to 10 mm.
mm. If the particle size exceeds the upper limit, the adhesion of microorganisms is biased to the surface of the carrier, and the purification efficiency is deteriorated. Conversely, if the particle size is smaller than the lower limit, clogging may occur.
The porosity of the foam glass is high, and specifically, the total pore volume is 0.5 to 5.0 ml / g, preferably 2 to 5.0 ml / g.
3.5 ml / g, water absorption 40-85%, preferably 70
~ 85 (Vol / Vol), central pore diameter (volume) 1 ~
50 μm, preferably 5 to 50 μm, bulk specific gravity 0.1 to
1.5, preferably 0.15 to 0.5.

The above-mentioned highly porous granular foam glass is, for example,
A granular foam glass having a water absorption of 5 to 20% manufactured by a conventional method is immersed in warm water or an alkaline solution to remove soluble alkali components in the granular foam glass, and the surface layer of the granular foam glass and the independent It can be manufactured by providing an opening in a bubble.

Alternatively, a blowing agent may be added to a glass powder with a metal oxide having a high melting point, for example, 5 to 10% of alumina, silica, zirconia, etc., fired, and then quenched to generate fine bubbles. Can be manufactured.

Such a porous ceramic made of, for example, porous granular foam glass has a large specific surface area and a large pore volume because it is porous as described above. Microorganisms can be maintained at a high concentration. Therefore, when the biofilm filtration layer 45 is formed of a carrier made of a porous ceramic, the processing capacity is further increased and the size can be reduced.

Further, the specific gravity is close to 1, and the position is changed even by a small amount of flow and stirring is performed. That is, the backwash power may be extremely small. Further, the water is opened below the support plate 39 at the bottom of the biofilm filtration tank B, that is, below the biofilm filtration layer 45, and the treated water purified by the biofilm filtration tank 45 is supplied to the treatment water tank H. In addition, a pipe 47 is provided for back-feeding the treated water in the treated water tank H to the biofilm filtration tank B at the time of back washing. The pipe 47 allows the biofilm filtration tank B and the treated water tank H to communicate with each other. In the treated water tank H, a backwash pump 53 for backwashing and an air lift pump 54 as an example of a treated water circulation device are installed.
A main pipe 57 is provided in connection with the air lift pump 54, and this main pipe 57 is branched into return pipes 58a and 58b in the middle as shown in the figure.

The return pipe 58a extends to the sedimentation separation tank D1 in order to circulate a part of the treated water while returning it. On the other hand, the return pipe 58b provided as a preferred embodiment extends to the biofilm filtration tank B in order to return a part of the treated water to the biofilm filtration tank B.

A part of the treated water in the treated water tank H is circulated while being returned to the sedimentation / separation tank D1.
This is for performing denitrification (denitrification) of the treated water decomposed into nitrite ions or nitrate ions. This sedimentation separation tank D
Although the mechanism of denitrification by circulating treated water in the interior cannot be clearly explained at this time, one fact is that the adoption of a constant circulation ratio as described later will significantly improve the nitrogen removal performance. It turns out that. As a result, the treated water returned to the sedimentation separation tank D1 receives oxygen in the nitrite ions and nitrate ions in the sedimentation separation tanks D1 and D2. Is released into the atmosphere as N ₂ gas, and it is considered that inorganic nitrogen in the wastewater is removed.

In this case, the circulation ratio, that is, the circulation ratio of the treated water to the sedimentation / separation tank D1 with respect to the raw water inflow amount is in the range of 2 to 5, and particularly preferably in the range of 3 to 4.

If this value is less than 2, the nitrogen removal rate of the treated water will be poor. On the other hand, if this value exceeds 5, unnecessary circulation will occur, which is not preferable. The circulation ratio thus defined can be said to be a relatively narrow range, but this is thought to be due to the fact that denitrification is attempted using a sedimentation / separation tank D having a simple structure that has never been considered before. Can be
Indeed, although the specified range of the circulation ratio becomes narrower, by using the sedimentation separation tank D,
A new effect that the operation rate can be improved without fear of occurrence of blockage and maintenance can be performed very easily is exhibited.

Further, it is possible to circulate a part of the treated water in the treated water tank H while returning it to the biofilm filtration tank B.
Ammonia nitrogen remaining in the treated water can be completely nitrified into nitrite and nitrate nitrogen.
This is a preferable mode for reducing the size of the device. That is, by returning a part of the treated water to the biofilm filtration tank B, the dissolved oxygen (DO) in the upper part of the biofilm filtration tank B is increased, and the biochemical oxygen demand (BOD) is reduced. In addition, the amount of water passing through the biofilm filtration tank B increases, whereby the raw water is evenly dispersed throughout the biofilm filtration tank B, thereby increasing the activity of nitrite and nitrate bacteria, and removing ammonia. It can be oxidized to nitrite and nitrate ions. In this case, the circulation ratio, that is, the circulation ratio of the treated water to the biofilm filtration tank B with respect to the raw water inflow amount is
0.5 to 4, particularly preferably 1 to 2.

If this value is less than 0.5, the nitrification rate of the treated water becomes poor, while if this value exceeds 4, unnecessary circulation is caused, which is not preferable. If the capacity of the biofilm filtration tank B is large and the treatment capacity is large, it is not always necessary to circulate a part of the treatment water in the treatment water tank H to the biofilm filtration tank B.

In the apparatus provided with the sedimentation separation tank D and the biofilm filtration tank B as described above, a part of the treated water in the treatment water tank H is returned to the sedimentation separation tank D1, whereby the nitrite ionization of ammonia and the nitrite ionization can be prevented. Nitrate ionization as well as denitrification in the oxidized nitrogen compounds are performed.

By the way, the overflow water in the treated water tank H is sent to the disinfecting tank S, and neutralization and sterilization of the treated water in which the organic substance is treated are performed in the small chamber 61 therein. Released.

The above-mentioned purifying apparatus of the present invention comprises the individual tanks (peak cut tank C, sedimentation separation tank first chamber D1, second chamber D2,
Backwash drainage tank R, biofilm filtration tank B, treated water tank H, etc.) can be individually prepared, and these can be connected to each other by piping. However, usually, each tank is made of a material such as reinforced plastic (FRP). Are integrally formed, and a carrier 43, a pipe,
It is preferable to incorporate a pump or the like and have a predetermined function in order to make the purification device compact.

Next, a method of treating sewage in the above-described purification apparatus will be described.

The purifying apparatus 1 of the present invention is intended for purifying general household wastewater and human waste. Therefore, the size of each tank of the purifying apparatus is set to a corresponding size.

The sewage is first sent from the first inlet 3 through the aeration screen 4 to the peak cut tank C. The sewage stored in the peak cut tank C is sent to the sedimentation separation tank D1 by the pump 5 provided in the peak cut tank C. Then, when the water level of the sedimentation separation tank D1 rises and reaches a predetermined height, sewage flows out from the opening 8 on the side surface. When sewage passes through the tank, primary decomposition and adsorption of organic substances are performed. The passed water raises the water level of the sedimentation separation tank D2, and similarly, decomposition and adsorption of organic substances are performed in the tank of the second chamber D2. Further, the water that has passed through the sedimentation separation tank D2 flows into the backwash drainage tank R and the biofilm filtration tank B. The water that has flowed into the biofilm filtration tank B passes through the biofilm filtration layer 45 in a downward flow. As described above, the biofilm filtration layer 45 is filled with a large number of carriers 43 made of granular porous ceramic, and descends while bending the inside.

At this time, the aeration blower 35 operates, and the aeration / backwash pipe 37 (3) framed at the bottom.
Air bubbles are blown out from 7a) and rise. Since the bubbles rise in a curved manner while colliding with the carrier 43, they do not suddenly become coarse, and the residence time is increased. As a result, a high oxygen utilization rate can be obtained, so that high-load operation is possible.

As described above, the raw water and the air are brought into countercurrent contact with each other in the biofilm filtration layer 45 to perform contact aeration, dissolve oxygen in sewage, enhance the biooxidation function, decompose organic matter, and remove microorganisms. As well as proliferating, the water is purified more efficiently by the filtering action between the carrier particles and the adsorption on a wide surface of the biofilm to make the treated water.

As will be described later, since the biofilm filtration layer 45 is backwashed every predetermined time, it hardly precipitates at the bottom.

The treated water passes through a pipe 47 and is placed in a treated water tank SH.
Sent to

A part of the treated water tank H is circulated while being returned by the air lift pump 54 to the sedimentation / separation tank D1 via the return pipe 58a. Here, denitrification of the treated water decomposed into nitrite ions and nitrate ions is performed. The details are as described above.

Further, a part of the treatment water tank H may be circulated to the biofilm filtration tank B by the air lift pump 54 via the return pipe 58b in a fixed amount. By this circulation, the untreated ammonia nitrogen is completely oxidized to nitrite and nitrate nitrogen, and the size of the apparatus can be reduced. The details are as described above.

By the way, most of the treated water in the treated water tank H is finally discharged through the disinfecting tank S after neutralization or sterilization by chemical injection or the like. This discharge rate is usually set according to the processing capacity of the biofilm filtration layer 45 of the biofilm filtration tank B.

As a result of the sewage treatment, the biofilm filtration layer 45
Organic substances and propagation sludge are attached to the carrier 43,
When the backwash pump 53 is activated before the sediment is removed from the carrier 43 and the backwash pump 53 is operated, the treated water stored in the treated water tank H flows back through the pipe 47, and the biofilm filtration layer is discharged from the bottom of the biofilm filtration tank B. We blow up in 45.

By this upward flow, the sludge and the like, which are adhered and captured in the biofilm filtration layer 45, are removed from the aeration blower 35.
It is removed in combination with the air bubbles blown out from the pipe through the aeration / backwash pipe 37 and floats in the backwash drainage. Here, the biofilm filtration layer 45 is a large number of granular porous ceramic carriers 43 as described above. Since the specific gravity is close to 1, the carriers 43 fly up and collide with each other, and the captured growth Sludge will be desorbed and washed.

Since the treated water in the treated water tank H is sent in by the backwash pump 53, the water level in the biofilm filtration tank B rises, and the backwash drainage tank R is used as backwash drainage together with the floating sludge.
It is sent backward and flows in. For this reason, part or all of the backwash drainage is performed by the pump 9 provided in the backwash drainage tank R.
It is returned to the first chamber D1 of the precipitation separation tank, and the water level of the entire apparatus is adjusted. The backwash wastewater returned to the sedimentation separation tank D1 again
The same processing as described above is performed via the precipitation separation tanks D1 and D2.

Such backwashing is performed every predetermined time, and
The biofilm filtration layer 45 is washed to restore the decomposition and adsorption capacity, the growth sludge is returned to the sedimentation separation tank D1, and the growth sludge is periodically inserted by inserting a cleaning pump nozzle from the cleaning cylinder 6 of the sedimentation separation tank D. And process it. Such a backwashing method is optimal for always maintaining a constant processing capacity without reducing the processing capacity of the biofilm filtration tank B.

After the backwashing is completed, the flow of sewage into the peak cut layer C (sedimentation separation tank D) continues, and normal purification treatment is performed.

Such backwashing is performed, for example, once a day.
It is enough to do.

In the embodiment of the present invention, the air lift pump, which is an example of the treated water circulation device, is installed in the treated water tank H, but is not limited thereto. May be installed anywhere if it can be returned to the precipitation separation tank D1.

In the embodiment of the present invention, a part of the treated water is returned to the sedimentation / separation tank D1, but it is needless to say that the treated water may be returned to the sedimentation / separation tank D2. Moreover, you may return to both precipitation separation tanks D1 and D2.

Next, a specific purification experiment was performed using an apparatus as shown in FIG.

Experimental Example 1 The circulation ratio from the treatment water tank H to the first chamber D1 of the sedimentation / separation tank was changed, and the resulting nitrogen removal performance and the change in BOD were examined.

That is, first, raw water is flowed in from the inlet and normal purification treatment is performed, and then an air lift pump 54 as a treated water circulating device is operated to discharge a fixed amount of treated water into the first separation / separation tank. The purification treatment was performed while circulating only in the chamber D1. In this case, the rate of circulation is
Various changes were made.

The results are shown in Table 1 below. In Table 1, the circulation ratio r represents the ratio of the amount of circulating treated water to the first chamber D1 of the sedimentation / separation tank with respect to the amount of raw water inflow. The raw water TN and the treated water TN represent the total nitrogen content in the raw water and the treated water, respectively. The amount of inflow water is 200l / (person / day)
And

[0059]

[Table 1] From the results shown in Table 1, with respect to the BOD removal performance, the BOD removal rate in the case of not circulating (r = 0) is 90% or more, and BOD can be removed to some extent without circulation. 2,3,4,5) further confirmed that the processing performance was improved and stable processing was performed. Regarding the nitrogen removal performance, the nitrogen removal rate in the case of not circulating (r = 0) was about 40%, while the nitrogen removal rate was in the case of circulation (r = 2, 3, 3).
4,5) shows 70% or more, confirming that the processing performance is dramatically improved.

[0060]

As described in detail above, according to the present invention,
A process in which biological nitrification and denitrification are performed while returning part of the treated water in the treated water tank, which has been processed through the sedimentation separation tank, the biofilm filtration tank, and the treatment water tank, back to the sedimentation separation tank for circulation. A water circulating device is provided, and the circulating ratio of the treated water circulating device to the sedimentation / separation tank with respect to the amount of inflow of raw water is 2 to 5, so the BOD removal performance and the denitrification processing capability are extremely excellent. In addition, since it has a simple structure including a sedimentation separation tank, there is an effect that there are few troubles during operation and maintenance can be performed extremely easily.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of the configuration of a purification device of the present invention.

[Explanation of symbols]

 D1: Precipitation / separation tank first chamber D2: Precipitation / separation tank second chamber B: Biofilm filtration tank H: Treatment water tank 39: Support plate 43: Carrier 45: Biofilm filtration layer 54: Treatment water circulation device

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-354592 (JP, A) JP-A-63-4899 (JP, A) JP-A-63-229144 (JP, A) 83695 (JP, U)

Claims (1)

(57) [Claims] 1. A purification apparatus having a sedimentation separation tank , a biofilm filtration tank filled with a granular porous carrier, and a treatment water tank, wherein the sedimentation separation tank stores sludge generated by separation from raw water.
The apparatus comprises a sedimentation separation tank, a biofilm filtration tank, and a treated water tank, which is treated water sequentially passed through a treated water tank.
A treated water circulating device for performing biological nitrification and denitrification while returning a part of the treated water containing no water to the sedimentation separation tank , and circulating the treated water. The circulation ratio to the precipitation separation tank is from 2 to 5.