JP2000140887A - Method for purifying sewage and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the waste water purifying time and to efficiently remove the malodor with a relatively small floor space. SOLUTION: This device is provided with an agitated tank 4 for mixing and agitating a raw liq. to be treated and a flocculant, settling tanks 5, 6 and 7 for flocculating the solid from the liq. mixture of raw liq. and flocculant and setting the flocculated solid and an aeration and adsorption tank 8 with the passage connected to the upper end of the setting tank 7 and receiving the supernatant of the liq. mixture. The agitated tank 4 is divided into plural tanks, and the liq. mixture of the raw liq. and the flocculant supplied to each tank is batch-discharged to the settling tank 5. Plural downward inclined passages are meanderingly formed at regular intervals in the vertical direction in the aeration and adsorption tank 8, and an adsorption layer for the malodors, etc., corrugated in the downflow direction of the supernatant is furnished on the passage surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of various kinds of sewage such as wastewater and sewage and night soil, and more particularly to the promotion of purification by coagulation and sedimentation using a coagulant and the removal of odor and color using activated carbon. The present invention relates to a method and an apparatus for purifying sewage in which odorless and transparent processing can be promoted by simultaneous progress of odor and aeration.

[0002]

2. Description of the Related Art Various wastewater treatment facilities such as wastewater and night soil are provided with solids contained in the sewage in a sedimentation tank, and then aerated in an aeration tank. The basic structure is that after repeated secondary aeration, chlorine is disinfected in the chlorination facility and then discharged. In such treatment equipment, the activated sludge method is frequently used at present as a high-grade treatment technology for municipal sewage and organic wastewater.

In this activated sludge method, a mixed population of living organisms is continuously cultured using various organic substances contained in wastewater as a culture medium and using dissolved oxygen, and the contaminating organic substances are aggregated, adsorbed, oxidatively decomposed, and precipitated. It is to remove. That is, in the aeration tank, the operation is performed so that the ratio of the BOD component of the wastewater to the purified microorganism is constant, and the BOD using dissolved oxygen is used.
The components are brought into sufficient contact with flocs constituted by microorganisms of different populations to aerobically oxidize and decompose, thereby purifying sewage.

[0004]

While the activated sludge method is an effective means in the field of water treatment, one drawback is that the processing speed is slower than that of a chemical reaction in order to utilize a biological reaction. The slow processing speed means that if the equipment must process a large amount of sewage, the processing tank needs to be large, and the installation area of the equipment increases. And even if the equipment is enlarged in this way, it is difficult to increase the throughput of the wastewater to a level corresponding to the size of the equipment because the biological reaction rate has an upper limit.

In the case of sewage containing a large amount of night soil, it is important to remove not only solids and sewage but also odor and color. In order to remove the odor and the color, an adsorption method using activated carbon has conventionally been adopted as an effective means. This adsorption using activated carbon utilizes an adsorption tank filled with activated carbon, and the odor and color are removed when the wastewater permeates and exits the activated carbon layer in the adsorption tank.

However, in the conventional adsorption tank, the wastewater is supplied so as to be filled in a closed vessel, so that most of the wastewater flows off without contacting the air. For this reason, the odor that could not be adsorbed by the activated carbon is discharged into the wastewater without being diffused into the air, and the odor is not sufficiently removed.

[0007] As described above, the purification time of the conventional sewage by the activated sludge method is prolonged, and the odor tends to remain when the odor is removed using activated carbon in a closed container. Regarding the problem of the processing time and the odor, for example, if the equipment is made large so that the process of purification and odor removal can be repeated, it can be a tentative measure. However, at present, the facility area is large, so it is difficult to allocate more site area due to land conditions.

An object of the present invention is to provide a sewage treatment apparatus and method capable of shortening drainage purification time and efficiently removing odor with a relatively small facility area.

[0009]

The sewage purification method of the present invention comprises the steps of mixing and stirring a stock solution to be treated and a coagulant, and removing solids contained in the stock solution after the mixing and stirring process. The method further comprises a step of coagulating and precipitating with the coagulant, and a step of simultaneously performing an aeration operation and an adsorption operation of odor and the like on the supernatant of the stock solution after the coagulating and precipitating step.

The sewage purification apparatus of the present invention further comprises a stirring tank for mixing and stirring the stock solution to be treated and the flocculant, and aggregating solids from the mixed solution of the stock solution and the flocculant from the stirring tank. A single or multi-stage settling tank to be settled, and an aeration / adsorption tank connected to a flow path at an upper end side of the settling tank to receive a supernatant of the mixed solution, wherein the stirring tank is divided into a plurality of tanks. In addition, the mixed solution of the stock solution and the coagulant supplied to each of the tanks can be discharged to the settling tank as a batch system, and the aeration / adsorption tank has a plurality of downwardly inclined flow passages spaced vertically. And an adsorbent layer for odor and the like having a wavy shape in the downward direction of the supernatant liquid is provided on the surface of the flow path.

[0011] In the purification apparatus having such a configuration,
The adsorbent layer includes a package mounted on the surface of the flow path and forming both sides of the flow path in a streamlined direction in a streamline direction by mutual arrangement, and charcoal or activated carbon stored in the package. The surface facing the streamline direction may be provided with an opening through which the supernatant liquid can pass.

[0012]

FIG. 1 is a side view schematically showing a sewage treatment apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic plan view. In this example, sewage containing human waste is treated.

In the figure, a sewage treatment apparatus includes a stock solution stirring tank 1 for supplying sewage and stirring and mixing water and solids.
Coagulant tank 2 for supplying coagulant for purifying sewage
And a frame 3 on which other devices are mounted. The undiluted solution stirring tank 1 is provided with two stirring blades 1b each rotated by a motor 1a. The undiluted solution stirring tank 1 is obtained by stirring and mixing water and solids from the undiluted solution supply pipe 1c using a pressure pump (not shown) or the like. Send out. The coagulant tank 2 stores a coagulant for promoting sewage purification (the composition of the coagulant will be described later) and incorporates a cutoff valve 2 incorporated in a coagulant supply pipe 2a connected to the lower end thereof.
By b, it is possible to supply almost quantitatively. In the frame 3, a stirring tank 4, a primary sedimentation tank 5, a secondary sedimentation tank 6, a tertiary sedimentation tank 7, and an aeration / adsorption tank 8 for stirring and mixing the sewage stock solution and the flocculant are arranged in this order. ing.

As shown in FIG. 2, the stirring tank 4 is divided into first, second, and third tanks 4a, 4b, and 4c having the same size.
A stock solution supply pipe 1c and a flocculant supply pipe 2a are connected to each. The stock solution supply pipe 1c has first to third tanks 4a to 4
The conduit to c is provided with a valve unit 1d for opening / closing and flow control, and the coagulant supply pipe 2a is also provided with a valve unit 2c for opening / closing and flow control in each conduit. Each of these valve units 1d and 2c uses an electromagnetic valve, is operated by a controller (not shown) for controlling the entire equipment, and includes first to third tanks 4a to 4c.
The undiluted solution and the flocculant whose flow rates have been adjusted are supplied to each of c.

A supply header 4 d is provided between the first to third tanks 4 a to 4 c of the stirring tank 4 and the primary sedimentation tank 5. The supply header 4d is provided with a cut-out valve 4 using an electromagnetic on-off valve in a conduit communicating with the first to third tanks 4a to 4c.
e, and only one of the first to third tanks 4a to 4c is communicated with the primary sedimentation tank 5 by opening and closing these cut-out valves 4e. That is, the stock solution and the coagulant are supplied to the first to third tanks 4a to 4c, respectively, in a fixed amount, respectively, and are stirred and mixed. When finished, the stock solution and the flocculant are fed again to restart the stirring. On the other hand, by providing the first to third tanks 4a to 4c, what is sufficiently stirred in each of the tanks 4a to 4c can be supplied to the primary precipitation tank 5 as a batch type. The precipitation rate can be controlled uniformly.

The primary sedimentation tank 5 is a hopper-shaped container having a tapered lower end side. A tray 5a is disposed at the upper end of the primary sedimentation tank immediately below the supply header 4d. 5b. The secondary sedimentation tank 6 includes a guide tray 6a at a lower level than the tray 5a of the primary sedimentation tank 5, and a downcomer 6b connected thereto. The guide tray 6a communicates with the inside of the primary sedimentation tank 5 to allow a mixed solution of a stock solution and a flocculant that exceeds its own level to flow in, and supplies the mixture from the downcomer 6b to the bottom. The secondary and tertiary sedimentation tanks 6 and 7 are provided with baffles 6c and 7a, respectively. The baffles 6c and 7a change the flow upward and downward, and aeration is performed from the upper end of the third sedimentation tank 7 in the final stage. -It is discharged to the adsorption tank 8.

Since solids precipitate in the primary to tertiary sedimentation tanks 5 to 7, the solids are periodically taken out and collected as cakes. Is connected to the solid content recovery pipe 9. Each of these solids recovery pipes 9 has an electromagnetic on-off valve 9a and is connected to one collecting pipe 9b. The collecting pipe 9b is provided with a sterilizer 9c for sterilizing and purifying organic substances contained in the solid matter,
At the end, there is provided a compression device 9d for compressing the solid matter into a cake. The sterilizing device 9c may be any device that sterilizes the organic matter by irradiating ultraviolet rays, and the compressing device 9d may be one that can compress the supplied solid content with a piston or the like.

The aeration / adsorption tank 8 has a passage connected to the upper end of the tertiary sedimentation tank 7 and has a ventilation structure in which the inside is open to the outside air. They are arranged. The uppermost guide plate 8a has a higher height on the tertiary sedimentation tank 7 side, and is gently inclined downward toward the left end side.
On the contrary, it is arranged such that the left end side is high and the tertiary sedimentation tank 7 side is low. The third and lower rows are arranged in a similar relationship, and the lowermost guide plate 8a is inclined downward toward the left end. With such an arrangement of the guide plates 8a, the purified treated water from the upper end of the tertiary sedimentation tank 7 flows meandering while repeating detours to the left and right, and from the left end of the lowermost guide plate 8a via the drain pipe 8b. Is discharged.

FIG. 3 is a front view of a main part of the connecting portion between the uppermost guide plate 8a and the tertiary sedimentation tank 7 as viewed from the downstream side. The tertiary sedimentation tank 7 has a side wall 7b facing the aeration / adsorption tank 8. A large number of weirs 7c are formed at the upper end in a protruding manner, and the treatment water is allowed to flow down onto the guide plate 8a from between the weirs 7c. Then, a package 11 filled with charcoal 10 for removing color and odor from the treated water is mounted on the guide plate 8a except for the lowermost one.

FIG. 4 shows details of the package 11 and the charcoal 10 filled therein. The package 11 is a container having a triangular opening cross section made of, for example, a thin synthetic resin, and has two outer walls. A large number of openings 11a are formed in the surface facing the upstream and downstream of the treated water. Charcoal 1
Numeral 0 is a general one which has been conventionally used, and the package 11 is densely packed. Then, the package 11 includes a guide plate 8a as shown in FIG.
It has a size that is slightly lower than the level of the treated water flowing on the guide plate 8a when mounted on the guide plate 8a, and is arranged in a state of being in contact with the entire length of the guide plate 8a as shown in FIG. ing.

The coagulant used in the sewage treatment apparatus of the present invention includes gypsum, aluminum sulfate, sodium hydrogen phosphate, sodium carbonate, sodium alkylate, and a copolymer of sodium acrylate and acrylamide in a weight ratio. 65-75: 10-20: 0.5-1.5: 7-1
3: 0.5 to 1.5: 2 to 5 are mixed at a ratio of 95% by weight or more of the inorganic material. In the flocculant having such a composition, gypsum covers the surface of the solid content to increase the particle size to facilitate separation from water, and aluminum sulfate is effective in accelerating the precipitation of the solid content. Also, sodium hydrogen phosphate promotes sedimentation of metal components,
Sodium carbonate contributes to pH adjustment, sodium alkylate acts as a dispersant, and the copolymer of sodium acrylate and acrylamide serves to further assemble the larger solids particles to form a larger flocculated float. Fulfill. The inventors of the present invention have confirmed that by setting these compositions in the relationship of the above mixing ratios, the functions of the respective compositions are sufficiently exhibited and can be suitably used as a flocculant.

In the above arrangement, the stock solution and the flocculant are supplied from the stock solution stirring tank 1 and the flocculant tank 2 to the stirring tank 4 respectively. At this time, the first to third tanks 4a of the stirring tank 4
The stock solution and the flocculant are supplied to all of 4c to 4c, and the stirring blades 4a-1, 4b-1, and 4c-1 are respectively driven to rotate to continue stirring. Then, for example, the period in which the first tank 4a is cut into the primary sedimentation tank 5 is also set in the second and third tanks 4b and 4
In step c, the stirring is continued, and when the treated water in the first tank 4a is exhausted, the treated water in the second tank 4b is cut out to the primary sedimentation tank 5, and at the same time, the first tank 4a that is empty becomes fresh. The stock solution and the flocculant are supplied to and stirred. As described above, the stock solution and the flocculant can be batch-operated independently by using the first to third tanks 4a to 4c to stir and cut out the primary sedimentation tank 5 independently. Is always supplied with a sufficiently stirred mixture of a stock solution and a flocculant.

In the first to third tanks 4a to 4c, the stock solution and the flocculant are forcibly stirred by the rotation of the high-speed rotating stirring blades 4a-1, 4b-1, 4b-1, and the micro floc is formed by the flocculant. It forms and grows in a short time. As a result, the degree of contact between the solid particles contained in the stock solution and the flocculant can be improved, and the solid particles are completely captured by the flocculant, thereby forming microflocs in a short time. Can be encouraged.

The treated water stirred in the first tank 4a for a certain period of time is supplied to the supply header 4d by operating the cut-out valve 4e.
From the primary sedimentation tank 5. In the primary sedimentation tank 5, since its internal volume is large and there is no agitation, the growth of micro flocs is further promoted, and flocs are gradually formed and settle down.

As described above, by stirring in the first tank 4a, micro flocs can be formed in a short time, and can be grown in the primary sedimentation tank 5 into flocs of an appropriate size. Therefore, the growth of large flocs is promoted with the micro flocs as nuclei, thereby shortening the time until the final floc formation, that is, the time until the coagulation and sedimentation is completed.

The supernatant liquid in the primary sedimentation tank 5 is transferred to the secondary sedimentation tank 6
To the tertiary sedimentation tank 7. At this time, the flow of the processing liquid repeats upward and downward by the baffle plates 6c and 7a, and sedimentation is promoted by the grown flocs, and the cleaned supernatant liquid is aerated / aerated from between the weirs 7c shown in FIG. It is discharged to the adsorption tank 8 side. The solid matter deposited on the bottom of each of the sedimentation tanks 5 to 7 is discharged to the solid matter recovery pipe 9 by periodically opening the solenoid on-off valve 9a, and is sterilized by the sterilizing device 9c, and then compressed by the compressing device 9d. To form a cake.

As described above, the first to third tanks 4a of the stirring tank 4
The treated water mixed with the stock solution and the coagulant supplied to the tanks 4c to 4c is sent to the aeration / adsorption tank 8 after the solids are precipitated in order in each of the tanks 4a to 4c. In the aeration / adsorption tank 8, the treated water contacts the charcoal 10 in the package 11 while flowing on the guide plate 8a and flows while being exposed to air. In such a flow of the treated water, a large number of guide plates 8a are vertically arranged and the flow meanders around a long distance, so that the contact with the charcoal 10 is sufficiently performed and the odor and color from the treated water are reduced. Efficiently removed. Then, as is clear from FIG. 3, the surface of the treated water traveling on the surface of the guide plate 8a is:
Since it is exposed to air and flows on the surface that is corrugated due to the arrangement of the triangular packages 11, the treated water actively repeats contact with air. Therefore, unnecessary gases and volatile substances dissolved in the treated water are quickly diffused into the air. Further, if the aeration / adsorption tank 8 is structured so that the outside air can freely enter and exit, the dissolution of oxygen in the air by the aeration into the treated water is promoted, so that the adsorption of organic substances proceeds and the odor becomes more effective. Is removed.

Thus, in the sewage treatment apparatus of the present invention,
By adding the coagulant, the settling time of the solid content in the primary sedimentation tank 5 can be significantly reduced, and the treatment time is shortened as compared with the activated sludge method. Further, in the aeration / adsorption tank 8, the diffusion of the odor and the dissolution of oxygen proceed by the contact with the air at the same time as the adsorption of the odor by the charcoal 10, and the odor removal and the adsorption of the organic substances are efficiently achieved.

In the above embodiment, charcoal is used as an example for adsorbing odors and the like, but activated carbon may be used for this. Activated carbon has relatively small particles, so it has a large contact area with treated water and is optimal for odor adsorption.
In a facility that handles a large amount of treated water, it is preferable to use charcoal that is easily captured in the package 11 described above.

[0030]

According to the present invention, the organic solids are precipitated and removed by flocculation using a flocculant, so that the treatment time is greatly reduced. After the precipitation is removed, the adsorption of the color and odor by charcoal and the aeration treatment are simultaneously performed. Since this is performed, the diffusion of the odor and the adsorption of the remaining organic substances due to the dissolution of oxygen are promoted, and the regenerated water with a sufficient transparency to remove the odor is obtained.

Further, in the case where the stirring tank for mixing and stirring the stock solution and the flocculant is divided into a plurality of tanks and each of the tanks is supplied to the precipitation tank in a batch system, the flocculant is sufficiently stirred with the flocculant. Since the undiluted solution is always supplied to the settling tank, the settling time in the settling tank can be further reduced. When the flow path of the aeration / adsorption tank is formed in a meandering shape in the vertical direction, the process of removing the aeration and the odor can be lengthened, the installation floor area can be reduced, and the equipment area can be reduced.

Further, in the case where the charcoal-adsorbing layer made of charcoal in the adsorption / aeration tank is composed of a package having a shape that is continuous in a wave shape, and charcoal or activated carbon housed in the package, the flowing supernatant liquid is ruffled to form air. And promotes contact with water, and can release unnecessary gases and volatile substances to the atmosphere, thereby increasing the odor removal rate. Further, by storing the charcoal in the package, installation on the flow channel surface is facilitated, and the burden of backwashing and replacement work is reduced.

[Brief description of the drawings]

FIG. 1 is a side view showing an outline of a sewage treatment apparatus of the present invention.

FIG. 2 is a plan view showing an outline of the sewage treatment apparatus of FIG.

FIG. 3 is a schematic view of a main part of a weir provided on a side wall of a tertiary sedimentation tank and a guide plate viewed from a downstream side.

FIG. 4 is a package for charcoal mounted on a guide plate, in which (a) is a front view of a main part viewed in a flow direction of treated water, and (b) is a longitudinal sectional view.

[Explanation of symbols]

 Reference Signs List 1 stock solution stirring tank 1a motor 1b stirring blade 1c stock solution supply pipe 2 coagulant tank 2a coagulant supply pipe 2b cutout valve 2c valve unit 3 frame 4 stirring tank 4a first tank 4b second tank 4c third tank 5 primary Sedimentation tank 6 Secondary sedimentation tank 7 Tertiary sedimentation tank 8 Aeration / adsorption tank 8a Guide plate 9 Solid recovery pipe 9a Solenoid on-off valve 9b Collecting pipe 9c Sterilizer 9d Compressor 10 Charcoal 11 Package 11a Opening

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C02F 1/28 C02F 1/28 F 1/52 ZAB 1/52 ZABE

Claims (3)

[Claims] 1. A step of mixing and stirring a stock solution to be treated and a flocculant, a step of coagulating and precipitating solids contained in the stock solution with the coagulant after the step of mixing and stirring, A method of simultaneously performing an aeration operation and an odor adsorption operation on the undiluted supernatant liquid after the step. 2. A stirring tank for mixing and stirring an undiluted solution to be treated and a flocculant, and a single or a plurality of sedimentation tanks for sedimenting solids from the mixed solution of the undiluted solution and the flocculant from the stirred tank while coagulating. An aeration / adsorption tank for connecting a flow path to the upper end side of the settling tank and receiving the supernatant of the mixed liquid, wherein the stirring tank is divided into a plurality of tanks and the stock solution supplied to each tank. The mixed solution with the coagulant can be discharged to the settling tank as a batch type, and the aeration / adsorption tank forms a plurality of downwardly inclined flow paths in a meandering shape at intervals in the vertical direction. An apparatus for purifying sewage, comprising an adsorption layer for odors or the like having a wavy shape directed in a flow direction of the supernatant liquid on a surface of the flow path. 3. The adsorbent layer includes a package mounted on the surface of the flow path and forming both sides of the flow path in a streamlined direction in a streamline direction by mutual arrangement, and charcoal or activated carbon stored in the package. 3. The sewage purification treatment apparatus according to claim 2, wherein the package has an opening on a surface facing the streamline direction through which the supernatant liquid can pass.