JPS61192390A - Semi-fluidized bed type water treatment apparatus - Google Patents

Abstract

PURPOSE:To enable continuous treatment by preventing clogging, by vertically providing an air lift pipe, into which air is sent, to the central part of a semi- fluidized bed type treatment tank and communicating a carrier particle introducing pipe to the lower end opening of the air lift pipe. CONSTITUTION:Raw water flowed in from a raw water supply pipe 4 is dispersed throughout the entire lower region of a tank from a porous dispersing plate 3 and rises between carrier particles to be flowed out from the apertures 15a of a press plate 15. At this time, carrier particles 14 are fluidized by the flow of raw water and a fixed bed part (a) is formed to the lower side of the press plate 15. A fluidized bed part (b) is formed below the fixed bed part (a) so as to reach the porous dispersing plate 3 and raw water receives treatment due to bacteria during passage through both beds (a), (b) while treated water rises through the apertures 15a of the press plate 15 and passes through a treated water sump 16 from a treated water outflow pipe 17 to be discharged out of the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a semi-fluidized bed wastewater treatment apparatus equipped with an automatic cleaning mechanism for carrier particles.

"Prior Art" It is known to use a semi-fluidized bed wastewater treatment device in which a layer of fine carrier particles is formed, the lower part of which is fluidized and the upper part of which is cast, in the treatment of wastewater with microorganisms. . By combining a fluidized bed section and a fixed bed section, this semi-fluidized bed treatment has the advantages of both high speed processing due to complete mixing in the fluidized bed section and finishing treatment using a dense microbial layer in the fixed bed section. This method has the advantage of increasing the microbial concentration per tank volume, allowing high-speed processing, and downsizing of the processing tank.

However, in this semi-fluidized bed type treatment, as the treatment progresses, the fixed bed becomes clogged with suspended solids in the wastewater or microbial flocs detached from carrier particles, causing the wastewater treatment to be temporarily interrupted and cleaning treatment often required. The problem is that it has to be done.

In order to solve this problem, we installed a perforated plate that restrains the fixed layer section so that it can move up and down, and when the fixed layer section becomes blocked, the perforated plate is raised to fluidize the fixed layer section. A proposal has been made to discharge suspended solids, microbial flocs, etc. that cause blockages through the holes of a perforated plate (see % JP-A-55-106594, Japanese Patent Publication No. 59-32197, etc.).

However, even with this method, during the cleaning cycle in which the perforated plate is raised to fluidize the fixed bed, wastewater treatment must be interrupted for cleaning, and the conventional difficulties have not yet been solved. .

``Problems to be solved by the present invention'' The major problem with the semi-fluidized bed treatment of wastewater mentioned above is that continuous treatment of wastewater is efficient without clogging the fluidized bed or fixed bed in the treatment tank. The goal is to be able to perform well. The present invention has been made to solve this problem, and by providing a mechanism in the treatment tank to sequentially wash and return the carrier particles in the fixed bed during wastewater treatment, the present invention improves the visibility of the fixed bed. The present invention aims to provide a semi-fluidized bed wastewater treatment device that enables continuous treatment of wastewater while preventing clogging, enables efficient microbiological treatment of wastewater, and is easy to operate and maintain.

[Means for solving the problem 1: An airlift pipe through which gas is introduced is installed upright in the center of a semi-fluidized bed treatment tank consisting of a fluidized bed section and a fixed bed section above the fluidized bed section. A carrier particle introduction pipe whose upper end opens into the fixed bed section is connected to the lower end opening of the air lift pipe, and the carrier particles flowing out from the pipe are returned to the fluidized bed section, and the washed wastewater flowing out is connected to the upper end of the air lift pipe. This is characterized by providing a means for discharging the water out of the tank.

"Embodiments" Hereinafter, embodiments of the apparatus of the present invention will be described with reference to the drawings.

In the figure, 1 is a treatment tank formed long in the vertical direction, and a porous distribution plate 3 is provided at the bottom of the tank at a required distance from the tank bottom 2, and a raw water supply pipe 4 is connected between them. has been done. Further, in the center of the processing tank 1, an air lift pipe 6 is installed, the upper and lower ends of which are opened at a required interval between the porous dispersion plate 3 and the top plate 5, respectively. An air supply pipe 7 protrudes into the lower end of the pipe 6. An exhaust gas pipe 8 communicating with the upper end of the processing tank through the top plate 5 is connected to this air supply pipe via a blower 9. A separation tube 10 is provided in the upper part of the treatment tank 1 to surround the upper part of the air lift pipe 6, and on the outside of the separation tube 10, a drainage pipe 13 leading to a drainage sump 12 provided outside the tank 1 is connected. Flow chamber 11
is provided.

Between the tank wall at the top of the treatment tank 1 and the wastewater overflow chamber 11, there is a restraining plate 15 for regulating the flow of carrier particles 14 housed in the tank 1.
is provided with a large number of holes 15 m and 15a having a diameter smaller than that of the carrier particles 14, and a treated water outflow pipe 17 leading to a treated water reservoir 16 provided on the outside of the treatment tank 1 is provided above the hole. is connected.

On the outside of the air lift tube 6, there is provided a carrier particle introduction tube 18 whose upper end has an opening 18a located below the restraining plate 15, and whose lower end is located below the lower end of the air lift tube 6 and is closed by a bottom plate. , its lower end communicates with the lower end of the air 1/ft pipe 6. A return pipe 19 for the carrier particles 14 is provided at the lower end of the separation cylinder 10 so as to surround the outside of the introduction pipe 18, extend downward, and open its lower end to the lower part of the processing tank 1. Carrier particles 1 that flowed out
4 flows down in this return pipe 19 and is returned to the lower part of the processing tank 1.

Note that 20 in the figure is a circulation pipe provided for supplying a portion of the treated water to the bottom of the treatment tank by a pump 21.

"Operation" In the processing apparatus configured as described above, carrier particles 14 are accommodated in the processing tank 1 in the same manner as in a conventional semi-fluid processing tank. In this case, it is preferable to use two types of carrier particles with a slight difference in specific gravity. The raw water flowing in from the raw water supply pipe 4 is dispersed throughout the lower part of the tank by the porous dispersion plate 3, rises between the carrier particles, and flows out through the holes 15a of the restraining plate 15. At this time, the carrier particles 14 are fluidized by the flow of raw water, and the lighter ones of the carrier particles 14 rise, and the fluidization is suppressed by the holding plate 15. Therefore, a fixed layer portion a is formed below the holding plate 15. A fluidized bed section is formed below the fixed layer section a up to the porous dispersion plate 3, and the raw water is treated by microorganisms while passing through each of these main sections a and b. The treated water rises through the hole 15a of the holding plate 15, passes through the treated water reservoir 16 from the treated water outflow pipe 17, and is discharged 22 to the outside of the tank.

Due to this raw water treatment, pollutants in the raw water and biofilms that have grown or fallen off will gradually accumulate on the fixed layer part a, causing clogging between the carrier particles 14.
As in the conventional processing tank, during this processing, gas is injected into the air lift pipe 6 via the air supply pipe.

As shown in the example diagram, in the method of performing anaerobic treatment in which the treatment tank 1 is sealed with a top plate 5, a part of the digestion gas (methane fermentation gas) generated by the biological treatment is transferred to the processor.
The air is refluxed through 9 and injected into the air pipe 6, but when performing aerobic treatment, outside air is injected.

By injecting gas into the air lift tube 6, an air lift effect is generated, and the carrier particles 14 and waste water in the fixed layer part a that entered through the upper end opening 18a are introduced into the lower end of the air lift tube 6 and rise inside the tube. However, the carrier particles 14 are subjected to a cleaning action, and the pollutants, biofilm flocs, etc. adhering thereto are separated and flowed out from the upper end of the air lift tube 6. Here, the carrier particles with heavy specific gravity settle down, and the return pipe 18
It is returned to the fluidized bed section at the bottom of the tank from its lower end. In addition, sewage, pollutants, etc. overflow from the drainage overflow chamber 11 and are discharged 23 through the drainage pipe 15 through the drainage basin 12.

In this way, carrier particles, pollutants, etc. in the fixed bed section a and the fluidized bed section are washed and separated by the washing action when ascending through the air lift tube 6 during raw water treatment, and the washed carrier particles The particles are returned to the lower part of the tank, and the pollutants are discharged and removed outside the tank.Biological treatment of the raw wastewater, cleaning of carrier particles in the fixed tank section A1, fluidized bed section, and pollutants, etc. This is done at the same time.

"Effects of the Invention" As explained above, in the processing apparatus of the present invention, gas is introduced into the center of the semi-fluidized bed processing tank, which has a fluidized bed section and a fixed bed section formed above the fluidized bed section. An air lift tube is installed upright, and a carrier particle introduction tube whose upper end opens into the fixed bed section is communicated with the lower end opening of the air lift tube, and at the same time, the carrier particles flowing out from the air lift tube are connected to the fluidized bed section at the upper end of the air lift tube. In addition to returning the washed wastewater, we have also provided a means to discharge the washing wastewater out of the tank, so that at the same time we treat the wastewater, we also wash the fixed bed section, which is particularly prone to clogging, and separate and discharge pollutants. This enables continuous wastewater treatment without clogging, and the efficiency of microbiological treatment of wastewater can be significantly improved.

In addition, the fixed bed section is automatically cleaned by simply injecting gas into the air lift tube, and the structure is simple and easy to operate and maintain, providing an excellent semi-fluidized bed treatment tank management system. It is possible.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of the apparatus of the present invention, and FIG. 2 is a cutaway plan view taken along the line A--A in FIG.

Claims (1)

[Claims] An air lift pipe through which gas is fed is installed upright in the center of a semi-fluidized bed processing bed consisting of a fluidized bed part and a fixed bed part formed above the fluidized bed part, and the upper end is fixed to the lower end opening of the air lift pipe. A carrier particle inlet pipe opened into the bed part is communicated with the air lift pipe, and a means is provided at the upper end of the air lift pipe to return the carrier flowing out from the pipe to the fluidized bed part and to discharge the washing wastewater flowing out to the outside of the tank. A semi-fluidized bed water treatment device characterized by: