JPH0225675B2 - - Google Patents

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'' In the microbial treatment of wastewater, it is known to use a semi-fluidized bed wastewater treatment device in which a bed of fine carrier particles is formed, the lower part of which is fluidized and the upper part is stationary. This semi-fluid bed treatment is
By having both a fluidized bed section and a fixed bed section, it is possible to obtain the advantages of both high-speed processing due to complete mixing in the fluidized bed section and finishing processing due to a dense microbial layer in the fixed bed section, and it is possible to achieve a This method has the advantage of increasing the concentration of microorganisms, enabling high-speed processing, and miniaturization of the processing tank.

However, in this semi-fluidized bed type treatment, as the treatment progresses, the fixed bed becomes clogged by suspended solids in the wastewater or microbial flocs detached from carrier particles, causing the wastewater treatment to be temporarily interrupted and cleaning treatment often to be performed. 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 the perforated plate (see Japanese Patent Laid-Open Nos. 55-106594, 1982-32197, 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 it still does not solve the problems of the conventional method. do not have.

``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 fixed bed can be washed and returned. The objective is 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'' An air lift pipe through which gas is introduced is installed upright in the center of a semi-fluidized bed treatment bed 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 tube 6 is installed upright, and the upper and lower ends are opened between the multi-optical dispersion plate 3 and the top plate 5 with a required interval between them. An air pipe 7 protrudes into the lower end. 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. A flow chamber 11 is provided.

A restraining plate 15 is provided between the tank wall at the top of the treatment tank 1 and the wastewater overflow chamber 11 to regulate the flow of the carrier particles 14 housed in the tank 1.
A large number of holes 15a, 15a having a diameter smaller than 4 are provided, and a treated water outflow pipe 17 leading to a treated water reservoir 16 provided outside the treatment tank 1 is connected to the upper part of the holes 15a, 15a.

Further, on the outside of the air lift pipe 6, an opening 18a is formed at the upper end at a position below the holding plate 15, and
A carrier particle introduction tube 18 whose lower end is located below the lower end of the air lift tube 6 and is closed by a bottom plate is provided, and its lower end is communicated with the lower end of the air lift tube 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 and extend downward, with its lower end opening at the bottom of the processing tank 1. The carrier particles 14 flow down within this return pipe 19 and are 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 from the holes 15a of the restraining plate 15. that time,
The carrier particles 14 are fluidized by the flow of raw water, and lighter ones of the carrier particles 14 rise and reach the holding plate 15.
Fluidization is suppressed by the pressure plate 1.
A fixed layer part a is formed below the fixed layer part a, and a fluidized bed part b between the fixed layer part a and the polyoptic dispersion plate 3 is formed below the fixed layer part a, and the raw water flows through each layer. While passing through parts a and b, the treated water is treated by microorganisms, rises through the hole 15a of the holding plate 15, and is discharged 22 from the treated water outflow pipe 17 through the treated water reservoir 16 to the outside of the tank. become.

Conventionally, it has been known that by 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 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 refluxed by the blower 9. However, when performing aerobic treatment, outside air is injected into the air lift pipe 6.

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

In this way, carrier particles, pollutants, etc. in the fixed bed section a and the fluidized bed section b 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 bottom of the tank, and the pollutants are removed from the tank by biological treatment of the raw wastewater, cleaning of carrier particles in the fixed tank section a and fluidized bed section b, and pollutants. etc. are removed 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 also installed a means to discharge the washing wastewater out of the tank, so that the wastewater can be treated at the same time.
It is possible to wash the fixed bed part, which is particularly prone to clogging, and to separate and discharge pollutants, etc., making it possible to continuously treat wastewater without clogging, and to improve the microbiological treatment of wastewater. Efficiency can be significantly improved.

In addition, the fixed bed section is automatically cleaned by simply injecting gas into the airlift pipe, and the structure is simple and easy to operate and maintain, providing an excellent semi-fluidized bed wastewater treatment system. It's something you get.

[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. 1... Treatment tank, 4... Raw water supply pipe, 6... Air lift pipe, 7... Air supply pipe, 10... Separation tube, 11
...Drainage overflow chamber, 13...Drain pipe, 14...Carrier particles, 15...Suppressing plate, 17...Treatment water outflow pipe,
18...Introduction pipe, 19...Return pipe.

Claims (1)

[Claims] 1. An air lift pipe through which gas is introduced 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 connected to the lower end opening of the air lift pipe. A carrier particle introduction pipe opened into the fixed bed section 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 section, and to discharge washing wastewater flowing out to the outside of the tank. A semi-fluidized bed water treatment equipment.