JPH0688038B2 - High-concentration suspended solid wastewater treatment device and its treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of a wastewater treatment device.

[Prior Art] From the viewpoint of preventing water pollution, in recent years, the demand for advanced treatment of sewage has increased.

Conventionally, sand (filtration) is a gravity type single-layer filtration device, and is widely used for removing suspended solids (SS) after biological treatment and sedimentation. However, the field of wastewater treatment was limited to tertiary treatment.

The biggest reason why sand filters have not been used in the field of wastewater, even though they have been widely used in the field of tap water, most of the suspended solids SS in the inflow water are removed on the surface of the sand layer in the conventional sand filters. Therefore, it can be said that when the SS concentration of sewage is high, the head loss is increased rapidly and the overtime is shortened. In sand filtration, only the surface of the layer is used for capturing SS, not the entire area.

Therefore, in order to use a gravity-type single-layer device in the field of sewage, it is necessary to use the layer effectively and to extend the over-duration time.
Particle size larger than 2.55 to 2.65 sand) and specific gravity (1.4 to
Development of an over-layering device that doubles or multiple layers, such as filling with a small material of 1.6), has been performed.

Furthermore, it has been developed that a special over-mechanism is provided in the over-device to disperse the SS content trapped on the surface, delay the rise of head loss and extend the over-duration time. In such a special passing mechanism, for example, air is sent so that a swirl flow is generated in the upper part of the bed, and large particles trapped on the surface of the bed are suspended by the swirl flow.

On the other hand, a sewage treatment method has also been developed in which a large number of floating microorganisms for adhering growth of microorganisms are placed in an aeration tank where a sewage is biochemically aerated (Japanese Patent Laid-Open No. 50-38956).

In addition, a biological filtration system was developed in which the aeration tank and the sand filtration tank were combined and the precipitation tank was omitted.

However, there is still a demand for a sewage treatment apparatus that can obtain a high degree of purification and can be easily managed.

[Problem to be Solved by the Invention] Accordingly, an object of the present invention is to provide a compact and easy-to-manage sewage treatment apparatus by combining a carrier floating aeration tank and a sand filtration tank.

[Means for Solving the Problems] In order to achieve the above object, the sewage treatment apparatus of the present invention comprises:
It consists of a carrier floating aeration tank and a sand filtration tank arranged below it so that wastewater flows in series, and a porous granular carrier material (also called a carrier) is used so that it can float freely in the carrier floating aeration tank. The stirrer installed in the upper part of the carrier floating aeration tank was operated during backwashing to scrape off the sludge adhering to the carrier substance and the carrier floating aeration tank was installed to remove the scraped sludge together with the wastewater. A backwash drain is arranged, and a net member provided on the overflow weir of the backwash drain is arranged in the backwash drain so that the carrier substance does not flow out during the backwash. A lower water collecting device is provided, and an air diffuser for feeding air is arranged above the bed so that the air from the air diffuser is used for aeration and stirring and a swirling flow is generated above the bed. The lower water collecting device has air piping and Backwash water pipe is disposed the air in the underdrain system is adapted to be compressed rises through the layers by backwash water.

[Operation] When sewage is treated by the sewage treatment apparatus configured as described above, the carrier floating aeration tank has a specific gravity of 1.0 as a carrier substance.
By suspending the following small porous granules so that they can move freely, the suspended matter that causes clogging of the sand layer first adheres to the porous granules, and the suspended matter that adheres to the porous granules. It is possible to adsorb soluble organic substances. Therefore, according to the conventional apparatus, SS is trapped on the surface of the layer or inside the layer, SS and organic substances are adsorbed to it, SS is growing, and clogging occurs early. It was possible. Therefore,
In the present invention, the over-continuation time of the sand filter is longer than that of the conventional device.

As a result of stacking the carrier floating aeration tank and the sand permeation tank, the air diffuser and the agitator can be used for the dual purpose of preventing clogging of the sand layer and scraping off the sludge attached to the carrier material, which leads to downsizing of the entire apparatus.

In addition, since the treated water is passed by the passing mechanism that uses the air compressed by the backwash water from the bottom of the sand washing tank, it is possible to extend the duration of the sand overlayer, reduce the backwash water amount, and shorten the backwash time. In addition to being possible, this air also helps suspend the carrier material.

In this way, even a single layer sand flow tank with a simple gravity flow can perform high-level purification treatment.

[Examples] Examples will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a sewage treatment apparatus 10 of the present invention. The sewage treatment apparatus 10 comprises a carrier floating aeration tank 12 and a sand filtration tank 14 arranged below the carrier floating aeration tank 12 so as to allow sewage to flow in series. A porous granular carrier material 16 is placed in the carrier floating aeration tank 12 so as to be freely floatingly moved. Carrier floating aeration tank 12
Is operated at the time of backwashing to scrape off the sludge adhering to the carrier substance 16 or agitator 18 whose position can be adjusted up and down in order to generate a swirling flow in the wastewater, and remove the scraped sludge together with the backwashing. Therefore, the backwash drainage groove 20 is arranged. A mesh member 22 provided at the overflow weir of the backwash drainage groove 20 is arranged in the backwash drainage groove 20 so that the carrier substance 16 does not flow out during the backwashing.

The sand tank 14 is a layer 24 filled with fine sand and a lower water collecting device.
It consists of 26 and. An air diffuser that pumps air above layer 24
28 is arranged so that it can be vertically adjusted so that the air from the air diffuser 28 is used for aeration and stirring, and a swirl flow is generated above the layer 24. An air pipe 30 and a backwash water pipe 32 are arranged in the lower water collecting device 26 so that the air in the lower water collecting device 26 is compressed by the backwash water and rises in the bed 24.

Raw water enters the carrier floating aeration tank 12 by a supply pump (not shown). In the carrier floating aeration tank 12, sewage is circulated in the carrier floating aeration tank 12 as a swirling flow due to aeration and stirring air, and the raw water is mixed and aerated by the circulating water in which oxygen is sufficiently dissolved, and is adsorbed and oxidized. The sewage is filtered by gravity in the sand filter tank 14 and discharged from the discharge pipe 36.

The specific gravity of the porous granular carrier substance 16 is 1.0 or less, and the porous granular carrier substance 16 is floating freely in the wastewater by the aeration and stirring air from the air diffusing device 28. Since the porous granular carrier substance 16 has a large surface area, it captures microorganisms as well as suspended substances. Furthermore, since it floats freely in the treated water so that it can move freely, mass exchange becomes large. The porous granular carrier substance 16 is 5 to 70% by volume of the carrier floating aeration tank 12.
Occupy Therefore, the sewage will be absorbed by the porous granular carrier material 16
Circulates in the carrier floating aeration tank 12 while making sufficient contact with.

Suitable porous particulate carrier materials 16 are organic polymeric compounds such as polyurethane foam. Polyurethane foam has continuous pores, which are excellent porous granules, with a diameter of 5 to 50 mm, a specific gravity of 20 to 80 kg / m ³ , and continuous pores.
Organic polymer compounds of 0.1 to 3 mm are preferred.

As described above, the aeration and stirring air is sent from the air diffuser 28 to the bed.
A swirling flow occurs at the top of 14. This swirl flow serves to suspend large particles trapped on the surface of layer 14. Therefore, in the upper part of the layer 14, a gentle swirling flow is generated, in which suspended particles that have been once trapped and a part of newly introduced large particles are suspended.

Sewage in the sand tank 14 passes through the layer 24 while descending. At this time, by contacting aerobic microorganisms adhering to the surface of the material, decomposition of residual organic matter, adsorption of residual suspended solids and physical excess are carried out, and purification is highly performed.

The thickness of layer 24 is preferably about 25 cm. Due to this layer, the suspended matter in the wastewater that has not been captured by the porous granular carrier material 16 is captured by the layer 24. This creates a plug in layer 24, resulting in a rise in water level. When the water level rises and reaches a predetermined backwash water level 10b, backwash starts. Moreover, the air pipes 30 of the lower water collecting device 26 before full-scale backwashing.
It is also possible to deal with the clogging in the layer 24 by activating. That is, the water level is the operating water level 10a.
When there is an air supply from the air pipe 30, the air accumulated in the lower water collecting device 26 is then activated, compressed by the backwash water sent from the backwash water pipe 32, in the layer 24. To rise. At this time, this air serves to send the particles trapped on the surface and inside of the layer 24 into the swirling flow above the layer 24. As a result, since the layer 24 can be regenerated, the water level rarely reaches the backwash water level 10b, and the backwash operation for a long time unlike the conventional case is not required. In this way, the function of the porous granular carrier substance suspended in the carrier floating aeration tank and the operation of the air pipe and the backwash water pipe provided in the lower layer water collector can prolong the duration of the layer. In addition, the backwashing time of the layer can be shortened.

The sewage is supplied from the injection pipe 34, and the normal drainage is performed from the drain pipe 36. Further, the stirrer 13 is operated when the sand filtration tank is clogged and the water level of the carrier floating aeration tank 12 rises to a predetermined position, but at this time, from the floating substances attached to the porous granular carrier substance, microorganisms, etc. The resulting sludge is scraped from the carrier substance and discharged from the backwash drain together with the backwash water containing the sludge separated from the material.

[Advantages of the Invention] Since the present invention is configured as described above, it has the effects described below.

The over-duration can be significantly extended.

It is a single layer, and the water flow is also gravity. It is possible to perform advanced purification treatment even in a sand filtration tank of a simple shape.

In the sewage treatment apparatus of the present invention, the soluble organic matter remaining in the secondary treated water is highly decomposed by the adherent microorganisms, and the residual suspended solids can be removed by biological adsorption and physical excess. Moreover, in the conventional furnace layer, the particles to be captured on the surface and inside of the layer were sent into the swirling flow in the upper part of the layer, and as a result of being trapped by the porous granular carrier substance suspended in the carrier floating aeration tank, SS Since the amount of water stored can be increased, high SS wastewater can be treated.

Therefore, a compact and multifunctional wastewater treatment device having a wide range of use can be obtained.

[Brief description of drawings]

FIG. 1 is a system diagram schematically illustrating a wastewater treatment device of the present invention. In the figure, reference numerals represent the following. 10 …… Sewage treatment equipment, 12 …… Carrier floating aeration tank, 14 …… Sand filtration tank, 16 …… Porous granular carrier material, 18 …… Stirrer, 20 …… Backwash drain, 22 …… Mesh member , 24 …… Layer, 26 …… Lower water collecting device, 28 …… Air diffuser, 30 …… Air pipe, 32 …… Backwash water pipe, 34 …… Inflow pipe 36 …… Discharge pipe

Claims (3)

[Claims] 1. A carrier floating aeration tank and a sand filtration tank below which a sewage is arranged so as to inflow sewage in series, and a carrier substance is placed in the carrier floating aeration tank so that it can freely float and move. The upper part of the carrier floating aeration tank is equipped with a stirrer that is operated during backwashing to scrape off the sludge adhering to the carrier material and a backwash drainage channel that removes the scraped sludge together with the wastewater. A mesh member provided in the overflow weir of the backwash drain is arranged in the groove so that the carrier substance is not washed away during the backwash, and the sand filter tank has a filter layer and a lower water collecting device. An air diffuser for feeding air is placed above the air diffuser, and the air from the air diffuser is used for aeration and stirring, and a swirl flow is generated above the filter bed. The air pipe and the backwash water pipe are arranged in the lower water collecting equipment. High concentration suspended solids wastewater treatment apparatus air of the inner is characterized in that is adapted to be compressed rises through the filter layer, filter bed by backwash water. 2. A backwashing method for a high-concentration suspended solid wastewater treatment apparatus comprising a carrier floating aeration tank for suspending a carrier substance in sewage and a sand filtration tank having a sand filter layer disposed thereunder. Operating the machine, scraping off the sludge adhered to the carrier material, discharging the scraped sludge from the backwash drain with backwash water, the sludge trapped on the upper surface of the sand filter layer, The process of floating by the swirling flow of the stirrer and the swirling flow of the air diffuser installed above the sand filter layer, and the air sent from the air pipe in the lower water collecting device rises inside the sand filter layer. A step of suspending the sludge trapped inside the sand filter layer and sending it into the swirling flow; and a step of sending backwash water from the backwash water pipe in the lower water collecting device to perform backwash. , Backwash water, rising air, swirling air and sludge by agitator High concentration suspended solids backwash method sewage treatment apparatus characterized by shortening the reduction and backwash time backwash water by a combination of scraping. 3. A predetermined backwash water level is set, the air blown into the lower water collecting device is compressed by the backwash water and rises in the sand filter layer, and then the backwash water is the sand filter layer. 3. The method according to claim 2, wherein the value is increased.