JPH05237487A - Treating apparatus for water - Google Patents

Abstract

PURPOSE:To decrease generation of foaming and excess sludge and to improve treating performance by positioning alternatively a pair of aeration tanks and a pair of precipitation tanks and returning a sludge from the first precipitation tank to the first aeration tank and returning the sludge from the second precipitation tank to the second aeration tank. CONSTITUTION:The first precipitation tank 21 is placed between the contact aeration tank 11 and the second tank 12 and the second precipitation tank 22 is provided next to the second contact aeration tank. Sludges in the first and the second precipitation tanks are respectively returned to the first and the second contact, aeration tanks. The organism phases of a pair of the contact aeration tanks are made thereby to be independent each other and self-digestion is promoted and excess sludge is made less. In addition floating sludges are made more by returning the sludges and foaming is made less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment apparatus for purifying wastewater by a contact aeration method, and more particularly to a water treatment apparatus which can be suitably used for purifying wastewater containing a relatively large amount of organic substances such as urban wastewater or domestic wastewater.

[0002]

2. Description of the Related Art Conventionally, a water treatment apparatus for purifying water by a contact aeration method comprises a contact aeration tank and a settling tank for receiving treated water and discharging supernatant water. A raw water pit will be installed to adjust the flow rate. FIG. 2 shows such a conventional water treatment apparatus. In this conventional example, the contact aeration tank is the first
It is divided into a chamber 1 and a second chamber 2, and a precipitation tank 3 is adjacent to the second chamber. An air diffuser 6 that discharges the air sent from the biological contact filter 4 and the blower 5 into each chamber of the contact aeration tank 6
Is provided. Reference numeral 7 is a wastewater introduction pipe, and 8 is a discharge pipe.

Microorganisms adhere to the contact filter media 4 filled in each chamber of the contact aeration tank, and the air sent from the blower 5 is discharged from each air diffuser 6 to agitate the waste water in the tank and transform the microorganisms into microorganisms. Oxygen is sent to decompose organic matter in wastewater by catalytic oxidation of microorganisms for treatment. The water biologically treated in the second chamber of the contact aeration tank is introduced into the precipitation tank 3, where it is separated into sludge and supernatant water, and the supernatant water is discharged.

[0004]

In the conventional apparatus, most of the sludge is adhered, and the amount of suspended sludge is small, so that the total converted sludge (MLSS) is small, and therefore the treatment performance is not good. In addition, unlike the activated sludge method, since there is little floating sludge, foaming is large in domestic wastewater or urban wastewater containing surfactants such as food and detergent, and the self-extinction of sludge is proportional to the total converted sludge amount. Self-extinguishment of sludge does not proceed,
There was a problem that a large amount of excess sludge was generated and the generated amount reached 30 to 40%. Furthermore, since each chamber of the contact aeration tank does not have an independent system, there is a single biota, so the food chain does not progress, and excess sludge also increases from this aspect.

The present invention is to eliminate the above-mentioned problems of the prior art. Therefore, even in the treatment of waste water containing a surfactant, the generation of foaming and excess sludge can be reduced, and the treatment performance can be improved. An object of the present invention is to provide a water treatment device by an aeration method.

[0006]

A feature of the water treatment apparatus according to the present invention is that the contact aeration tank comprises a pair of tanks 11 and 12, and a first settling tank 21 is arranged between them, and a first contact aeration tank is provided. Treated water is sent to the first settling tank, the supernatant water of the first settling tank is introduced to the second contact aeration tank, and the second settling tank 22 for receiving the treated water of the second contact aeration tank 22. When,
It comprises a device for returning sludge from the first settling tank to the first contact aeration tank and a device for returning sludge from the second settling tank to the second contact aeration tank.

[0007]

In this water treatment device, sludge is returned from the settling tank to each contact aeration tank, and since the sludge becomes floating sludge, there is considerable floating sludge in addition to the adhered sludge inhabiting the contact filter medium.
The total conversion sludge increases. Therefore, the sludge self-extinguishes, and the first contact aeration tank, the first settling tank and the second sludge
The contact aeration tank and the second settling tank of the plant are biologically independent of each other, so that they form mutually independent biota, thus promoting the food chain of the organisms, and thus the amount of excess sludge generated. Less. Moreover, since the amount of suspended sludge increases due to the return, foaming is also greatly reduced, and the treatment performance is further improved.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows an example of this water treatment apparatus. As shown in the figure, this apparatus has a pair of contact aeration tanks 1
In addition to 1 and 12, a pair of precipitation tanks 21 and 22 are provided. One settling tank, that is, the first settling tank 21 is arranged between a pair of contact aeration tanks, and the treated water of the first contact aeration tank 11 is introduced into the settling tank 21 and the supernatant water of the settling tank 21. Is introduced into the second contact aeration tank 12.

Therefore, the pair of contact aeration tanks are biologically independent from each other because the precipitation tank 21 is interposed therebetween. The other settling tank 22 is adjacent to the second contact aeration tank 12, receives the treated water of the second contact aeration tank 12, and discharges the supernatant water. The pair of contact aeration tanks and the pair of precipitation tanks are preferably constructed by dividing one large tank as shown in the figure, but may be composed of separate tanks if desired. As in the conventional case, the biological contact filter 4 and the air diffuser 6 are installed in each contact aeration tank, and air is sent from the blower 5 to each air diffuser. The waste water to be treated is fed into the first contact aeration tank 11 by the introduction pipe 7, and the final treated water in the second precipitation tank 22 is discharged by the discharge pipe 8.

Further, in this water treatment apparatus, a pump 23 is installed in the settling tank 21 for returning the sludge in the first settling tank 21 to the first contact aeration tank 11, and is connected to the discharge side of the pump. And a pipe 13 extending from there to the wastewater inlet side of the first contact aeration tank 11 beyond the tank. A pump 24 is installed in the second settling tank 22 for returning the sludge in the second settling tank 22 to the second contact aeration tank 12, and is connected to the discharge side of the pump 24. A pipe 14 extending to the inflow side of the second contact aeration tank 12 is provided.

Raw water to be treated is introduced into a first contact aeration tank 11 through an introduction pipe 7, where it is biologically treated by aeration from an air diffuser 6, and the treated water is sent to a first settling tank 21. In the settling tank 21, large sludge is settled and separated, and the supernatant water is introduced into the second contact aeration tank 12 where it is biologically treated again. The treated water in the second contact aeration tank 12 is the second
The sludge is sent to the sedimentation tank 22 and the supernatant water is discharged through the discharge pipe 8.

Preferably, as shown in FIG. 1, the first settling tank 21 has a smaller capacity than the second settling tank 22,
Therefore, the residence time in the first settling tank 21 is relatively short, for example, about 30 minutes, and only large sludge is settled. In one example, when the first settling tank 21 is 30 minutes, the residence time of the second settling tank 22 is 1.0 to 1.5 hours. The settling sludge in the first settling tank is returned to the first contact aeration tank 11 by the pump 23 and the pipe 13, and the settling sludge in the second settling tank is set in the second contact aeration tank 12 by the pump 24 and the pipe 14. Will be returned to.

Thus, the first and second contact aeration tanks 1
Since the first precipitation tank 21 is interposed between the first and second tanks 12 and 12, and the supernatant water of the precipitation tank is introduced into the second contact aeration tank 12, the first contact aeration tank 11 and the first precipitation tank 21. Second against
The aeration tanks 12 are biologically independent systems, so that in each contact aeration tank, independent biota are generated. As a result, the food chain of living things progresses and excess sludge is reduced.

Since the sludge is returned from the settling tank to the contact aeration tanks 11 and 12, a large amount of floating sludge is added in addition to the sludge adhering to the contact filter medium 4, and the total converted sludge (MLSS) is added. Will increase. Therefore, the treatment performance is improved, and the self-extinction of the sludge is promoted, so that the amount of excess sludge generated is significantly reduced. Particularly in the treatment of wastewater containing a surfactant such as domestic wastewater, foaming is significantly reduced due to the presence of a large amount of suspended sludge caused by returning.

As a concrete example, in the treatment of urban wastewater, in the prior art, the total residence time in the first and second chambers of the contact aeration tank was 6 hours, and the residence in the precipitation tank was 2 hours. 50% filled with string-like filter material, wastewater (raw water) BO
When operated at D100 mg / L, adhered sludge (converted ML
SS) 2200mg / L, average treated water quality is 18m
It was g / L.

In the apparatus of the present invention, the contact aeration first tank 4 hours, the first precipitation tank 0.5 hours, the contact aeration second tank 2 hours, the second (final) precipitation tank 1.5 hours respectively. Then
When the return rate is 30% in both the first tank and the second tank, the wastewater BOD is 100 mg / L and the average BOD is 6.4 m.
g / L, adhered sludge 2200 mg / L, floating sludge 500 m
The total sludge (MLSS) was 2700 mg / L. As for the excess sludge, the conventional 30% is 16%
And drastically decreased. Waste water BOD is 1000 mg /
Similar results are obtained for L as well.

[0017]

As described above, according to the present invention, the total conversion sludge is increased by returning sludge, so that the treatment performance is improved and independent biota are formed in the two contact aeration tanks. Therefore, self-extinguishing progresses and excess sludge decreases. Further, the presence of a large amount of suspended sludge can significantly reduce foaming.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a water treatment device according to the present invention.

FIG. 2 is a side view schematically showing a conventional water treatment device by a contact aeration method.

[Explanation of symbols]

 11 First Aeration Tank 12 Second Aeration Tank 21 First Precipitation Tank 22 Second Precipitation Tank 13 Piping 14 Piping 23 Pump 24 Pump

Claims (1)

[Claims] 1. A first and second contact aeration tank for purifying water by a contact aeration method, and a treated water which is present between the first contact aeration tank and receives the treated water from the first contact aeration tank and which is a supernatant water. A first settling tank for advancing the gas to the second contact aeration tank;
A second for receiving the treated water from the second contact aeration tank
Settling tank, a first returning device comprising a pump and a pipe for returning sludge from the first settling tank to the first contact aeration tank, and the second contacting aeration tank from the second settling tank A water treatment device including a second returning device including a pump and a pipe for returning sludge to the inside.