JPS596985A - Treatment of waste water with activated sludge - Google Patents

Abstract

PURPOSE:To effectively use the thermal energy of high-temp. compressed air, while inhibiting the rising of the temp. of a liquid in an aeration tank, by bringing the high-temp. compressed air sent out through an aerating blower into contact with dehydrated sludge to cool it, and then injecting it into the aeration tank. CONSTITUTION:Waste water 1 is collected in a conditioning tank 2, wherein pretreatments, e.g. making its flow amount and concentration uniform, the adjustment of its pH and the diffusion of volatile BOD substance, are performed. Thereafter, the predetermined amount of said waste water is continuously supplied to an aeration tank. The waste water is mixed with activated sludge in the aeration tank 3 while agitating the waste water by aeration and continuously introduced to a precipitation tank 4. Activated sludge is separated therein by precipitation, while a supernatant liquid is let overflow, pasteurized 5 and then drained as treated water 6. The activated sludge precipitated in the precipitation tank 4 is returned to the aeration tank 3 to hold the concentration of sludge in it. An amount corresponding to the propagation of sludge in the tank is withdrawn as excess sludge 7 outside the system, reformed into dehydrated sludge 10 and then disposed by drying and burning 23.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an activated sludge treatment method for wastewater.

In order to efficiently operate the aeration tank in wastewater activated sludge treatment method 8, it is ideal to control the temperature inside the tank at 20 to 30°C throughout the year.

By the way, when compressed air (j) is blown into an aeration tank, it becomes high temperature due to the compression heat and frictional heat generated when the air is compressed by an aeration blower. However, especially in the summer, the temperature of the liquid in the aeration tank rises to 35-38℃ due to the reaction heat of the waste liquid itself and the high temperature air, causing the aeration tank to overflow. could not drive efficiently.

Therefore, this invention prevents the temperature of the liquid in the aeration tank from rising, and also prevents the liquid temperature from rising in the aeration tank by lowering the temperature of the compressed air by bringing it into contact with dehydrated sludge and then blowing it into the aeration tank. The purpose is to effectively utilize the thermal energy contained in the air.

Hereinafter, the present invention will be explained based on the accompanying drawings.

FIG. 1 shows the processing steps of this wastewater activated sludge treatment method.

First, the basic processing steps of the activated sludge treatment method will be explained.

Collect wastewater 1 in adjustment tank 2, and put it in this adjustment tank 2? After performing pre-treatments such as equalizing the inflow amount, equalizing the concentration, adjusting the pH, and scattering volatile substances, a certain amount of the liquid is continuously supplied to the aeration tank 3. In this aeration tank 3, the activated sludge and wastewater are mixed while being aerated and stirred, and the mixed liquid is continuously led to the settling tank 4, where the activated sludge is sedimented and separated, and the supernatant liquid is allowed to flow, and sterilized and disinfected. After that, it is discharged as treated water 6. The activated sludge settled in the settling tank 4 is transferred to the aeration tank 3.
The activated sludge concentration in the aeration tank is maintained. An amount corresponding to the amount of sludge multiplied in the aeration tank 3 is pulled out of the system as surplus sludge 7, collected in a sludge storage tank 8, and then converted into dewatered sludge 10 by a dewatering filter 9, dried, and incinerated 23 for disposal.

The feature of this invention is that the thermal energy of the compressed air 11 blown into the aeration tank 3 is used to dry the dehydrated sludge 10. That is, the high temperature compressed air 11 sent out from the aeration blower 12 is dehydrated ('Fi mud 10
The dehydrated sludge 10 is dried and the compressed air 11 is cooled by making the dehydrated sludge absorb the heat of the compressed air 11 of 7j27M.

Next, a heat exchange device 13 that cools the compressed air 11 by bringing the compressed air 11 into contact with the dehydrated sludge 10 efficiently.
We will explain the structure of That is, as shown in FIGS. 2 to 4, a shaft 16 having a spiral blade 15 is installed inside the casing 14, and by rotating the shaft 16, one end of the casing 14 (the provided sludge inlet) is installed. The dehydrated sludge 10 introduced from the shaft 17 is pushed to the other end.An air passage 1B is formed in the axial center of the shaft 16, and this air passage 1B is provided protruding from the outer peripheral surface of the shaft 16. The aeration blower 1 also communicates with a large number of outlets 19.
The high-temperature compressed air 11 sent from the dehydrated sludge 10
It is blown into the casing 14 and the air passage 18 from the discharge side of the dehydrated sludge 10, and is discharged from the input side of the dehydrated sludge 10. In FIG. 2, 20 indicates an air supply port, and 21 indicates an air discharge port. In this way, high temperature compressed air 11
By blowing into the casing 14, contact with the dehydrated sludge 10 is achieved extremely well, and the casing 14
The dehydrated sludge 10 introduced from one end is transferred to the casing 14.
It is dried while being discharged from the discharge port 22 at the other end. On the other hand, the high temperature compressed air 11 transfers its heat to the dehydrated sludge 10.
The dehydrated sludge 100 is cooled while being discharged from the input side.

The compressed air 11 cooled by the heat exchange device 13 is blown into the aeration tank 3.

In addition, if the temperature rise in the aeration tank 3 becomes a problem during the winter season, or if the aeration tank 3 needs to be heated,
It is preferable to blow the high-temperature compressed air directly into the aeration tank 3 without cooling it by the heat exchange device 13.

The present invention is configured as described above, and has the effects listed below.

(1) After the high temperature compressed air sent out from the aeration blower is cooled by contacting with dehydrated sludge,
Since it is sent into the aeration tank, it does not increase the liquid temperature in the aeration tank. Therefore, even in the summer, a cooling device for lowering the temperature of the liquid in the aeration tank becomes unnecessary or small, and processing costs can be reduced.

(2) By bringing the high-temperature compressed air sent from the aeration blower into contact with the dehydrated sludge, the moisture content of the dehydrated sludge can be lowered, which not only reduces the amount of fuel used to incinerate the dehydrated sludge, but also reduces the amount of sludge. Drying and incineration equipment can also be downsized.

(3) When the air for aeration comes into direct contact with dehydrated sludge, it becomes odor-laden air, but since this air is blown into the aeration tank, biological deodorization takes place in the aeration tank, and special deodorization equipment is not required. Fl.

[Brief explanation of the drawing]

Fig. 1 is a treatment process diagram of the activated sludge treatment method of the present invention, Fig. 2 is a perspective view of the heat exchange device, Fig. 3 is a cutaway front view of the same part, and Fig. 4 is A--A in Fig. 3. FIG. 3 is a cross-sectional view taken along the A line. 3... Aeration tank, 10... Dehydrated sludge, 11... Compressed air, 12... Aeration blower Patent applicant: Kubota Iron Works Co., Ltd. Agent: Kama 1) Text 2 Figure 1 ￥2 Figure A 491

Claims (1)

[Claims] A wastewater activated sludge treatment method characterized in that high-temperature compressed air sent from an aeration blower is brought into contact with dehydrated sludge, cooled, and then blown into an aeration tank.