JPS6068095A - Batch activated sludge process equipment - Google Patents

Abstract

PURPOSE:To carry out efficiently the waste water treatment including denitrification by opening and closing a valve on the basis of a water level detected with a water level gauge, and selecting a suction pipe for discharging the supernatant water. CONSTITUTION:The original waste water is supplied into a treating tank 1 from a supply pipe 11, mixed by operating a mechanical agitator 2 with an appropriate amt. of treated water which is left in the treating tank 1 in the preceding cycle of the discharging stage, and anaerobically treated. Air is blown into the treated water in the treating tank 1 from an air sparger 3 by driving a blower 8, and the aeration and agitation are carried out. Thereafter, the blowing of air from the air sparger 3 is stopped, and the settling is carried out in the treating tank 1. Then the supernatant water is discharged from a suction pipe with a pump 7 by opening and closing valves 4, 4', and 4'', and selecting the suction pipe 5, etc. for discharging the supernatant water on the basis of the water level detected with a water level gauge 6.

Description

[Detailed description of the invention] The present invention relates to a batch type activated sludge treatment apparatus.

In recent years, nitrogen and phosphorus have been pointed out as sources of pollution in closed water bodies, especially lakes, and some local governments have begun to regulate the discharge of these substances. Therefore, there is a need to improve the functionality of wastewater treatment facilities, regardless of their size, but nitrogen removal, that is, denitrification treatment, is still insufficient. One treatment method that can perform such denitrification treatment is to treat nitrogen compounds in wastewater with microorganisms under aerobic conditions to remove NO2 and NO.
3, that is, an aerobic treatment step, and after this aerobic treatment step, microbial treatment is performed again under anaerobic conditions to remove NO.
A biological treatment method has been proposed that includes both a process of reducing and removing NO2 and NO3 as N2 gas, that is, an anaerobic treatment process. However, conventional treatment equipment that embodies this treatment method as a continuous type performs the aerobic treatment process, anaerobic treatment process, and sedimentation separation process in separate treatment tanks, which requires installation space and operation management. etc. tend to become large-scale. By the way, in industries such as small and medium-sized enterprises, where the work is done every day, the outflow time of wastewater is constant, and the amount of wastewater is relatively evening, it is difficult to install a single treatment tank in terms of installation space and operation management. Although a batch type activated sludge treatment apparatus is most suitable, conventional batch type activated sludge treatment apparatuses do not actually embody the above-mentioned treatment method including both the aerobic treatment step and the anaerobic treatment step. Nitrogen has not been removed sufficiently.

The present invention improves the conventional equipment as described above, allows the aerobic treatment process, anaerobic treatment process, and sedimentation separation process to be performed in a rational batch manner in one treatment tank, thereby reducing the This system is also designed to efficiently perform wastewater treatment including denitrification bed treatment. The present invention will be described in detail below based on examples.

In FIG. 1, reference numeral 1 is a processing tank, and the apparatus of the present invention is provided with a mechanical stirring device 2, an aeration device 3, and suction sections a', a', a'', etc. in the processing tank 1. with different valves, each with 4 valves.
．． Multiple suction pipes with 4', 4", 5.5
', 5'', and a water level gauge 6 are provided.In the process of discharging the supernatant water after sedimentation and separation in the treatment tank 1,
Based on the water level detected by the water level gauge 6, the valve 4. 4
', 4'', . . . to select the suction pipe 5. 5', 5'', . . . for discharging supernatant water. Here, the valve 4. 4', 4".

... is an automatic operation type such as an electromagnetic type, an electric type, or a pneumatic type, which is automatically operated by an appropriate control device (not shown) based on the water level signal of the water level gauge 6, or a manual type. , an operator may operate the water level manually based on the water level signal from the water level gauge 6. Reference numeral 7 is a supernatant water discharge pump, 17 blower 19 is an excess sludge extraction pump, 1
0 is an excess sludge extraction pipe, and 11 is a raw wastewater supply pipe.

The operation of the present invention in such a configuration will be explained below based on the typical operation sequence shown in FIG. 2 and FIG. 6.

[1]・□ Anaerobic treatment process Raw wastewater to be treated is intermittently supplied into the treatment tank 1 from the raw wastewater supply pipe 11 during this process, and the mechanical stirring device 2 is operated. The supplied raw wastewater is mixed with the treated water that remained in an appropriate amount in the treatment tank 1 in the discharge process of the previous cycle to perform anaerobic treatment. The remaining treated water has undergone oxidation and nitrification of organic matter in the raw wastewater in the aerobic treatment process of the previous cycle, and contains nitrate and nitrite nitrogen produced by nitrification. Denitrification bed treatment is performed using nitrogen bodies and organic matter in the raw wastewater supplied in this cycle. In this step, air is not blown from the air diffuser 3.

In this anaerobic treatment process, raw wastewater is supplied irregularly into the treatment tank 1, but since the mechanical stirring device 2 is operating in the treatment tank 1 as described above, the Nitrate and nitrite nitrogen contained in the treated water of the cycle come into good contact with the organic matter of the raw wastewater, making it possible to perform efficient denitrification bed treatment.

Air is blown into the treated water in the treatment tank 1 from the air device 3 to perform aeration and stirring. Since the treated water is thus stirred by air blowing, there is no need to operate the mechanical stirring device 2 that was operated in the anaerobic treatment process. However, activation is also possible in some cases. In this step, microbial treatment is used to oxidize organic matter and nitrify nitrogen compounds in the raw wastewater supplied during the previous step.

[6] Sedimentation separation process After the predetermined pre-process is completed, the operation of mechanical devices such as the air diffuser 3 and air blowing is stopped, and the processing tank 1 is used as a settling tank. This step creates an interface between activated sludge and supernatant water to allow the next discharge step to be carried out efficiently, but since this step is also in a kind of anaerobic state, a certain degree of denitrification bed treatment is performed.

[4] - Discharge process After completion of a predetermined pre-process, a suction pipe 5 for discharging supernatant water by opening and closing the valves 4, 4/, 4tt, etc. based on the water level detected by the water level gauge 6; 5/, 5/
/.

- is selected, and the supernatant water is discharged from the suction pipe thus selected by the supernatant water discharge pump 7. In addition, if proliferation of activated sludge is observed, excess sludge is pulled out by an appropriate sludge extraction device provided at an appropriate location, for example, an excess sludge extraction pump 9 from an excess sludge extraction pipe 10 as shown. After the above discharge process is completed, the next cycle of anaerobic treatment process is started again.

Here, the suction pipe 5 based on the water level detected on the water level side 6
．． The selection of 5' and 5'' is performed as follows, for example in FIG.

■ When the water level gauge 6 indicates between D and E, open valve 94', close valves 4.4', . The supernatant water is discharged to a height of .

■ When the water level gauge 6 indicates between C and 9, the valve 4' is opened, the valves 4.4'', etc. are closed, the suction pipe 5' is selected, and the height of the suction part a' is The supernatant water will be drained.

■ When the water level gauge 6 indicates between B and 0, the valve 4 is opened, the valves 4', 4'', etc. are closed, and the suction pipe 5 is selected to reach the height of its suction part a. The supernatant water is discharged.

In this way, when the water level of the treatment tank 1 is high, a suction pipe with a suction part located at a high position is selected and the suction pipe is moved to a high position, and when the water level is low, a suction pipe with a suction part located at a low position is selected. Since the supernatant water is discharged from a low-positioned casing, compared to a conventional batch-type activated sludge treatment device shown in Figure 4, which has a single suction pipe, the treatment tank after the sedimentation separation process is A predetermined proportion or more of treated water can always remain in the treatment tank 1 with respect to the total amount of treated water in the treatment tank 1.

In this way, the residual treated water above a predetermined ratio can be denitrified in the anaerobic treatment process of the next cycle as described above, so the overall theoretical nitrogen removal rate of the supernatant water relative to the raw wastewater is can be maintained above the predetermined ratio 9 at all times. For example, if 50% or more of the treated water remains at all times, the theoretical nitrogen removal rate can also be 50% or more.

As described above, when the present invention sequentially performs an anaerobic treatment process, an aerobic treatment process, a sedimentation separation process, and a discharge process in one treatment tank, all supernatant water is removed in the discharge process. Rather than discharging it, it is possible to carry out denitrification rice processing extremely efficiently by using a structure that actively retains a predetermined percentage or more of it and brings it to the anaerobic treatment process in the next cycle. A feature of this method is that wastewater treatment using activated sludge, including denitrifying rice treatment, can be realized in a batch manner. In particular, the present invention provides a treatment tank with a plurality of suction pipes each having a valve at different heights and a water level gauge, and in the discharge process, the water level is determined based on the water level detected by the water level gauge. By opening and closing each of the valves, the suction pipe for discharging the supernatant water is selected, and in this way, a predetermined proportion or more of the treated water can always remain in the total treated water after the precipitation process with easy operation. By doing so, it has the feature that the theoretical nitrogen removal rate can always be maintained at a constant value or higher regardless of the amount of raw water supplied. Since the present invention is capable of performing activated sludge treatment including denitrification rice treatment in a batch manner, it is possible for small and medium-sized enterprises to do the work every day, and the outflow time of wastewater is constant, and the amount of wastewater is reduced. It is ideal for industries where a relatively small amount of water is required, and has the feature of significantly reducing installation costs. In addition, the shape of the treatment tank 1 is vertical if it is a vertical shape, so that the boundary between settled sludge and supernatant water can be made large in the zero sedimentation separation process, and when pulling out settled sludge as surplus sludge, The purpose is that it is possible to draw out concentrated sludge due to the action of the sludge's own weight, and when discharging supernatant water, it is possible to have a width between the suction parts of multiple pipes connected to the discharge pump. It has advantages in that it becomes easy to control the discharge amount of supernatant water and prevents the settling sludge from being sucked up, but it does not necessarily have to be a vertical type.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the overall configuration of an embodiment of the present invention, Fig. 2 is an explanatory diagram showing a typical operation sequence of the device of the present invention,
This figure is an explanatory diagram of the apparatus of the sequence shown in FIG. 2, and FIG. 4 is an explanatory diagram of the overall configuration of a conventional batch type activated sludge treatment apparatus. Code 1... Processing tank, 2... Mechanical stirring device, 3... Air diffuser, 4. 4', 4"... Valve, 5.5'
, Te', ... Suction pipe, 6... Water level gauge, I...
・・Supernatant water discharge pump, 8・・Plower 19・・Excess sludge extraction pump, 10 Excess sludge extraction pipe, 11・・
・Raw wastewater supply pipe,

Claims (1)

[Claims] The treatment tank is equipped with a mechanical agitation device, an aeration device, a plurality of suction pipes each having a valve at different heights, and a water level gauge. In the process of discharging supernatant water after the process, the valve is opened and closed based on the water level detected by the water level gauge to select a suction pipe for discharging the supernatant water after the sedimentation separation process. A batch-type activated sludge treatment device characterized by being configured such that a predetermined proportion or more of treated water always remains in the total treated water.