JPH03181397A - How to operate an agitator and aerator in an endless waterway - Google Patents

Abstract

PURPOSE:To simultaneously perform denitrification treatment with aerobic treatment by providing an agitator to the inner circumferential side of an aqueduct slow in flow velocity and supplying the amount of necessary oxygen by an aerator provided to the outer circumferential side of the aqueduct by intermittent operation while always securing the necessary water flow. CONSTITUTION:An aerator 2 is arranged at the outer circumferential side of a terminalless aqueduct 13 and provided in the tangential direction to the aqueduct. An agitator 3 is arranged at the inner circumferential side of the aqueduct 13 and also a fitting angle for the aqueduct is regulated in the tangential direction of the aqueduct. In order to prevent sludge from being deposited on the bottom part of the aqueduct and to prevent deterioration of water quality, the agitator 3 is continuously operated so that the necessary flow velocity is always obtained in the aqueduct. The aerator 2 is intermittently operated. When operating this aerator, necessary water flow is generated in the aqueduct by the cooperative action of the agitator. While sewage is agitated, aeration is performed and aerobic fermentation treatment of sewage is performed. Water flow due to the agitator is generated in the aqueduct by stopping operation of an aerator but sewage is not aerated. Therefore denitrification of sewage is performed at the time the aeration is suspended.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to an endless waterway that uniformly mixes wastewater throughout the waterway to perform efficient and uniform aeration and also denitrification. This paper relates to a method of operating the agitator and aeration equipment in the plant.

[Conventional technology]

When treating sewage containing organic matter such as sewage sewage and industrial waste sewage, an aerator is installed in an aeration tank that has a so-called endless waterway, such as an oblong circulation waterway or a double circular waterway. A method has been proposed in which sewage is mixed and stirred while continuously supplying oxygen from the air to the sewage to warm air, that is, perform aerobic fermentation treatment.

[Problem to be solved by the invention]

In a double circular aeration tank with an endless water channel, two air machines are installed parallel to each other in a direction perpendicular to a straight line passing through the center of the tank, and from 180 degrees from the installation position of this air machine. At a slightly turned position, 12 current meters were placed at required intervals from the inner circumference to the outer circumference of the waterway, and the flow velocity at each point in the waterway was measured while operating the aerator.

The measurement results at each of the measurement points shown in Figure 6 a, b, c, and d revealed that the flow velocity was slower on the inner circumference of the waterway and faster toward the outer circumference.

In this way, the unevenness of flow velocity in the waterway is 1! Even if aeration is carried out, good aeration cannot be achieved, and a swirl phenomenon occurs and sludge accumulates on the inner circumferential side of the waterway, and this accumulated sludge rots, causing a new problem of deteriorating water quality.

Also, install multiple aerators in the endless waterway! When operating the aerator by controlling the number of units and controlling the rotation speed, if the inflow load (inflow water amount x inflow water concentration) at the start of the aerator operation is low, the operation time will be long to ensure the required flow rate. This results in overaeration, and in this state, although aerobic issuance treatment can be performed, denitrification treatment cannot be performed.

In view of this, the present invention arranges an agitator on the inner circumference side and an aeration device on the outer circumference side of the endless waterway to be aerated, thereby increasing the flow velocity on the inner circumference side of the waterway circle compared to the outer circumference side. In this way, the aim is to equalize the flow velocity throughout the waterway, mix uniformly with less power, prevent sludge accumulation and water quality deterioration, perform efficient aeration, and perform denitrification. .

[Means to solve the problem]

In order to achieve the above object, the present invention installs an agitator on the inner circumferential side of the waterway and an aeration device on the outer circumferential side of the waterway in an endless waterway such as an aeration tank, and adjusts the flow velocity on the inner circumferential side of the waterway to the outer circumferential side. The gist is to uniformly mix and aerate inside the tank by increasing it compared to the side. In addition, the agitator installed on the inner circumferential side of the endless waterway is operated continuously, and the aeration equipment installed on the inner and outer circumferential sides of the waterway is operated intermittently, so that aeration is carried out while maintaining the flow rate in the waterway at the required flow rate at all times. and denitrification. Furthermore, the installation angle of the agitator and/or aeration device relative to the waterway can be adjusted to increase the flow velocity inside the waterway.

[For production]

The agitator and aeration device installed in the endless waterway are installed in the waterway by installing the agitator in the waterway R111 and the aeration device on the outer circumference side of the waterway so that the flow velocity on the inner circumference side of the waterway is higher than that on the outer circumference. The wastewater in the tank is mixed uniformly and swirl phenomenon is prevented. This makes it possible to solve the problem of sludge accumulation and poor water quality, and also allows aerobic treatment and denitrification treatment of sewage to be performed at the same time.

[Indeed, F! q) The present invention will be explained below based on the illustrated embodiments.

The one in FIG. 1 is an embodiment using a double circular @air tank in which the endless water channel is circular.

1 is a double circular @air tank, which has a small diameter circumferential wall 11 and a large diameter outer R wall 12 arranged concentrically.

A circulation waterway 13 having a required width and depth is formed between the inner and outer circumferential walls '11 and 12.

2 is a self-priming screw type aeration device, which is composed of a hollow shaft directly connected to a motor and a screw, as shown in detail in Figure 4.The rotation of the screw generates a water flow, and the tip of the screw generated accordingly. Air is sucked through a hollow shaft using the negative pressure of the pump, and is supplied as fine bubbles into the wastewater, so that the bubbles are efficiently dissolved into the water.

The aeration system Wt2 has a motor 22 fixed to a mounting frame 21 disposed across the upper part of the water channel 13, a hollow shaft 23 directly connected to the motor 22, and a cover 24 covering the motor and the hollow shaft. The motor etc. are attached to the frame through this cover, but in this case, a mounting angle m adjuster 25 is provided as necessary, and the horizontal mounting angle of the aeration device relative to the waterway can be adjusted arbitrarily via this adjuster 25. A screw 26 having a desired shape is provided at the tip of the hollow shaft.

The aeration device 2 is placed on the outer periphery of the endless waterway 13, but it can be installed in the tangential direction to the waterway as shown in the first construction drawing, or in the tangential direction as shown in FIG. The mounting angle can be adjusted so as to move slightly inward, and the horizontal angle can be set to a required angle, and the horizontal mounting angle can also be adjusted as necessary.

In addition, 3 in the figure is a stirrer, and this stirrer 3 is the @%*! 2
and is fixed to the mounting frame 21.

The agitator 3 is disposed on the inner circumferential side of the water channel 13, and the angle at which it is attached to the water channel can be adjusted such that it is tangential to the water channel, similar to the aeration system 'f12, or so that it faces inward. shall be taken as a thing.

The agitator 3 is operated continuously to maintain the required flow velocity in the waterway to prevent sludge from accumulating at the bottom of the waterway and to prevent deterioration of water quality.The aerator 2 is operated intermittently. Eggplant. When this aeration device is in operation, the necessary water flow is generated in the waterway in cooperation with the agitator, and the sewage is aerated while being stirred, thereby performing aerobic issuance treatment of the sewage. When the operation of the aeration device is stopped, a water flow is generated by the agitator in the waterway, but since aeration is not performed, denitrification of the active water is performed when the aeration is stopped.

In addition, in the embodiment shown in FIGS. 1 and 2, the stirring a3 and aeration device! ! This is a case where only one set of 2 parallel arrangement is installed in the waterway 13, but this pair of agitator and aeration device is installed in the same waterway at the required interval, for example, 180mm as shown in Fig. 3.
It is also possible to install two sets at different positions. In this way, when two or more sets are provided in the same waterway, it is possible to control the number of units in addition to the above-mentioned operation control, which allows for more detailed operation and promotes denitrification.

Figure 8 and the following are graphs showing a comparison of wastewater treatment by the method according to the present invention and the conventional method. The figures similarly show the bottom flow velocity of the waterway of the present invention, and from this graph it is clear that the present invention has better values for both the Do value and the flow velocity than the known embodiments shown in Figures 10 and 11. I understand that. From this, in the conventional method, the Do value is always 0. S
At rIIg/Q or higher, denitrification did not progress; however, in the method of the present invention, the Do value was around 0.5/Q, indicating that denitrification was progressing.

〔Effect of the invention〕

According to the present invention, the agitator is provided on the inner circumferential side of the endless waterway where the flow velocity is difficult to reach, and while ensuring the necessary water flow at all times,
The required amount of oxygen is supplied by an aeration device installed on the outer periphery of the waterway and operated intermittently, making it possible to treat sewage by setting aerobic and anaerobic time periods, compared to conventional aerobic treatment. Denitrification treatment can also be performed simultaneously with the treatment.

In addition, by making it possible to adjust the mounting angle of the agitator and/or @gas device, it is possible to install it according to the shape and size of the endless waterway, enabling more uniform mixing and higher denitrification performance. It has advantages such as:

[Brief explanation of drawings]

Figures 1 to 4 show embodiments of the present invention. Figure 1 is a plan view of a circular endless waterway with a set of agitator and aeration device installed in the tangential direction to the waterway, and Figure 2 is the same. A plan view showing the angle of installation of the agitator and aeration device with respect to the waterway can be adjusted.
Fig. 3 is a plan view of a case where two pairs of stirrers and @air devices are installed, Fig. 4 is an explanatory diagram of the @air equipment, and Fig. 5. 6 and 7 are explanatory diagrams of known methods, FIGS. 8 to 11 are graphs comparing the present invention and known examples, and FIG. 8 is a graph showing changes in Do of the present invention over time; FIG. 9 is a graph showing the flow velocity at the bottom of the waterway according to the present invention, FIG. 10 is a graph showing the change in Do over time in a known example, and FIG. 11 is a graph showing the flow velocity at the bottom of the same waterway. ↓ is an aeration tank, 3 is a waterway. 2 is aeration equipment, 3 is stirring. Patent applicant Hitachi Kiden Industries, Ltd. Figure 4 (A) CB)

Claims (3)

[Claims] (1) In an endless waterway such as an aeration tank, the agitator is installed on the inner circumference side of the waterway, and the aeration device is installed on the outer circumference side of the waterway, so that the flow velocity on the inner circumference side of the waterway is increased compared to the outer circumference side. A method for operating an agitator and aeration device in an endless waterway, characterized by uniformly mixing and aerating the tank. (2) The agitator installed on the inner periphery of the endless waterway is operated continuously, and the aeration equipment installed on the inner and outer periphery of the waterway is operated intermittently, thereby constantly maintaining the flow rate in the waterway at the required flow rate while aeration is carried out. 2. The method of operating an agitator and aeration device in an endless waterway according to claim 1, characterized in that denitrification is carried out and denitrification is carried out. (3) A stirrer and aeration in an endless waterway, characterized in that the angle at which the agitator and/or aeration device is attached to the waterway is adjustable to increase the flow velocity inside the waterway as set forth in item 1 or 2. How to operate the equipment.