JPH04277088A - Aeration device for waste liquid treatment - Google Patents

Abstract

PURPOSE:To carry out an anaerobic operation requiring the stirring of waste liquid and an aerobic operation requiring air supply and stirring simultaneously using a single unit of aerator and causing an easy switching action to take place therebetween. CONSTITUTION:An aerating device which comprises a hollow shaft 2 having a screw 1 at its lower end connected to a hollow motor shaft 3a; and an air ventilation pipe 4 provided passing through the motor shaft 3a and the hollow shaft 2, whereby the lower end projecting distance of the air ventilation pipe 4 is regulated to permit the amount of the air ventilated to be adjusted, irrespective of the number of revolutions of the screw.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention uses a single aerator to easily switch between anaerobic operation for stirring sewage and aerobic operation for simultaneously supplying air and stirring. This invention relates to a treatment aeration device.

0002

BACKGROUND OF THE INVENTION In recent years, natural water bodies such as lakes and rivers have become increasingly eutrophic, red tides and blue-green algae occur frequently, and environmental problems have become a focus of attention in various places. Major causes of eutrophication are red tide, the discharge of treated sewage water containing high concentrations of nitrogen and phosphorus, which are nutrients for blue-green algae, into natural water bodies, and the direct discharge of domestic wastewater. To solve this problem, it is essential to develop water treatment technology that removes nitrogen and phosphorus from wastewater with high efficiency and to install a complete sewer system. Among these, the following mechanism for nitrogen removal has been clarified. That is, nitrogen exists in sewage as ammonia nitrogen, and aeration progresses nitrification and changes to nitrate nitrogen and nitrite nitrogen. Further, under anaerobic conditions, these nitrogens are deprived of oxygen by denitrifying bacteria and diffused from the water into the atmosphere as nitrogen gas, resulting in denitrification. To denitrify wastewater, it is sufficient to bring the wastewater into an anaerobic state. However, since wastewater undergoes biological treatment, aerators are commonly used to blow air into the wastewater. A self-priming aerator is often used to efficiently perform this aeration and also to perform stirring.

0003

Therefore, in a treatment pond or tank equipped with a self-priming aerator, an anaerobic state for denitrification can be obtained by stopping the aerator. However, in such cases, the denitrifying bacteria settle together with the sludge, reducing the efficiency of contact with the wastewater, making it impossible to perform sufficient treatment. Therefore, in order to perform denitrification efficiently, it is necessary to stir and mix wastewater even in an anaerobic state. A method has been proposed in which this aeration and anaerobic stirring are performed using a single self-priming aerator. During aeration operation, air is taken in using the negative pressure generated in the water area at the tip of the screw by opening the intake valve, and air is supplied into the wastewater as fine bubbles, and during anaerobic operation, the intake valve is closed. If the system is operated in this way, air will not be sucked into the wastewater and only agitation will occur. For this reason, the aerator requires an intake valve.

[0004] When using one self-priming aerator and switching between aerobic and anaerobic operation alternately while opening and closing the intake valve, the operating method is simply to preset the aerobic and anaerobic operation times using a timer, and then turn the -This is done in OFF operation. For this reason, there are drawbacks such as insufficient denitrification and changes in nitrification and denitrification performance due to load fluctuations.

[0005] The purpose of the present invention is to switch between aerobic and anaerobic operation by using a ventilation pipe penetrating the hollow shaft, without using a valve, and to easily adjust the amount of ventilation and switch the operation. do.

[0006]

[Means for Solving the Problems] The present invention has been made to achieve the above object, and includes connecting a hollow shaft having a screw at the lower end to a hollow motor shaft, and The main feature is that the vent tube is formed by penetrating a single vent pipe, and by adjusting the amount of protrusion of the lower end of the vent pipe, the amount of ventilation can be adjusted regardless of the rotational speed of the screw.

[0007]

[Operation] A hollow motor shaft and a vent pipe passing through the hollow shaft are made to protrude into the screw tip water area, and the vent pipe is slid to adjust the amount of protrusion of its lower end. As a result, the negative pressure in the lower end region of the ventilation pipe changes, so that the ventilation amount can be arbitrarily adjusted from the set maximum value to zero.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the illustrated embodiments. In the figure, 1 is a screw of an aeration device that efficiently stirs wastewater and generates the required negative pressure in the water area at the tip. This screw 1 is fixed to the tip of a hollow shaft 2 of a specified length. . The base end side of the hollow shaft 2 is directly connected or connected to the hollow motor shaft 3a of the motor 3.
The motor shaft 3a and the hollow shaft 2 are made into a single piece, and their internal cavities are electrically connected to each other.

The upper end of the motor shaft 3a protrudes outward from the motor cover 3b of the motor 3, and
a. A single ventilation pipe 4 is passed through the internal cavity of the hollow shaft 2, and the lower end side 4a of this ventilation pipe 4 is placed at the most protruding position at a predetermined distance L from the vicinity of the screw end face A, as shown in FIG. It is inserted and supported within the hollow shaft 2 so that up to B extends and retracts.

A packing 5 is interposed between the vent pipe 4 and the hollow shaft 2 to prevent dirty water from entering and floating above the water level along the hollow shaft through the gap between the outer circumferential surface of the vent pipe and the inner circumferential surface of the hollow shaft. At the same time, a screw 4c is carved on the upper outer periphery of this ventilation pipe 4, and a female thread is carved directly on the inner peripheral surface of the motor shaft 3a, or a nut-shaped screw member is fitted and fixed inside the motor shaft as shown in the figure. 7, and this ventilation pipe 4.
By rotating the screw, the amount of protrusion of the lower end of the vent pipe 4 from the screw end at the tip of the hollow shaft can be adjusted. In this case, the distance L that is the maximum permissible range for the vent pipe 4 to protrude and retract is the distance L from the tip of the screw or the lower end 2a of the hollow shaft to which the screw is fixed. The area where suction is possible is determined appropriately in the wastewater, and at position B, which is the maximum protrusion point, the negative pressure in the water is 0 and the ventilation pipe 4 is closed.
Intake is stopped from the upper end 4b. Note that even if the screw 1 rotates through the motor shaft 3a and the hollow shaft 2 due to the drive of the motor 3, the ventilation pipe 4 passing through the hollow shaft is supported so as not to rotate. It is also possible to rotate the vent pipe 4 together with the hollow shaft and connect the upper end of the vent pipe to a cylinder or the like via a rotary joint, so that the vent pipe 4 can be moved in the longitudinal axis direction by operating the cylinder.

[0011] Therefore, the case where wastewater is treated in an aerobic or anaerobic atmosphere in the aeration apparatus constructed as described above will be described below. First, air is blown into the wastewater, and in order to decompose organic substances in the wastewater by aerobic fermentation, the ventilation pipe 4 is inserted into the hollow shaft along its longitudinal axis, and the lower end of the ventilation pipe 4 is connected to the lower end of the hollow shaft. Protruding and fixing between point A and point B. This is determined so that air can be efficiently sucked into the wastewater depending on the load. This drives the motor 3 and the negative pressure generated in the water area at the tip of the screw by the rotation of the screw 1 acts on the inside of the ventilation pipe 4, sucks air from the top end of the ventilation pipe, flows down inside the ventilation pipe, and enters the water from the bottom end of the ventilation pipe. It is released as fine bubbles and diffused into the wastewater to bring the wastewater into an aerobic state and achieve the required aerobic operation.

Next, while operating the screw 1 at a predetermined rotational speed, the vent pipe 4 is moved so as to protrude from the lower end of the hollow shaft, and at the position where it reaches point B, the negative pressure generated in the water area at the tip of the screw becomes 0. Become. Therefore, as the lower end of the ventilation pipe 4 moves from point A to point B, the negative pressure generated in the water area gradually decreases, and when it reaches point B, the negative pressure becomes 0, so the intake air amount becomes 0, and the air is dispersed into the wastewater. Qi stops. Even at this time, screw 1
Since it rotates at the required rotation speed, stirring of the wastewater is performed as efficiently as during aerobic operation.

[0013] As a method of adjusting the amount of ventilation (the amount of air diffused into the waste water) by making the ventilation pipe 4 protrude and retract from the end of the screw, it is also possible to use a cylinder or a rod provided at the upper part of the ventilation pipe. In this case, a rotary joint is used between the vent pipe and the cylinder. This allows automatic switching between aerobic and anaerobic operation.

[0014]

[Effects of the Invention] According to the present invention, a ventilation pipe is slidably inserted into a hollow shaft connected to a hollow motor shaft, and the amount of protrusion of the tip of this ventilation pipe from the hollow shaft or the lower end of the screw is adjusted. Since the amount of air supplied to the wastewater is adjusted, ventilation control can be performed without changing the rotational speed of the screw, and has the advantage that the configuration is simpler than the conventional method.

[Brief explanation of the drawing]

FIG. 1 is an embodiment diagram showing the entire aeration apparatus of the present invention.

FIG. 2 is an enlarged sectional view of main parts.

[Explanation of symbols]

1 Screw 2 Hollow shaft 3 Motor 3a Motor shaft 4 Ventilation pipe

Claims (1)

[Claims] Claim 1: A hollow shaft with a screw provided at the lower end is connected to a hollow motor shaft, and a vent pipe is passed through the motor shaft/hollow shaft, and the lower end of the vent pipe protrudes. An aeration device for sewage treatment, characterized in that the amount of aeration can be adjusted regardless of the rotational speed of the screw.