JPH0478358B2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> This invention is applicable to various types of organic wastewater containing nitrogen (urban sewage, domestic wastewater, industrial wastewater from food factories, chemical factories, pulp factories, etc., livestock wastewater). The present invention relates to a deep-layer wastewater treatment device that processes wastewater (e.g.), and in particular, to a deep-layer wastewater treatment device that can easily maintain an anaerobic state in the denitrification tank when the wastewater treatment liquid is returned from the nitrification tank to the denitrification tank.

<<Prior art>> As is well known, there is an activated sludge method as a type of wastewater treatment equipment, and this method uses microorganisms called activated sludge to perform biochemical treatment to decompose organic matter in wastewater. .

In such wastewater treatment methods, it is necessary to aerate the wastewater source liquid stored in the treatment tank with oxygen or air, but if the treatment tank is made horizontal, the installation area becomes larger and the amount of oxygen dissolved in the wastewater source liquid is reduced. For this reason, for example, as disclosed in Japanese Patent Publication No. 59-38031, a deep type wastewater treatment device in which a treatment tank is installed underground at a depth of 40 m or less has been proposed.

By the way, as a deep-layer wastewater treatment apparatus of this type, there is a conventional apparatus shown in FIG. 2 that removes nitrogen from wastewater.

The wastewater treatment equipment shown in the figure consists of a vertical denitrification tank 1
and a nitrification tank 2 are installed, and the inside of the denitrification tank 1 is maintained in an anaerobic state, and the inside of the nitrification tank 2 is aerated by supplying oxygen, so that the inside of the nitrification tank 2 is maintained in an aerobic state.

The nitrification tank 2 and the denitrification tank 1 are connected through a return passage 3.

This wastewater treatment equipment has the advantage that there is no need to supply methanol from the outside because the carbon source necessary for denitrification uses organic matter in the inflowing wastewater. Ammonia nitrogen in the stock solution is aerated in the nitrification tank 2 and turns into nitrate nitrogen, which is then returned to the denitrification tank 1 via the return passage 3.
The nitrogen gas is removed as nitrogen gas by the action of microorganisms in the tank 1, but in this case, the following problems arose.

≪Problems to be solved by the invention≫ In other words, in the wastewater treatment device shown in Fig. 2,
The denitrification tank 1 is maintained in an anaerobic state, but since the treated liquid circulated through the return passage 3 is introduced from the nitrification tank 2 in an aerobic state, it naturally contains a considerable amount of dissolved oxygen. .

Therefore, if this is supplied as is, it will be difficult to maintain the inside of the denitrification tank 1 in an anaerobic state.

In particular, since the inside of the nitrification tank 2 is aerated as mentioned above, the treated liquid taken out from the return passage 3 contains a considerable amount of air bubbles. It was difficult to maintain anaerobic conditions.

As a measure to maintain the anaerobic state in the denitrification tank, dissolved oxygen, etc. are removed by using the nitrogen gas generated from the denitrification tank and aerating the treated liquid in a gas separation tower installed in the middle of the return passage. is possible.

However, since the nitrogen gas generated from the denitrification tank contains a large amount of corrosive gases such as hydrogen sulfide, it is difficult to maintain and manage the corrosion prevention of the gas separation tower, and it is not possible to install an inexpensive and long-life gas separation tower. There was an issue of economics.

The present invention has been made in view of these conventional problems, and its purpose is to facilitate the maintenance and management of gas separation towers, and to provide inexpensive and long-life ones. ,
It is an object of the present invention to provide a wastewater treatment device that can easily and reliably maintain an anaerobic state in a denitrification tank by performing air aeration efficiently.

<Means for Solving the Problems> In order to achieve the above object, the deep wastewater treatment device of the present invention includes a treatment tank consisting of a denitrification tank and a nitrification tank, and a wastewater treatment liquid from the nitrification tank is transferred to the denitrification tank. In a deep-layer wastewater treatment device that includes a return passage for introduction and a gas separation tower installed in the middle of the return passage, and denitrifies and nitrifies the raw wastewater sent to the treatment tank, the deep-layer wastewater treatment device , a gas generator for separating oxygen and nitrogen in the air, an oxygen gas supply path for introducing the oxygen gas separated by the gas generator into the nitrification tank, and a gas generator for introducing the nitrogen gas separated by the gas generator into the nitrification tank. A nitrogen gas supply path is provided on the upstream side of the gas separation column.

<<Operation>> According to the deep-layer wastewater treatment apparatus configured as described above, the nitrogen gas separated by the gas generator is supplied to the gas separation tower via the nitrogen gas supply path, so that the oxygen gas for aeration in the nitrification tank is supplied. The gas generator provided for manufacturing can be utilized more effectively. In addition, the nitrogen gas separated and generated by the gas generator does not contain corrosive gases and has a high nitrogen content, which facilitates the maintenance and management of the gas separation tower to which the nitrogen gas is supplied, and provides a high aeration effect. .

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a deep wastewater treatment apparatus according to the present invention.

The wastewater treatment apparatus shown in the figure consists of a denitrification tank 14 into which wastewater stock solution A is supplied to its upper space 12 via a raw water supply path 10, and a nitrification tank 16 that communicates with the denitrification tank 14 at its lower end. Equipped with a processing tank.

The denitrification tank 14 and the nitrification tank 16 are both vertical treatment tanks that are installed underground and have an effective water depth of about 30 to 35 m.

In the denitrification tank 14 and nitrification tank 16,
Partition walls 18, 18 that vertically partition the interior, respectively.
A is provided at a predetermined interval from the upper and lower ends of each tank 14, 16, and one side of each partition wall 18, 18a is filled with fixed bed type filter media 20, 20a to retain microorganisms, respectively. At the same time, passages 19 and 19a are provided on the other side.

The filter media 20, 20a filled in the denitrification tank 14 and the nitrification tank 16 may be flat materials such as nonwoven or woven fabrics, honeycomb tubes, fixed or irregularly shaped filter media, or the like.

In addition, a circulation pump 22 with a suction port connected to the other side of the partition wall 18 is installed in the denitrification tank 14, and by driving the circulation pump 22, a downward flow is caused in the denitrification tank 14 on the filter medium 20 side of the partition wall 18. Flow is created and an upward flow is created in the passageway 19 on the opposite side of the filter media 20.

On the other hand, in the nitrification tank 16, a blower 24 is installed in a pipe connecting the upper space 12a and the middle part of the passage 19a, and when the blower 24 is driven, oxygen gas is supplied to this space 12a as described later. is sent to the middle part of the passage 19a to perform aeration, create a downward flow on the filter medium 20a side, and create an upward flow on the passage 19a side.

Further, a discharge path 26 for discharging the treated wastewater treatment liquid B is connected to the nitrification tank 16,
The waste water treatment liquid B taken out through this discharge path 26 is then sent to a vacuum degassing tower 28 and a final settling tank 30.
After being processed, it is released to the outside.

Further, the discharge passage 26 is provided with a return passage 32 that branches off from it, the other end of this return passage 32 is connected to the denitrification tank 14, and a gas separation tower 34 is connected to the denitrification tank 14 in the middle of the return passage 32. is provided.

A nitrogen gas supply line 38 through which nitrogen gas is fed from a gas generator 36 is connected to the upstream side of the gas separation tower 34 .

The gas generator 36 is a device that separates and produces oxygen gas by feeding air into a tower filled with an adsorbent and selectively adsorbing nitrogen in the air with the adsorbent. Oxygen gas is supplied to the gas generator 36 and the upper space 1 of the nitrification tank 16.
Nitrogen gas is introduced into the nitrification tank 16 via an oxygen gas supply path 40 provided between the adsorbent 2a, and the nitrogen adsorbed by the adsorbent is desorbed by changing the pressure, and the desorbed nitrogen gas is Gas supply path 3
8.

In the deep type wastewater treatment apparatus configured as described above, the wastewater raw solution A is sent into the denitrification tank 14 through the raw water supply path 10, and the circulation pump 22 and blower 24 are driven to connect the denitrification tank 14 and the nitrification tank 16. The waste water stock solution A is treated while creating water flows in the directions of the arrows as shown in FIG.

In such a treatment process, the ammonia nitrogen contained in the raw wastewater solution A is removed from the passage 1 by the blower 24 when oxygen gas is sent into the upper space 12a from the gas generator 36 in the nitrification tank 16.
Since aeration is carried out by being sent to the middle part of 9a,
The wastewater treatment liquid B taken out to the discharge passage 26 is converted to nitric nitrogen, and when this is circulated to the denitrification tank 14 via the return passage 32, it is removed as nitrogen gas.

In this case, in the processing apparatus of this embodiment, 34 of the gas separation tower provided in the middle of the return passage 32 is
Since nitrogen gas is supplied from the gas generator 36 to the upstream side of the gas generator 36 via the nitrogen gas supply line 38, the wastewater treatment liquid B introduced from the nitrification tank 16 into the gas separation tower 34 is treated in the separation tower 34. The gas is aerated, the dissolved oxygen is released, and the air bubbles are also separated.

Therefore, the wastewater treatment liquid b circulated to the denitrification tank 14
Since dissolved oxygen and air bubbles are almost completely removed, the influence on the anaerobic state of the denitrification tank 14 is extremely small.

Here, the nitrogen gas separated and generated by the gas generator does not contain corrosive gases such as flowing hydrogen, and approximately
Since it contains 90% or more of the nitrogen component and has a high aerobic effect, dissolved oxygen and bubbles in the treatment liquid can be efficiently removed and the anaerobic state of the denitrification tank 14 can be easily maintained.

<<Effects of the Invention>> As explained in detail in the embodiments above, according to the deep wastewater treatment apparatus according to the present invention, the gas separation tower installed in the return passage that introduces the wastewater treatment liquid from the nitrification tank to the denitrification tank Nitrogen gas generated from a gas generator installed to produce oxygen gas for aeration is supplied to the upstream side via a nitrogen gas supply path, so the oxygen gas and nitrogen gas separated by the gas generator are By using nitrogen gas, which can be used effectively and is separated from air and does not contain corrosive gases, it has a high aeration effect.
The goal is to easily remove dissolved oxygen and bubbles from the treated liquid in the gas separation tower, maintain the anaerobic state in the denitrification tank, and make circulation equipment such as the gas separation tower inexpensive and long-lasting. effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is an overall view of a wastewater treatment device according to the present invention, and FIG. 2 is an explanatory diagram of a conventional wastewater treatment device. 10...Raw water supply channel, 14...Denitrification tank, 16...
... Nitrification tank, 32 ... Return passage, 34 ... Gas separation tower, 36 ... Gas separation device, 38 ... Nitrogen gas supply path, 40 ... Oxygen gas supply path.

Claims (1)

[Claims] 1 Consisting of a treatment tank consisting of a denitrification tank and a nitrification tank, a return passage that introduces the wastewater treatment liquid from the nitrification tank to the denitrification tank, and a gas separation tower installed in the middle of the return passage, In a deep-layer wastewater treatment device that denitrifies and nitrifies wastewater concentrate, the deep-layer wastewater treatment device includes a gas generator that separates oxygen and nitrogen from the air, and a gas generator that separates oxygen gas from the gas generator. A deep wastewater treatment comprising: an oxygen gas supply line that introduces the nitrification tank; and a nitrogen gas supply line that supplies the nitrogen gas separated by the gas generator to the upstream side of the gas separation column. Device.