JP4651201B2 - Air diffuser and air diffuser - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aeration method and an aeration apparatus, and particularly relates to a technique for supplying oxygen to activated sludge in an aeration tank by a water treatment technique.
[0002]
[Prior art]
Conventionally, in the membrane separation activated sludge method which is one of the activated sludge methods, an aeration device is arranged below the membrane separation device immersed in the aeration tank, and the air in the aeration tank is diffused by the air diffused from the aeration device. The mixed liquid in the tank containing activated sludge is aerated, and the membrane surface of the membrane separation device is washed by the upward flow of the solid-gas / liquid mixed phase generated by the rise of the diffused air.
[0003]
Oxygen necessary for biological treatment in the membrane-separated activated sludge method is ensured by supplying an aeration air amount set based on oxygen dissolution efficiency in the activated sludge with a predetermined aeration blower. Increasing the oxygen dissolution efficiency is desirable because it reduces power consumption by reducing the size of the aeration blower and reducing the aeration time.
[0004]
For this purpose, the diameter of the air outlet of the air diffuser is reduced to generate fine air bubbles, or a mechanical stirrer is provided to reduce the air bubbles diffused from the air diffuser by powerful water flow. Is distributed.
[0005]
[Problems to be solved by the invention]
However, in order to make the bubbles finer with the mechanical stirring device, power for driving the mechanical stirring device is required, and there is a limit to the practical bubble size in terms of power efficiency. In addition, if the diameter of the air outlet of the air diffuser is reduced, the air outlet is likely to be blocked by impurities in the water that reversely flow into the air diffuser when the air diffuser stops, and the degree of opening in the air diffuser decreases. Air is concentrated from some of the air outlets, and the bubbles at that location increase. Furthermore, in the activated sludge, a dissolution phenomenon occurs through the interface between water and gas. When sludge is present in the sludge, the sludge inhibits the contact between water and gas, and depending on the nature of the sludge, the oxygen dissolution efficiency is greatly reduced.
[0006]
The present invention solves the above-mentioned problems, and provides an air diffusion method and an air diffusion device that can eliminate the adverse effects of sludge, retain fine bubbles in the tank for a long time, and improve the oxygen dissolution efficiency. The purpose is to do.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the air diffusion method of the present invention according to claim 1 separates the mixed liquid in the tank of the reaction section that performs biological treatment with activated sludge, suppressing the inflow of foreign substances in the activated sludge and sludge. Supplying to the dissolution part through the means, maintaining the sludge concentration in the dissolution part at a sludge concentration lower than the sludge concentration in the reaction part, aeration of the mixed liquid in the tank in the dissolution part, and the mixed liquid in the tank in which oxygen is dissolved to the reaction part To supply .
[0008]
In the configuration described above, the separating means is composed of a screen, a nonwoven fabric, a membrane, etc., and through this separating means, the mixed liquid in the tank of the reaction part is supplied to the dissolving part, so that the activated sludge in the reaction part and the foreign matters in the sludge are dissolved in the dissolving part And the sludge property of the mixed liquid in the tank in the dissolution part is modified to one that does not contain foreign substances and at the same time a low sludge concentration is maintained.
[0009]
For this reason, in the dissolution part, the sludge concentration in the mixed liquid in the tank becomes low, and there is no foreign matter that blocks the air outlet of the air diffuser. The state of being diffused as fine bubbles can be continued for a long period of time, and the oxygen dissolution efficiency can be increased by making the diffused air into minute bubbles. Furthermore, since there is little sludge which inhibits the dissolution phenomenon through the interface between water and gas, the oxygen dissolution efficiency is increased. The mixed solution in the tank is circulated between the dissolution part and the reaction part, and is processed by a biological reaction under sufficient dissolved oxygen.
[0010]
The air diffuser of the present invention according to claim 2 is a reaction part that performs biological treatment with activated sludge, a dissolving part in which an air diffuser is disposed, and the inflow of foreign matter in the activated sludge and sludge to the mixed liquid in the tank of the reaction part. A separation means for maintaining the sludge concentration in the dissolution part lower than the sludge concentration in the reaction part, and a circulation system for returning the mixed liquid in the tank from the dissolution part to the reaction part. Is.
[0011]
With the configuration described above, the mixed solution in the tank of the reaction unit flows to the dissolution unit through the separating means, and after being aerated with the air diffused from the diffuser pipe in the dissolution unit, the mixed solution in the tank of the dissolution unit passes through the circulation system to the reaction unit. As the circulation is repeated, biological treatment is performed mainly in the reaction section.
[0012]
In this circulation, the mixed solution in the tank of the dissolving part suppresses the inflow of activated sludge in the mixed liquid in the tank of the reaction part and the foreign matters in the sludge into the dissolving part by separation means such as a screen, nonwoven fabric, membrane, etc. Thus, the sludge properties are modified to those containing no foreign matter, and the sludge concentration is lowered. For this reason, it becomes possible to reduce the diameter of the air outlet of the air diffuser by eliminating foreign matters that block the air outlet of the air diffuser, and the state where air is diffused as fine bubbles can be continued for a long time. Oxygen dissolution efficiency is increased by the minute bubbles. Furthermore, since there is little sludge which inhibits the dissolution phenomenon through the interface between water and gas, the oxygen dissolution efficiency is increased.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a dissolution part 3 is formed inside a tank body 1 by being surrounded by a separation means 2 made of a screen, a nonwoven fabric, a separation membrane, etc., and a reaction communicated with the periphery of the dissolution part 3 via the separation means 2. Part 4 is formed.
[0014]
An inflow pipe 5 for supplying water to be treated is opened in the dissolving part 3 (also possible in the reaction part 4), an outflow pipe 6 for taking out treated water is opened in the reaction part 4, and a blower 7 is provided in the dissolving part 3. A diffuser tube 8 connected to is disposed. A circulation system 10 having a circulation pump 9 is provided between the dissolution unit 3 and the reaction unit 4. The circulation system 10 communicates with the bottom of the dissolution unit 3 at the proximal end and communicates with the bottom of the reaction unit 4 at the distal end.
[0015]
With the configuration described above, the water level in the dissolution unit 3 is maintained lower than the water level in the reaction unit 4 by circulating the mixed liquid in the tank of the dissolution unit 3 through the circulation system 10 to the reaction unit 4 by the circulation pump 9. Cause a head differential.
[0016]
In this state, the mixed solution in the tank of the reaction unit 4 flows into the dissolution unit 3 through the separation means 2 using the water head difference as a driving pressure. At this time, since the separation means 2 suppresses the activated sludge in the mixed liquid in the tank of the reaction section 4 and the foreign matter in the sludge from flowing into the dissolving section 3, the sludge property of the mixed liquid in the tank in the dissolving section 3 is a foreign matter. The sludge concentration is lowered while being modified to contain no slag.
[0017]
In the dissolving part 3, the air supplied from the blower 7 is ejected from the diffuser tube 8, and the mixed liquid in the tank is aerated with this air. At this time, since the liquid mixture in the tank of the dissolution unit 3 has a low sludge concentration and does not contain foreign matter, the air outlet of the air diffuser 8 is not blocked, and the diameter of the air outlet can be reduced. It becomes possible, and the state where air is diffused as fine bubbles can be continued for a long period of time, and the oxygen dissolution efficiency is increased by the fine bubbles. Furthermore, since there is little sludge which inhibits the dissolution phenomenon through the interface between water and gas, the oxygen dissolution efficiency is increased.
[0018]
In addition, the circulation system 10 that opens to the bottom of the tank sucks the mixed liquid in the tank, so that the mixed liquid in the tank flows downward from the upper region toward the lower region. On the other hand, the air diffused from the diffuser tube 8 rises from the lower region toward the upper region, so that the mixed liquid in the tank and the aerated air are in gas-liquid countercurrent contact. For this reason, the rise of the air bubbles is suppressed by the downward flow of the mixed liquid in the tank, and the residence time of the bubbles in the tank becomes longer, and the oxygen dissolution efficiency is increased.
[0019]
The in-tank mixed solution in which oxygen is sufficiently dissolved in the dissolution unit 3 is circulated from the dissolution unit 3 to the reaction unit 4 through the circulation system 10 and is processed by a biological reaction under sufficient dissolved oxygen.
At this time, the mixed liquid in the tank flows into the reaction unit 4 in an upward flow from the bottom, so that the mixed liquid in the tank of the reaction unit 4 is stirred and the reaction efficiency between the activated sludge and oxygen and pollutants is increased. Is promoted. For this reason, the power of the circulation pump 9 can be contributed to the improvement of reaction efficiency without waste. The mixed liquid in the tank is biologically treated mainly in the reaction part 4 while circulating through the dissolution part 3 and the reaction part 4, but biological reaction also occurs in the dissolution part 3.
[0020]
FIG. 2 shows another embodiment of the present invention. In FIG. 2, the dissolution unit 3 and the reaction unit 4 are provided as independent tank bodies, and the dissolution unit 3 is connected to the reaction unit 4 through a natural flow system 11, and the reaction unit is connected through a circulation system 10 having a circulation pump 9. 4 is connected to the melting part 3, and an outside tank type membrane separation device 12 is interposed in the circulation system 10.
[0021]
In this configuration, the circulating pump 9 circulates the mixed solution in the tank of the reaction unit 4 through the circulation system 10 and the membrane separator 12 to the dissolving unit 3, and the separation means 2 activates the sludge in the mixed solution in the tank of the reaction unit 4. In addition, by preventing the foreign matter in the sludge from flowing into the dissolution part 3, the mixed liquid in the tank in the dissolution part 3 is modified so that the sludge property does not contain foreign matters and the sludge concentration is kept low. Other functions and effects are the same as in the previous embodiment. In addition, when taking out the treated water from the reaction unit 4, a separate membrane separation device may be provided outside the tank, and an immersion type membrane separation device may be disposed inside the reaction unit 4.
[0022]
【The invention's effect】
As described above, according to the present invention, the separation means suppresses the activated sludge in the mixed liquid in the tank of the reaction section and the foreign matter in the sludge from flowing into the dissolving section, and the sludge properties of the mixed liquid in the tank of the dissolving section. By reducing the sludge concentration, the air outlet of the air diffuser tube is not ejected by foreign matter, and the air outlet of the air diffuser tube is made smaller to diffuse fine air bubbles. It can be continued for a long time, and the oxygen dissolution efficiency can be increased by the minute bubbles. Furthermore, oxygen dissolution efficiency can be increased by eliminating sludge that inhibits the dissolution phenomenon through the interface between water and gas. By flowing the mixed liquid in the tank in the dissolving part in the downward flow, the air diffused from the diffuser tube is brought into gas-liquid countercurrent contact, and the rise of the air bubbles is suppressed by the downward flow, thereby reducing the residence time of the bubbles in the tank. The oxygen dissolution efficiency can be increased by increasing the length.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an air diffuser according to an embodiment of the present invention.
FIG. 2 is a schematic view showing an air diffuser according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tank body 2 Separation means 3 Dissolution part 4 Reaction part 5 Inflow piping 6 Outflow piping 7 Blower 8 Aeration pipe 9 Circulation pump 10 Circulation system 11 Natural flow system 12 Membrane separation device

Claims (2)

The mixed liquid in the tank of the reaction section that performs biological treatment with activated sludge is supplied to the dissolution section through separation means that suppresses the inflow of foreign substances in the activated sludge and sludge, and the sludge concentration in the dissolution section is lower than the sludge concentration in the reaction section. An air diffusion method characterized by maintaining the sludge concentration, aeration of the mixed liquid in the tank at the dissolving section, and supplying the mixed liquid in the tank in which oxygen is dissolved to the reaction section . A reaction section that performs biological treatment with activated sludge, a dissolution section with an aeration tube, and a mixture in the reaction section are supplied to the dissolution section while suppressing the inflow of foreign matter in the activated sludge and sludge. An aeration apparatus comprising separation means for maintaining the sludge concentration at a sludge concentration lower than the sludge concentration in the reaction section, and a circulation system for returning the mixed liquid in the tank from the dissolution section to the reaction section .

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