JP2003245662A - Waste water treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce excess sludge and to provide an effective treatment method for waste water. <P>SOLUTION: A microbubble generation means, a cavitation technique and a discharge system are provided in order to solve the problem. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment system and a mixing device, and more particularly to a novel treatment of wastewater generated from various industries, domestic wastewater from processes, sewage and other wastewater (abbreviated as wastewater). Wastewater treatment system.

[Prior Art] When wastewater generated from various industries such as food plants, pulp plants, chemical plants, etc. and household wastewater or sewage and other wastewater are discharged as they are, not only rivers, lakes and oceans but also soil and The environment is also polluted, and the human life itself is in a critical state, so countermeasures against it are an urgent task. In order to avoid such a situation, industrial facilities, local governments, etc. have installed wastewater treatment devices to discharge environmentally friendly wastewater.

By the way, conventional wastewater treatment methods for treating wastewater generated from various industries, domestic wastewater from households, sewage, and other wastewater are roughly classified into physical types in which contaminants or contaminants are separated and removed by filtration, precipitation, or the like. Processing,
A chemical treatment has been performed in which fine particles are aggregated and removed by using a chemical agent or the like. In addition to this, the activated sludge method utilizing microorganisms has recently been drawing attention. The activated sludge method utilizing microorganisms is characterized in that wastewater that is difficult to remove physically or chemically can be effectively treated without using a special chemical, that is, without adversely affecting the environment.

Usually, microorganisms are classified into aerobic and anaerobic ones. Aerobic bacteria grow and grow under aerobic conditions and eventually die under anaerobic conditions. On the contrary, anaerobic bacteria grow and proliferate under anaerobic conditions, and become a growth quiescent state under aerobic conditions, and eventually die. However, microorganisms absorb organic substances or nitrogen and phosphorus as nutrients under their growth and growth conditions, but the absorption action of such nutrients is stopped in a growth quiescent state, so organic substances are not treated in wastewater treatment using microorganisms. Although it is treated, nitrogen and phosphorus are left untreated and are not necessarily effective for wastewater containing a large amount of nitrogen and phosphorus.

[Problems to be Solved by the Invention] In general wastewater, as represented by BOD (biological oxygen demand) and COD (amount of suspended solids), nitrogen and phosphoric acid are mixed together with organic matter. Therefore, in order to treat such wastewater with microorganisms, it is necessary to install special treatment equipment that has formed aerobic and anaerobic conditions, which makes the treatment operation complicated and Since the equipment becomes large, there is a problem that the equipment cost and the operation cost are also increased.

In order to solve the problems of the conventional equipment for treating wastewater using the above-mentioned microorganisms, wastewater and a microorganism mainly composed of Bacillus and an activator of this microorganism are injected into the rotary treatment section, A method for purifying wastewater by microorganisms (Japanese Unexamined Patent Publication No. 11-42496) has been proposed, which is configured to rotate the crossed porous tissue rotating body made of a fibrous material such as a constituent resin under the condition of being partially immersed in the wastewater. There is.

[0007] Further, as a method for purifying other waste water by microorganisms, a method of promoting nitrification by aeration in a raw water adjusting tank, or ozone treatment at the inlet of the raw water adjusting tank to damage molecules A method for accelerating the purification of wastewater by microorganisms is carried out by a method of accelerating the treatment, or a method of performing a primary nitrification treatment by providing a rotating disk or a fixed tank at the outlet of the raw water adjusting tank. However, all of these conventional techniques were developed mainly as a measure for adding an aeration tank, and the contents of the conventional techniques are merely to promote bionitrification, and the initial cost and running cost of the entire wastewater treatment system Could not be significantly reduced.

The present invention has been made in order to improve the above-mentioned conventional wastewater treatment system, and its object is to provide a novel wastewater treatment system which has extremely high treatment efficiency and is economical.

[Means for Solving the Problem] In order to solve the above-mentioned problems, the invention according to claim 1 is a wastewater treatment system for treating wastewater, and in the wastewater treatment system, fine bubble generating means for generating microbubbles and the fine bubble generating means. A high-pressure pulse is added to the depressurized wastewater, which comprises a pressurizing means for pressurizing the microbubbles generated by the bubble-generating means into wastewater containing bacterial cells, and a depressurizing means for rapidly depressurizing the pressurized fluid. It is characterized in that oxygen in the microbubbles is converted into radicals by discharging.

According to a second aspect of the present invention, in a wastewater treatment system for treating wastewater, fine bubble generating means for generating microbubbles containing oxygen gas as a main component and microbubbles generated by the fine bubble generating means are provided. The waste water containing the bacterial cells is provided with a pressurizing means for pressurizing and a depressurizing means for rapidly depressurizing the pressurized fluid, and the depressurized waste water is charged with oxygen in the microbubbles by high-pressure pulse discharge. It is characterized in that it is radicalized.

According to a third aspect of the present invention, in a wastewater treatment system for treating wastewater, microbubble generating means for generating microbubbles containing ozone gas, and microbubbles generated by the microbubble generating means include bacterial cells. The wastewater is provided with a pressurizing means for pressurizing and a depressurizing means for rapidly depressurizing the pressurized fluid, so that the high-pressure pulse discharge is applied to the depressurized wastewater to increase the radicals in the microbubbles. It is characterized by having done.

According to a fourth aspect of the present invention, in a wastewater treatment system for treating wastewater, microbubble generating means for generating microbubbles, and microbubbles generated by the fine bubble generating means for wastewater containing bacterial cells, It is provided with a pressurizing unit for pressurizing and a depressurizing unit for rapidly depressurizing the pressurized fluid, and the depressurized wastewater is irradiated with ultraviolet rays to radicalize oxygen in the microbubbles. Characterize.

According to a fifth aspect of the present invention, in a wastewater treatment system for treating wastewater, microbubble generating means for generating microbubbles containing ozone gas, and microbubbles generated by the microbubble generating means include bacterial cells. The wastewater is provided with a pressurizing means for pressurizing and a depressurizing means for rapidly depressurizing the pressurized fluid.

The invention according to claim 6 is characterized in that a microbial cell fixing means for fixing microbial cells is added to the subsequent stage of claims 1 to 5.

The invention according to claim 7 is the same as claim 1 to 6
It is characterized in that it is processed under the condition of H8 or more and 12 or less.

Claim 1, Claim 2, Claim 3, and Claim 4
According to the invention, microbubbles and cavitation power, oxidative decomposition by radical generation by discharge,
The wastewater treatment efficiency can be greatly improved due to the synergistic effect of microemulsion and the like by crushing and dispersing.

According to the sixth aspect of the invention, the treatment efficiency is further improved by passing the radical-treated waste liquid through the fixing tank in which the bacterial cells suitable for its properties are fixed and propagated.

Next, the basic principle of the new technology will be described. Fluid mixed with a large amount of microvalve is pressurized,
Cavitation occurs due to repeated rapid depressurization or strong agitation, and further discharge in the mixing section causes oxygen molecules to radicalize, and bubble destruction also occurs at the same time, causing local heat generation. Oxidative decomposition is promoted. Then, a phenomenon such as breaking the bonds of organic substances contained in the wastewater occurs to lower the molecular weight, and is stripped from the water in the form of methane, ethane, propane, etc., and nitrification is likely to occur in the latter stage. In addition, the oil damage also becomes a microemulsion, which covers the surface of the bacterial cells and causes an oxygen intake failure.

In the case where only this treatment is carried out in the raw water conditioning tank, the residence time is about half a day, so the microorganisms produced by this treatment flow into the latter aeration tank, but inside or outside the treatment outlet tank. The treatment level is markedly improved by providing a cell-fixing tank in the. The immobilization carrier may be any substance that can immobilize bacterial cells, such as a simple substance applied with a braiding technique, an interstitial porous tissue made of synthetic fibers, a ceramic porous body, or the like.
In addition, it is possible to enhance the emulsification ability by adding a fine bubble generator in combination with the inlet of the fixing tank. Immobilization of Bacillus is effective as a microorganism to be fixed in the cell-fixing tank, and it is common that a plurality of the following microorganisms are contained. That is, as microorganisms, Opelclaria, Volticera,
Kinetokimul, paramesium, colpoda, colpidium, vodo, eucomonas, monas, pleuromonas, lab drymus, filogina, pristina, zogrea,
Examples include Begia Toa and Spherocillus. The BOD removal rate by this treatment is 70% or more, and the removal rate of nitrogen and phosphorus is 9%.
Achieved 0% or more.

Further, a method has been proposed in which excess sludge is treated with high pressure or mixed with ozone and oxides, solubilized and retreated in an aeration tank, but the microflora changes remarkably or the treatment condition is poor. However, there are problems such as concentration of phosphorus. By introducing these treatment liquids into the wastewater treatment system of the present invention, a sufficient sludge reduction effect can be obtained even if these treatment capacities are reduced to less than half, and obstacles are eliminated.

Further, this system was confirmed by changing the PH conditions, and it was confirmed that the sludge reducing effect was obtained under the conditions of PH8-12. BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic flow diagram of a wastewater treatment system using microorganisms according to an embodiment of the present invention.

As shown in the figure, in the wastewater treatment system of this embodiment, a screen 1 for filtering dust and the like mixed in the wastewater, which is raw water, and a raw water pit 2 for storing the raw water filtered by this screen 1. And a mixer 4 for injecting microbubbles and bacterial cells into raw water flowing out from the raw water pit 2 under pressure and reduced pressure, and a bacterial cell fixing tank 5 in which Bacillus bacterial cells are fixed
A raw water adjusting tank 3 into which raw water containing microbubbles and bacteria flows, an aeration tank 6 for aerating the raw water adjusted by the raw water adjusting tank 3, and a precipitation tank 7 for storing the raw water aerated by the aeration tank 6. A discharge pit 8 for discharging the supernatant of the settling tank 7, a high-pressure pulse discharge device 9, a compressor 10 for pressurizing air and injecting it into the mixer 4, and a sludge settling in the settling tank 7. It is composed of a sludge tank 11 and a sludge dehydrator 12 that dehydrates the sludge in the sludge tank 11 into a cake.

Next, the operation of this embodiment will be described. In the figure, by injecting the microbubbles generated by the mixer 4 into the bacterial cell fixing tank 5, a large amount of the mixed bacterial cells and air are pressurized to the raw water adjusting tank 3 together with the waste water which is the raw water. Although it flows in, the mixer 4 repeats pressurization and depressurization, so cavitation that occurs at this time and the subsequent turbulent flow destroys the microbubbles, and further discharges oxygen molecules into radicals, thereby oxidizing the wastewater that is raw water. Decomposition occurs. At the same time, when the wastewater is flowed into the raw water adjusting tank 3, the organic substances contained in the wastewater are disconnected and stripped from the water in the form of methane, ethane, propane or the like. Then, since the micro bubbles in the wastewater discharged into the raw water adjusting tank 3 remain for a long time, the supersaturated dissolved oxygen state is kept in the raw water adjusting tank 3 during that time, and the biological oxidation proceeds.

Generally, as the biological oxidation progresses, a large amount of anaerobic bacteria will flow into the aeration tank 6 next to the raw water conditioning tank 3, which causes a reduction in the treatment capacity. Since the inside of the raw water adjusting tank 3 maintains a supersaturated dissolved oxygen state, aerobic bacteria flow into the aeration tank 6 to help the wastewater treatment. Further, the sludge dehydrated by the sludge dehydrator 12 is carried out as a cake to the outside.

In the figure, the aeration tank 6 is the first aeration tank 6
A, the second aeration tank 6B, and the third aeration tank 6C are composed of three tanks. Such a structure is determined depending on the polluted state of the waste water, and one tank may be used, or when five tanks are used. There is also a possibility. This also applies to the raw water adjusting tank 3.

As described above, the waste water is treated in the raw water adjusting tank 3, but the amount of return from the outlet of the raw water adjusting tank to the inlet is 1 turn in 2 hours with respect to the amount of water held in the raw water adjusting tank 3. The BOD load can be reduced to 1 / by operating the emulsion mixing line at a processing flow rate of
It becomes 2 to 1/3. As a result of the experiment, it was clarified that the generation of excess sludge was significantly reduced and the removal rate of nitrogen and phosphorus was significantly improved. The microorganisms used at this time were mainly Monas, Opelclaria, Borticella, and the like. The results are shown in Table 1 (Excess sludge reduction rate)
And Table 2 (removal rates of nitrogen and phosphorus).

[0027]

[Table 1]

[0028]

[Table 2]

According to the results of this experiment from this table, BOD:
1200 mg / l, SS: 7000 mg / l, water amount 50
The amount of surplus sludge was 3 t / day (dehydrated cake) in raw wastewater of 0 t / day, but after the emulsion treatment of the present invention, it became BOD: 300 mg / l, SS: 400 mg / l, and the surplus sludge amount was almost It disappeared, and I had to clean dust and sand several times a day. In the same raw wastewater as in Table 1, N: 700 mg / l, P: 44.4 mg
/ L was N: 300 mg / l and P: 20.0 mg / l after the emulsion treatment of the present invention, and further N: 15 mg / l in the case where the immobilization tank was installed.
1, P: 3 mg / l.

As described above, the wastewater treatment system of the present invention is effective for reducing the load of wastewater treatment by the activated sludge method in food factories, reducing excess sludge, and countermeasures for nitrogen and phosphorus. It is also effective in reducing the load of wastewater treatment by activated sludge method at pulp mills, chemical mills, etc., reducing excess sludge, and countermeasures for nitrogen and phosphorus. Furthermore, it is effective for reducing the load of wastewater treatment by the activated sludge method of human waste water, reducing excess sludge, and taking measures for nitrogen and phosphorus.

For the comparison of the radical generation amount, a liquid cyclone is installed inline at the treated water outlet in the process of the same treatment with pure water, and the introduced gas amount is excessively added to compare the ozone concentration in the cyclone separation gas. The results are shown in Table 3.

[0032]

[Table 3]

MLSS for changes under alkaline conditions
MLS with the same circulation treatment using 5000 wastewater sludge
Table 4 shows the results obtained by comparing the S reduction rates.

[0034]

[Table 4]

Further, the mixing apparatus of the present invention is not limited to the above-mentioned structure. For example, one flow path through which a fluid flows is branched, and the fluid flowing through the branched flow path is flowed at a very high speed. Any device can be used as the mixing device of the present invention as long as it is a device that creates a state in which air and the like are mixed with microbubbles by colliding and forming one flow path. As an example of this, Japanese Patent Laid-Open No.
-261525 and the emulsification device described in JP-A-7-10
The atomization device described in Japanese Patent No. 0404 can be mentioned.

[Effects of the Invention] As described above, according to the wastewater treatment system of the present invention, microorganisms can be surely destroyed and can be used in various fields in which sterilization of microorganisms is required, and efficient reduction of excess sludge can be achieved. It is also possible to prevent slime generation in the production of paper pulp, and it is also effective as a measure to reduce the load at the front stage of the septic tank due to the spread of disposers.

[Brief description of drawings]

FIG. 1 is a schematic flow diagram of a wastewater treatment system that is an embodiment of the present invention.

[Explanation of symbols]

1. ． ． Screen, 2. ． ． Raw water pit, 3. ． ． Raw water adjusting tank, 4. ． ． Mixer, 5. ． ． Fixed tank,
6. ． ． Aeration tank, 6A. ． ． First aeration tank, 6B. ． ． Second aeration tank, 6C. ． ． Third aeration tank, 7. ． ． Settler,
8. ． ． Release pit, 9. ． ． Compressor, 1
0. ． ． Discharge device, 11. ． ． Sludge layer, 12. ． ． Sludge dehydrator

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 1/78 C02F 1/78 4G036 3/06 3/06 C12M 1/40 C12M 1/40 Z F term (reference) 4B029 AA27 BB02 CC03 4D003 AA01 BA02 CA01 CA10 EA17 EA18 EA24 EA30 FA07 4D037 AA11 BA18 BA26 BB04 BB05 BB07 CA07 CA12 CA14 4D050 AA12 BB01 BB02 BC09 BC10 BD03 BD06 CA07 CA13 CA17 CA20 4G035 AB36 AE05

Claims (7)

[Claims] 1. A wastewater treatment system for treating wastewater, comprising fine air bubble generating means for generating microbubbles,
The wastewater containing microbes generated by the microbubble generating means, a pressurizing means for pressurizing, and a depressurizing means for rapidly depressurizing the pressurized fluid, to the depressurized wastewater, A wastewater treatment system characterized in that oxygen in microbubbles is converted into radicals by high-voltage pulse discharge. 2. A wastewater treatment system for treating wastewater, wherein microbubble generating means for generating microbubbles containing oxygen gas as a main component, and microbubbles generated by the microbubble generating means are added to wastewater containing bacterial cells. A pressurizing means for pressurizing and a depressurizing means for rapidly depressurizing the pressurized fluid are provided, and high-pressure pulse discharge is applied to the depressurized waste water to radicalize oxygen in the microbubbles. A wastewater treatment system characterized in that 3. A wastewater treatment system for treating wastewater, wherein microbubble generating means for generating microbubbles containing ozone gas, and microbubbles generated by the microbubble generating means are added to the wastewater containing bacterial cells under pressure. It is characterized in that it is provided with a pressure means and a decompression means for rapidly decompressing the pressurized fluid, and is characterized in that radicals in the microbubbles are increased by subjecting the decompressed wastewater to high-pressure pulse discharge. Wastewater treatment system. 4. A wastewater treatment system for treating wastewater, comprising fine air bubble generating means for generating microbubbles,
The wastewater containing microbes generated by the microbubble generating means, a pressurizing means for pressurizing, and a depressurizing means for rapidly depressurizing the pressurized fluid, to the depressurized wastewater, A wastewater treatment system characterized in that oxygen in microbubbles is converted into radicals by irradiation with ultraviolet rays. 5. A wastewater treatment system for treating wastewater, wherein microbubble generating means for generating microbubbles containing ozone gas, and microbubbles generated by the microbubble generating means are added to the wastewater containing bacterial cells under pressure. A wastewater treatment system comprising: a pressure means and a decompression means for rapidly decompressing the pressurized fluid. 6. The method according to any one of claims 1 to 5, wherein a microbial cell fixing means for fixing the microbial cell is added. Wastewater treatment system. 7. A wastewater treatment system, characterized in that the treatment according to any one of claims 1 to 6 is carried out under a condition of PH 8 or more and 12 or less.