JP2003251384A - Pretreatment method for biological wastewater treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel and economical wastewater pretreatment system extremely enhanced in treatment efficiency. <P>SOLUTION: A filter is arranged at the central part of a biological wastewater treatment front stage by a wastewater pressurizing means and a pipe for supplying pressurized water and air is attached to the upper part thereof. A mixing device is constituted of a mixing container main body having an outflow port provided to the lower part thereof and a plurality of baffles arranged to the lower part of the filter arranged so that flow channels become narrower in a downstream direction. The load of wastewater can be reduced by providing this mixing device in a state to pass the wastewater. <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 in particular to treating wastewater generated from various industries, domestic wastewater from households, sewage and other wastewater (abbreviated as wastewater). Wastewater treatment system.

[Prior Art] Various types of waste water pretreatment devices have been proposed, such as a rotating disk method and a fixed tank method, all of which are on an extension of the prior art and are based on biological treatment.
The present invention is applied to our company, wastewater treatment system and mixing device.

[Reference number] FM00001

[Submission date] This was based on November 30, 2001. [Problems to be Solved by the Invention]
Various proposals such as the rotating disk method and the fixed tank method have been proposed, but they are an extension of the conventional technology and are based on biological treatment. The present invention is the application of the present invention, a wastewater treatment system and a mixing device.

[Reference number] FM00001

[Submission date] This was based on November 30, 2001.

Pretreatment method for biological wastewater treatment which enables combined use of oxidative decomposition and biological oxidation, reduction of excess sludge by dismantling and re-nutritioning excess sludge, and halving the size of the entire treatment equipment. Is to provide.

[Means for Solving the Problem] In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that, in the pretreatment stage of biological wastewater treatment, the central portion is provided with a means for pressurizing the wastewater to a condition of 0.3 MPaG or less. A filter is placed on the top of the mixing vessel, a pipe for supplying pressurized water and air is attached to the top, and a mixing container body with an outlet is provided at the bottom, and the flow path becomes narrower toward the bottom of the filter as it goes downstream. After passing through a mixing device characterized by comprising a plurality of baffles arranged in, the microbes having a size of 1 micron or less are contained in an amount of 20 weight percent or more of the fluid amount at atmospheric pressure, It is characterized in that it is adapted to pass through a microbial cell fixing means which fixes the body.

According to a second aspect of the present invention, in the biological wastewater pretreatment method according to the first aspect, a cross plate is arranged between the outlet of the baffle plate and the outlet of the mixing container. To do.

According to a third aspect of the present invention, in the biological wastewater pretreatment method according to the first aspect, the filter is a cylindrical ceramic filter or a hollow fiber membrane is provided in a columnar body having holes. It is a filter.

According to a fourth aspect of the present invention, in the pretreatment stage of biological wastewater treatment, a filter is arranged in the central portion by means of pressurizing the wastewater to a condition of 0.3 MPaG or less, and pressurized water and air are supplied to the upper part. And a plurality of baffle plates arranged so that the flow passage becomes narrower toward the lower part of the mixing container main body having an outlet provided at the lower part thereof. It is characterized in that fine bubbles of 1 micron or less are contained in an amount of 20 weight percent or more of the fluid amount in terms of atmospheric pressure by passing through the mixing device.

According to a fifth aspect of the present invention, in the biological wastewater pretreatment method according to the fourth aspect, a cross plate is arranged between the outlet of the baffle plate and the outlet of the mixing container. To do.

According to a sixth aspect of the present invention, in the pretreatment method for biological wastewater treatment according to the fourth aspect, the filter is a cylindrical ceramic filter, or a hollow fiber membrane is provided in a hollow cylindrical body. It is a filter.

The invention according to claim 7 is the pretreatment method for biological wastewater treatment according to claim 1, characterized in that the fine bubbles mainly contain oxygen gas.

The invention according to claim 8 is the pretreatment method for biological wastewater treatment according to claim 1, characterized in that the fine bubbles contain ozone gas.

The invention according to claim 9 is the pretreatment method for biological wastewater treatment according to claim 4, characterized in that the fine bubbles contain ozone gas.

The invention according to claim 10 is the pretreatment method for biological wastewater treatment according to claim 4, characterized in that the fine bubbles mainly contain oxygen gas.

The invention according to claim 11 is characterized in that in the pretreatment method for biological wastewater treatment according to claim 1, the fine bubbles have a temperature of 70 ° C. or higher.

According to the twelfth aspect of the present invention, in the pretreatment method for biological wastewater treatment according to the first aspect, the fine bubbles mainly contain oxygen gas at 70 ° C. or higher.

The invention according to claim 13 is characterized in that in the pretreatment method for biological wastewater treatment according to claim 1, the fine bubbles have a temperature of 70 ° C. or higher.

According to a fourteenth aspect of the present invention, in the biological wastewater treatment pretreatment method according to the fourth aspect, the fine bubbles have a temperature of 70 ° C. or higher.

The invention according to claim 15 is the pretreatment method for biological wastewater treatment according to claim 4, characterized in that the fine bubbles mainly contain oxygen gas at 70 ° C. or higher.

The invention according to claim 16 is defined by claims 1 to 15.
In the biological wastewater treatment pretreatment method described, the mixing device is a static mixer.

The invention according to claim 17 is the invention according to claims 1 to 15.
In the biological wastewater treatment pretreatment method described above, a pressure means is provided at the outlet of the mixing device, and the mixing treatment is repeated a plurality of times.

Next, the basic principle of the new technology will be described. The mixer of the present invention has the functions of arbitrarily controlling the size of the microvalve and adjusting the film surface speed, and maximizing the mixing bubble amount at low pressure. It is considered that the mixed microbubbles hit the baffle plate to maximize turbulence and activate oxygen molecules. Normally, this phenomenon occurs even in ozone treatment, but when it is introduced into wastewater, it reacts and is consumed immediately. It is presumed that, since microbubbles are activated in water, changes occur at each bubble interface, which promotes an efficient decomposition reaction at low pressure. Such a technology is a completely new invention, It can change the basis of wastewater treatment technology.

At the same time, a bubble destruction phenomenon occurs and heat is locally generated to accelerate oxidative decomposition. 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. By this treatment, in the treatment of rice washing wastewater, which is considered to be untreatable, the efficiency of the order of magnitude was achieved, compared with the ordinary bucky method.

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 flora changes markedly and 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.

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 the raw water, and a raw water pit 2 for storing the raw water filtered by this screen 1 And a mixer 4 for injecting micro bubbles and bacteria into the raw water flowing out from the raw water pit 2.
And a bacterial cell fixing tank 5 on which the bacterial cells are fixed, a raw water adjusting tank 3 into which raw water containing microbubbles and bacterial cells flows, an aeration tank 6 for aeration of the raw water adjusted by the raw water adjusting tank 3, and this aeration tank Settling tank 7 for storing the raw water aerated in 6 and this settling tank 7
A discharge pit 8 for storing the supernatant liquid, a compressor 10 for pressurizing air and injecting it into the mixer 4,
The sludge tank 11 stores the sludge settled in the settling tank 7, and the sludge dewatering machine 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, in the mixer 4, microbubbles of 1 micron or less are uniformly pressurized and mixed at high speed, and the oxygen molecules in the microbubbles are activated by the violent turbulence that occurs at this time, which results in the oxidation of the raw water. Decomposition occurs. 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 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 3 hours with respect to the amount of water held in the raw water adjusting tank 3. The BOD load is reduced to 1/2 to 1/3 by operating the mixing line so as to pass through the mixing line. 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, etc. The results are shown in Table 1 (reduction rate of excess sludge), and compared with the aeration method using persistent rice washing wastewater. It shows in Table 2.

[0031]

[Table 1]

[0032]

[Table 2]

As described above, the wastewater treatment system of the present invention is extremely effective as a measure for reducing the load of wastewater treatment by the activated sludge method in food factories. Further, it is effective for reducing the load of wastewater treatment by the activated sludge method in pulp mills, chemical mills, etc. and reducing excess sludge. Further, it is effective for reducing the load of wastewater treatment by the activated sludge method of human waste water and reducing excess sludge.

Further, the comparison of COD (Cr) concentration under each condition was carried out by an experiment using a persistent rice wash wastewater, and the results are shown in Table 3.

[0035]

[Table 3] Raw water was adjusted to a COD (Cr) concentration of 1000 PPM, and 10 liters / 1000 liters of undiluted solution
The minute pressure was 0.3 MPaG, the gas mixture amount was 0.2 micron, and the fine bubbles were 20 weight percent of the fluid amount in terms of atmospheric pressure.

[Effects of the Invention] As described above, according to the wastewater treatment system of the present invention, it can be used in various fields in which organic load reduction is required, and it becomes possible to efficiently reduce excess sludge and the like. It is possible to reduce the capacity of the treatment tank to 50% or less, 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.

2A and 2B are schematic configuration diagrams of a mixing device according to an embodiment of the present invention. FIG. 2A is a sectional view, FIG. 2B is a perspective view of an upper portion of a container, and FIG. 2C is a cross plate. Perspective view.

[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 ... sedimentation tank, 8 ... discharge pit, 9 ... compressor, 10 ... Sludge layer ... 11 Sludge dewatering machine 20 ... Mixing container body, 21
... filter, 22 ... baffle plate, 23 ... cross plate,
23a ... Partition plate, 24 ... Lid, 25 ... Outflow port, 26, 2
7 ... tube.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 1/78 C02F 1/78 3/06 3/06

Claims (17)

[Claims] 1. The waste water is treated in the first stage of biological wastewater treatment,
By a means for pressurizing to a condition of 3 MPaG or less, a filter is arranged in the central part, a pipe for supplying pressurized water and air is attached to the upper part, and a mixing container main body having an outlet in the lower part, and a lower part of the filter. Through a mixing device characterized in that it is composed of a plurality of baffles arranged so that the flow path becomes narrower as it goes downstream, A method for pretreatment of biological wastewater treatment, characterized in that after containing 20 weight% or more, the cells are passed through a cell fixing means in which cells are fixed. 2. The biological wastewater treatment pretreatment according to claim 1, wherein a cross plate is arranged between the outlet of the baffle plate and the outlet of the mixing container. Law. 3. The method for pretreatment of biological wastewater treatment according to claim 1, wherein the filter is a cylindrical ceramic filter or a filter in which a hollow fiber membrane is provided in a perforated columnar body. Characteristic biological wastewater treatment pretreatment method. 4. The waste water is treated in an amount of 0, 3 before the biological waste water treatment.
A filter is arranged in the central part by means of pressurizing under conditions of MPaG or less, a pipe for supplying pressurized water and air is attached to the upper part, and a mixing container main body having an outlet in the lower part, and a lower part of the filter. Through a mixing device characterized in that it is composed of a plurality of baffles arranged so that the flow path becomes narrower as it goes downstream, Two
A pretreatment method for biological wastewater treatment, characterized in that it is contained in an amount of 0 weight percent or more. 5. The method for pretreatment of biological wastewater treatment according to claim 4, wherein a cross plate is arranged between the outlet of the baffle plate and the outlet of the mixing container. Law. 6. The biological wastewater pretreatment method according to claim 4, wherein the filter is a cylindrical ceramic filter,
Alternatively, a biological wastewater treatment pretreatment method is characterized in that it is a filter in which a hollow fiber membrane is provided in a cylindrical body having holes. 7. The biological wastewater treatment pretreatment method according to claim 1, wherein the fine bubbles mainly contain oxygen gas. 8. The biological wastewater treatment pretreatment method according to claim 1, wherein the fine bubbles contain ozone gas. 9. The pretreatment method for treating biological wastewater according to claim 4, wherein the fine bubbles contain ozone gas. 10. The pretreatment method for biological wastewater treatment according to claim 4, wherein the fine bubbles mainly contain oxygen gas. 11. The biological wastewater treatment pretreatment method according to claim 1, wherein the fine bubbles have a temperature of 70 ° C. or higher. 12. The biological wastewater treatment pretreatment method according to claim 1, wherein the fine bubbles mainly contain oxygen gas at 70 ° C. or higher. 13. The biological wastewater treatment pretreatment method according to claim 1, wherein the fine bubbles have a temperature of 70 ° C. or higher. 14. The biological wastewater treatment pretreatment method according to claim 4, wherein the fine bubbles have a temperature of 70 ° C. or higher. 15. The pretreatment method for treating biological wastewater according to claim 4, wherein the fine bubbles mainly contain oxygen gas at 70 ° C. or higher. 16. The biological wastewater treatment pretreatment method according to claim 1, wherein the mixing device is a static mixer. 17. The method for pretreatment of biological wastewater treatment according to claim 1, wherein a pressure means is provided at the outlet of the mixing device to repeat the mixing treatment a plurality of times.