JPH0966292A - Treatment of water containing organic substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the life of a membrane and to make a treatment apparatus compact by bringing activated humic pellets into contact with a mixed soln. containing a sludge like reaction substance and adding a ceramic powder to the mixed soln. SOLUTION: Activated sludge obtained from raw waste water is brought into contact with the activated humic pellets 109 and/or powder immersed in the mixed soln. in a biological reactor 102 and the reaction such as bonding, granulation, flocculation, condensation or polymerization of the soluble substance in the sludge is advanced and the granulation reaction of solid particles resulting from waste water is also advanced and the offensive smell peculiar to sewage is markedly reduced. Further, a ceramic powder is supplied to the mixed soln. in the biological reactor 102 from a ceramics powder supply device 110 and, since the ceramic powder is fluidized along with the mixed soln. by a blower 103, the surface of the membrane module of a membrane separator 106 is ground and washed by the powder and the adhesion of a polymeric component to a membrane is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating wastewater containing organic substances such as domestic wastewater such as urban sewage and community wastewater, livestock wastewater, marine product processing wastewater, agricultural product processing wastewater and the like. More specifically, the present invention is a so-called "membrane separation activated sludge method" in which wastewater containing an organic substance is biologically treated and a mixed solution containing a sludge-like reactive substance produced is solid-liquid separated by a membrane module. And the like, the present invention relates to a method for treating wastewater in which the membrane life can be extended by further increasing the membrane permeated water, the treatment apparatus can be made compact, and the amount of sludge generation does not increase.

[0002]

2. Description of the Related Art Conventionally, a standard activated sludge method using an apparatus as shown in FIG. 5 has been generally performed as a method for treating the above-mentioned waste water. In this method, drainage is temporarily stored in the adjusting tank 1, and if necessary, liquid is made uniform, nutrients are added, and pH is adjusted.
After adjustment and the like, a certain amount thereof is supplied to the aeration tank 2.
While staying in the aeration tank 2 for a certain period of time, the organic substances contained in the waste water are oxidatively decomposed by the aerobic bacteria that are actively active by the air sent from the blower 3, and include sludge-like reaction substances. A mixed solution, i.e. activated sludge, is formed.

This mixed solution is sent to the sedimentation tank 4.
The sludge-like substance in which the solid content is concentrated by being retained and settled in the settling / separation tank 4 for a certain period of time is sent to the dehydrator 5 and dehydrated to obtain a dehydrated cake. In addition, a part of the sludge-like substance concentrated in the sedimentation separation tank 4 is returned to the aeration tank 2 by the sludge pump SP and circulated for use to maintain the concentration of the solid content in the aeration tank, thereby aerobic bacteria. The oxidative decomposition reaction by is maintained.

In such a standard activated sludge method, when an organic substance contained in the waste water is treated in the aeration tank 2 in a suitable manner, the settling and separating ability of the activated sludge in the settling and separating tank 4 is deteriorated. There are problems such as generation of a peculiar odor, difficulty in treatment when the biochemical oxygen demand (hereinafter referred to as BOD) is high, and failure to follow fluctuations in BOD concentration.

Particularly, when the BOD concentration of raw wastewater is high, the oxidative decomposition reaction by aerobic bacteria does not proceed sufficiently. Therefore, in order to treat wastewater having a predetermined BOD concentration or higher by the activated sludge method, It was necessary to reduce the BOD concentration of the wastewater to be treated by adding a large amount of dilution water. for that reason,
In addition to the large aeration tank 2 and complicated operation management,
There have been problems such as an increase in various expenses such as a facility for supplying dilution water and an increase in the power cost of the blower 3 due to the enlargement of the aeration tank 2.

Further, in the treatment of sewage, the achievement of water quality environmental standards, prevention of organic pollution and eutrophication of closed water areas,
For the purpose of promoting the reuse of treated water and supplying environmental water,
Advanced processing is being performed. However, if advanced treatment is to be performed at an existing sewage treatment plant, it will be necessary to newly install various tertiary treatment devices for dephosphorization, ozone treatment, activated carbon treatment, etc. There was a problem that it had to be expanded, or that it was not possible to deal with sufficiently advanced processing.

Among the above-mentioned problems, in order to solve the problems of generation of odor, high concentration BOD and fluctuation of BOD concentration, metabolism containing oxidase described in JP-A-59-160587. Activated sludge processes have been proposed using products, especially active humus precursors. According to this method, in a wastewater treatment apparatus comprising a bioreactor 12 and a sedimentation tank 14 as shown in FIG. 6, a metabolite is supplied from a metabolite supply tank 17 to a mixed solution containing sludge-like reactants in the bioreactor 12. The addition of humus and humus precursors promotes the binding, particle formation, agglomeration, condensation and polymerization of soluble substances such as organic substances in raw wastewater, and the enlarging of solid particles contained in raw wastewater. And the generated reaction product is settling and separating tank
The solid-liquid separation is carried out by 14 and dehydrator 15.

Also, instead of adding the metabolites, FIG.
A part of the mixed solution containing the sludge-like reaction substance in the bioreactor 22 is introduced to the culture device (bioreactor) 28 and mixed with active humus to make a culture sludge, and The method of returning the mixed solution to the bioreactor 22 to improve the solid-liquid separation of the mixed solution is disclosed in JP-A-61-200895.
No., published in Japanese Unexamined Patent Publication No. If the activated sludge method using these activated humus substances is adopted, the amount of sludge generation can be reduced to about 50% of the standard activated sludge method.

In addition, among the above problems, in order to solve the problems of poor sedimentation / separation of activated sludge and the problem of securing land for advanced treatment, organisms in which a membrane separation device composed of a membrane module is immersed. A solid-liquid separation method using a reactor has been proposed (Japanese Patent Publication No. 4-70958). In this method, a membrane separation device 36 made up of a UF (ultrafiltration) or MF (microfiltration) membrane module is immersed in a bioreactor 32 as shown in FIG. The membrane permeated water is obtained by suctioning the secondary side of the to reduce the pressure, which is one form of a method called a membrane separation activated sludge method. According to this method, since the sedimentation separation tank is not required, the processing apparatus can be made compact, and it is easy to add a tertiary processing apparatus for advanced processing.

However, when such an activated sludge method is adopted, binding, particle formation, aggregation, condensation, and polymerization due to a chemical reaction of a soluble substance such as an organic substance occur, so that a high concentration in a mixed solution in a bioreactor is produced. The molecular component increases. This polymer component is estimated to have a molecular weight of 200,000 or more. Therefore, when the membrane separation method is applied as a solid-liquid separation method in the activated sludge method, the membrane is contaminated by the generated polymer substance,
Not only does the amount of water permeating through the membrane decrease, the amount of treatment decreases remarkably over time, and the life of the membrane also shortens remarkably. Therefore,
It was difficult to apply the membrane separation method to the activated sludge method using activated humus.

[0011]

As described above, in the conventional method for treating wastewater containing organic substances, the existing standard sewage / sewage treatment facility is improved to be highly treated, and the conventional standard activated sludge method is used. In order to solve some problems of
If you try to adopt a membrane separation activated sludge method that uses activated humus, the polymer components will increase in the mixed solution in the bioreactor, so the membrane will be rapidly contaminated and the equipment will operate stably for a long time. It was difficult to continue.

An object of the present invention is to provide a method for treating wastewater containing an organic substance which can prolong the membrane life, compact the treatment apparatus and does not increase the sludge generation amount in the membrane separation activated sludge method and the like. To provide.

[0013]

According to the present invention, when a wastewater containing an organic substance is treated by using a bioreactor in which a membrane separation device composed of a membrane module is installed, the inside of the bioreactor is treated. The activated humic substance pellets and / or the activated humic substance powder are brought into contact with the mixed solution containing the sludge-like reaction substance generated in step 1, and ceramic powder is added to the mixed solution, and treated water is separated from the mixed solution by membrane separation. It is a method for treating wastewater containing an organic substance, which is characterized in that the present invention is preferably such that the ceramic powder is an oxide ceramic powder, and the present invention is an oxide ceramic powder. ,Aluminum oxide,
It is preferable to contain one or more selected from silicon dioxide, calcium oxide and iron oxide as a main component. Further, in the present invention, the ceramic-based powder has the general formula Mg
₆ R ₂ (OH) ₁₆ CO ₃ .4H ₂ O (R = Al, Cr, Fe) is preferably a powder of hydrous carbonate mineral represented by the present invention, the present invention, the maximum particle size of the ceramic powder is It is preferably 150 μm or less.

Further, according to the present invention, the mixed solution containing the ceramic powder is fluidized in a bioreactor equipped with a membrane separator, and the surface of the membrane module is washed with the ceramic powder in the mixed solution. Preferably.

[0015]

Hereinafter, the present invention will be described in more detail. Figure 1,
2, FIG. 3 and FIG. 4 are configuration diagrams of the wastewater treatment equipment used in the wastewater treatment method of the present invention. 1 is a wastewater treatment device in which the active humus pellets 109 are immersed in the bioreactor 102, FIG. 2 is a wastewater treatment device in which the bioreactor 208 is filled with the active humus pellets, and FIG. 3 is a bioreactor 30.
2 is a wastewater treatment device in which the active humus pellets 309 are dipped and the active humus powder is supplied.
A wastewater treatment apparatus in which the active humic powder is supplied to the bioreactor and the bioreactor 408 is filled with the active humic pellets is shown.

Raw effluent containing organic substances (hereinafter referred to as effluent) is first introduced to the adjusting tank 101, 201, 301 or 401, and subjected to pretreatment if necessary. Next, the wastewater is supplied to the bioreactor 102, 202, 302 or 402, and the organic matter contained in the wastewater is actively activated by oxygen-containing gas such as air sent from the blower 103, 203, 303 or 403. It is oxidatively decomposed by active aerobic bacteria to form a mixed solution containing sludge-like reactants, that is, activated sludge.

The activated sludge is immersed in the active humic pellets 109 immersed in the mixed solution in the bioreactor 102, the active humic pellets filled in the bioreactor 208, and the mixed solution in the bioreactor 302. Active humic pellets 309 and active humic powder feeder 307 added to the mixed solution in bioreactor 302, or active humic pellets and active humic powder filled in bioreactor 408. By contact with the active humic powder added from the feeder 407 to the mixed solution in the bioreactor 402, the soluble substances contained therein are bound, granulated, aggregated, condensed, polymerized, etc. The reaction of enlarging the solid particles progresses, and the odor characteristic of sewage is significantly reduced.

The active humus powder supply devices 307 and 407
Is composed of a hopper, a feeder, and the like. Further, the mixed solution in the bioreactor 102, 202, 302 or 402 contains
Membrane separation device composed of membrane module 106, 206, 306
Or 406 is dipped and the secondary side of the membrane module is plumbed to the vacuum pump VP. The vacuum pump VP sucks the secondary side of the membrane module of the membrane separation device 106, 206, 306 or 406 to reduce the pressure, whereby the treated water is obtained as membrane permeated water.

As described above, in the present invention, since the solid separation of the mixed solution is performed by the membrane module, the quality of the sedimentation separation property of sludge does not matter. The membrane module in the present invention includes a UF (ultrafiltration) membrane, MF
An example is a filtration membrane module selected from (microfiltration) membranes and the like. Further, a ceramic-based powder supply device is added to the mixed solution in the bioreactor 102, 202, 302 or 402.
Ceramic-based powder is supplied from 110, 210, 310 or 410. The added ceramic-based powder particles flow in the bioreactor together with the mixed solution due to the oxygen-containing gas such as air supplied from the blower 103, 203, 303 or 403, so that the membrane separators 106, 206, 30
The surface of the membrane module 6 or 406 is, as it were, polished and washed with these ceramic powder particles.

Therefore, it is considered that the polymer components generated in the mixed solution are prevented from adhering to and depositing on the membrane surface, and the membrane contamination is reduced to lower the membrane permeated water amount or the membrane permeated water amount with time. The decrease is suppressed, which leads to the extension of the membrane life. Since the activated sludge method, which is an aerobic treatment, has been described above, the fluidizer for the mixed solution in the bioreactor is a blower for oxygen-containing gas such as air for oxidizing and decomposing organic substances 103, 203, 303 or Although it was 403, as the fluidizing device for the mixed solution according to the present invention, a stirrer provided in the bioreactor is preferably used including the case of anaerobic treatment, and the fluidizing of the mixed solution is possible. If so, the system of the fluidizing device is not particularly limited.

Here, the above-mentioned active humic substance pellet or active humic substance powder in the present invention is a granular substance, lump or powder of the active humic substance, and the active humic substance is
Carbon-based humic substances (coal, lignite, brown coal, grass charcoal, etc.) that have been carbonized or oxidatively decomposed, such as humin, humic acid,
It is a mixture of fulvic acid and clay minerals, and its water extract shows strong acidity.

The shape, particle size, and size of the active humic substance particles, lumps, or powders are not particularly limited, and can be appropriately selected depending on the water quality of the raw wastewater, the amount to be treated, and the like. Table 1, Table 2 and Table 3 show component analysis values, dissolution test results and X-ray diffraction results of the two types of active humus A and B, respectively.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

The ceramic-based powder added in the present invention is represented by oxide ceramic-based powder or the general formula Mg ₆ R ₂ (OH) ₁₆ CO ₃ .4H ₂ O (R = Al, Cr, Fe). Preferred are hydrous carbonate mineral powders, or mixtures thereof. The oxide ceramic powder preferably contains, as a main component, one or more selected from aluminum oxide, silicon dioxide, calcium oxide, iron oxide and the like.

Typical examples thereof include alumina powder for polishing, calcium silicate powder, zeolite powder, coal ash (fly ash) powder, and various ferrite (ferrite) powders. Formula _{Mg 6 R 2 (OH) 16} CO 3 · 4H 2 O (R = Al, C
Examples of the powder of the hydrous carbonate mineral represented by r, Fe) include hydrotalcite powder represented by the chemical formula Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O.

It is preferable that the particles of the ceramic-based powder are relatively fine, but if the maximum particle diameter is 150 μm or less, there is no difference in the effect of polishing the film surface, so to speak.
For economic reasons, it is not advantageous to unnecessarily select fine particles. In the present invention, the maximum particle size is 1
The term “50 μm or less” means that, when sieving with a JIS standard sieve having a sieve opening of 150 μm, 90 wt% or more thereof is below 150 μm.

Also, depending on the type of membrane module selected, since the particle size of the powder is smaller than the pore size of the membrane, the pores in the membrane may be clogged. Therefore, the minimum particle size should be larger than the pore size of the membrane. Is desirable. The amount of ceramic powder added was 10 for the mixed solution in the bioreactor.
It is preferable to add it in the range of 00 to 4000 mg / L.

The addition of the ceramic powder contributes to the increase in the sludge generation amount, but this increase is offset or reduced by the decrease in the sludge generation amount due to the use of the active humus as described above. Furthermore, by appropriately selecting the type of ceramic-based powder, the concentration of phosphoric acid or ammonia in the treated water can be significantly reduced by adsorption.

Alumina powder and hydrotalcite powder are suitable for the adsorption removal of phosphoric acid phosphorus. Zeolite powder and coal ash powder are suitable for the adsorption removal of ammonium ions.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Domestic wastewater was treated using a test device of the activated sludge method using activated humus as shown in FIG. In FIG. 2, 201 is an adjusting tank, 202 is a bioreactor, 203 is a blower, 205 is a dehydrator, 206 is a membrane separator, 208 is a bioreactor, 210 is a ceramics powder supply device composed of a hopper, a feeder, etc. , SP is a sludge pump, and VP is a vacuum pump.

The volume of the reaction tank of the bioreactor 202 is 45 L,
The amount of raw wastewater treated is 150 L / day and the residence time in the reaction tank is 7.2 hours. Table 1, Table 2 and Table 3 in the bioreactor 208
The active humus B pellets (diameter 2 cm, length 2-4 cm) consisting of the active humus B having the properties shown in (1) were filled. The volume of active humus B pellets filled is 2L.

The UF (ultrafiltration) membrane module used by immersing it in the reaction tank of the bioreactor 202 has a molecular weight cut-off.
It is a hollow fiber type with 13000 and an effective membrane area of 0.2 m ² .
While supplying air to the mixed solution in the reaction tank of the bioreactor 202 with a blower 203 at a flow rate of 2 L / min,
Alumina powder for polishing (maximum particle size 0.05 μm) was added to the mixed solution so that the concentration was 3000 mg / L, and after fluidization, the secondary side of the membrane module was depressurized to about 0.2 atm with the vacuum pump VP to permeate the membrane. Continuous suction of the mixed solution was performed for 30 minutes while returning water to the mixed solution.

The M of the mixed solution before addition of the alumina powder was
LSS (solid content concentration) was 2708 mg / L. As a result, the amount of membrane permeated water was 1.47 m ³ / m ^{2 at the} beginning of the treatment of raw wastewater.
/ Day, after 30 minutes was 1.03 m ³ / m ² / day. The amount of water permeated through the membrane when the alumina powder for polishing was not added under the same conditions was 1.10 m ³ / m ² / day at the beginning of the treatment of raw wastewater and after 30 minutes.
It was 0.83 m ³ / m ² / day.

As described above, the addition of the oxide ceramic powder effectively suppressed the decrease in the amount of membrane permeated water with time, and increased the amount of membrane permeated water as compared with the conventional membrane separation activated sludge method. This result was obtained by continuous suction for 30 minutes. By appropriately selecting the suction pattern, the decrease in the amount of water permeated through the membrane was minimized, or by adding ceramics powder to the mixed solution of the same MLSS concentration, the membrane permeation was performed. The amount of water can be increased.

[0037]

INDUSTRIAL APPLICABILITY As described above in detail, in the treatment of wastewater containing an organic substance, active humus pellets and active humus powder are immersed in a mixed solution in a bioreactor, fed or sludge return system. By filling and supplying in the installed bioreactor, at the same time adding ceramics powder to the mixed solution, and further immersing the membrane module in the bioreactor and performing biological treatment while sucking the secondary side, As compared with the membrane separation activated sludge method, the amount of permeated water can be increased, and the membrane life can be remarkably extended, so that the membrane cost in wastewater treatment can be significantly reduced.

Further, according to the present invention, the treatment apparatus can be made compact, and the removal rate of phosphoric acid and ammonia can be significantly improved without increasing the sludge generation amount. In addition, the improvement of the dehydration of activated sludge, which is a feature of the activated sludge method using activated humus, and the reduction of odor peculiar to sewage,
Further, it is possible to enjoy the advantage that it is possible to cope with high concentration BOD and concentration variation of BOD.

Therefore, the present invention is far superior to the conventional treatment technology in the treatment of wastewater containing organic substances such as domestic wastewater such as urban sewage and community wastewater, livestock human wastewater, marine product processing wastewater, agricultural product processing wastewater, and the like. It provides processability and facilitates the advanced processing of processing equipment.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a wastewater treatment device used in a wastewater treatment method of the present invention.

FIG. 2 is a configuration diagram of a wastewater treatment device used in the wastewater treatment method of the present invention.

FIG. 3 is a configuration diagram of a wastewater treatment device used in the wastewater treatment method of the present invention.

FIG. 4 is a configuration diagram of a wastewater treatment device used in the wastewater treatment method of the present invention.

FIG. 5 is a block diagram of a conventional wastewater treatment device using a standard activated sludge method.

[Fig. 6] Fig. 6 is a configuration diagram of a conventional wastewater treatment device by an activated sludge method using a metabolite containing an oxidase.

FIG. 7 is a configuration diagram of a conventional wastewater treatment apparatus by an activated sludge method using activated humus.

FIG. 8 is a configuration diagram of a conventional wastewater treatment apparatus using a membrane separation activated sludge method.

[Explanation of symbols]

 1,11,21,101,201,301,401 Control tank 2 Aeration tank 3,13,23,33,103,203,303,403 Blower 4,14,24 Sedimentation separation tank 5,15,25,105,205,305,405 Dehydrator 12,22,32,102,202,302,402 Bioreactor 17 Metabolite supply tank 28,208,106,206, Bioreactor 36,306 Membrane separator 109,309 Activated humus pellets 110,210,310,410 Ceramics powder feeder 307,407 Activated humus powder feeder SP Sludge pump VP Vacuum pump

Claims (5)

[Claims] 1. A sludge-like reaction substance produced in a bioreactor when treating wastewater containing an organic substance by using a bioreactor having a membrane separation device composed of a membrane module installed therein. Organic humor characterized by contacting active humus pellets and / or active humus powder to a mixed solution containing the same, adding ceramics powder to the mixed solution, and obtaining treated water by membrane separation from the mixed solution Method for treating wastewater containing substances. 2. The method for treating wastewater containing an organic substance according to claim 1, wherein the ceramic-based powder is an oxide ceramic-based powder. 3. The organic substance according to claim 2, wherein the oxide ceramic powder contains, as a main component, one or more selected from aluminum oxide, silicon dioxide, calcium oxide and iron oxide. Wastewater treatment method. 4. The ceramic-based powder has the general formula Mg ₆ R
_The method for treating wastewater containing an organic substance according to claim 1, which is a powder of a hydrous carbonate mineral represented by ₂ (OH) ₁₆ CO ₃ .4H ₂ O (R = Al, Cr, Fe). 5. The maximum particle size of the ceramic-based powder is
It is 150 micrometers or less, The processing method of the wastewater containing the organic substance in any one of Claims 1-4.