JPH0938680A - Treatment of waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a waste water treating device by adding an inorg. flocculating agent to water which is to be treated and is introduced into an aeration vessel, adding an amphoteric org. high-molecular flocculating agent thereto in the state of adjusting its pH value to a specific one and subjecting the water to a solid liquid sepn. by a separating member while subjecting the water to an aeration treatment. SOLUTION: The inorg. flocculating agent is added to the waste raw water to be treated to adjust its pH value to 5 to 8 before the water is transferred into the aeration vessel 1. While the amphoteric org. high-molecular flocculating agent is added to the waste water adjusted in the pH in the aeration vessel 12, the water-soluble components are decomposed by active sludge and the waste water is subjected to the solid liquid sepn. by a hollow fiber membrane module 14. The filtrate is released into rivers, etc. The sediment is thickened in a sludge thickening vessel and is then disposed by removing water therefrom with a dehydrating machine. The amphoteric org. high-molecular flocculating agent contains a carboxyl group or its salt as an anionic group. The cation equiv. Cv value of the amphoteric org. high-molecular flocculating agent is specified to 1.0 to 4.0meq/g, the anion equiv. value Av to 0.3 to 2.0meq/g and the Cv/Av ratio to 1.5 to 8.0.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sewage treatment plant, a night soil treatment plant,
The present invention relates to a method for treating wastewater such as organic industrial wastewater with high efficiency.

[0002]

2. Description of the Related Art Conventionally, microbial treatment has been used for the treatment of sewage, night soil treatment process and organic wastewater discharged from food factories, and precipitation separation has been used for the final solid-liquid separation. . However, in this precipitation separation, when the load changes, SS
Was likely to occur. Further, when a membrane separation method is used for solid-liquid separation of wastewater, a settling tank is unnecessary, the outflow of SS can be completely prevented, and the activated sludge concentration in the aeration tank can be increased, so that excess sludge Attention has been paid to the advantage that the generation of wastewater can be reduced and the size of the wastewater treatment device can be reduced.

[0003]

The wastewater treated with activated sludge is an organic gel, and when these are subjected to solid-liquid separation with a separation membrane, the membrane is severely clogged, and substantial solid-liquid separation takes a long time. It is difficult to carry out continuously, and the membrane performance itself deteriorates. On the other hand, a method of treating organic wastewater by separating activated sludge treatment and membrane separation treatment is disclosed in Japanese Patent Publication No.
No. 10720 and Japanese Patent Publication No. 1-41118. However, although it is possible to reduce the SS content of the discharged water by these methods, the size of the device is reduced,
It cannot be used as a domestic wastewater treatment device.

[0004]

Therefore, the present inventor has studied to develop a wastewater treatment method capable of reducing the size of the wastewater treatment apparatus, having a long membrane life, and producing a small amount of sludge. The present invention has been completed. The gist of the present invention is that the water to be treated, which has been introduced into the aeration tank, is added with an inorganic coagulant, and the pH value thereof is adjusted to 5 to 8 with the amphoteric organic polymer coagulant added to the aerated tank. A method for treating wastewater is characterized in that solid-liquid separation is performed by a separation membrane while performing treatment.

The amphoteric organic polymer flocculant used for carrying out the present invention contains a carboxyl group or a salt thereof as an anionic group, and has a cation equivalent value Cv of 1.0 to 4.0.
meq / g, anion equivalent value Av is 0.3 to 2.0 meq / g, Cv
It is preferable to use one having an / Av ratio of 1.5 to 8.0.

The separation membrane used for carrying out the present invention may be either a hollow fiber membrane or a flat membrane, and in particular, as a hollow fiber membrane module, as shown in the perspective view of FIG. An internal water collection channel having a separation membrane composed of hollow fiber membranes composed of hollow fibers of the present invention and tubular supports provided at both ends of the separation membrane, wherein the filtrate contained in the hollow fibers is formed in the tubular support. It is preferable to use a separation membrane module that can pass through the.

Further, as another type of separation membrane module used for carrying out the present invention, as shown in FIG. 4, a plurality of hollow fibers are folded back at their central portions, and a plate-shaped spacer is sandwiched between the hollow fibers, and the spacer is A U-shaped hollow fiber membrane module having a tubular support provided at one end thereof and an open end of a hollow fiber coupled to an internal water collecting passage formed inside the tubular support is efficiently used.

As another type of separation membrane module, as shown in FIG. 5, a flat spacer having an internal space and having a plurality of holes for communicating the outside with the internal space formed on the surface thereof, and the spacer It has a porous separation membrane that covers it, and a tubular support provided at one end of the spacer, and the filtrate that has entered the internal space of the spacer flows inside the internal water collection channel formed inside the tubular support. There is a separation membrane module that can pass through.

According to the present invention, solid-liquid separation treatment is carried out by a separation membrane while aerating a wastewater having an adjusted pH value with an amphoteric organic polymer in an aeration tank. At this time, the order of adding the inorganic coagulant and the amphoteric polymer coagulant is important, and the inorganic coagulant is always added first. By adding an inorganic coagulant in advance to neutralize the electric charge of the organic sludge, and adding an amphoteric polymer coagulant to this, a strong and uniform particle size floc having an inorganic substance as a core can be formed. By performing solid-liquid separation with a separation membrane, especially a hollow fiber membrane, in the state where such flocs are formed, clogging (increase in differential pressure) is suppressed, and the permeation flow velocity of the separation membrane is increased for a long time in a state where the differential pressure is low. It can be maintained, and high-speed solid-liquid separation of waste water can be performed by the separation membrane.

In the present invention, when a U-shaped hollow fiber membrane module having a folded portion from the central portion of the hollow fiber is used as the hollow fiber membrane module, solid-liquid separation is carried out by the separation membrane and the filtrate taken into the hollow fiber. Passes through the hollow fiber, enters the internal water collection passage of the tubular support from its end, passes through the inner water collection passage, and is discharged. With this method, one tubular support may be used for one separation membrane, and cost reduction and miniaturization can be promoted. Further, by disposing the spacers between the folded separation membranes, there is no adhesion between the separation membranes, and the filtration performance does not deteriorate due to the separation membranes being bundled.

When the membrane module having the structure shown in FIG. 5 is used in the present invention, the filtrate which is solid-liquid separated by the separation membrane and has permeated through the separation membrane passes through the holes formed in the spacer to form the spacer. It is taken into the internal space, enters the internal water collection passage of the tubular support body through the inner space, and is discharged through the internal water collection passage. With this method, one tubular support may be used for one separation membrane, and cost reduction and miniaturization can be promoted. Further, by disposing the spacers between the folded separation membranes, there is no adhesion between the separation membranes, and the filtration performance does not deteriorate due to the separation membranes being bundled. In addition, a material other than the hollow fiber membrane can be used as the separation membrane, and the range of choice of the separation membrane can be expanded.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but it should be understood that the present invention is not construed as being limited thereto.

[First Embodiment] In the waste water treatment method of the present embodiment, as shown in FIG.
Transfer to At this time, it may be processed in the precipitation tank before being transferred to the aeration tank 12. In the first settling tank, relatively large suspended matter is separated by settling. Then, the treated water is transferred to the aeration tank and the sediment is transferred to the sludge thickening tank. Further, before transferring to the aeration tank 12, an inorganic coagulant is added to adjust the pH value to 5-8. In the aeration tank, while adding the amphoteric polymer coagulant to the pH-adjusted waste water, the activated sludge decomposes water-soluble components such as BOD and COD in the waste water, and the hollow fiber membrane module 14 performs solid-liquid separation. The filtered water after solid-liquid separation is discharged to a river or the like. The sediment is transferred to a sludge thickening tank, where it is concentrated and then dewatered by a dehydrator for disposal.

The separation membrane module 14 is as shown in FIG. 2, and comprises a separation membrane 18 composed of a hollow fiber membrane composed of a plurality of hollow fibers, and tubular supports 20 provided at both ends of the separation membrane 18. It has a general structure. Various porous and tubular hollow fibers can be used as the hollow fiber, for example, cellulose-based, polyolefin-based, polyvinyl alcohol-based, PM
Materials made of various materials such as MA and polysulfone can be used. Of these, materials having high elongation such as polyethylene and polypropylene are preferable. Further, although not particularly limited, the outer diameter of the hollow fiber is 20 to 2000 μm.
It is preferable that m, the pore diameter is 0.01 to 1 μm, the porosity is 20 to 90%, and the thickness of the hollow fiber membrane is 5 to 300 μm.

Further, the separation membrane is preferably a so-called permanent hydrophilization membrane having a hydrophilic group on the surface. If the surface of the separation membrane is hydrophobic, a hydrophobic interaction between the organic substances in the water to be treated and the surface of the separation membrane will occur, causing adsorption of organic substances on the membrane surface, which leads to clogging of the membrane surface and the filtration life. This is because it tends to be short. In addition, clogging caused by adsorption is generally difficult to recover filtration performance even by membrane surface cleaning. However, by using the permanent hydrophilization membrane, the hydrophobic interaction between the organic matter and the surface of the separation membrane can be suppressed, and the adsorption of the organic matter can be suppressed. Furthermore, when the air scrubbing process described later is performed on a hydrophobic film, the film surface may be in a dry state due to air bubbles, which further enhances hydrophobicity and may cause a decrease in flux. The flux is unlikely to be reduced even when the film is dried.

The tubular support member 20 is a tubular member having an internal water collecting passage 24 formed therein, one end of which is closed, and the other end of which is connected to the suction pump 16 and a pipe 22.
The tubular support 20 shown in FIG. 2 has a cylindrical shape, but it is not limited to this, and for example, the outer shape may be a square pole. Further, the side wall 26 of the tubular support 20 has slits 2 along its length.
8 are formed. The separation film 18 is formed in the slit 28.
While the end of is inserted, it is blocked by the sealing material to be filled,
The separation membrane 18 is firmly supported and fixed. That is, in the separation membrane module 14, both ends of the separation membrane 18 are supported by the two tubular supports 20, respectively. In this case, the end of the separation membrane 18 is both ends of the hollow fiber in the fiber direction, and both ends of each hollow fiber are located in the internal water collecting passage 24 of the tubular support 20.

The width of the slit 28 is preferably 30 mm or less, more preferably 10 mm or less. This is because by narrowing the width of the slit 28, it becomes easier to arrange the hollow fibers constituting the separation membrane 18 in one row in a more orderly manner. If the hollow fibers are not aligned and the hollow fiber membrane is disturbed and formed, a plurality of hollow fibers will be bundled and adhered and integrated due to the adhesion of sludge, etc., and the surface area as a separation membrane cannot be used effectively, resulting in a decrease in separation performance. Resulting in. The length of the slit is not particularly limited, but if it is too short, the membrane area of the separation membrane cannot be increased, and the separation performance cannot be improved. If the length is too long, the production becomes difficult. 100 to 2000 mm is appropriate.

The sealing material bundles and fixes each hollow fiber of the separation membrane 18 in the slit 28 while keeping the end of the hollow fiber open, and liquid-tightly seals the internal water collecting passage 24 of the tubular support 20 from the outside. It is formed by filling the slit 28 with a liquid of epoxy resin, unsaturated polyester resin, polyurethane or the like and curing it. In addition, insert the separation membrane in two or more rows for one slit,
If fixed, or if two or more slits are formed in one tubular support and a separation membrane is inserted and fixed in each slit, a plurality of separation membranes 18 are formed per separation membrane module 14. It becomes possible. As the number of the separation films 18 increases, the overall film area can be increased, and the processing performance can be improved. However, if three or more separation membranes are provided, the washing effect of the separation membrane located inside cannot be enhanced at the time of washing the separation membrane described later. Therefore, two separation membranes are appropriate.

A plurality of separation membrane modules 14 having such a structure can be arranged in one aeration tank 12. By arranging a plurality of separation membrane modules 14, the membrane area as a whole can be increased and the processing performance can be improved. Further, in consideration of downsizing of the aeration tank and cleaning efficiency of the separation membrane described later, it is preferable that the distance between the adjacent separation membrane modules 14 is narrow. However, if the interval is too narrow, clogging with sludge is likely to occur, and bubbles may not easily pass between the separation membrane modules. For this reason,
The spacing between each separation membrane module should be selected in consideration of the size of the separation membrane module occupying the separation membrane module, the number of separation membrane modules, the thickness of the tubular support, the conditions such as air scrubbing and backwashing. Are required, and the interval is 5-1.
The range of 00 mm is preferable, and the range of 5 to 70 mm is more preferable.

The internal water collecting passage 24 of each tubular support 20 is connected to the suction pump 16 by a pipe 22. Therefore, by operating the suction pump 16, the internal water collection channel 24
The permeated liquid that has entered is forcedly transferred.

In the aeration tank 12, below the separation membrane 18, it is preferable to arrange an air diffuser 30 for diverging gas. The air diffuser 30 is a hollow body having a large number of pores, and is connected to a pneumatic pump 32. By operating the compressed air pump 32, air bubbles are emitted from the air diffuser 30. By using this air diffuser 30, air scrubbing can be performed. That is, the hollow fiber membrane oscillates due to bubbles rising from the air diffuser 30 and the hollow fibers rub against each other due to this oscillating, or the relative flow of the hollow fiber and water causes the surface of the hollow fiber to move. The attached sludge will be removed. Further, by causing air to be emitted from the air diffuser 30, oxygen is supplied to the microorganisms of the activated sludge in the aeration tank, and the treatment capacity by the activated sludge method can be enhanced.

Considering the air scrubbing process by the air diffuser 30, it is desirable to arrange the separation membrane module 14 so that the membrane surface of the separation membrane 18 is along the vertical direction. By arranging the membrane surface along the vertical direction, the bubbles rising from below act almost uniformly on the entire membrane surface of all the separation membranes 18 and the aeration tank 12 smoothly.
This is because it is easier to pass above. On the contrary,
When the separation membrane module is arranged in a state where the separation membrane 18 is laid horizontally, the diverged bubbles will hit the separation membrane arranged at the bottom and then scatter horizontally outward along the separation membrane. As a result, the air scrubbing process cannot be effectively performed on the separation membrane arranged above.

Further, in this embodiment, the amphoteric polymer flocculant is added after the inorganic flocculant such as iron or aluminum is added. Examples of the inorganic flocculant used in the present invention include a sulfuric acid band, ferric chloride, ferrous sulfate, and polyferric sulfate. Among them, an iron-based inorganic flocculant is preferable. The pH value of the organic sludge after the addition of the inorganic flocculant needs to be within the range of 5-8. It is more preferable that the pH value is 6 to 7. If the pH value is out of this range, even if an amphoteric organic polymer flocculant is added to produce flocs,
This is because the particle size is small or does not aggregate.

When the pH value after addition of the inorganic coagulant is within the range of 5 to 8, it is not necessary to adjust the pH in particular, but when it is out of the range, the pH is adjusted with alkali or acid. Suitable alkalis are, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide and ammonia. Examples of the acid include sulfuric acid, hydrochloric acid, acetic acid, sulfamic acid and the like, among which sulfuric acid and hydrochloric acid are preferable.

The amphoteric polymer flocculant is a polymer flocculant having a cationic group and an anionic group in one molecule. Examples of the cationic group include tertiary amines, neutralized salts thereof, quaternary salts and the like, and examples of the anionic group include a carboxyl group, a sulfone group and salts thereof. Particularly, an amphoteric polymer flocculant having a carboxyl group is preferable. Further, a nonionic component may be contained in addition to these ionic components. More specifically, examples of the anionic monomer unit include acrylic acid, methacrylic acid, and alkali metal salts thereof. Examples of the cationic monomer unit include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, allyldimethylamine, and neutralized salts thereof.
Grade salts and the like. Examples of the nonionic monomer unit include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide and the like.

In the amphoteric organic polymer flocculant used in the present invention, the cation equivalent value Cv and the anion equivalent value Av are
The cation equivalent value Cv is 1.0 to 4.0 me in terms of solubility in water in a dissolution tank before addition to sludge, sludge aggregation performance, and the like.
q / g, anion equivalent value Av is 0.3 to 2.0 meq / g, Cv /
It is preferable that the ratio of Av is 1.5 to 8.0. Cation equivalent value Cv is 1.3 to 3.8 meq / g, anion equivalent value A
v is 0.4 to 1.8 meq / g, and the ratio of Cv / Av is 1.8 to 7.
It is preferably 0.

In the present invention, the cation equivalent value Cv and the anion equivalent value Av of the amphoteric polymer flocculant are determined by the colloid titration method described below. (1) Measurement of cation equivalent value First, a 500 ppm aqueous solution of a sample is prepared. Sample 0.
2 g (not converted to dry product) is precisely weighed, taken in a triangular corb with a stopper, and dissolved in 100 ml of deionized water. This 25 ml is made up with deionized water in a 100 ml volumetric flask to prepare a 500 ppm aqueous solution. Next, in a conical beaker, 90 ml of deionized water and 500 p of the sample prepared above
Add 10 ml of pm solution, adjust the pH to 3.0 with aqueous hydrochloric acid, and stir for about 1 minute. Next, 2-3 drops of toluidine blue indicator are added and titrated with N / 400-polyvinyl potassium sulfate reagent (N / 400-PVSK). The titration rate was 2 ml / min, and the test water changed from blue to magenta and 10
The end point is the time when more than a second is held. By applying the obtained PVSK titration amount to the following formula, the cation equivalent value Cv (meq /
g) is converted.

[Equation 1]

(2) Measurement of anion equivalent value First, a 500 ppm aqueous solution of a sample is prepared. Sample 0.
1 g (not converted to dry product) is precisely weighed, taken in a triangular corb with a stopper, and dissolved in 100 ml of deionized water. This 50 ml is made up with deionized water in a 100 ml volumetric flask to prepare a 500 ppm aqueous solution. Next, in a conical beaker, 90 ml of deionized water and 0.5 ml of N / 10-sodium hydroxide aqueous solution are taken, 5 ml of N / 200-methyl glycol chitosan reagent solution is added with stirring, and the mixture is stirred for 1 minute or more. To this, 10 ml of the 500 ppm solution prepared above
Is slowly added, and after the mixture is further stirred for 5 minutes or more, 2-3 drops of toluidine blue indicator is added and titrated with N / 400-polyvinyl potassium sulfate reagent (N / 400-PVSK). The titration rate is 2 ml / min, and the end point is when the test water changes from blue to reddish purple and is held for 10 seconds or more.
In addition, the thing which does not add a sample was made into the blank reagent. The obtained PVSK titer is applied to the following formula to convert the anion equivalent value Av (meq / g).

[Equation 2]

When an inorganic flocculant and an amphoteric polymer flocculant are added to the aeration tank, 0.5 to 10 parts by weight of the inorganic flocculant and 100 parts by weight of the suspended solid (SS) in the waste water, the amphoteric system are used. The amount of the polymer flocculant is preferably 0.05 to 1 part by weight, more preferably 1 to 8 parts by weight and 0.1 to 0.8 parts by weight, respectively. Exceeding these addition amounts is not preferable because the flocs may be redispersed or the adhesion of the flocs to the separation membrane may increase.

By adding the inorganic coagulant to the aeration tank, first, the viscous substance layer and the dissolved components in the organic sludge react with the inorganic coagulant to neutralize the charge and hydrophobize the hydrocolloid. Thus, the sludge is modified so as to form a strong core having a small particle size but a small tackiness. After that, when the amphoteric polymer flocculant is added, the amphoteric polymer flocculant ionically dissociates in the liquid phase and has both positive and negative charges, and at the same time, the polymers are crosslinked with each other or metal ions. Then, the crosslinked polymer reacts with the nuclei of the sludge particles to form relatively large and high-strength fine flocs, and a dense cake layer is not formed on the surface of the separation membrane. The peelability from the film is enhanced.
Therefore, the high permeation flux of the separation membrane can be maintained. That is, as the membrane separation by suction filtration increases, the sludge concentration in the aeration tank tends to increase and the permeation flux of the membrane tends to decrease, but the addition of the coagulant increases the sludge concentration. Even if the viscosity of the waste liquid is high, a high permeation flux can be maintained with a low transmembrane pressure.

The generated flocs are stirred and the like,
It becomes a strong floc with more hydrophobicity and shrinkage. Further, there is almost no residual metal ion or polymer in the liquid phase, and the liquid phase is free from viscous drainage and has good releasability. Therefore, even if it is difficult to dehydrate sludge, it becomes easy to perform coagulation treatment.

In the wastewater treatment method of this embodiment in which such a separation membrane module 14 is provided in the aeration tank, the waste liquid is
The inorganic coagulant is added and flows into the aeration tank 12 and is stored therein. Then, after confirming whether the pH is appropriate, the amphoteric polymer flocculant is added. And the suction pump 16
When activated, the treated water in the aeration tank 12 is suction-filtered by the separation membrane 18, and only the suspended substance in the treated water is captured on the surface of the separation membrane 18 to separate the treated water and the suspended substance. The treated water (filtrate) from which the suspended solids have been removed in this way passes through the hollow fibers constituting the separation membrane 18 by the suction pump 16,
The gas is discharged from the aeration tank 12 via the internal water collection passage 24 and the pipe 22 of the tubular support 20 provided at the end thereof. Further, by appropriately washing the separation membrane by the air scrubbing treatment, it is possible to prevent the deterioration of the separation ability.

The separation membrane can be washed not only by air scrubbing but also by backwashing. That is, by using the suction pump 16 also as a pressure pump, the clean water is passed through the internal water collecting passage 24 of the tubular support 20 into the hollow fiber and is discharged from the surface of the separation membrane 18 to discharge the clean water. Suspended matter adhering to the surface can be removed. Alternatively, a method in which a granular material such as a sponge ball is sprayed in a membrane separation tank and brought into contact with the separation membrane, or the separation membrane is vibrated by applying ultrasonic vibration can be applied. Further, the surface of the separation membrane can be cleaned by chemical cleaning. Although chemical cleaning is expensive, the amount of chemical used can be reduced by using air scrubbing or backwashing together. Washing with air scrubbing or backwashing is performed with the filtration process by suction stopped, but if backwashing is not necessary due to the nature of the waste liquid, etc., use air scrubbing during the wastewater filtering process. Cleaning can also be performed.

According to the wastewater treatment method of this embodiment, the suspended solids (SS) in the treated water can be highly separated and removed. In particular, it is possible to flexibly deal with load fluctuations due to changes in the amount of suspended solids, and prevent the outflow of suspended solids. Therefore, it can contribute to the purification of rivers and the like. Also,
Since the membrane separation device can be made much smaller than the sedimentation tank or the sand filtration tank, it can be installed in a narrow place or contribute to effective use of the site.

Further, it is possible to remarkably suppress an increase in pressure loss with time in suction filtration using a separation membrane, and to maintain a high permeation flux for a long time under a filtration condition with a small pressure loss. Therefore, the suspended solid (SS) can be stably separated and removed, and the membrane area of the separation membrane to be used can be reduced. Further, the load on the separation membrane can be reduced, and the life of the separation membrane can be extended. Further, since the flocs adhering to the separation membrane are easily separated, the frequency of cleaning the membrane surface can be reduced, and in particular, the chemical cleaning treatment can be reduced. In addition, although the example which performed suction filtration was shown in the said example, pressure filtration can also be applied.

[Example 2] Depending on various conditions, the function of activated sludge treatment may be reduced by adding a coagulant to the aeration tank. In that case, as shown in FIG. 3, after the treatment with the aeration tank 10 of activated sludge, an inorganic coagulant is added, and thereafter, the inorganic coagulant is introduced into the membrane separation tank 13 equipped with the separation membrane module 14, and the amphoteric polymer coagulates. Add agent. Then, as described above, it is better to perform the solid-liquid separation process with the separation membrane.

[Example 3] The same procedure as in Example 1 except that the separation membrane module having the structure shown in Fig. 4 is used. As shown in FIG. 4, the separation membrane module of the third embodiment has a separation membrane 34 composed of a plurality of hollow fibers, a plate-like spacer 36, and a tubular support 38 having an internal water collecting passage. Composed. The spacer 36 is covered by the separation film 34, and the sheet-shaped separation film is folded back so that the spacer 36 is sandwiched between them. The separation film uses heat sealing or an adhesive agent on both side peripheral portions 40, 40. By doing so, it adheres to form a bag. In addition, the end of the portion corresponding to the opening of the bag is fixed by the tubular support 38, and the end of each hollow fiber forming the separation membrane is fixed to the internal water collection passage 2 of the tubular support 38.
Position it within 4.

In the separation membrane module having this structure, the waste liquid in the aeration tank is solid-liquid separated and suspended by the separation membrane 34 by operating the suction pump communicating with the internal water collecting passage 24 of the tubular support 38. The filtrate from which the substances have been removed and which has been taken into the hollow fiber passes through the hollow fiber, enters the internal water collecting passage 24 of the tubular support 38 from the end thereof, passes through the inner water collecting passage 24, and passes through the suction pump. To be released.

In this separation membrane module, one tubular support may be used for one separation membrane, and cost reduction and miniaturization can be promoted. Further, by disposing the spacers between the folded separation membranes, there is no adhesion between the separation membranes, and the filtration performance does not deteriorate due to the separation membranes being bundled.

[Mode 4] The same procedure was performed as in the wastewater treatment method of mode 1 except that the separation membrane module having the structure shown in FIG. 5 was used. As shown in FIG. 5, the separation membrane module of Embodiment 4 is composed of a flat spacer 42, a separation membrane 44 covering the spacer 42, and a tubular support 38 provided at one end of the spacer 42. The spacer is a box-shaped one having an internal space formed therein, and of the six faces forming the spacer 42, an opening 46 is formed on one face and the other face is formed on the surface. A plurality of holes are formed, and the holes communicate the outside and the internal space. The opening 46 is connected to the internal water collection channel 24 of the tubular support 38.

When the separation membrane module having this structure is used, the waste liquid in the aeration tank is solid-liquid separated by the separation membrane 44 by operating the suction pump communicating with the internal water collecting passage 24 of the tubular support 38. The suspended matter is removed, and the separation membrane 44
The filtrate permeated through the spacer 42 is taken into the internal space of the spacer 42 through the holes formed in the spacer 42, passes through the internal space, enters the internal water collection passage 24 of the tubular support 38 through the opening 46, and After passing through the water collection channel 24, it is discharged via a suction pump.

With this separation membrane module, one tubular support 38 may be used for one separation membrane 44, and cost reduction and miniaturization can be promoted. Further, since the spacers 42 are arranged between the folded separation membranes, the separation membranes do not adhere to each other, and the filtration performance does not deteriorate due to the separation membranes being bundled. In addition, a material other than the hollow fiber membrane can be used as the separation membrane, and the range of choice of the separation membrane can be expanded.

[0043]

According to the present invention, clogging (increase in differential pressure) is suppressed in solid-liquid separation in the aeration tank of wastewater by the separation membrane, and the permeation velocity of the separation membrane is increased for a long time in a state where the differential pressure is low. It can be maintained, and high-speed solid-liquid separation of waste water can be performed by the separation membrane.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a wastewater treatment method of the present embodiment example.

FIG. 2 is a perspective view showing a separation membrane module of form example 1. FIG.

FIG. 3 is a schematic configuration diagram showing a wastewater treatment method of form example 2.

FIG. 4 is a diagram showing a separation membrane module of Embodiment 3;
4A is a front view, and FIG. 4B is a sectional view taken along the line bb of FIG. 4A.

5 is a view showing the separation membrane module of Embodiment 4, and FIG.
5A is a front view, and FIG. 5B is a sectional view taken along the line bb of FIG. 5A.

[Explanation of symbols]

 10 Aeration Tank 12 Aeration Tank 13 Membrane Separation Tank 14 Separation Membrane Module 16 Separation Pump 18 Separation Membrane 20 Tubular Support 24 Internal Water Collection Channel 28 Slit 30 Diffuser 34 Separation Membrane 36 Spacer 38 Tubular Support 42 Spacer 44 Separation Membrane

Claims (5)

[Claims] 1. An aeration treatment is carried out by adding an amphoteric organic polymer coagulant to the water to be treated which has been introduced into an aeration tank and adding an inorganic coagulant and having a pH value of 5-8. A method for treating wastewater, which comprises performing solid-liquid separation using a separation membrane provided in an aeration tank. 2. The amphoteric organic polymer flocculant contains a carboxyl group or a salt thereof as an anionic group, and the cation equivalent value Cv of the amphoteric organic polymer flocculant is 1.0 to 4.0 meq /.
g, anion equivalent value Av is 0.3 to 2.0 meq / g, Cv / A
The method for treating wastewater according to claim 1, wherein the v ratio is 1.5 to 8.0. 3. The method for treating wastewater according to claim 1, further comprising a separation membrane composed of hollow fiber membranes composed of a plurality of hollow fibers, and tubular supports provided at both ends of the separation membrane. A method for treating wastewater, comprising using a separation membrane module capable of passing a filtrate contained in a hollow fiber through an internal water collecting passage formed in a tubular support. 4. The method for treating wastewater according to claim 1 or 2, wherein a solid-liquid separation by a separation membrane is performed by a separation membrane composed of a plurality of hollow fibers, and a plate-like member that is folded back and sandwiched between the separation membranes. And a tubular support provided at one end of the spacer, and both ends of the hollow fiber are located in an internal water collecting passage formed inside the tubular support, A method for treating wastewater, which comprises using a separation membrane module capable of passing an entered filtrate through an internal water collecting channel. 5. The method for treating wastewater according to claim 1 or 2, wherein a solid-liquid separation by a separation membrane has an internal space, and a plurality of holes for communicating the outside with the internal space are formed on the surface. Of the spacer, a porous flat membrane separation membrane that covers the spacer, and a tubular support provided at one end of the spacer, and the filtrate that has entered the internal space of the spacer is A method for treating wastewater, which comprises using a separation membrane module that can pass through an internal water collection channel formed inside.