JP2003300089A - Method for treating activated sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for reducing the clogging of filter media when activated sludge is subjected to solid-liquid separation by filtration in an activated sludge treatment method. <P>SOLUTION: The method of subjecting the activated sludge added with the culture, microbial cells or treated matter of the microbial cells of bacteria functioning as a filter aid, yeast or at least one kind of microorganisms belonging to molds to the solid-liquid separation by filtration. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid-liquid separation method in an activated sludge treatment method.

[0002]

2. Description of the Related Art In the treatment of wastewater, an activated sludge treatment method has been used for a long time, in which wastewater is purified by using microorganisms. The activated sludge treatment method involves aeration in water,
A method of degrading BOD by aerobic metabolism of microorganisms,
A method is known in which sludge is circulated between an anaerobic tank and an aerobic tank to denitrify. Further, the A ₂ O method and the like are known as methods for biologically dephosphorizing using phosphorus-accumulating bacteria.

In these methods, there is a step of providing a sedimentation tank in the latter stage of the apparatus to settle the sludge entrained in the treated water. After sludge is settled by gravity, the supernatant liquid is discharged as treated water into rivers, oceans, etc. is doing. In order to improve the sedimentation property of this sludge, a method of adding bacteria to the aeration tank is known (Japanese Patent Laid-Open No. 62-282697), but in recent years a sedimentation step is not required for cleaning treated water. There is a demand for a simpler method.

In recent years, the settling tank of waste water treatment equipment has been omitted to minimize the installation area, and in order to make up for the lack of clean water, microorganisms and solids are removed from the clean water and reused as clean clean water. For this purpose, a method for obtaining clean treated water by using a membrane separator immersed in an aeration tank has been developed. By using this apparatus, Escherichia coli and pathogenic Cryptosporidium are removed, and further solid matter can be removed, so that clean treated water with high transparency can be obtained.

However, in the above-mentioned membrane separator, the membrane becomes clogged due to the increase in the viscosity of the activated sludge during the operation of the wastewater treatment, the separation of the bacterial cells from the activated sludge, etc., and the filtration resistance increases and the treatment capacity is increased. descend. The tendency of the filtration resistance to rise also differs depending on the season, and the filtration resistance rises sharply especially in winter, resulting in a high frequency of membrane blockage. As a method of suppressing the membrane clogging and extending the life of the membrane, filtration is stopped for a certain period of time and backwashing with air is performed, but this is not a sufficient method. Furthermore, as a membrane regeneration method, there is also a method of backwashing with a hypochlorous acid solution, but since the hypochlorous acid solution, which is a biological poison, is mixed in the treatment tank, the sludge treatment capacity is temporarily reduced. Occurs. At present, when membrane clogging becomes remarkable, the treatment of waste water is stopped, the membrane is taken out of the system and immersed in a hypochlorous acid solution for regeneration, but this treatment requires time and expense for regeneration of the membrane.

[0006]

The present invention achieves stable filtration efficiency by promoting solid-liquid separation of activated sludge through a membrane, and as a result, chemical washing can be omitted or the number of chemical washings can be reduced. The purpose is to provide a method.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors added a culture of microorganisms, cells or treated cells of cells functioning as a filter aid to activated sludge. By doing so, it was found that the clogging of the filter medium at the time of solid-liquid separation of activated sludge by filtration is reduced,
The present invention has been completed.

That is, the present invention is as follows. [1] A method for treating activated sludge, which comprises adding to the activated sludge a culture, a microbial cell or a treated cell of at least one microorganism belonging to bacteria, yeasts or molds which functions as a filter aid.

[2] A culture of at least one microorganism belonging to bacteria, yeasts or molds, which functions as a filter aid.
A method for solid-liquid separation of activated sludge, which comprises filtering the activated sludge to which cells or treated cells are added. In the method [2], it is preferable that the filtration is performed using a filtration membrane. The method may exhibit a filtration efficiency index of at least 1.33. The method may also exhibit a filter media filtration resistance index of 0.71 or less. Further, the method can also exhibit a sludge cake filtration resistance index of 0.77 or less. It is preferable that the microorganism used has a growth ability at 5 ° C to 35 ° C.

[3] The microorganism is a Microbacterium genus,
Pseudomonas spp, Saccharomyces spp, Debaryomyces spp, Hansenula spp, Rhodosporidium spp, Candida spp, Tollopsis spp, Pichia spp, Sporoboromyces spp, Rhodotorula spp, Absidia spp, Aspergillus spp, Aureobasidium spp, Botrytis spp, Catheomium, Cladosporium), Kungamera, Dipoduscus, Endomyces, Fusarium, Galactomyces, Geotricum, Gibberella, Helicostillum, Moritellia, Mucoa, Neurospora, Ophilorus, At least one kind belonging to a genus selected from the group consisting of Penicillium genus, Rhizopus genus, Synthephalastrum genus, Trichoderma genus, Verticillium genus and Tigorincus genus, or a combination thereof, [1] or [ 2] Method.

In the method [3], specifically, the microorganisms are Microbacterium sp. Nura Anomala, Hansenula Miso, Hansenula Satanus, Rhodes polydium toluroydes, Candida parapsilosis, Candida Utilis, Candida Boydini, Candida tropicalis,
Candida tropicalis, Torrlopsis Candida, Torrlopsis famata, Torrlopsis bobina,
It is preferably at least one selected from the group consisting of Torulopsis coliculosa, Torulopsis faerica, Pichia pormofa, Pichia membrane Blanchiens, Sporoboromyces johnsonii, Sporoboromyces salmonicara, Rhodotorula graminis and Rhodotorula parida. Particularly, it is preferable that the microorganism is Torulopsis candida IFO768 strain.

[4] A filter aid containing at least one microorganism belonging to bacteria, yeast or mold. The filter aid of [4] preferably has a filtration efficiency index of at least 1.33. The filter aid may be one that promotes filter medium permeation of the filtrate in the filtration of activated sludge. The promotion of permeation of the filtrate through the filter medium may be due to a reduction in clogging of the filter medium. The filter aid may also have a filter media filtration resistance index of 0.71 or less. Furthermore, the filter aid may also have a sludge cake filtration resistance index of 0.77 or less.
This filter aid preferably has activity at 5 ° C to 35 ° C. As the microorganisms used for this filter aid,
Same as [3].

[5] A method for treating activated sludge, which comprises adding the filter aid according to the above [4] to activated sludge. [6] A method for solid-liquid separation of activated sludge, which comprises filtering the activated sludge to which the filter aid described in [4] above is added.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below. In the activated sludge treatment, the decrease in the solid-liquid separation ability due to the filtration of the membrane separator is promoted especially in winter. In other words, if the growth activity of Bacillus bacteria, which is vigorous for reproduction, decreases due to a decrease in water temperature, and the nutrient source in the wastewater that Bacillus bacteria ingested becomes an excess, even slow-growing microorganisms that produce viscous substances are also discharged in the wastewater. As a result, a slow supply of viscous matter-producing microorganisms is more actively propagated. As a result, the amount of the viscous material produced increases, so that the viscosity of the activated sludge increases and it is considered that filtration of the activated sludge is hindered. From such a phenomenon, it is considered that the microorganisms that thrive in reproduction function as a filter aid.
As one of the methods of prioritizing the microorganisms functioning as a filter aid in any season regardless of the season, there is a method of utilizing the microorganisms that not only function as a filter aid but also thrive in low temperature conditions. . If it becomes impossible to supply nutrients to microorganisms that produce viscous substances by adding such vigorous microorganisms, the viscosity of sludge will not increase and the solid-liquid separation ability of the membrane separation device will not decrease. Therefore, it was thought that stable device operation would be possible. The present invention has been completed based on the above idea. However, the present invention is not limited to the one based on the above action mechanism.

1. Filtering Aid In the present invention, the "filtering aid" is one that is added to the activated sludge to promote solid-liquid separation by filtering the activated sludge. The promotion of this solid-liquid separation may be specifically due to the promotion of the filter medium permeation of the filtrate. More specifically, the filter aid of the present invention is a formulation having properties capable of promoting permeation of a filter medium through a filtrate, for example, any one of the following properties (1) to (4): (1) Increase the hydrophobicity of activated sludge, (2) reduce the viscosity of activated sludge, (3) reduce clogging of filter media during filtration of activated sludge, or (4) reduce filtration resistance of activated sludge .

In the present invention, "functioning as a filter aid" means the above-mentioned effect as a filter aid, that is, addition to activated sludge to promote solid-liquid separation by filtration, or filtration of activated sludge. In this case, it means to promote the permeation of the filtrate through the filter medium, specifically to have the characteristics (1) to (4). The effect of accelerating the solid-liquid separation of the filter aid in the present invention is not only to say that the solid-liquid separation of the activated sludge is promoted in the comparison before and after the addition of the filter aid, but also the filter aid. When a certain amount of time has passed since the addition of the filter aid, compared to the activated sludge before the addition of the filter aid, even if the solid-liquid separation is not promoted, the same time is added without adding the filter aid. It also includes the fact that solid-liquid separation is promoted as compared with activated sludge of the nature that it will have when the time elapses. Further, in the present invention, that the filter aid is “active” means that the effect as the above filter aid is actually observed.

The filter aid of the present invention contains a culture, fungus body or treated product of at least one microorganism belonging to bacteria, yeasts or molds which functions as a filter aid. Microorganisms used as a filter aid in the present invention is not particularly limited as long as it promotes solid-liquid separation by filtration by adding to activated sludge,
It is preferable that it has a growth ability even at a low temperature range of 5 to 35 ° C, preferably 5 to 10 ° C. Examples of such microorganisms include, for example, bacteria such as Microbacterium (Microbacterium).
m) Genus and Pseudomonas
Genus, Saccharomyces
As a genus and yeast, Debaryomyces
ces genus, Hansenula genus,
Rhodosporium
Genus, Candida genus, Torulopsis genus, Pichia
Genus, Sporobolomyces
s) genus, Rhodotorula genus, Endomyces genus and Galactomyces genus, and as molds, Absidia genus, Aspergillus genus (As)
pergillus), Aureobasidium (Aur
The genus Eobasidium, Botrytis
tis) genus, Cateomium
Genus, Cladosporium
Genus, Cunninghamella
Genus, Dipodascus, Fusarium, Geotricum (Geo)
genus tricum, gibberella
Genus Helicostylum
Genus, Moritierella genus,
Mucor genus, Neurospora (Neuro)
spora), Ophilorus
Genus, Penicillium genus, Rhizopus genus, Syntheoharastrum genus, Trichoderma genus, Verticillium (V)
erticillium) and the Tigo Lincus (Zyg
those belonging to the genus Orhynchus). Specific examples of such microorganisms include those listed in Table 1 below.

[0018]

[Table 1]

In Table 1, AKU, ATCC, HUT, IA
The stock names indicated by using the abbreviations M, IFO, or JCM are catalog numbers of each consignment organization. AKU is "Facility of Agricultural, K
yoto University, Kyoto, Jap
"an", ATCC is "American Type C"
ultra Collection Rockville
le, U. S. A "and HUT are" Facility of
Engineering, Hiroshima Uni
Versity, Hiroshima, Japan ",
IAM stands for "Institution of Applied
Microbiology, University
of Tokyo, Japan ", IFO is" Inst
it for for Fermentation, Os
"aka, Japan", JCM is "Japan Col
collection of Microorganism
s, RIKEN ”. Each of the strains listed in Table 1 can be easily obtained from each distribution agency according to the catalog number.

Further, in Table 1, Microbacterium sp.
U. bacterium (hereinafter sometimes abbreviated as "25 U bacterium"), and Pseudomonas putida (Pseudom)
onas putida) No. 37U (hereinafter referred to as "37U
Abbreviated as "Bacteria" and Pseudomonas fluorescens (Pseudomonas fluor)
escens) 38U bacterium (hereinafter sometimes abbreviated as "38U bacterium") is an independent administrative agency, National Institute of Advanced Industrial Science and Technology, Patent Biological Depository Center (1-1, 1-1 Higashi, Tsukuba-shi, Ibaraki) , FERM P-18629 for No. 25U and FE for No. 37U
FE for RM P-18630 and No. 38U
Deposited as RM P-18631. The above-mentioned strain is a bacterium isolated from natural soil by the present inventors. The mycological properties of 37U and 38U are as follows (Tables 2 and 3).

[0021]

[Table 2]

[0022]

[Table 3]

Based on the properties determined as described above, 37
Pseudomonas (Pseudomon)
as putida), Pseudomonas 38U
Fluorescence (Pseudomonas fluo
resences). The mycological properties of No. 25U are as follows (Table 4).

[0024]

[Table 4]

Based on the properties determined as described above, 25
The U bacteria is called Aerobacterium sp.
Lactobacillus sp. However, since the genus Aerobacterium was integrated into the genus Microbacterium in 1998, the bacteria No. 25U was finally identified as Microbacterium sp.
p. ) Was identified. 25U, 37U and 38U
Other mycological properties of No. bacterium can be examined by a method known to those skilled in the art. In addition, the classification of these microorganisms is described in "Bergey's Manual", which is a general textbook on taxonomy.
of Determinative Bacteriology 9th Edition (John G. Holt
Ed., (1994) Williams & Wilkins, Baltimore) ”.

In the present invention, the culture of the above-mentioned microorganisms may be carried out by a standard method. The carbon source contained in the medium is preferably, for example, a polysaccharide such as starch, a disaccharide such as maltose, lactose or sucrose, a monosaccharide such as glucose, fructose, mannitol or sorbitol sugar. Nitrogen source is ammonia, ammonium sulfate, ammonium chloride, ammonium nitrate or the like, as an organic nutrient source, for example, yeast extract, meat extract, malt extract, peptone or taste liquid, phosphate as an inorganic salt, magnesium salt, potassium salt, Sodium salt, iron salt, cobalt salt or other trace metal salts can be used. It is possible to use an ordinary medium in which these medium-containing substances are appropriately selected and contained at an appropriate ratio. Preferably the pH of the medium is 4-10, more preferably 6-9. Regarding the culture conditions, the culture temperature is 10 to 40 ° C., preferably 20 to 3
It is 0 ° C., and the culture period is 10 hours to 100 hours, preferably 20 hours to 48 hours.

In the present invention, the culture of the microorganism obtained as described above can be used as a filter aid. Furthermore, in the present invention, the bacterial cells collected by subjecting the culture to centrifugation or filtration can also be used as a filter aid. In the present invention, the culture is further treated with a microbial cell, that is, a form in which the culture or the harvested microbial cell is appropriately treated in a state where its survival is maintained,
For example, those in the form of immobilized cells can be used. As the form of the immobilized cells, a fixed product containing alginic acid or acrylamide in the culture or the collected cells,
Examples thereof include immobilized products adsorbed on rice bran or rice husks.
These cultures of the above microorganisms, bacterial cells or processed bacterial cells,
It may be used as a filter aid itself, or may be used as a filter aid in a state of being mixed with a suitable additive such as an inorganic coagulant and / or a polymer coagulant.

2. Addition of filter aid to activated sludge The filter aid prepared as in 1 above is then added to the activated sludge. In the present invention, "activated sludge" means
"Muddy substance obtained by growing obligately aerobic and / or facultative anaerobic cells in sewage, wastewater, etc., which have a high assimilation capacity for the contained organic substances". When adding a filter aid to activated sludge, 1 × 10 ² to 1 × per 1 L of activated sludge
It is preferred to apply an amount of filter aid containing 10 ⁶ microorganisms.

When the method of the present invention is used in an actual wastewater treatment or a test simulating the same, raw water is added to the activated sludge after addition of the filter aid of the present invention, as in the usual wastewater treatment method. It is preferable. Examples of raw water used include sewage, human waste water, industrial waste water, and artificial substrate waste water. The artificial base wastewater preferably contains, as a carbon source, a polysaccharide such as starch, a disaccharide such as maltose, lactose or sucrose, a monosaccharide such as glucose, fructose, mannitol or sorbitol sugar. As the nitrogen source contained in the artificial substrate wastewater, ammonia, ammonium sulfate,
Examples of organic nutrient sources such as ammonium chloride or ammonium nitrate include yeast extract, meat extract, malt extract, peptone, taste liquid, and inorganic salts such as phosphate, magnesium salt, potassium salt, sodium salt, iron salt, and cobalt salt. Alternatively, other trace metal salts and the like are preferable. PH of artificial substrate wastewater
Is preferably 4 to 10, more preferably 6 to 9.
These raw waters may be added at intervals or continuously.

In the present invention, "acclimation" means that the growth of activated sludge is maintained after addition of a filter aid (in the case of a control, water or an inert substance instead). . However, this growth does not require any particular culturing operation, as activated sludge is a growth product by nature. That is, acclimatization is not an essential step in the method of the present invention. It should be noted that an optional step such as adding raw water to the activated sludge may be performed in a state where the growth of the activated sludge is continued. Such an optional step corresponds to, for example, the raw water treatment step after the addition of the filter aid in the actual wastewater treatment. Therefore, in a test simulating actual wastewater treatment, a step of culturing by adding raw water to the activated sludge after addition of the filter aid may be carried out. The step of culturing by adding such raw water is also conveniently "acclimated" in the present invention.
Call.

3. Of activated sludge treated with filter aid
Solid-Liquid Separation by Filtration The activated sludge to which the filter aid is added according to the above method 2 is subjected to solid-liquid separation by filtration. In the present invention, by carrying out such biological treatment of activated sludge using a filter aid, solid-liquid separation by filtration of activated sludge can be promoted. Therefore, a biological treatment method for activated sludge, which is carried out according to the methods 1 and 2 above, characterized by adding the filter aid of the present invention to the activated sludge,
Within the scope of the present invention.

In the present invention, the term "filtration" for providing activated sludge means that a test solution containing activated sludge and a microorganism functioning as the above-mentioned filter aid is applied to the filter medium so that it cannot pass through the pore size of the filter medium. While the solid substance in the solution remains in the space before passing through the filter medium, the liquid contained in the test solution passes through the filter medium and moves to the space on the opposite side of the filter medium. It is a technique that allows a solid substance and a liquid to be separated. In order to allow the liquid contained in the test solution to pass through the filter medium, various known techniques can be used. Although not limited thereto, for example, the test solution may be added above the filter medium added so that the filtration direction becomes vertical, and the liquid in the test solution may pass through the filter medium by gravity. For filtration utilizing gravity, a container provided with a filter material on the bottom surface is placed in the test solution, and the container is pulled up from the liquid surface,
It also includes a method of allowing the liquid contained in the test solution to pass through the filter medium. Further, for example, the liquid in the test solution may be passed through the filter medium by applying a negative pressure and suction from the side opposite to the side where the test solution is added to the filter medium (vacuum filtration), Conversely, the liquid in the test solution may be passed through the filter medium by pressurizing the filter medium from the side to which the test solution is added. In the case of filtration under reduced pressure, the test solution may be placed on the filter material and suctioned from the lower part of the filter material to allow the liquid in the test solution to pass by the additive action of gravity, and the filter material is provided. A suction tube may be placed in the test solution, and negative pressure may be applied to the inside of the suction tube to suck the liquid so that the liquid in the test solution passes through the filter medium.

As the filter material in the present invention, any material that can be used for filtering activated sludge can be used. Such a filter medium preferably has an average pore size of 0.01 to
20 μm, more preferably 0.1 to 1 μm. Although not limited, in the present invention, it is preferable to use a membrane as the filter medium. The membrane used as the filter medium is, for example,
Semipermeable membranes, dialysis membranes, ultrafiltration membranes, osmosis membranes, reverse osmosis membranes, flat membranes, hollow fiber membranes and filter papers can be mentioned.

As used herein, “promoting solid-liquid separation”
Means that the filtration amount obtained as a result of subjecting the test solution to filtration increases. In the present invention, the increase in the filtration amount is obtained by subjecting the control solution to which the filter aid is not added to the filtration to the filtration amount obtained by subjecting the test solution to which the filter aid is added to the filtration. It is indicated by an increasing proportion of the quantity. Further, "promoting filtration medium permeation through the filter medium" means facilitating permeation of the liquid contained in the test solution through the filter medium, specifically, the permeability of the liquid in the activated sludge through the filter medium. By increasing the filtration rate of the liquid in the activated sludge or increasing its filtration rate. Increased permeability of liquid in activated sludge to such filter media is
For example, it may be by increasing the hydrophobicity of the activated sludge, may be by reducing the viscosity of the activated sludge, may be by reducing the clogging of the filter medium, It may be by reducing the filtration resistance of the activated sludge. Further, the promotion of the permeation of the filtrate through the filter medium may be carried out by smoothing the surface of the pores of the filter medium, decomposing the viscous substance in the activated sludge, or the like.

With respect to the filter aid of the present invention and the biological treatment method of activated sludge using the filter aid, the effect of promoting solid-liquid separation by filtration can be evaluated.
Such an effect of promoting solid-liquid separation can be directly evaluated based on the measured value by measuring the amount of filtration from the test solution. However, in the present invention, such a solid-liquid separation accelerating effect, the filtration rate, the hydrophobicity of the activated sludge, the viscosity of the activated sludge, the degree of clogging of the filter medium and the filtration resistance of the activated sludge, etc. By measuring a property closely related to the promotion of permeation and using that value as an index,
You may evaluate indirectly.

The measurement of the filtration amount from the test solution and the evaluation of the effect of promoting solid-liquid separation based on the measurement can be usually carried out by using a conventional filtration test method. As a filtration test method,
For example, the following filter paper filtration method or vacuum filtration method can be used. However, the filtration test method that can be used in the present invention is not limited to the test methods described below.

Examples of the filter paper filtration method that can be used in the present invention include the following methods.
First, a filter paper (as an example, diameter 15 cm, pore diameter 1 micron, manufactured by Advantech Toyo Co., Ltd.) is folded into an octagon and set in a funnel (FIG. 1). After hydrophilizing the filter paper with fresh water, 50 ml of activated sludge prepared by adding a filter aid and acclimatizing as described in 1 and 2 above was poured all at once into the filter paper, and 5 minutes after the first filtrate was confirmed. The filtration rate is measured by volume. The filtration amount after 5 minutes can be treated as the filtration amount in the present invention (that is, the filtrate amount or the liquid amount that has passed through the filter medium). Such a filter paper filtration method is known to have a filtration characteristic that correlates with a filtration characteristic exhibited by an actual membrane filtration facility using a membrane type activated sludge treatment tank as described in the following section. It can be usefully used as a model system for activated sludge treatment actually used in the field.

As the filtration test method, for example, the following vacuum filtration method can be used. First, a vacuum filtration device (for example, FIG. 2) is prepared. 600 ml of activated sludge prepared by adding a filter aid and acclimatizing it to a filter (for example,
Multi-purpose tank holder MdelKST-142-UH; made by Advantech), and then a specific pressure (eg 30KPa)
Depressurize to. The reduced pressure is preferably maintained at a constant degree of reduced pressure in the entire system by the action of a controller connected to a sensor, for example. Then, the filtration amount after the start of filtration is measured by volume over time. The filtration amount at the specific elapsed time can be treated as the filtration amount in the present invention (that is, the filtrate amount or the liquid amount that has passed through the filter medium).

The effect of promoting solid-liquid separation by filtration of activated sludge containing a filter aid can be directly evaluated based on the filtration amount obtained in the filtration test methods including the above-mentioned filter paper filtration method and vacuum filtration method. This evaluation can be performed according to the following procedure.

First, in order to enable effective comparison and examination of the above effects, it is preferable to characterize the activated sludge to which the filter aid is added according to a certain index. Such indicators include, but are not limited to, MLSS (Mixed Li), which is used to represent activated sludge concentration.
The value of quor suspended solid) can be used. Therefore, in the filtration test method, it is preferable to first measure the MLSS value of the activated sludge to which the filter aid is added.

The MLSS value is measured, for example, as follows. First, the activated sludge uniformly dispersed by a magnetic stirrer is weighed (for example, 10 ml), then the activated sludge is dried in a dryer at 105 ° C. for 2 hours and cooled, and then the weight of the dried residue is measured. . The amount of this dry weight is the amount of activated sludge to be weighed first (10 m in the above case).
l) Converted to the number of mg per liter is the general MLSS
It is a value. The MLSS value can also be easily measured using a commercially available MLSS meter.

Subsequently, the filtration amount of the untreated sample (the sample before adding the filter aid etc.) for the activated sludge is measured. Therefore, a part of the activated sludge whose MLSS value was measured as described above is subjected to the filtration test as described above, and the filtration amount obtained after a certain period of time is taken as the filtration amount of the untreated sample.

Next, to the activated sludge whose MLSS value was measured, a filter aid (in the case of the control, water or an inactive substance instead) was added to prepare a sample as described in the above 2. As a test sample, a filter aid is added to activated sludge having a predetermined MLSS value (for example, 10% of the final volume). As a control sample, for example, the same amount of water as the filter aid used in the test sample is added instead of the filter aid added to the test sample. Then, the test sample and the control sample are acclimated while adding raw water (for example, artificial drainage). When adding the raw water, it is preferable to extract the culture in an amount equal to that of the raw water to be added and add the raw water instead. In this way, the raw sludge is added and the activated sludge is acclimated under constant culture conditions. The activated sludge after being acclimated for a certain period of time, that is, the test sample and the control sample are referred to as acclimation samples in the present specification. For these acclimatized samples, the MLSS value is measured in the same manner as above.

Subsequently, each of these conditioned samples (test sample and control sample) is subjected to the same filtration test as that in which the filtration amount of the untreated sample was measured. The filtration amount obtained after the same elapsed time as that of the untreated sample is set as the filtration amount of the conditioned sample.

According to the above-mentioned filtration test method, the MLSS value of the untreated sample, the MLSS value of the acclimatized sample, the filtration amount of the untreated sample, and the filtration amount of the test sample (with the addition of a filter aid) for a specific activated sludge. The amount of filtration of the control sample (without addition of filter aid) is determined. Then, the post-acclimation filtration efficiency of the test sample and the control sample can be determined based on these values. In the present invention, for example, when the filtration amount of the untreated sample is represented as [C] and the filtration amount of the conditioned sample is represented as [D], the filtration efficiency after acclimation of each of the test sample and the control sample is [D] / [C ] Can calculate. Furthermore, for each experimental group using activated sludge with the same MLSS value, from the calculated post-acclimation filtration efficiencies of the test sample and control sample, determine the extent to which the post-acclimation filtration efficiency of the test sample is improved over the control sample. be able to. In the present invention, the degree to which the filtration efficiency of the test sample after acclimation is improved is calculated by the filtration efficiency of the test sample / the filtration efficiency of the control sample. The value thus calculated is referred to as "filtration efficiency index" in the present specification. This filtration efficiency index is a value that represents the degree of improvement in filtration efficiency after acclimation of a test sample, and is effectively used in the present invention as an index that objectively shows an increase in filtration amount when a filter aid is added to activated sludge. be able to. That is, the filtration efficiency index ([R] in the present invention
Is a relative value when the filtration efficiency of the control sample is 1, and can be obtained by the following formula.

[0046]

[Equation 1]

Here, when the filtration amount of the untreated sample of activated sludge used for the test sample and the control sample, that is, [C1] and [C2] are equal, this filtration efficiency index
[R] can be finally calculated as the filtration amount [D1] of the test sample / the filtration amount [D2] of the control sample. It can be judged that the higher the value of this filtration efficiency index [R], the higher the solid-liquid separation promoting effect of the filter aid used in the test sample on the activated sludge. In the filter aid of the present invention and the method for biologically treating activated sludge using the filter aid, the filtration efficiency index is preferably 1.33 or more, particularly preferably 2 to 10. This filtration efficiency index shows that even when the same strain of microorganism is used as a filter aid, the ML of activated sludge is
Due to differences in filtration test conditions such as SS value and filtration test method,
Although with some variability, the method or filter aid of the present invention is at least 1.33% above at least one filtration test condition.
The above shows the filtration efficiency index.

The effect of promoting solid-liquid separation in the present invention can also be evaluated using an index other than the above-mentioned filtrate amount measurement value and filtration efficiency index. Here, the promotion of the solid-liquid separation of the present invention is preferably due to the promotion of the filtration medium permeation of the filtrate. The promotion of the filtration medium permeation of such a filtrate is a property that can promote the filtration medium permeation of the filtrate shown by adding a filter aid to the activated sludge, specifically, the following (1) to (4): It may be based on the properties shown: (1) increase the hydrophobicity of the activated sludge, (2) reduce the viscosity of the activated sludge, (3) reduce clogging of the filter medium during filtration of the activated sludge, or (4) Reduction of filtration resistance of activated sludge.

Therefore, for the method or filter aid of the present invention, these properties exhibited when the filter aid is added to the activated sludge are evaluated in comparison with the case where the filter aid is not added to obtain a solid-liquid solution. The effect of promoting separation can also be evaluated indirectly. These test methods may follow the methods described below.

Measurement of Hydrophobicity of Activated Sludge The hydrophobicity of activated sludge can be measured by measuring the ionicity of the surface charge of the activated sludge. In this case, the surface charge of the activated sludge is measured for anionicity or cationicity. As a result, if the anionicity is high, the activated sludge shows hydrophilic properties, and if the cationicity is high, it shows hydrophobic properties. to decide. If the cationicity of the activated sludge increases, the permeability of the activated sludge to the filter medium increases,
It can be judged that the filterability is improved. A method known to those skilled in the art can be used for the measurement of anionic or cationic property (for example, “Sewage test method” (3rd edition, Heisei 1).
(1 year, published by the Japan Sewerage Association), according to the cationic and anionic analysis method of the polymer flocculant described in the first volume, pages 318 to 323).

In the above-mentioned cationic or anionic measuring method, the activated sludge is tested by a colloid titration method to obtain a colloid equivalent value. For example, cationic is, for example, 0.1
Adjust the pH of the activated sludge sample to 4.0 with mol / L hydrochloric acid, add toluidine blue indicator, and titrate with a 0.0025 mol / L polyvinyl potassium sulfate solution. From the required number of ml of 0.0025 mol / L polyvinyl potassium sulfate solution, calculate the colloid equivalent value (meq / g) by the following formula.

Colloid equivalent value (meq / g) = [(ab) / 2] / [500 / s] (wherein the required number of ml of 0.0025 mol / L polyvinyl potassium sulfate solution is a for the sample and b for the blank) The mass (mg) of the dried sample is expressed as s.) Generally, the colloid equivalent value calculated in this way is 3.5 meq / g or more strong cationic, and 1.5 meq / g or less weakly cationic. . If the colloid equivalent value calculated as described above increases in the activated sludge containing the filter aid, it can be considered that the hydrophobicity of the activated sludge increases.

B. Measurement of Viscosity of Activated Sludge The viscosity of activated sludge can be measured by the following measuring method. For measurement, for example, B type viscometer (Model B8L TOKIMEC
Company) is used. First, add 20 ml of activated sludge prepared by acclimatizing by adding a filter aid to a BL adapter, and put it at 25 ° C.
It is dipped in the water bath of No. 3 and mounted, and after rotating at a rotation speed of 6 rpm for 5 minutes, rotation is stopped and the indicated value is read. This indicated value is
The viscosity (mPas) is obtained under the condition of 25 ° C. The lower the viscosity value, the lower the viscosity of activated sludge.

C. Clogging of filter media and filtration resistance of activated sludge
The clogging of the filter medium and the filtration resistance of the activated sludge can be measured by a method known to those skilled in the art, but it is basically preferable to use a method according to the Nutsche test (for example, “sewage test method”). (3rd edition, 1999, published by Japan Sewer Association, first volume, pages 310 to 315). The measured value of the filtration rate by the Nutsche test is applied to the "Loose's constant pressure filtration rate formula" described in the above-mentioned document.

In the present invention, the resistance coefficient (Km) of the filter material and the sludge cake specific resistance (α
m) can be calculated. The resistance coefficient (Km) of this filter medium serves as an index of clogging of the filter medium. Also, the sludge cake resistivity
(αm) is an index of filtration resistance of activated sludge. The smaller the resistance coefficient (Km) of the filter material, the less the resistance of the filter material, that is, the less clogging of the filter material. Sludge cake resistivity (α
The smaller the value of m), the smaller the filtration resistance of activated sludge.

Loose constant pressure filtration rate formula: (V + V0) ² = K ・ (t + V0 ² / K) t / V = V / K + 2V0 / V = κ ・ αm ・ μ / (2ΔP ・ A ² ) ・ V + μ ・ Km / (ΔP ・ A)

In the formula, V is the amount of filtrate (m ³ ), t is the filtration time (minutes),
κ is solid concentration (ppm), μ is filtration viscosity (cp), ΔP is filtration pressure
(kPa), A is the filtration area (m ² ), K is the loose filtration constant (m ⁶ /
Min), Km is the resistance coefficient (1 / m) of the filter medium, and αm is the sludge cake specific resistance (m / kg). Loose filtration constant Based on the filtration amount obtained over time by vacuum filtration, plotting the filtration amount V against the reciprocal t / V of the filtration amount filtered at a certain time, the linear relationship is obtained. can get. The value of the Y intercept of this straight line is μ · Km / (ΔP · A).

4. Activated sludge organisms in production membrane filtration equipment
Use of filter aid in biological treatment In one embodiment of the present invention, in order to promote solid-liquid separation by filtration of activated sludge in a membrane separation device immersed in an activated sludge treatment tank, a filter aid is used. A method for treating activated sludge, which comprises adding a culture, a microbial cell or a treated product of at least one microorganism belonging to a bacterium, yeast, or mold that functions as a membrane to a membrane activated sludge treatment tank. In this method, for example, by operating the activated sludge treatment device with the microorganisms functioning as a filter aid being prioritized in the treatment tank, the frequency of regenerating the membrane of the membrane separation device is reduced and stabilized. The device can be operated.

When the wastewater is biologically treated in the activated sludge treatment facility, the treated water can be taken out of the system by using the membrane separation device immersed in the aeration tank. Therefore, in one embodiment of the present invention, in such an activated sludge treatment facility, a filter aid is added to the activated sludge to promote solid-liquid separation by filtration of the activated sludge, thereby treating water. It can be taken out of the system efficiently. Similarly, when activated sludge treatment equipment is composed of an anaerobic tank and an aeration tank, sludge is circulated between these tanks, and when the treated water is taken out of the system using a membrane separation device immersed in the aeration tank, By adding the filter aid of the present invention to activated sludge, solid-liquid separation by filtration is promoted, whereby treated water can be efficiently taken out of the system.

In the present invention, the solid-liquid separation by filtration can be advantageously promoted also in the ordinary activated sludge treatment equipment other than the above-mentioned activated sludge treatment equipment by adding the filter aid of the present invention. The present invention also relates to the use of filter aids for any such activated sludge treatment plant.

[0061]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. [Examples 1 to 46] In the following description, Examples 1 to 46 using different microorganisms are collectively described.

1. Preparation of filter aid (microorganism culture) 100 ml of the medium was poured into a 500 ml Erlenmeyer flask, a cotton plug was placed, and the mixture was sterilized at 121 ° C. for 20 minutes in an autoclave.
Next, each of the microorganisms of Examples 1 to 46 shown in Table 5 below was inoculated into each flask one by one and shake-cultured at 24 ° C. for 43 hours, and the culture solution was diluted or concentrated to 1 × 10 6. ⁶ / m
It was set to l. The medium composition used is as shown in Table 6. The pH of the medium was adjusted to 7.0.

[0063]

[Table 5]

[0064]

[Table 6]

2. Measurement of MLSS value of activated sludge Activated sludge collected from an industrial wastewater treatment plant was uniformly dispersed by a magnetic stirrer and weighed 10 ml, dried at 105 ° C for 2 hours in a dryer, cooled, and then dried. The weight of the residue was measured. The MLSS value of the activated sludge was calculated from the weight of the dried residue. Tables 8 and 9
Shows the MLSS value (represented by [A]) of the untreated sample for each activated sludge tested.

3. Addition and acclimation of filter aid to activated sludge
The nutrient 500ml Erlenmeyer flask, the activated sludge from industrial waste water treatment plant was measured MLSS value above 2 was charged by 90 ml, further culture of a microorganism prepared in the above 1 for each Example, 10ml each to each flask I prepared it. The mixture of this activated sludge and microbial culture is rotated at a rotation speed of 230r.
2.5m at a fixed time once a day while shaking with a pm rotary shaker (Takasaki Kagaku Kikai Co., Ltd.)
l, and then drain the artificial substrate drainage instead of 2.5 m
1 was added and acclimated for 7 days at a temperature of 15 ° C. (test sample). As a control sample, 10 ml of tap water was added to the flask containing no microorganism instead of the culture of the microorganism for acclimation. As control samples, 10 kinds of activated sludges having different MLSS values were prepared. Evaporated water was obtained by weighing the container once a day and calculating the difference from the initial value, and replenishing the amount with tap water. Table 7 shows the composition of the artificial substrate drainage used. The pH of the artificial substrate drainage was adjusted to 7.0.

[0067]

[Table 7]

4. Measurement of filtration amount by filter paper filtration method (Example
1-37) No5C filter paper (diameter 15 cm, pore size 1 micron,
Advantech Toyo Co., Ltd.) was folded into 8 corners and set in a funnel. After hydrophilizing the filter paper with fresh water,
50 ml of the activated sludge of the untreated sample or the activated sludge of the acclimatized sample was poured all at once onto the filter paper, and the filtration amount 5 minutes after the first filtrate was confirmed was measured by volume with a graduated cylinder. In addition, this test method was used in the test as a method having a correlation with the actual membrane filtration equipment as described in the summary of the 32nd Annual Meeting of the Japan Society on Water Environment (1998), page 190.

In Examples 1 to 37, the untreated samples for each activated sludge prepared in 1 to 3 above and the activated sludge (test sample) to which the culture of each microorganism shown in Table 5 was added as a filter aid The filter paper filtration amount was measured as described above for both acclimated samples of 5 kinds of activated sludge controls (control samples) having different MLSS values.
The results of these Examples 1 to 37 are shown in Table 8. In Table 8, [B] / [A], [D] / [C], and [R] values are indicated by two significant digits.

Each experimental group collectively shows activated sludge having the same MLSS value in order to calculate a filtration efficiency index as an index for effective comparison of filtration amounts. Filtration efficiency index for control samples in each experimental group
([R]) is indicated by 1. As shown in Table 8, Examples 1 to 1
The filtration efficiency index shown in 37 is 1.3 in all cases.
It is 3 or more. That is, the microorganisms used in Examples 1 to 37 were shown to be useful as filter aids.

[0071]

[Table 8]

5. Measurement of filtration amount by vacuum filtration method (Example
38-46) The MLSS value was measured for various samples corresponding to Examples 38-46 prepared according to the above 1-3. The measured samples are an untreated sample, a conditioned sample of activated sludge added with a filter aid (test sample), and a control acclimated sample of activated sludge without addition of a filter aid (control sample). Further, the vacuum filtration amount of each of these samples was measured according to the following vacuum filtration method. As the samples to be subjected to the vacuum filtration method, 600 ml each was used.
In order to prepare this sample, in the step 3 above,
Seven Erlenmeyer flasks were prepared for each example. In addition,
The microorganisms used in these Examples 38 to 46 were randomly selected from the microorganisms used in Examples 1 to 37.

The vacuum filtration apparatus shown in FIG. 2 was used for the vacuum filtration method in this example. In this vacuum filtration device,
Filter (Multipurpose tank holder MdelKST-142-UH;
Advantech), a graduated cylinder for measuring the filtrate, a sensor (OKANO WORKS TYPE AVGN), a solenoid valve, a needle valve, and an aspirator are connected by a polypropylene tube. The upper part of the graduated cylinder is fitted with a silicon stopper matching the inner diameter of the graduated cylinder so that the entire system can be maintained at the set degree of reduced pressure even when the pressure is reduced. When decompressing with the aspirator, the pressure will exceed the set value, but at that time, the sensor will work when the decompression degree exceeds the set value, the solenoid valve will automatically open and close, and the decompression degree of the set value will It is a mechanism to be maintained. At this time, the needle valve is adjusted in advance in order to suppress a sudden decrease in the degree of pressure reduction. 600 ml of each sample was put into the filter of this vacuum filtration device, and the amount of filtrate after the start of filtration was measured with a 500 ml graduated cylinder over time.

For Examples 38 to 46, 1 after starting filtration.
The results based on the amount of filtrate for 0 minutes are shown in Table 9. In Table 9, [B] / [A], [D] / [C], and [R] values are indicated by two significant digits. In order to calculate the filtration efficiency index as an index for performing effective comparison of the filtration amount, each experimental group was subjected to M
It is a group of activated sludges having the same LSS value. Filtration efficiency index for control samples in each experimental group
([R]) is indicated by 1. As shown in Table 9, Example 38
All of the filtration efficiency indexes shown in FIGS.
33 or more. As described above, it was shown that the microorganisms used in Examples 38 to 46 were also useful as filter aids, even when measured by the vacuum filtration method.

[0075]

[Table 9]

For Examples 38 to 46, the sludge cake specific resistance (αm) and the resistance coefficient (Km) of the filter medium were calculated from the filtration amount measured with time, based on the loose pressure constant filtration rate equation. The sludge cake specific resistance (αm) indicates the filtration resistance of the activated sludge, and the resistance coefficient (Km) of the filter medium indicates the degree of clogging. Based on these values, it was calculated further sludge cake filtration resistance index in order to perform a valid comparison between the experimental groups [R.alpha _m] and media filter resistance index [R _Km]. Sludge cake filtration resistance index [Rα _m ]
Is the relative value of the sludge cake specific resistance (αm) of each Example with respect to the control of the experimental group to which each Example belongs. The filter medium filtration resistance index [R _Km ] is a relative value of the resistance coefficient (Km) of the filter medium of each Example with respect to the control of the experimental group to which each Example belongs. The results are shown in Table 10.

[0077]

[Table 10] From the results of Table 10, all the microorganisms used in Examples 38 to 46 were sludge cake filtration resistance index [Rα _m ].
Was 0.77 or less and the filter medium resistance index [R _Km ] was 0.71 or less, which showed that the filtration resistance and the degree of clogging of the activated sludge were reduced. That is, these microorganisms are considered to enhance the permeability of the liquid in the activated sludge to the filter medium,
It was found to function effectively as a filter aid.

When the results shown in Tables 8 to 10 were examined, it was found that the yeast Torulopsis candida IFO768 strain used in Examples 9 and 40 had a filtration efficiency index of 6.20 as a result of Example 9. It was found that the result of 40 was 14.4, which was a relatively high value in both the filter paper filtration method and the vacuum filtration method. At the same time, the sludge cake filtration resistance index [Rα _m ] was 0.01, and the filtration material resistance index [R _Km ] was 0.02, which were very low values. Therefore, it was shown that the Torulopsis candida IFO768 strain is very useful as a filter aid.

[0079]

INDUSTRIAL APPLICABILITY In the present invention, by adding a culture, a microbial cell or a treated product of a microbial cell that functions as a filter aid to the activated sludge, solid-liquid separation by filtration of the activated sludge is effectively promoted. be able to.

[Brief description of drawings]

FIG. 1 illustrates a test apparatus for use in a filter paper filtration method.

FIG. 2 illustrates a test apparatus used in a vacuum filtration method.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeho Tanaka             3-10-1, Daikokucho, Tsurumi-ku, Yokohama-shi, Kanagawa             Ryo Rayon Co., Ltd., Chemical Products Development Laboratory F-term (reference) 4D006 GA07 KA01 KA63 KB22 KC14                       KC16 KD24 MB02 PA01 PB08                       PB24 PC54                 4D028 AA01 AA02 BC17 BD17                 4D040 DD03 DD07

Claims (22)

[Claims] 1. A method for treating activated sludge, which comprises adding to the activated sludge a culture, a microbial cell, or a treated product of at least one microorganism belonging to bacteria, yeasts or molds which functions as a filter aid. . 2. An activated sludge, which is obtained by filtering an activated sludge to which a culture of at least one microorganism belonging to bacteria, yeasts or molds functioning as a filter aid, a microbial cell or a treated product of the microbial cell is added. Solid-liquid separation method. 3. The method according to claim 2, wherein the filtration uses a filtration membrane. 4. A method according to claim 2 or 3 which exhibits a filtration efficiency index of at least 1.33. 5. The method according to any one of claims 2 to 4, which exhibits a filter media filtration resistance index of 0.71 or less. 6. The method according to claim 2, which exhibits a sludge cake filtration resistance index of 0.77 or less. 7. The method according to claim 1, wherein the microorganism has a growth ability at 5 ° C. to 35 ° C. 8. The microorganisms are Microbacterium, Pseudomonas, Saccharomyces, Debaryomyces,
Hansenula, Rhodosporidium, Candida, Torlopsis, Pichia, Sporoboromyces,
Rhodotorula, Absidia, Aspergillus, Aureobasidium, Botrytis, Catheomium, Cladosporium, Kuningamela, Dipoduscus, Endomyces, Fusarium, Galactomyces, Geotrichum, Gibberella, Helicosti Genus Lamb, genus Moritiella, genus Mucoa, genus Neurospora,
8. At least one kind belonging to a genus selected from the group consisting of Ophilorus genus, Penicillium genus, Rhizopus genus, Synthephalastrum genus, Trichoderma genus, Verticillium genus and Tigo Lincus genus, or a combination thereof. The method according to any one of 1. 9. The microorganisms are Microbacterium sp., Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas ovalis, Saccharomyces ruxy, Saccharomyces ovarum, Saccharomyces carlsbergensis, Debarriomyces hanzenii, Hansenula anomala, Hansenurilla sohane, Hansenula miso, Hansenula miso, Hansenula miso Torroides, Candida Parapsilosis, Candida
Yutiryisu, candy Daboi Dini, Candida tropicalis, Torulopsis Candida, Torulopsis Famata, Torulopsis Bobina, Torulopsis Korikyurosa, Torulopsis Faerika, Pichia Porumofa, Pichia membrane tumefaciens, Suporoboromisesu Jonsoni, Suporoboromisesu Sarumonikara, Rhodotorula graminis and Rhodotorula pallida The method according to claim 1, wherein the method is at least one selected from the group consisting of: 10. The method according to any one of claims 1 to 7, wherein the microorganism is Torulopsis candida IFO768 strain. 11. A filter aid containing at least one microorganism belonging to bacteria, yeast or mold. 12. The filter aid of claim 11, which exhibits a filtration efficiency index of at least 1.33. 13. The filter aid according to claim 11, which accelerates the permeation of the filtrate through a filter medium in the filtration of activated sludge. 14. The filter aid according to claim 13, wherein the promotion of the permeation of the filtrate through the filter medium is achieved by reducing the clogging of the filter medium. 15. The filter aid according to any one of claims 11 to 14, which exhibits a filter media filtration resistance index of 0.71 or less. 16. The filter aid according to claim 11, which has a sludge cake filtration resistance index of 0.77 or less. 17. The filter aid according to claim 11, which has an activity at 5 ° C. to 35 ° C. 18. The microorganisms are Microbacterium, Pseudomonas, Saccharomyces, Debaryomyces, Hansenula, Rhodosporidium, Candida, Torlopsis, Pichia, Sporoboromyces, Rhodotorula, Absidia. Genus, Aspergillus genus, Aureobasidium genus, Botrytis genus, Cathemium genus, Cladosporium genus, Kuningamera genus, Dipoduscus genus, Endomyces genus, Fusarium genus, Galactomyces genus, Geotricum genus, Gibberella genus, Helicostillum genus, Moritelliera Genus, Mucoa, Neurospora, Ophilorus, Penicillium, Rhizopus,
The filter aid according to any one of claims 11 to 17, which is at least one kind belonging to a genus selected from the group consisting of Synthiferastrum genus, Trichoderma genus, Verticillium genus and Tigorincus genus, or a combination thereof. Agent. 19. The microorganisms are Microbacterium sp., Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas ovalis, Saccharomyces ruxii, Saccharomyces ovarum, Saccharomyces curlsbergensis, Debarriomyces hansenii, Hansenula anomala, Hansenula miso,
Hansenula satanas, Rhodosporium torroides, Candida parapsilosis, Candida utilis, Candida Boydini, Candida tropicalis, Candida tropicaris, Torlopsis candida, Torlopsis famata, Torlopsis bovina, Torlopsis porricopsilaci, Coryculosa Pichia Membran Faciens, Sporoboromyces johnsoni, Sporoboromyces salmonikala, Rodotorula
The filter aid according to any one of claims 11 to 17, which is at least one selected from the group consisting of graminis and Rhodotorula parida. 20. The method according to any one of claims 11 to 17, wherein the microorganism is Torulopsis candida IFO768 strain.
The filter aid according to the item. 21. A method for treating activated sludge, which comprises adding the filter aid according to any one of claims 11 to 20 to activated sludge. 22. A method for solid-liquid separation of activated sludge, which comprises filtering the activated sludge to which the filter aid according to any one of claims 11 to 20 is added.