JP2017121602A - Dewatering method of sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dewatering method of sludge by detecting variation of cohesiveness and dewatering property of sludge with detecting specific microorganism relating dewatering property of the sludge contained in the sludge and adjusting a dewatering treatment condition of the sludge.SOLUTION: There is provided a dewatering method of sludge having an aggregation floc formation process for forming an aggregation floc by adding a polymer coagulant to sludge and a solid solution separation process for separating the formed aggregate floc, wherein percentage of microorganism belonging to Chloroflexi based on present amount of all microorganism in the sludge is detected and a condition of the solid solution separation process and/or the aggregation floc formation process is adjusted based on detection results thereof.SELECTED DRAWING: None

Description

  The present invention relates to a sludge dewatering method, and more particularly, to detect microorganisms in sludge involved in sludge dewaterability and to determine the necessity of adjusting sludge dewatering treatment conditions based on the abundance thereof. About.

  The dewatering treatment of organic sludge generated in the treatment process of organic industrial wastewater generated in sewage and human waste treatment plants and various industries is strong, coarse, and the moisture content of the cake after dehydration according to the properties of the sludge and the type of dehydrator Is required to be a flocculated floc. For this reason, suitable polymer flocculants are selected and used from cationic polymer flocculants, anionic polymer flocculants, amphoteric polymer flocculants and the like.

  The selection of these polymer flocculants is a macro evaluation such as the average particle size of the floc floc, the amount of filtrate per unit time during solid-liquid separation, filtrate turbidity, floc floc strength, cake moisture content after dehydration, etc. A suitable agent is derived from the evaluation results.

  However, when sludge causes a change in properties over time, the treatment state deteriorates, and it is necessary to select a polymer flocculant suitable for the current situation each time. In order to perform an efficient and stable dehydration process, it is important to capture factors that affect dehydration as accurately as possible.

  One of the causes of sludge property changes is considered to be the microbial flora that occupies most of the sludge. In general, the flora of microorganisms in sludge causes changes over time due to seasonal changes and the like. Changes in the flora of microorganisms in the sludge change the sludge properties. Until now, there is no known report that associates the abundance of specific microorganisms with the evaluation results of the dewaterability of sludge of the polymer flocculant.

  On the other hand, in the biological treatment of organic wastewater including the activated sludge method, various methods have been proposed as methods for predicting and grasping troubles in operation of the apparatus during wastewater treatment. Among them, a plurality of methods for detecting specific microorganisms that are considered to cause trouble and a method for managing the operation of an apparatus during wastewater treatment based on the detection results have been proposed (Patent Documents 1 to 5). However, in the case of causing sludge property change over time, any of the documents of Patent Documents 1 to 5 is insufficient to improve the cohesiveness and dewaterability of sludge, and sludge that is industrially satisfactory. It could not be a dehydration method.

Japanese Patent No. 4830307 Japanese Patent No. 4370956 Japanese Patent No. 4272774 JP 2002-119300 A JP-A-10-70999

Ammann RI (1995) In situ identification of micro-organism by whol cell hybridization with rRNA-targeted nucleic probes. In: Akkerman ADC, van Erasas JD, de Bruijn FJ (eds) Molecular microbiology manual. Kluwer, The Netherlands, pp1-15

  The purpose of the present invention is to detect sludge coagulation and dehydration fluctuations by detecting specific microorganisms involved in the sludge dewaterability contained in the sludge, and to adjust sludge dewatering treatment conditions. It is to provide a dehydration method.

  As a result of intensive studies to solve the above-mentioned problems, fluctuations in the abundance of specific types of microorganisms contained in sludge affect the coagulation and dehydration properties of sludge. Specifically, the abundance of microorganisms belonging to the Chloroflexi gate It was found that the fluctuation affects the cohesiveness and dewaterability of sludge. Furthermore, when the ratio of the abundance of microorganisms belonging to Chloroflexi gate to the abundance of all microorganisms in sludge is reduced, the dewaterability of sludge deteriorates, and the abundance of microorganisms belonging to Chloroflexi gate to the abundance of all microorganisms in sludge is reduced. As the ratio increased, the dewaterability of sludge was improved, and the present invention was completed.

  That is, the present invention is a sludge dewatering method comprising a coagulation floc forming step of forming a floc floc by adding a polymer flocculant to sludge, and a solid-liquid separation step of separating the formed floc floc. A sludge dewatering method that detects the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the medium and adjusts the conditions of the solid-liquid separation step and / or the floc-floc formation step based on the detection result Exist.

  The present invention also provides a method for dewatering the sludge, which increases the rate of addition of the polymer flocculant to the sludge when the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the sludge is reduced. Lies in the way.

  The present invention also provides a method for dewatering the sludge, which reduces the rate of addition of a polymer flocculant to the sludge when the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the sludge is increased. Lies in the way.

  Further, the present invention resides in the above sludge dewatering method, wherein the polymer flocculant is at least one of a cationic polymer flocculant and an amphoteric polymer flocculant.

  Furthermore, the present invention resides in the sludge dewatering method for detecting the abundance of microorganisms belonging to the Chloroflexi gate based on genetic information.

  According to the sludge dewatering method of the present invention, by accurately detecting the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the sludge, it is possible to grasp the change in sludge properties, By detecting changes in dewaterability and adjusting sludge dewatering conditions, sludge dewatering can be performed more efficiently and stably.

The present invention is described in detail below.
In the present invention, the microorganism belonging to the Chloroflexi gate refers to a bacterial group classified into the Chloroflexi gate among the taxonomic taxonomic group. In the present invention, the abundance of microorganisms belonging to Chloroflexi gate refers to the number, concentration, and dominance of microorganisms belonging to Chloroflexi gate obtained based on genetic information of Chloroflexi gate.

  In the sludge dewatering method of the present invention, first, the abundance of microorganisms belonging to Chloroflexi with respect to the total amount of microorganisms contained in the sludge is measured over time using a method based on genetic information, and subsequently the variation of the measured value Based on the above, the necessity of adjusting sludge dehydration conditions is determined. As a result, it is possible to accurately grasp the change in the property of sludge over time, and to improve the sludge processability by adjusting the sludge dehydration conditions before the sludge processability is completely deteriorated. .

  The detailed mechanism by which the ratio of the abundance of microorganisms belonging to Chloroflexi to the total abundance of microorganisms in sludge affects the aggregation and dehydration properties of sludge is unknown, but many of the microorganisms belonging to Chloroflexi have a filamentous morphology. Therefore, it may act as a support when the aggregated floc is formed, or the polymer flocculant and the microorganism belonging to Chloroflexi react to show a cross-linked state in a simulated manner. For this reason, it is considered that microorganisms belonging to the Chloroflexi gate affect the cohesiveness and dewatering property of sludge, particularly surplus sludge and digested sludge with little fibrous material.

  A known method can be used as a method for detecting a microorganism belonging to the Chloroflexi gate based on genetic information. For example, a dot hybridization method in which an oligonucleotide having a sequence complementary to a specific base sequence specific to a specific microorganism is allowed to act, a microarray method, a fluorescence in situ hybridization method (hereinafter referred to as FISH method) Quantitative PCR method, PCR-DGGE method and the like can be used, but it is more preferable to use FISH method.

  The FISH method avoids problems such as PCR bias and PCR artifacts, and performs observation and analysis at the cell level. Therefore, it becomes possible to grasp the abundance of microorganisms belonging to the Chloroflexi gate more quantitatively. For detection and quantification of microorganisms belonging to Chloroflexi using the FISH method, a method using a microscope such as a fluorescence microscope or a laser microscope, a fluorescence measuring device such as a fluorescence image scanner, a nucleic acid hybridization detection device, a flow cytometer, a thermal cycler A method using an electrophoresis apparatus or the like can be used. When using a microscope, microorganisms belonging to the Chloroflexi gate can be directly measured from the acquired image, or the area occupied by the microorganisms belonging to the Chloroflexi gate can be measured using image analysis software. ImageJ or the like can also be used as image analysis software.

  In the present invention, if the oligonucleotide is designed to have a sequence complementary to a base sequence specific to a microorganism belonging to Chloroflexi, a known oligonucleotide sequence is used as a probe. Alternatively, it may be newly designed and used. Examples of known probes include “GNSB941” or “CFX1223” shown in Table 1. In the present invention, these may be used alone or in combination. .

  The probe must be labeled. Examples of the fluorescent labeling substance when a fluorescent substance is used for the label include FITC (manufactured by Tokyo Chemical Industry Co., Ltd.), Rhodamine (manufactured by Tokyo Chemical Industry Co., Ltd.), and the like, but are not limited to these fluorescent labeling substances.

  Furthermore, when detecting the abundance of all microorganisms contained in the sludge as necessary, it is necessary to label all microorganisms, for example, DAPI (4,6′-Diamino-2-phenylindole chloride, manufactured by Sigma-Aldrich) ), Hoechst 33258 (manufactured by Sigma Aldrich), SYTO9 (manufactured by Invitrogen), SYTO60 (manufactured by Invitrogen), etc., but particularly those that do not interfere with detection of microorganisms belonging to the Chloroflexi gate. It is not limited.

  Examples of the sludge dehydrator used in the present invention include a centrifugal dehydrator, a belt press dehydrator, a screw press dehydrator, a vacuum dehydrator, a filter press dehydrator, and a multiple disk dehydrator. However, it is not limited to these.

  The adjustment method of sludge dehydration treatment conditions when the ratio of the amount of microorganisms belonging to Chloroflexi to the amount of all microorganisms in the sludge increases or decreases, regardless of the type of dehydrator used, Adjustment of dehydration conditions by increasing / decreasing the rate of addition to sludge, adjustment of dehydration conditions by increasing / decreasing the concentration of polymer flocculant, adjustment of dehydration conditions by changing the method of adding polymer flocculant, Examples include adjustment of dehydration conditions by increasing or decreasing the amount of sludge supplied, adjustment of dehydration conditions by reselecting the polymer flocculant, and adjustment of dehydration conditions by changing the type of polymer flocculant. Adjustment methods depending on the type of dehydrator include, for example, the case of a belt press dehydrator, such as adjusting the dehydration process conditions by increasing or decreasing the rotation speed and adjusting the dehydration process conditions by increasing or decreasing the rotational speed difference in the case of a centrifugal dehydrator. In the case of a screw press dehydrator, such as adjustment of dehydration conditions by increasing or decreasing the stirring strength in the coagulation tank and adjustment of dehydration conditions by increasing or decreasing the filtration speed, dehydration by increasing or decreasing the pressing force of the pressure control plate Examples include adjustment of conditions, adjustment of dehydration treatment conditions by changing the hole diameter of the punching metal, and adjustment of dehydration treatment conditions by increasing or decreasing the screw rotation speed. In addition, when a plurality of types of sludge are mixed to perform a dehydration treatment, adjustment of the dehydration treatment conditions by increasing or decreasing the mixing ratio of the sludge can be cited as one of the adjustment methods. There is no particular restriction on the method of adjusting the sludge dehydration treatment conditions, but since it can be adjusted relatively easily and regardless of the type of dehydrator, the dehydration treatment conditions can be adjusted by increasing or decreasing the rate of addition of the polymer flocculant to the sludge. It is more preferable to perform adjustment.

  Examples of the sludge used in the present invention include mixed raw sludge, surplus sludge, digested sludge, and mixtures of various sludges, and are not particularly limited, but surplus sludge and digested sludge are more preferable. If it is the said sludge kind, since the correlation of the fluctuation | variation of the abundance of the microorganisms which belong to Chloroflexi gate and the moisture content fluctuation | variation of a dewatering cake will become stronger, it will become possible to catch the property change of sludge more correctly.

  The lower limit of the solid content in the sludge (hereinafter referred to as TS) is usually preferably 0.5% or more, and preferably 1.0 or more. Moreover, as an upper limit, 6.0% or less is preferable and 5.0 or less is more preferable. If it is in the said range, when a polymer flocculant is mixed in sludge, the dewatering process of sludge can be performed efficiently.

  The upper limit value of the cation requirement, which is an indicator of the charged state of the sludge surface particles, is preferably −0.10 meq / g-TS or less, and more preferably −0.15 meq / g-TS or less. Moreover, as a lower limit, -1.0 meq / g-TS or more is preferable, and -0.5 meq / g-TS or more is more preferable. If it is in the said range, even when the sludge deteriorates over time, the cohesiveness and dewaterability of the sludge can be improved.

  The required amount of cation here is a value obtained by colloidal titration of the surface charge of the sludge particles using PVSK (Polyvinyl Potassium Sulfate) and the following mathematical formula.

Cv (meq / g-TS) = 2 * (N / 400 PVSK titration (mL)) * (N / 400 PVSK titer)

  Examples of polymer flocculants used for sludge dehydration include cationic polymer flocculants, anionic polymer flocculants, and amphoteric polymer flocculants. Since the type of polymer flocculant used differs depending on the type and properties of sludge, it cannot be generally stated, but at least one of a cationic polymer flocculant and an amphoteric polymer flocculant is often selected. The agent is not particularly limited as long as the agent has high cohesiveness and dewatering efficiency with respect to the sludge to be dewatered.

  Examples of the cationic polymer flocculant include amidine-based cationic polymers containing amidine structural units, polyvinylamine, dialkylaminoalkyl (meth) acrylate / alkyl chloride quaternary salt polymers, dialkylaminoalkyl (meth) acrylate / alkyl. Examples thereof include water-soluble polymers having a strong cation density such as a copolymer of chloride quaternary salt and (meth) acrylamide. Because it can efficiently reduce the cohesiveness of sludge and the moisture content of the dewatered cake, it must be an amidine cationic polymer containing an amidine structural unit and a dialkylaminoalkyl (meth) acrylate / alkyl chloride quaternary salt polymer. Is preferred.

  The amidine-based cationic polymer containing an amidine structural unit is a polymer having an amidine structural unit represented by either the following general formula (1) or the following general formula (2).

(However, in General Formula (1) and General Formula (2), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and X ⁻ represents an anion.)

  The amidine-based cationic polymer can be obtained by copolymerizing N-vinylformamide and acrylonitrile by an adiabatic polymerization reaction or the like and performing a hydrochloric acid hydrolysis reaction.

  The lower limit of the content of the amidine structural unit with respect to all the monomer structural units of the amidine-based cationic polymer is preferably 30 mol% or more, and more preferably 40 mol% or more. Moreover, as an upper limit, 90 mol% or less is preferable and 80 mol% or less is more preferable.

  As the amphoteric polymer flocculant, an acidic monomer such as (meth) acrylic acid or 2-acrylamido-2-methylpropanesulfonic acid is mixed with the raw material monomer used in the production of the cationic polymer flocculant. And an amphoteric polymer copolymerized.

Since the cohesiveness of sludge and the moisture content of the dewatered cake can be efficiently reduced, the amphoteric polymer flocculant used is dialkylaminoalkyl (meth) acrylate / alkyl chloride quaternary salt, (meth) acrylamide, A copolymer of (meth) acrylic acid (salt) is preferred.
The cationic polymer flocculant and the amphoteric polymer flocculant are polymers having a cationic structural unit represented by the following general formula (3).

(In the formula, R ³ represents a hydrogen atom or a methyl group, R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁶ has 1 carbon atom. represents to 4 alkyl or benzyl group, Y represents an oxygen atom or NH, Z ^- represents an anion, n is an integer of 1 to 3).

The cationic polymer flocculant is a polymer having the cationic structural unit or the cationic structural unit and a nonionic structural unit.
The amphoteric polymer flocculant is a polymer having a cationic structural unit, an anionic structural unit, and a nonionic structural unit.

  The cationic polymer flocculant other than the amidine-based cationic polymer and the amphoteric polymer flocculant can be produced by a photopolymerization reaction, an adiabatic polymerization reaction, a suspension polymerization reaction, an emulsion polymerization reaction, or the like.

  The polymer flocculant can be used as an aqueous solution. The lower limit value of the concentration of the aqueous solution is usually preferably 0.01% by mass or more, and more preferably 0.03% by mass or more. Moreover, as an upper limit, 2.0 mass% or less is preferable, and 0.5 mass% or less is more preferable. If it is in the said range, a polymer flocculent can be efficiently mixed with sludge.

  In the present invention, in addition to the polymer flocculant, at least one of an inorganic coagulant and an organic coagulant (hereinafter collectively referred to as “coagulant”) may be used in combination. Even when the polymer flocculant is used in combination with a coagulant, it can sufficiently exert a dewatering effect on sludge. Examples of the organic coagulant include polyamine, polydiallyldimethylammonium chloride, alkylamine / epichlorohydrin condensate, alkylene dichloride / polyalkylene polyamine condensate, dicyandiamide / formalin condensate, dimethyldiallylammonium chloride polymer, dialkylaminoalkyl ( Examples thereof include water-soluble polymers having a low molecular weight and a strong cation density, such as a copolymer of (meth) acrylate / alkyl chloride quaternary salt and (meth) acrylamide, and cationic surfactants.

  The lower limit of the amount of the polymer flocculant added to the sludge is usually preferably 0.01% by mass or more and more preferably 0.05% by mass or more with respect to the TS of the sludge. Moreover, as an upper limit, 5.0 mass% or less is preferable, and 4.0 mass% or less is more preferable. Within the above range, it is possible to form a strong coagulation floc having good cohesiveness and dewatering efficiency without excess or deficiency of the polymer coagulant.

  Increase ratio when increasing the rate of addition of the polymer flocculant to the sludge when the ratio of the amount of microorganisms belonging to Chloroflexi to the amount of all microorganisms in the sludge is reduced by 1.5 to 15% The lower limit is preferably 1.05 or more and more preferably 1.20 or more when the addition rate of the polymer flocculant before the ratio of the abundance of microorganisms belonging to Chloroflexi is reduced to 1. Moreover, as an upper limit, 3.0 or less are preferable and 2.0 or less are more preferable. If it is in the said range, even when the sludge deteriorates over time, the cohesiveness and dewaterability of the sludge can be improved.

  Reduction ratio when decreasing the rate of addition of the polymer flocculant to the sludge when the ratio of the amount of microorganisms belonging to Chloroflexi to the amount of all microorganisms in the sludge is increased by 1.5 to 15% When the addition rate of the polymer flocculant before the ratio of the abundance of microorganisms belonging to Chloroflexi is increased to 1, the lower limit value is preferably 0.3 or more, and more preferably 0.5 or more. Moreover, as an upper limit, 0.95 or less is preferable and 0.8 or less is more preferable. If it is in the said range, when the property of sludge improves over time, the sludge can be dehydrated without adding an unnecessary polymer flocculant to the sludge.

  When the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the sludge increases or decreases, the abundance of microorganisms belonging to Chloroflexi when the rate of addition of the polymer flocculant to the sludge is increased or decreased. Detection can be performed continuously or intermittently. When detecting intermittently, it is preferable to detect at a period of 15 to 30 days.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not restrict | limited by the following description, unless the summary is exceeded. In the examples and comparative examples, “%” indicates “% by mass” unless otherwise specified.

  The polymer flocculants used in the examples and comparative examples are shown in Table 2. The numerical values in the table indicate the content of the cationic monomer structural unit, the anionic monomer structural unit, and the nonionic monomer unit with respect to the total monomer structural units of each polymer flocculant in mol%.

Abbreviations in Table 2 are as follows.
AAm: acrylamide structural unit DME: dimethylaminoethyl acrylate methyl chloride quaternary salt structural unit DMC: dimethylaminoethyl methacrylate methyl chloride quaternary salt structural unit AA: acrylic acid (salt) structural unit NVF: N-vinylformamide structural unit AN: Acrylonitrile structural unit VAM: Vinylamine hydrochloride structural unit AMJ: Amidine hydrochloride structural unit

Example 1
-Surplus sludge (hereinafter referred to as sludge A) was collected at the city A sewage treatment plant and the following tests were conducted.

1. Detection of microorganisms belonging to Chloroflexi by FISH method 2 mL of sludge A was collected, dissolved in 50 mM phosphate buffered saline (hereinafter referred to as PBS, pH 7.4), mixed with 2 mL of 8% paraformaldehyde, and 15 hours Immobilization treatment was performed. After the immobilization treatment, centrifugation was performed at 13000 rpm for 1 minute, and the resulting pellet was washed 3 times with 50 mM PBS (pH 7.4).

  After washing, the pellet was resuspended in 50 mM PBS, the suspension was applied to a slide glass, and then dried at 48 ° C. for 2 hours. Subsequent operations after the dehydration treatment of the microbial cells were carried out according to the method described in Non-Patent Document 1 to label microorganisms belonging to Chloroflexi.

  A mixture of probes “GNSB941” and “CFX1223” shown in Table 1 labeled with FITC is used as an oligonucleotide having a sequence complementary to a base sequence specific to a microorganism belonging to Chloroflexi. Was performed at 46 ° C. in a buffer containing 35% formamide. Further, SYTO60 (manufactured by Invitrogen) was used for labeling all the microorganisms, and a preparation was prepared.

  The prepared preparation was observed using a confocal laser microscope (Carl Zeiss, LSM5 PASCAL). FITC fluorescence was excited with a 488 nm laser light source, SYTO 60 was excited with a 633 nm laser light source, and an image was acquired using a 20 × objective lens. Images were obtained for 10 fields of view in order to calculate the abundance of microorganisms belonging to the Chloroflexi gate described later. In the image, FITC is set to green, SYTO 60 is set to red, and pseudo colors are set so that green represents microorganisms belonging to the Chloroflexi gate and red represents all microorganisms.

  Regarding the abundance of microorganisms belonging to the Chloroflexi gate contained in the sludge, image analysis software “ImageJ” was used to measure the area where all the microorganisms and the microorganisms belonging to the Chloroflexi gate emitted fluorescence. X is the occupation area of all microorganisms, Y is the exclusive area of microorganisms belonging to Chloroflexi gate, and the ratio of the amount of microorganisms belonging to Chloroflexi gate to the total amount of microorganisms contained in the sludge is calculated as 100 Y / X, When the average value of 10 acquired images was calculated, the proportion of the abundance of microorganisms belonging to the Chloroflexi gate contained in the sludge A was 35.2%.

2. Table 3 shows the results of measuring physical properties of sludge A collected in the dewatering treatment test A city sewage treatment plant. TS was measured in accordance with the method described in “Sewage Test Method Vol. 1977” edited by the Japan Sewerage Association.

  Take 300 mL of the sludge A in a 500 mL beaker, add the polymer flocculant 1 (aqueous solution concentration 0.3%) to 0.55% with respect to TS of the sludge, and stir at 180 rpm for 30 seconds using a spatula. Agglomerated flocs were formed. The average floc diameter was measured visually to obtain the floc diameter.

Next, the aggregated floc was filtered through a 50 mesh nylon filter cloth, and the turbidity of the filtrate was visually evaluated. The turbidity of the filtrate was evaluated according to the following criteria.
-: The filtrate is almost transparent and suspended matter (hereinafter referred to as SS) is hardly seen (SS amount guideline: less than 50 ppm).
+: Some turbidity is observed in the filtrate and SS is slightly present (SS guideline: 50 ppm or more and less than 100 ppm).
++: The turbidity is partially observed in the filtrate, and SS is present in some places (standard amount of SS: 100 ppm or more and less than 200 ppm).
++++ Many turbidity is seen in the filtrate, and SS is present as a whole (SS amount guideline: 200 ppm or more and less than 500 ppm).
++++: Numerous turbidity is generally observed in the filtrate, SS is present as a whole, and partially present in a coarse size (SS amount guideline: 500 ppm or more and less than 1000 ppm).

Furthermore, the sludge was rolled 50 times on the filter cloth, and the floc strength (aggregation) was determined. Aggregability was evaluated according to the following criteria.
A: Water is cut off by rolling on the filter cloth, and the floc becomes a dumpling.
○: Water is cut off by rolling on the filter cloth, and flocs are formed in a lump.
Δ: Water is cut by rolling on the filter cloth, but the floc is broken and does not form a lump.
X: By rolling on a filter cloth, the coagulated sludge flows and becomes muddy.

After filtration, the floc remaining on the filter cloth was press-dehydrated at a pressure of 0.1 MPa for 1 minute to obtain a dehydrated cake, and the moisture content of the dehydrated cake was measured. The water content was measured in accordance with the method described in “The Sewerage Test Method, Vol. 1977,” p.
The test results are shown in Table 4.

(2) One month after collection of sludge A, surplus sludge was also collected at the city A sewage treatment plant (hereinafter referred to as sludge A '), and the abundance of microorganisms belonging to the Chloroflexi gate relative to the abundance of all microorganisms in the sludge When the ratio was calculated, the ratio of the abundance of microorganisms belonging to the Chloroflexi gate contained in the sludge A ′ was 24.8%. Based on this result, the sludge dewatering test was carried out in the case of the same addition rate of the polymer flocculant as in the sludge A and in the case of increasing the addition rate of the polymer flocculant.
Table 5 shows the results of measuring the physical properties of sludge A ', and Table 6 shows the results of the dehydration test.

  From the above test results, the moisture content of the dewatered cake of sludge A ′ was obtained in the case of Table 6 where the addition rate of the polymer flocculant was the same as in the case of sludge A in Table 4 from the result of detecting the abundance of microorganisms in Chloroflexi. It turns out that cohesion and floc intensity | strength are also falling. On the other hand, by increasing the addition rate of the polymer flocculant, the water content of the dewatered cake of sludge A ′ is lowered, and the cohesiveness and floc strength are maintained. From this, when the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms contained in the sludge decreases, the cohesiveness and dehydration of the sludge deteriorates. It was found that the floc diameter and dewaterability of sludge can be improved by increasing the sludge.

(Comparative Example 1)
For the sludge A and sludge A ′, a mixture of probes “GNSB941” and “CFX1223” for labeling microorganisms belonging to Chloroflexi gate, and a probe “G123-T for labeling microorganisms belonging to Cyanobacteria gate Thiothrix genus and microorganisms belonging to Eikeboom Type0221N. The procedure was the same as in Example 1 except that the hybridization conditions were changed to a buffer containing 40% formamide. The base sequence of “G123-T” is shown in Table 7. As a result, it was not possible to detect microorganisms belonging to the genus Cyanobacteria genus Thiothrix and microorganisms belonging to Eikeboom Type021N for both sludges A and A ′, and microorganisms belonging to the genus Cyanobacteria genus Thiothrix and microorganisms belonging to the genus Cyanobacterium Thiothrix02. The detection of the abundance was attempted but could not be detected, and it was found that the agglomeration and dehydration of sludge could not be predicted.

(Example 2)
(1) Mixed sludge (hereinafter referred to as sludge B) was collected at the city B sewage treatment plant, microorganisms belonging to the Chloroflexi gate were detected in the same manner as in Example 1, and the ratio of the abundance was calculated to be 31.9. %Met. Table 8 shows the results of measuring physical properties of the sludge B in the same manner as in Example 1. Table 9 shows the results of the sludge dewatering test performed in the same manner as in Example 1 except that the polymer flocculant 1 was replaced with the polymer flocculant 2.

(2) One month after collection of sludge B, the mixed sludge is collected at the city B sewage treatment plant (hereinafter referred to as sludge B '), and the abundance of microorganisms belonging to the Chloroflexi gate with respect to the abundance of all microorganisms in the sludge. When the ratio was calculated, the ratio of the abundance of microorganisms belonging to Chloroflexi gate contained in the sludge B ′ was 19.4%. Based on this result, the sludge dewatering test was carried out in the case of the same addition rate of the polymer flocculant as in the sludge B and in the case of increasing the addition rate of the polymer flocculant.
Table 10 shows the results of measuring the physical properties of sludge B ', and Table 11 shows the results of the dehydration test.

  From the above test results, in the case of Table 11 where the addition rate of the polymer flocculant 2 in Table 9 is the same, the moisture content and filtrate turbidity of the dehydrated cake are increased, and the cohesiveness and dehydrating property are deteriorated. I understand that. Moreover, it was confirmed that the moisture content of the dewatering cake similar to the sludge B is maintained by increasing the addition rate. From this, as in Example 1, when the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms contained in the sludge is reduced, the cohesiveness and dewaterability of sludge deteriorates. It was found that the dewaterability of sludge can be improved by increasing the addition rate of molecular flocculants.

(Example 3)
(1) Surplus sludge (hereinafter referred to as sludge C) is collected at the C food processing plant, microorganisms belonging to the Chloroflexi gate are detected in the same manner as in Example 1, and the ratio of the abundance is calculated to be 51.0%. Met. The results of measuring the physical properties of sludge C in the same manner as in Example 1 are shown in Table 12, polymer flocculant 1, polymer flocculant 2 (aqueous solution concentration 0.3%) and polymer flocculant 3 (aqueous solution). (Concentration 0.3%) was replaced with the polymer flocculant 4 mixed at a mass ratio of 60:40, and the polymer flocculant 4 was added except that it was added to 0.5% of sludge TS. Table 13 shows the results of the sludge dewatering test conducted in the same manner as in Example 1.

(2) One month after collection of sludge C, mixed sludge was collected at C city sewage treatment plant (hereinafter referred to as sludge C '), and the abundance of microorganisms belonging to Chloroflexi gate was calculated and included in sludge C'. The ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms was 60.6%. Based on this result, the sludge dewatering test was carried out with the same addition rate of the polymer flocculant as the sludge C dewatering test.
The results of measuring the physical properties of sludge C ′ are shown in Table 14, and the dehydration test results are shown in Table 15.

  From the above test results, in the sludge C ′ of Table 15, the moisture content of the dewatered cake is reduced and the cohesiveness and dewaterability are improved compared to the sludge C of Table 13 even when the polymer flocculant 4 has the same addition rate. You can see that It can also be confirmed that the filtrate turbidity and floc strength are also improved. From this, by increasing the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the sludge, it is possible to improve the cohesiveness and dewaterability of the sludge and further reduce the addition rate to the sludge. all right.

INDUSTRIAL APPLICABILITY The present invention can be widely applied as a sludge dewatering method that detects microorganisms belonging to the Chloroflexi gate contained in sludge and determines the necessity of adjusting sludge dewatering treatment conditions based on the abundance thereof.

Claims (5)

  A sludge dewatering method comprising a coagulation floc forming step for forming a floc floc by adding a polymer flocculant to the sludge and a solid-liquid separation step for separating the formed floc floc, and the presence of all microorganisms in the sludge A sludge dewatering method that detects a ratio of the abundance of microorganisms belonging to the Chloroflexi gate with respect to the amount, and adjusts the conditions of the solid-liquid separation step and / or the aggregated floc formation step based on the detection result.   The method for dewatering sludge according to claim 1, wherein when the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the sludge is decreased, the addition rate of the polymer flocculant to the sludge is increased.   The sludge according to claim 1 or 2, wherein when the ratio of the abundance of microorganisms belonging to Chloroflexi to the abundance of all microorganisms in the sludge is increased, the addition rate of the polymer flocculant to the sludge is decreased. Dehydration method.   The method for dewatering sludge according to any one of claims 1 to 3, wherein the polymer flocculant is at least one of a cationic polymer flocculant and an amphoteric polymer flocculant. The method for dewatering sludge according to any one of claims 1 to 4, wherein the abundance of microorganisms belonging to the Chloroflexi gate is detected based on genetic information.