WO2011013531A1

WO2011013531A1 - Device and method for membrane-separation active-sludge processing

Info

Publication number: WO2011013531A1
Application number: PCT/JP2010/062141
Authority: WO
Inventors: 進長谷川; 雅彦三浦
Original assignee: 株式会社神鋼環境ソリューション
Priority date: 2009-07-28
Filing date: 2010-07-20
Publication date: 2011-02-03
Also published as: JP4667531B2; JP2011045871A; JP5171931B2; MY158432A; JP2011067818A; TW201111296A; TWI480233B

Abstract

Disclosed is a membrane-separation active-sludge-processing device that can obtain purified water having a high level of purity while suppressing pollution of the aquatic environment and while suppressing clogging of a filter. The membrane-separation active-sludge-processing device comprises a biological processing unit that mixes wastewater and active sludge generating a water mixture and then biologically processes said water mixture, obtaining a biologically-processed sludge-containing water; a membrane unit that membrane filters the biologically-processed sludge-containing water by means of a filtration membrane; and a sludge dehydration unit that separates the biologically-processed sludge-containing water into dehydrated sludge and dehydration filtrate by means of dehydration. The membrane-separation active-sludge-processing device is provided with a mixing unit that mixes the permeated water generated by the aforementioned membrane unit with the aforementioned dehydration filtrate to obtain purified water; a first dehydration filtrate transportation channel that transports the dehydration filtrate to the aforementioned mixing unit without biological processing or membrane filtration; and a second dehydration filtrate transportation channel that returns the dehydration filtrate to the aforementioned biological processing unit. The membrane-separation active-sludge-processing device is configured so as to adjust the ratio of dehydration filtrate transported to the first dehydration filtrate transportation channel and the second dehydration filtrate transportation channel.

Description

[Title of Invention Determined by ISA Based on Rule 37.2] Apparatus and Method for Membrane Separation Activated Sludge Treatment

The present invention relates to a membrane separation activated sludge treatment apparatus and a membrane separation activated sludge treatment method.

2. Description of the Related Art Conventionally, a membrane separation activated sludge treatment apparatus has, for example, a biological treatment unit that mixes waste water and activated sludge to produce mixed water, and biologically treats the mixed water to obtain sludge-containing biological treated water. And a membrane unit for membrane filtration of the biologically treated water, and is used to purify wastewater containing organic matter and the like.

In addition, such a membrane separation activated sludge treatment apparatus has a sludge-containing biological treatment having surplus sludge, because surplus sludge is generated when biological species grow and biological sludge increases and the activated sludge increases. A sludge dewatering section for separating water into dehydrated sludge and dehydrated filtrate by dehydration is provided.
Furthermore, since the dehydrated filtrate generated in the sludge dewatering section may be contaminated when directly discharged into the water environment such as the ocean or river, such a membrane separation activated sludge treatment apparatus is The dehydrated filtrate is configured to be returned to the biological treatment unit (for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2004-305926 Japanese Unexamined Patent Publication No. 2009-28614

However, in such a membrane separation activated sludge treatment apparatus, the filtration membrane is clogged by the soluble microbial metabolite (SMP) contained in the dehydrated filtrate, resulting in a decrease in filtration efficiency. Have problems such as.

As a countermeasure for such a problem, since the permeated water obtained by membrane filtration has a sufficiently high water quality and can be produced in abundance, the permeated water and the dehydrated filtrate are mixed to produce mixed water and the mixed water A membrane separation activated sludge treatment apparatus configured to obtain water as purified water can be considered.

However, in recent years when purified water with higher purity is demanded, there is a possibility that such a membrane separation activated sludge treatment apparatus cannot sufficiently meet this demand.

MEANS TO SOLVE THE PROBLEM This invention is a membrane separation activated sludge processing apparatus and membrane separation which can obtain purified water with high purity, suppressing the pollution of water environment and suppressing clogging of a filtration membrane in view of the said problem and request. It is an object to provide an activated sludge treatment method.

The present invention relates to a biological treatment unit that mixes waste water and activated sludge to produce mixed water, and biologically treats the mixed water to obtain sludge-containing biologically treated water, and a membrane that membrane-filters sludge-containing biologically treated water using a filtration membrane. A membrane separation activated sludge treatment apparatus comprising a unit part and a sludge dewatering part for separating sludge-containing biologically treated water into dehydrated sludge and dehydrated filtrate by dehydration,
A mixing unit that obtains purified water by mixing the permeated water generated in the membrane unit and the dehydrated filtrate, and a first dehydration filter that transfers the dehydrated filtrate to the mixing unit without biological treatment and membrane filtration. A dehydration filter that includes a liquid transfer path and a second dehydrated filtrate transfer path that returns the dehydrated filtrate to the biological treatment unit, and is transferred to the first dehydrated filtrate transfer path and the second dehydrated filtrate transfer path, respectively. It exists in the membrane separation activated sludge processing apparatus comprised so that the transfer ratio of a liquid might be adjusted.

According to such a membrane separation activated sludge treatment device, mixing of dehydrated filtrate that can reduce the purity of purified water while suppressing the amount of dehydrated filtrate that may cause clogging of the filtration membrane to the biological treatment unit. Since the transfer rate of the dehydrated filtrate transferred to the first dehydrated filtrate transfer path and the second dehydrated filtrate transfer path can be adjusted so as to suppress the transfer amount to the section, Purified purified water with high purity can be obtained while clogging is suppressed. Moreover, since it can also suppress discharging | emitting dehydrated filtrate as it is to a water environment, the contamination of a water environment can be suppressed.

In the membrane separation activated sludge treatment apparatus according to the present invention, preferably, the concentration of soluble microbial metabolite (SMP) in the sludge-containing biologically treated water or dehydrated filtrate that is membrane-filtered by the membrane unit section is measured. And an SMP measuring device configured to adjust the transfer rate based on the measured value.

According to such a membrane separation activated sludge treatment apparatus, SMP is present in a large amount in the dehydrated filtrate, and since SMP is a causative substance for clogging of the filtration membrane, clogging of the filtration membrane is more reliably suppressed. However, there is an advantage that purified water with high purity can be obtained.

Furthermore, in the membrane separation activated sludge treatment apparatus provided with the SMP measuring device and the transfer rate being adjusted based on the measurement value, the transfer rate is preferably set so that the concentration of the SMP is less than or less than a reference value. It is configured to be adjusted.

According to such a membrane separation activated sludge treatment apparatus, there is an advantage that clogging of the filtration membrane can be more reliably suppressed.

In the membrane separation activated sludge treatment apparatus configured to adjust the transfer rate so that the concentration of the SMP is less than or less than a reference value, the reference value is preferably 20 mg / L or less. .

Moreover, the membrane separation activated sludge treatment apparatus according to the present invention preferably includes an organic matter concentration measuring device that measures the concentration of the organic matter in the dehydrated filtrate, and the transfer rate is adjusted based on the measured value. It is comprised as follows.

According to such a membrane separation activated sludge treatment apparatus, since most of the organic matter in the dehydrated filtrate is SMP, there is an advantage that the concentration of SMP can be grasped by measuring the concentration of the organic matter. is there. In addition, at present, it is easier to measure the concentration of organic matter in the dehydrated filtrate than to measure the concentration of SMP.

Further, in the membrane separation activated sludge treatment apparatus provided with the organic matter concentration measuring device and the transfer rate being adjusted based on the measurement value, preferably, the transfer rate is set so that the concentration of the organic matter is less than or less than a reference value. Is configured to be adjusted.

Further, in the membrane separation activated sludge treatment apparatus configured such that the transfer rate is adjusted so that the concentration of the organic matter is less than or less than a reference value, the organic matter concentration is preferably the total organic carbon concentration. The reference value is 30 mg / L or less.

Furthermore, in the membrane separation activated sludge treatment apparatus according to the present invention, preferably, the purified water is configured as a first purified water, and includes a first permeate transfer path for transferring the permeate to the mixing unit, It is comprised so that permeated water may be obtained as 2nd purified water, without mixing with a dehydrating filtrate, The permeated water is transferred to this 2nd purified water storage tank which stores the 2nd purified water The second permeated water transfer path is provided, and the ratio of the permeated water transferred to the first permeated water transfer path and the second permeated water transfer path is adjusted.

According to such a membrane separation activated sludge treatment device, when discharging the first purified water to the water environment outside the system, the remaining permeate is used as reclaimed water (various water) while suppressing contamination of the water environment. There is an advantage that you can.

Further, in the membrane separation activated sludge treatment apparatus configured so that the transfer rate of the permeated water is adjusted, preferably, the permeated water impurity measuring apparatus for measuring the permeated water purity and the dehydrated filtrate Dehydrated filtrate impurity measuring device for measuring impureness, permeated water amount measuring device for measuring the amount of permeated water transferred to the mixing unit per unit time, and per unit time of the dehydrated filtrate transferred to the mixing unit A dehydrated filtrate amount measuring device for measuring the amount of the permeated water, a dehydrated filtrate impurity measuring device, a permeated water amount measuring device, and a dehydrated filtrate amount measuring device. The purity of 1 purified water is determined, and the transfer rate of the permeated water is adjusted based on the purity of the 1st purified water.

According to such a membrane separation activated sludge treatment apparatus, it is possible to obtain more reclaimed water while diluting the dehydrated filtrate with permeate so that the first purified water satisfies the reference value as the discharged water more reliably. There is an advantage that you can.

In the membrane-separated activated sludge treatment apparatus configured to adjust the transfer rate of the permeate based on the purity of the first purified water, preferably, the purity of the first purified water is reduced. The permeated water transfer rate is adjusted so as to be less than or less than a reference value.

Further, the present invention resides in a membrane separation activated sludge treatment method for obtaining purified water from wastewater using the membrane separation activated sludge treatment apparatus.

As described above, according to the present invention, highly purified water can be obtained while suppressing contamination of the water environment and suppressing clogging of the filtration membrane.

1 is a schematic block diagram of a membrane separation activated sludge treatment apparatus according to an embodiment. The schematic block diagram which shows one state of the embodiment. The schematic block diagram which shows one state of the embodiment. The schematic block diagram which shows one state of the embodiment. The schematic block diagram of the membrane separation activated sludge processing apparatus which concerns on other embodiment. The schematic block diagram of the membrane separation activated sludge processing apparatus which concerns on other embodiment. 5C filter paper filtration volume with respect to SMP concentration. The schematic block diagram of the membrane separation activated sludge processing apparatus which concerns on the reference example 1. FIG. The schematic block diagram of the membrane separation activated sludge processing apparatus which concerns on the reference example 2. FIG. The schematic block diagram of the membrane separation activated sludge processing apparatus which concerns on the reference example 3. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the membrane separation activated sludge treatment apparatus 1 of the present embodiment mixes wastewater A and activated sludge to produce mixed water, and biologically treats the mixed water to obtain sludge-containing biologically treated water. The treatment unit 2, the membrane unit 3 for membrane filtration of the sludge-containing biologically treated water using a filtration membrane, the sludge dewatering unit 4 for separating the sludge-containing biologically treated water into dehydrated sludge C and a dehydrated filtrate by dehydration, and the membrane unit And a mixing unit 5 that obtains purified water B by mixing the permeated water generated in the unit 3 and the dehydrated filtrate.

Specific examples of the biological treatment include activated sludge treatment.
The activated sludge treatment is a treatment in which activated sludge having biological species such as bacteria, protozoa, and metazoans is mixed with waste water containing organic matter while aeration, and the organic matter is decomposed by the biological species.

The waste water A is not particularly limited as long as it contains organic matter that can be biodegraded, for example, domestic waste water, food factory, chemical factory, electronics industry factory, pulp factory, etc. The wastewater of the factory in

The biological treatment unit 2 includes a sludge-containing biological treated water storage tank 21 for storing the generated sludge-containing biological treated water, and an aeration means (not shown) for aerating the inside of the sludge-containing biological treated water storage tank 21. Become.

The membrane unit 3 is installed as an immersion membrane below the liquid surface in the sludge-containing biologically treated water storage tank 21.
The membrane unit 3 may be configured to be installed outside the sludge-containing biologically treated water storage tank 21.

The type of filtration membrane that the membrane unit 3 has is not particularly limited, and examples thereof include membranes that do not allow SMP to permeate, such as ultrafiltration membranes (UF membranes) and microfiltration membranes (MF membranes). It is done.

As the structure of the filtration membrane, a so-called hollow fiber membrane formed into a hollow fiber shape having a diameter of several millimeters formed of a material such as cellulose acetate, aromatic polyamide, polyvinyl alcohol, polyvinylidene fluoride, polytetrafluoroethylene, and the like Conventionally known types such as a so-called type and a type called a flat membrane which is a thin plate-like film can be employed.

The sludge dewatering unit 4 is supplied with the sludge-containing biologically treated water discharged from the sludge-containing biologically treated water storage tank 21 so that the sludge-containing biologically treated water is separated into dehydrated sludge C and dehydrated filtrate by dehydration. It is made up of.

The sludge dewatering unit 4 is not particularly limited. For example, a vacuum dehydrator, a centrifugal dehydrator, a filter press, a belt press, a screw press, a multi-disc dehydrator, a multi-disc outer cylinder screw press. Etc.

Further, in the membrane separation activated sludge treatment apparatus 1 of the present embodiment, the sludge-containing biologically treated water is in the sludge dewatering unit 4, the dehydrated sludge C is in the dehydrated sludge storage unit (not shown), the dehydrated filtrate is in the mixing unit 5 and The biological treatment unit 2 is configured to transfer permeate to the mixing unit 5 and purified water B to the purified water storage unit (not shown).
Specifically, as shown in FIG. 1, the membrane separation activated sludge treatment apparatus 1 of this embodiment includes a sludge-containing biologically treated water transfer path 6a for transferring the sludge-containing biologically treated water to the sludge dewatering unit 4, and the dehydrated sludge. The dehydrated sludge transfer path 6b for transferring C, the first dehydrated filtrate transfer path 6c for transferring the dehydrated filtrate to the mixing unit 5 without biological treatment and membrane filtration, and the dehydrated filtrate for the biological treatment part 2 A second dehydrated filtrate transfer path 6d for returning, a permeated water transfer path 6e for transferring the permeated water, and a purified water transfer path 6f for transferring the purified water B are provided.

Further, the membrane separation activated sludge treatment apparatus 1 of the present embodiment adjusts the transfer ratio of the dehydrated filtrate transferred to the first dehydrated filtrate transfer path 6c and the second dehydrated filtrate transfer path 6d, respectively. Consists of.
Specifically, in the membrane separation activated sludge treatment apparatus 1 of the present embodiment, the first valve 7a and the second valve 7b are provided in the first dehydrated filtrate transfer path 6c and the second dehydrated filtrate transfer path 6d, respectively. Provided with a valve mechanism (not shown) in which the flow path and flow rate are determined by opening and closing operations of each valve (first valve 7a and second valve 7b), and by the valve mechanism (not shown) The transfer rate is adjusted.

Furthermore, the membrane-separated activated sludge treatment apparatus 1 of the present embodiment measures the concentration of soluble microbial metabolite (SMP) in the sludge-containing biologically treated water or dehydrated filtrate that is membrane-filtered by the membrane unit 3. A measuring device (not shown) is provided.
The SMP measuring device (not shown) means a device that measures according to the method for measuring the concentration of soluble microbial metabolite (SMP) described in the examples described later.

Further, the membrane separation activated sludge treatment apparatus 1 of the present embodiment is configured such that the transfer ratio is adjusted based on the measurement value of the SMP measurement apparatus (not shown), specifically, The transfer rate is adjusted so that the concentration of the SMP is less than or less than a reference value.

The reference value is preferably 100 mg / L or less, more preferably 30 mg / L or less, and still more preferably 20 mg / L or less.

The membrane separation activated sludge treatment apparatus of this embodiment is configured as described above. Next, the membrane separation activated sludge treatment method of this embodiment will be described.

In the membrane separation activated sludge treatment method of this embodiment, purified water B is obtained from waste water A using the membrane separation activated sludge treatment apparatus of this embodiment.

Specifically, in the membrane separation activated sludge treatment method of the present embodiment, waste water A is supplied to the biological treatment unit 2, and the waste water A and activated sludge are mixed in the biological treatment unit 2 to generate mixed water and the mixing The water is biologically treated to obtain sludge-containing biologically treated water, and the membrane unit section 3 membrane-filters the sludge-containing biologically treated water to obtain permeated water.
When surplus sludge is generated, the sludge-containing biologically treated water having surplus sludge is transferred to the sludge dewatering unit 4, and the sludge-containing biologically treated water is dehydrated in the sludge dewatering unit 4 to dehydrated sludge C and the dewatering filter. Separate into liquid.

When dewatering in the sludge dewatering unit 4, in a state where the concentration of the SMP can be kept below or below a reference value, the second valve 7b is released and the first valve 7a is opened as shown in FIG. The dehydrated filtrate is returned to the biological treatment unit 2 from the second dehydrated filtrate transfer path 6d. Moreover, the permeated water obtained in the membrane unit 3 is transferred as purified water B to a purified water storage unit (not shown).
On the other hand, when it is likely that the SMP concentration cannot be kept below or below the reference value, the first valve 7a is opened and the second valve 7b is closed as shown in FIG. The dehydrated filtrate is transferred to the mixing unit 5 from the first dehydrated filtrate transfer path 6a. Further, the permeated water obtained in the membrane unit 3 and the transferred dehydrated filtrate are mixed and transferred as purified water B to a purified water storage unit (not shown).

In addition, although the membrane separation activated sludge treatment apparatus and the membrane separation activated sludge treatment method of the present embodiment have the above-described configuration, the membrane separation activated sludge treatment apparatus and the membrane separation activated sludge treatment method of the present invention are described above. The design is not limited to the configuration and can be changed as appropriate.

That is, in the membrane separation activated sludge treatment method of this embodiment, one of the first valve 7a and the second valve 7b is released and the other is closed, but the membrane separation activated sludge treatment method of the present invention is shown in FIG. As shown, the first valve 7a and the second valve 7b may be released.

In addition, the membrane separation activated sludge treatment apparatus 1 of the present embodiment includes the SMP measurement device (not shown), but the membrane separation activated sludge treatment apparatus of the present invention has a concentration of organic substances in the dehydrated filtrate. You may provide the organic substance density | concentration measuring apparatus which measures this.

Further, the membrane separation activated sludge treatment apparatus is configured such that the transfer rate is adjusted based on the measurement value of the organic substance concentration measurement apparatus, and specifically, the organic substance concentration is less than a reference value. Alternatively, the transfer ratio is adjusted so as to be less.

When the organic substance concentration is the total organic carbon concentration, the reference value is preferably 110 mg / L or less, more preferably 40 mg / L or less, and further preferably 30 mg / L or less.
Note that the total organic carbon concentration of the dehydrated filtrate is usually about 10 mg / L higher than the SMP concentration of the dehydrated filtrate when the wastewater is domestic wastewater.

Furthermore, the membrane separation activated sludge treatment apparatus of the present embodiment may include an impurity measurement apparatus that measures the impurity of the purified water B.
Examples of the impurity measuring device include an SS measuring device that measures SS concentration, a BOD measuring device that measures biochemical oxygen demand (BOD), and the like.
The SS measuring device and the BOD measuring device mean devices that measure according to the SS concentration and BOD measuring methods described in the examples described later.

Such a membrane separation activated sludge treatment device is configured such that the transfer ratio is adjusted based on at least one of the measurement value of the SMP measurement device and the measurement value of the impurity measurement device, Specifically, the transfer ratio is adjusted so that the measured concentration of the SMP is less than or less than a reference value and / or the measured concentration of the impurity measuring device is less than or less than the reference value. Consists of.

When the impurity is SS concentration, the reference value of the impurity is preferably 40 mg / L or less, more preferably 20 mg / L or less, and the impurity is BOD. Is preferably 20 mg / L or less, more preferably 10 mg / L or less.

Moreover, as shown in FIG. 5, the membrane separation activated sludge treatment apparatus 1 of this embodiment includes a dehydrated filtrate storage unit 8 for storing dehydrated filtrate, and before the dehydrated filtrate is returned to the biological treatment unit or It may be configured to be stored in the dehydrated filtrate storage unit 8 before being transferred to the mixing unit.

As shown in FIG. 6, in the membrane separation activated sludge treatment apparatus 1 of the present embodiment, a part of the permeated water generated in the membrane unit unit 3 is transferred to the mixing unit 5, Purified water B1 is obtained, the first purified water B1 obtained by the mixing unit 5 is transferred to a first purified water storage tank (not shown), and the remaining permeated water is not transferred to the mixing unit 5 but second. You may comprise so that it may be transferred to a 2nd purified water storage tank (not shown) as purified water B2.

Such a membrane separation activated sludge treatment apparatus 1 includes a first permeate transfer path 6e1 that transfers a part of the permeate to the mixing unit 5, and the second purification without mixing the remaining permeate with the dehydrated filtrate. It comprises a second permeate transfer path 6e2 that transfers the water B2 to a second purified water storage tank (not shown).

Moreover, the membrane separation activated sludge treatment apparatus 1 is configured such that the transfer ratio of the permeated water transferred to the first permeated water transfer path 6e1 and the second permeated water transfer path 6e2 is adjusted. . Specifically, in the membrane separation activated sludge treatment apparatus 1, a third valve 7 c and a fourth valve 7 d are interposed in the first permeate transfer path 6 e 1 and the second permeate transfer path 6 e 2, respectively. And a valve mechanism (not shown) in which the flow path and flow rate are determined by opening and closing each valve (the third valve 7c and the fourth valve 7d), and the transfer rate is adjusted by the valve mechanism (not shown). It is comprised so that it may be.

Furthermore, such a membrane separation activated sludge treatment apparatus 1 includes a permeated water impurity measuring device (not shown) for measuring the permeated water impurity, and a dehydrated filtrate impurity measuring device for measuring the dehydrated filtrate impurity. (Not shown), a permeated water amount measuring device (not shown) for measuring the amount of permeated water transferred to the mixing unit 5 per unit time, and per unit time of the dehydrated filtrate transferred to the mixing unit 5 And a dehydrated filtrate amount measuring device (not shown) for measuring the amount of the filtrate.
Examples of the permeated water impurity measuring device and the dehydrated filtrate impurity measuring device include a COD measuring device for measuring chemical oxygen demand (COD) and a BOD measuring device for measuring biochemical oxygen demand (BOD). Etc.
The COD measuring device means a device for measuring in accordance with the sewage test method, first volume -1997 edition- (Japan Sewerage Association). Specifically, COD is a method for obtaining an oxygen demand from the amount of potassium permanganate consumed when a specified amount of potassium permanganate, sulfuric acid and silver nitrate is added to a sample and reacted in a boiling water bath for 30 minutes. It means that measured by the following procedure.
(1) Put an appropriate amount of sample into a 300 ml Erlenmeyer flask and add distilled water to make 100 ml.
(2) While shaking the Erlenmeyer flask, add 5 ml of a silver nitrate solution (200 g / L) and 10 ml of sulfuric acid (1 + 2) into the Erlenmeyer flask.
(3) Further, 10 ml of 0.005 mol / L potassium permanganate solution is added to the Erlenmeyer flask and shaken.
(4) Place the Erlenmeyer flask in a boiling water bath and heat for 30 minutes.
(5) Remove the Erlenmeyer flask from the water bath, and immediately add 10 ml of sodium oxalate solution (0.0125 mol / L) to the Erlenmeyer flask and mix well to react.
(6) While maintaining the temperature of the water in the Erlenmeyer flask at about 60 ° C., titration is performed using a 0.005 mol / L potassium permanganate solution until it shows a slight red color (keep for about 30 seconds). a1 (mL)).
(7) Perform a blank test over 100 ml of distilled water instead of the sample over the entire procedure ((1) to (6)) to obtain the titer b1 (mL).
(8) The concentration of oxygen demand (COD _Mn ) by potassium permanganate at 100 ° C. is calculated by the following formula.
COD _Mn (mg / L) = (a1-b1) x F x (1,000 / sample volume ml) x 0.2
F: Factor of 0.005mol / L potassium permanganate solution (dimensionless)
In addition, an ultraviolet absorption photometry method (UV absorption photometry method) can be used for a sample with a small variation in organic composition and a small amount of suspended solids. The UV absorptiometry has a correlation between the amount of organic substances in water and the UV absorbance near the wavelength of 250 nm, so the UV absorbance of the sample is measured, and the sample is obtained from the relationship between the UV absorbance and the COD value obtained in advance. COD value is estimated.
The BOD measuring device means a device that measures in accordance with the BOD measuring method described in the examples described later.

In addition, the membrane separation activated sludge treatment apparatus 1 performs the first purification from the measured values of the permeated water impurity measuring device, the dehydrated filtrate impurity measuring device, the permeated water amount measuring device, and the dehydrated filtrate amount measuring device. The purity of water is determined, and the transfer rate of the permeated water is adjusted based on the purity of the first purified water. Specifically, the transfer ratio is adjusted so that the purity of the first purified water obtained from these measured values is less than or less than the reference value.
The reference value of the purity of the first purified water is preferably 40 mg / L or less, more preferably 20 mg / L or less when the impurity is COD, and when the impurity is BOD. , Preferably 20 mg / L or less, more preferably 10 mg / L or less.

Next, the present invention will be described more specifically with reference to test examples.

(Test Example 1: Relationship between SMP concentration and membrane permeability)
Organic waste water and activated sludge are mixed to produce mixed water, the mixed water is biologically treated to obtain sludge-containing biologically treated water, the sludge-containing biologically treated water is dehydrated, and the concentration of SMP (hereinafter, “ A plurality of dehydrated filtrates having different SMP concentrations) were collected. Place 5 kinds of C (JIS P 3801-1995) filter paper (Advantech Toyo Co., Ltd., diameter: 15 cm) on the filter, and drop 50 mL each of dehydrated filtrates with different SMP concentrations onto the filter paper. The amount of permeated water that passed through the filter paper when 5 minutes passed (5C filter paper filtration amount) was measured.
The SMP concentration was obtained by filtering sludge-containing biologically treated water with the above-mentioned 5 types C (JIS P 3801-1995) filter paper to obtain permeated water (5C permeated water), and filter paper (Millipore) with a maximum pore size of 0.1 μm. Permeated water (0.1 μm permeated water) is obtained by filtration with DURAPORE 0.1 μm VVPP (diameter: 4.7 cm), and the total organic carbon (TOC) concentration contained in these permeated water is measured with a TOC meter (trade name). : TOC-5000A, manufactured by Shimadzu Corporation) (combustion catalytic oxidation method), and calculated by the following formula (1).
SMP concentration = TOC concentration (5C permeated water) −TOC concentration (0.1 μm permeated water) (1)

Incidentally, the filter paper having a maximum pore diameter of 0.1 μm means a filter paper having a bubble point value of 480 kPa measured according to “Bubble point test method for microfiltration membrane element and module” (JIS K 3832). Here, the bubble point value means a value for water.

The results of Test Example 1 are shown in Table 1 and FIG.

The lower the SMP concentration, the higher the 5C filter paper filtration rate. That is, it was shown that the lower the SMP concentration, the better the membrane permeability.
Further, it was shown that when the SMP concentration was 20 mg / L or less, the 5C filter paper filtration amount was significantly increased as the SMP concentration was lower.
Furthermore, since the membrane permeability is said to be good if the 5C filter paper filtration rate is 10 mL / min or more, it can be seen that the membrane permeability is good if the SMP concentration is 20 mg / L or less.

(Test Example 2)
Reference example 1
As shown in FIG. 8, an immersion membrane (polyvinylidene fluoride (PVDF), pore diameter: 0.1 μm, surface area) as the membrane unit 3 in the sludge-containing biologically treated water storage tank 21 (water storage volume: 14.4 L). : 0.05 m ² ) is placed so that it can be located below the surface of the water. Further, waste water A (BOD concentration: 1300 mg / L) and activated sludge are added, and the waste water A and activated sludge are mixed. Mixed water was produced.
Thereafter, the waste water A is introduced at 29 L / d, purified water B as permeated water is obtained at 28.95 L / d by the membrane unit 3, and sludge-containing biologically treated water is further added at 0.5 L / d to the sludge dewatering unit 4. The dehydrated sludge C was obtained at 0.05 L / d and the dehydrated filtrate was obtained at 0.45 L / d. The dehydrated filtrate was returned to the sludge-containing biologically treated water storage tank 21 in its entirety. Thus, the operation | work which obtains the purified water B from the wastewater A was continuously implemented for 30 days or more. Measure BOD of purified water B as permeate immediately before the end of work, SS concentration of dewatered sludge C, and MLSS concentration, SMP concentration, and 5C filter paper filtration amount of sludge-containing biologically treated water in sludge-containing biologically treated water storage tank 21 did. The results are shown in FIG.
The BOD, MLSS concentration and SS concentration were measured according to the sewage test method, Vol. 1 -1997 edition- (Japan Sewerage Association).
<BOD measurement method>
BOD is the amount of oxygen required for biochemical stabilization of degradable substances in water in the presence of dissolved oxygen. Oxygen consumed for 5 days in a 20 ° C environment. It represents the quantity. Specifically, BOD was measured by the following procedure.
(1) Distilled water was taken and aerated at 20 ° C. in advance and allowed to stand to saturate dissolved oxygen. Then, 1 mL each of a buffer solution, a magnesium sulfate solution, a calcium chloride solution, and an iron (III) chloride solution was added to 1 L of this distilled water to obtain diluted water.
(2) A calculated amount of the sample with respect to the volume of the bottle corresponding to the dilution rate was added to the culture bottle, the space in the remaining bottle was filled with diluted water, and the bottle was sealed.
(3) The cells were cultured for 5 days in a thermostat adjusted to a temperature of 20 ± 1 ° C. or in a thermostatic water bath.
(4) The dissolved oxygen amount (DO1) (mgO / L) of the diluted sample before culturing (after 15 minutes from the preparation of the diluted sample) and the dissolved oxygen amount (DO2) (mgO / L) of the diluted sample after culturing / L). The amount of dissolved oxygen was measured by the diaphragm electrode method.
(5) The BOD in the sample was calculated from the difference in the amount of dissolved oxygen before and after the culture of the diluted sample according to the following formula.
BOD (mg / L) = (DO1-DO2) / (sample volume mL / diluted sample volume mL)
The buffer solution was dipotassium hydrogen phosphate (K ₂ HPO ₄ ) 21.75 g, potassium dihydrogen phosphate (KH ₂ PO ₄ ) 8.5 g, disodium hydrogen phosphate dodecahydrate (Na ₂ HPO). ₄ · 12H ₂ O) 44.6 g and ammonium chloride (NH ₄ Cl) 1.7 g are dissolved in distilled water to make 1 L. The magnesium sulfate solution means a solution obtained by dissolving 22.5 g of magnesium sulfate heptahydrate (MgSO ₄ .7H ₂ O) in distilled water to make 1 L. The calcium chloride solution means a solution prepared by dissolving 27.5 g of calcium chloride (CaCl ₂ ) in distilled water to make 1 L. The iron (III) chloride solution means a solution obtained by dissolving 0.25 g of iron (III) chloride hexahydrate (FeCl ₃ .6H ₂ O) in distilled water to make 1 L.
<Measurement method of MLSS>
The MLSS concentration was measured by the following procedure (centrifugation method).
(1) A 50 ml sample was placed in a sedimentation tube and centrifuged at 3,000 rpm for 10 minutes.
(2) The supernatant was carefully discarded, 10 ml of water was added to the precipitate, and the mixture was stirred well using a glass rod, and centrifuged again to discard the supernatant.
(3) The precipitate was poured into an evaporating dish with a mass (a2) (mg) previously washed with water.
(4) The precipitate on the evaporating dish was evaporated to dryness on a water bath.
(5) The precipitate on the evaporating dish was heated and dried at 105-110 ° C. for 2 hours and then allowed to cool in a desiccator to measure the total mass (b2) (mg) of the precipitate and the evaporating dish. .
(6) The concentration of suspended solids (mg / L) was calculated by the following formula.
Suspended matter (mg / L) = (b2-a2) x (1,000 / sample amount (50 ml))
<SS measurement method>
Furthermore, the SS concentration was measured by the following procedure (glass fiber filter method).
(1) A glass fiber filter paper was attached to the filter, and an appropriate amount of the sample passed through a 2 mm mesh sieve was poured and suction filtered.
(2) The suspended matter adhering to the wall of the filter was washed off with water on the filter paper, and the filter paper was removed from the filter.
(3) The filter paper was transferred to a watch glass, put in the dryer together with the watch glass, heated and dried at 105-110 ° C. for 2 hours, allowed to cool in a desiccator, and then weighed the filter paper.
(4) The difference (a3) (mg) in the mass of the filter paper before and after filtration was determined, and the concentration (mg / L) of suspended solids in the sample was calculated by the following formula.
Suspended matter (mg / L) = a3 x (1,000 / sample volume ml)

Reference example 2
As shown in FIG. 9, in a sludge-containing biologically treated water storage tank 21 (water storage volume: 14.4 L), an immersion membrane (polyvinylidene fluoride (PVDF), pore diameter: 0.1 μm, surface area) as the membrane unit 3 : 0.05 m ² ) is placed so that it can be located below the surface of the water. Further, waste water A (BOD concentration: 1300 mg / L) and activated sludge are added, and the waste water A and activated sludge are mixed. Mixed water was produced.
Thereafter, the waste water A is introduced at 29 L / d, the permeate is obtained at 28.5 L / d by the membrane unit 3, and the sludge-containing biologically treated water is transferred to the sludge dewatering unit 4 at 0.5 L / d for dehydration. Then, dehydrated sludge C is obtained at 0.05 L / d and dehydrated filtrate is obtained at 0.45 L / d, the permeate is transferred to the mixing unit 5 in total, and the mixing unit 5 is used instead of the sludge-containing biologically treated water storage tank 21. The whole amount of the dehydrated filtrate was transferred to the mixture, and the purified water B was obtained by mixing the permeated water and the dehydrated filtrate in the mixing unit 5. Thus, the operation of obtaining purified water B from waste water A was continued for the same period as in Reference Example 1. BOD of permeated water, BOD of purified water B, SS concentration of dewatered sludge C, and MLSS concentration, SMP concentration, and 5C filter paper filtration amount in sludge-containing biologically treated water storage tank 21 immediately before the end of work Was measured. The results are shown in FIG.

Reference example 3
As shown in FIG. 10, an immersion membrane (polyvinylidene fluoride (PVDF), pore size: 0.1 μm, surface area) as the membrane unit 3 in the sludge-containing biologically treated water storage tank 21 (water storage volume: 14.4 L). : 0.05 m ² ) is placed so that it can be located below the surface of the water. Further, waste water A (BOD concentration: 1300 mg / L) and activated sludge are added, and the waste water A and activated sludge are mixed. Mixed water was produced.
Thereafter, the waste water A is added at 29 L / d, and the permeated water is obtained at 28.5 L / d by the membrane unit 3, and part of the permeated water (13.5 L / d) is transferred to the mixing unit 5, The permeated water (15 L / d) is obtained as the second purified water B2 without being transferred to the mixing unit 5, and further, the sludge-containing biologically treated water is transferred to the sludge dewatering unit 4 at 0.5 L / d and dehydrated. Sludge C is obtained at 0.05 L / d and dehydrated filtrate is obtained at 0.45 L / d. The entire amount of dehydrated filtrate is transferred to the mixing section 5 instead of the sludge-containing biologically treated water storage tank 21, and the permeated water is mixed at the mixing section 5. And the dehydrated filtrate were mixed to obtain a first purified water B1. Thus, the operation of obtaining the first purified water B1 and the second purified water B2 from the waste water A was continued for the same period as in Reference Example 1. The BOD of the permeated water, the BOD of the first purified water B1, the BOD of the second purified water B2, the SS concentration of the dewatered sludge C, and the MLSS of the sludge-containing biological treated water in the sludge-containing biological treated water storage tank 21 immediately before the end of the work. Concentration, SMP concentration, and 5C filter paper filtration amount were measured. The results are shown in FIG.

The 5C filter paper filtration amount of the sludge-containing biologically treated water in Reference Examples 2 and 3 showed an extremely high value as compared with Reference Example 1. Therefore, it was shown that Reference Examples 2 and 3 have better membrane permeability than Reference Example 1.
Moreover, in Reference Example 3, purified water (purified water B2) having a BOD concentration extremely low (65 mg / L) as compared to Reference Example 2 while obtaining purified water (purified water B1) having a BOD concentration that can be tolerated as discharged water. )

1: membrane separation activated sludge treatment device, 2: biological treatment unit, 3: membrane unit unit, 4: sludge dewatering unit, 5: mixing unit, 6a: sludge-containing biologically treated water transfer route, 6b: dehydrated sludge transfer route, 6c : First dehydrated filtrate transfer path, 6d: second dehydrated filtrate transfer path, 6e: permeate transfer path, 6e1: first permeate transfer path, 6e2: second permeate transfer path, 6f: purified water transfer path 7a: 1st valve, 7b: 2nd valve, 7c: 3rd valve, 7d: 4th valve, 8: Dehydrated filtrate reservoir, 21: Sludge-containing biologically treated water reservoir, A: Waste water, B: Purification Water, B1: First purified water, B2: Second purified water, C: Dehydrated sludge

Claims

A biological treatment unit that mixes waste water and activated sludge to produce mixed water and biologically treats the mixed water to obtain sludge-containing biologically treated water; a membrane unit that membrane-filters sludge-containing biologically treated water with a filtration membrane; A membrane separation activated sludge treatment apparatus comprising a sludge dewatering unit that separates sludge-containing biologically treated water into dehydrated sludge and dehydrated filtrate by dehydration,
A mixing unit that obtains purified water by mixing the permeated water generated in the membrane unit and the dehydrated filtrate, and a first dehydration filter that transfers the dehydrated filtrate to the mixing unit without biological treatment and membrane filtration. A dehydration filter that includes a liquid transfer path and a second dehydrated filtrate transfer path that returns the dehydrated filtrate to the biological treatment unit, and is transferred to the first dehydrated filtrate transfer path and the second dehydrated filtrate transfer path, respectively. A membrane separation activated sludge treatment apparatus configured to adjust the liquid transfer rate.
The apparatus comprises an SMP measuring device that measures the concentration of soluble microbial metabolite (SMP) in the sludge-containing biologically treated water that is membrane-filtered in the membrane unit section or in the dehydrated filtrate, and the transfer rate is determined based on the measured value. The membrane separation activated sludge treatment apparatus according to claim 1, wherein the apparatus is configured to be adjusted.
The membrane separation activated sludge treatment apparatus according to claim 2, wherein the transfer rate is adjusted so that the concentration of the SMP is less than or less than a reference value.
The membrane separation activated sludge treatment apparatus according to claim 3, wherein the reference value is 20 mg / L or less.
The membrane-separated activated sludge treatment apparatus according to claim 1, further comprising an organic matter concentration measuring device for measuring the concentration of the organic matter in the dehydrated filtrate, wherein the transfer rate is adjusted based on the measured value.
The membrane separation activated sludge treatment apparatus according to claim 5, wherein the transfer rate is adjusted so that the concentration of the organic substance is less than or less than a reference value.
The membrane separation activated sludge treatment apparatus according to claim 6, wherein the organic matter concentration is the total organic carbon concentration, and the reference value is 30 mg / L or less.
It is comprised so that the said purified water may be obtained as 1st purified water, and it is provided with the 1st permeated water transfer path which transfers permeated water to a mixing part, so that permeated water can be obtained as 2nd purified water without mixing with a dehydrating filtrate. Comprising a second purified water storage tank for storing the second purified water, and a second permeated water transfer path for transferring the permeated water to the second purified water storage tank, The membrane-separated activated sludge treatment apparatus according to any one of claims 1 to 7, wherein a transfer rate of the permeate to be transferred to the second permeate transfer path is adjusted.
Permeate impurity measurement device that measures permeate impurity, dehydrated filtrate impurity measurement device that measures the purity of dehydrated filtrate, and the amount of permeated water that is transferred to the mixing unit A permeated water amount measuring device, and a dehydrated filtrate amount measuring device for measuring the amount of dehydrated filtrate transferred to the mixing unit per unit time, the permeated water impurity measuring device, the dehydrated filtrate impurity measuring device. The first purified water impurity is determined from the measured values of the permeated water amount measuring device and the dehydrated filtrate amount measuring device, and the transfer rate of the permeated water is adjusted based on the first purified water impurity value. The membrane separation activated sludge treatment apparatus according to claim 8, which is configured as described above.
The membrane-separated activated sludge treatment apparatus according to claim 9, wherein the permeated water transfer rate is adjusted so that the purity of the first purified water is less than or less than a reference value.
A membrane separation activated sludge treatment method for obtaining purified water from wastewater using the membrane separation activated sludge treatment apparatus according to any one of claims 1 to 7.
A membrane separation activated sludge treatment method for obtaining purified water from wastewater using the membrane separation activated sludge treatment apparatus according to claim 8.
A membrane separation activated sludge treatment method for obtaining purified water from wastewater using the membrane separation activated sludge treatment apparatus according to claim 9.
A membrane separation activated sludge treatment method for obtaining purified water from wastewater using the membrane separation activated sludge treatment apparatus according to claim 10.