JP2004267887A - Method and apparatus for treating water cleaning membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To concentrate physical washing wastewater produced from a membrane treatment device until the concentration of sludge becomes almost constant throughout a year without adding a flocculant, to set the cleaned water recovery rate of the whole of a system to 99.9% or above, to increase the dehydration speed in a dehydrator and to reduce the evil related to the effective utilization of dehydrated sludge. <P>SOLUTION: This water cleaning membrane treatment apparatus is equipped with a water arriving well 1 for receiving raw water taken in from rivers or the like, a pretreatment device 2 for pretreating the raw water from the water arriving well 1, a first membrane treatment device 3 for subjecting the raw water pretreated by the pretreatment device 2 to membrane filtering treatment and a second membrane treatment device 4 for further subjecting the physical washing wastewater from the first membrane treatment device 3 to membrane filtering treatment and further equipped with a sterilizing treatment device 7 for sterilizing the membrane filtered water from the first membrane filtering treatment device 3, a concentrator 5 for concentrating the physical washing wastewater from the second membrane filtering treatment device 4 and the dehydrator 6 for dehydrating the sludge concentrated by the concentrator 5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３６】
第２膜処理装置４から排出された固形物濃度０．１％の物理洗浄排水を、表２に示した仕様の膜濃縮装置９に通水して膜ろ過処理した結果、膜ろ過水の回収率９５％が得られ、濃縮汚泥の固形物濃度が２％であった。得られた膜ろ過水の水質分析結果を表３に示した。表３より、本実施例において得られた膜ろ過水は、水道水水質基準を満足することが分かり、塩素消毒装置へ送り滅菌処理を実施して水道水として供給した。その結果、システム全体の浄水回収率は９９．９８％であった。
【００３７】
【表２】

【００３８】
【表３】

【００３９】
【発明の効果】
以上述べたように、本発明の浄水膜処理装置によれば、凝集剤を添加することなくシステム全体の浄水回収率を９９．９％以上まで向上させることができる。また、固形物濃度１から６％の汚泥を脱水機へ投入することができ、脱水機における脱水速度の向上を図ることができる。さらに、脱水汚泥にアルミニウムを含まないため、脱水汚泥の有効利用に係る弊害を少なくする等、工業上有用な効果がもたらされる。
【図面の簡単な説明】
【図１】本発明の浄水膜処理装置による処理フローを示す図である。
【図２】本発明の他の浄水膜処理装置による処理フローを示す図である。
【図３】本発明のさらに他の浄水膜処理装置による処理フローを示す図である。
【図４】膜ろ過処理を行っている浄水場における従来処理フローを示す図である。
【図５】膜ろ過処理を行っている浄水場における他の従来処理フローを示す図である。
【符号の説明】
１：着水井
２：前処理装置
３：第１膜処理装置
４：第２膜処理装置
５：濃縮装置
６：脱水機
７：滅菌処理装置
８ａ、８ｂ：水路
９：膜濃縮装置
２０：着水井
２１：前処理装置
２２：膜処理装置
２３：排水池
２４：濃縮槽
２５：脱水機
２６：無機系凝集剤
２７：凝集混和装置
２８：膜処理装置
２９：シックナー
３０：脱水機
３１：滅菌処理装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water purification membrane treatment method and apparatus, and in particular, a water purification membrane treatment capable of efficiently treating physical cleaning wastewater discharged from a membrane treatment apparatus in a membrane-based water purification plant and improving a water purification recovery rate. The present invention relates to a method and an apparatus.
[0002]
[Prior art]
A conventional water purification process using a membrane filtration process will be described with reference to the drawings.
[0003]
FIG. 4 is a diagram showing a conventional processing flow in a water purification plant performing a membrane filtration process.
[0004]
In the water purification treatment shown in the figure, raw water taken from a river or the like is received by a landing well 20, then guided to a pretreatment device 21 for removing impurities in the raw water, and suspended in the raw water by a membrane treatment device 22. Removes turbid components, pathogenic protozoa and bacteria. The membrane filtered water obtained from the membrane treatment device 22 is subjected to chlorine disinfection by the sterilization treatment device 31 and supplied as tap water. The purified water recovery rate at that time is about 90 to 95%. In the membrane treatment device 22, a physical cleaning operation is periodically performed, and the physical cleaning wastewater discharged by the cleaning is sent to a drainage pond 23, where it is separated into sludge and supernatant water. The sludge is settled and concentrated by gravity in the concentration tank 24 and supplied to the dehydrator 25. The supernatant water from the concentration tank 24 is returned to the landing well 20 together with the supernatant water from the drainage pond 23 for the purpose of improving the recovery rate.
[0005]
In the conventional method having the above-described configuration, when the raw water turbidity is high, the solid concentration in the physical cleaning wastewater is also high. However, when the raw water turbidity is low, the solids concentration in the physical washing wastewater is low, so that the sedimentation speed of the sludge is slow, and it is difficult to apply sedimentation concentration by gravity in the concentration tank 24.
[0006]
In order to solve this problem, it is necessary to improve the sedimentation of sludge by using polyaluminum chloride (PAC) or a polymer flocculant as a flocculant in the concentration tank 24.
[0007]
In the standard membrane-based water purification treatment shown in FIG. 5, raw water taken from a river or the like is received by the landing well 20, and then, in order to remove impurities in the raw water, polyaluminum chloride (PAC) or the like is used. An inorganic coagulant 26 is added to the mixture, and the mixture is guided to a coagulation mixing device 27. The mixture is press-fitted into a membrane treatment device 28 to perform membrane filtration to remove suspended components, pathogenic protozoa and bacteria in raw water. The membrane filtered water obtained from the membrane treatment device 28 is subjected to chlorine disinfection by the sterilization treatment device 31 and supplied as tap water. The purified water recovery rate at that time is about 95 to 98%. In the membrane treatment device 28, a physical cleaning operation is periodically performed, and the physical cleaning wastewater discharged by the cleaning is guided to the thickener 29 and separated into concentrated sludge and supernatant water. The concentrated sludge is supplied to the dehydrator 30, and the supernatant water is returned to the landing well 20 for the purpose of improving the recovery rate.
[0008]
[Problems to be solved by the invention]
As described above, in FIGS. 4 and 5 of the conventional system, a case where a coagulant is added is generally used. When the concentrated sludge to which the coagulant has been added is introduced into the dewaterers 25 and 30, there is a problem that the dewatering speed of the sludge in the dewaterers 25 and 30 is greatly reduced, and the required number of dewaterers is increased. Further, when aluminum is contained in the dewatered sludge, there is a problem that its effective utilization is difficult.
[0009]
Therefore, the present invention has been completed as a result of earnest research to overcome the above-mentioned problems, and the physical cleaning wastewater generated from the membrane treatment apparatus without adding a coagulant has a substantially constant sludge throughout the year. A water purification membrane treatment method and apparatus capable of concentrating to a concentration, increasing the water purification rate of the entire system to 99.9% or more, improving the dehydration speed in a dehydrator, and reducing the adverse effects associated with the effective use of dewatered sludge. It is intended to provide.
[0010]
[Means for Solving the Problems]
The present invention has been made to solve the above problems, and has the following features.
[0011]
The invention described in claim 1 is that, when raw water taken from a river or the like is used as tap water by membrane filtration without adding a coagulant thereto, the raw water is subjected to a primary membrane filtration treatment, and then the primary water is filtered. The method is characterized in that the physical washing wastewater after the membrane filtration treatment is subjected to a secondary membrane filtration treatment, and the physical washing wastewater after the secondary membrane filtration treatment is concentrated.
[0012]
The invention described in claim 2 is characterized in that the physical washing wastewater after the secondary membrane filtration treatment is concentrated until the solid concentration of sludge becomes 1 to 6%.
[0013]
The invention described in claim 3 is a water purification membrane treatment apparatus that uses raw water taken from a river or the like as tap water by membrane filtration using a membrane treatment apparatus without adding a coagulant thereto, and using the raw water as a primary membrane. It is characterized in that a first membrane treatment device for filtering and a second membrane treatment device for secondary filtration of the physical cleaning wastewater from the first membrane treatment device are provided.
[0014]
The invention described in claim 4 is a water receiving well that receives raw water taken from a river or the like, a pretreatment device that pretreats raw water from the landing well, and a raw water pretreated by the pretreatment device. A first membrane processing device for performing a membrane filtration process, a second membrane processing device for further performing a membrane filtration of the physical washing wastewater from the first membrane processing device, and a sterilization process for sterilizing the membrane filtered water from the first membrane processing device It is characterized by comprising a treatment device, a concentration device for concentrating the physical cleaning wastewater from the second membrane treatment device, and a dehydrator for dewatering the sludge concentrated by the concentration device.
[0015]
In the invention described in claim 5, the membrane filtered water from the second membrane treatment device is sent to the sterilization device, and the treated water from the concentration device is returned to the second membrane treatment device. It is characterized in particular.
[0016]
In the invention described in claim 6, the membrane filtered water from the second membrane treatment device is returned to the first membrane treatment device, and the treated water from the concentration device is returned to the second membrane treatment device. It is characterized by being performed.
[0017]
In the invention described in claim 7, the concentrating device comprises a membrane concentrating device, and membrane filtration water from the membrane concentrating device is sent to the sterilization device, and membrane filtration from the second membrane processing device is performed. Water is characterized in that it is sent to the sterilization apparatus.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a water purification membrane treatment device for carrying out the water purification membrane treatment method of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a diagram showing a processing flow by the water purification membrane processing apparatus of the present invention.
[0020]
In FIG. 1, 1 is a landing well for receiving raw water taken from a river or the like, 2 is a pretreatment device for removing contaminants in the raw water, 3 is a suspension component in the raw water, pathogen. The first membrane treatment device 4 for removing sexual protozoa and bacteria is a suspension component in the physical washing wastewater discharged by the physical washing operation periodically performed in the first membrane treatment device 3, A second membrane treatment device 5 for removing protozoa and bacteria; a concentration device 6 for condensing physical washing wastewater discharged by a physical washing operation periodically performed in the second membrane treatment device 4; Is a dehydrator for dewatering the sludge concentrated in the concentrating device 5, and 7 is a sterilizing device for sterilizing the membrane filtered water from the first membrane processing device 3 and the second membrane processing device 4. .
[0021]
For the purpose of removing impurities in raw water, a simple rotary solid-liquid separator such as an auto strainer can be used as the pretreatment device 2.
[0022]
The separation membrane used in the first and second membrane treatment devices 3 and 4 may be any of an organic membrane and an inorganic membrane, and may be any of a microfiltration membrane and an ultrafiltration membrane. Specifically, the microfiltration membrane preferably has a nominal pore size of 0.01 to 0.45 μm, and the ultrafiltration membrane preferably has a nominal molecular weight cut-off of 1,000 to 1,000,000 daltons. As the shape of the membrane module, a hollow fiber shape, a spiral shape, a tubular shape, or a flat membrane shape is used. The filtration method of the membrane module may be any of a total filtration method and a cross-flow filtration method, and there is no problem with the water passing method to the membrane filtration either of the external pressure type or the internal pressure type. Further, any of a pressurized casing type for pressurizing the raw water side and a suction tank immersion type for depressurizing the filtered water side may be used.
[0023]
In the concentrating device 5, the physical washing wastewater from the second membrane processing device 4 can be concentrated until the solid concentration of the sludge becomes 1 to 6%. Any of mechanical concentration and flotation concentration may be used.
[0024]
According to the water purification membrane treatment apparatus of the present invention described above, raw water is treated as follows.
[0025]
First, after receiving raw water taken from a river or the like at the landing well 1, the raw water is guided to the pretreatment device 2 for removing impurities in the raw water, and suspended components in the raw water are collected by the first membrane treatment device 3, Eliminate pathogenic protozoa and bacteria. The membrane filtered water obtained in the first membrane processing device 3 is subjected to chlorine disinfection by the sterilization device 7 and supplied as tap water.
[0026]
In the first membrane treatment device 3, the physical washing wastewater discharged by the regular physical washing operation is sent to the second membrane treatment device 4 to further remove suspended components, pathogenic protozoa and bacteria. . As described above, the physical washing wastewater after the membrane filtration by the first membrane treatment device 3 is further subjected to membrane filtration by the second membrane treatment device 4, so that it is not necessary to add a coagulant to the raw water as in the related art. .
[0027]
The membrane filtered water obtained in the second membrane treatment device 4 is returned to the sterilization treatment device 7, subjected to chlorination, and supplied as tap water. In the second membrane processing apparatus 4, the physical cleaning wastewater discharged by the periodically performed physical cleaning operation is sent to the concentration apparatus 5 for processing. The treated water obtained from the concentrating device 5 is sent from the water channel 8a to the second membrane processing device 4, so that a total purified water recovery rate of 99.9% or more can be obtained. On the other hand, the concentrated sludge obtained intermittently or continuously from the concentration device 5 is sent to the dehydrator 6 and dewatered.
[0028]
In the above-mentioned water purification membrane treatment device, instead of returning the membrane filtered water from the second membrane treatment device 4 to the sterilization treatment device 7, it may be returned to the first membrane treatment device 3 as shown in FIG.
[0029]
Next, still another water purification membrane processing apparatus for carrying out the water purification membrane processing method of the present invention will be described with reference to the drawings.
[0030]
FIG. 3 is a diagram showing a processing flow by still another water purification membrane processing apparatus of the present invention. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description of the same parts will be omitted.
[0031]
In the water purification membrane treatment apparatus of FIG. 3, the membrane concentration apparatus 9 is used as a concentration apparatus, and the physical washing wastewater discharged from the second membrane treatment apparatus 4 by the physical washing operation which is periodically performed is used to reduce the solid concentration of sludge. Concentrate to 1-6%. In the water purification membrane treatment apparatus of FIG. 3 as well, the physical washing wastewater after membrane filtration by the first membrane treatment apparatus 3 is further subjected to membrane filtration by the second membrane treatment apparatus 4, so that the raw water has a coagulant as in the prior art. Need not be added. Further, the membrane filtered water obtained from the membrane concentrator 9 is subjected to chlorine disinfection by the sterilization device 7 from the water channel 8b and supplied as tap water to obtain a total purified water recovery rate of 99.9% or more. Can be.
[0032]
Here, the separation membrane used in the membrane concentrator 9 may be any of an organic membrane and an inorganic membrane, and may be any of a microfiltration membrane and an ultrafiltration membrane. As the shape of the membrane module, a hollow fiber shape, a spiral shape, a tubular shape, or a flat membrane shape is used. The filtration method of the membrane module may be any of a total filtration method and a cross-flow filtration method, and there is no problem with the water passing method to the membrane filtration either of the external pressure type or the internal pressure type. Further, any of a pressurized casing type for pressurizing the raw water side and a suction tank immersion type for depressurizing the filtered water side may be used.
[0033]
【Example】
Next, the water purification membrane treatment apparatus of the present invention will be described in more detail with reference to examples. The present invention is not limited by the following examples.
[0034]
(Example 1)
Raw water is treated according to the water purification treatment flow shown in FIG. The average turbidity of the raw water is 5 degrees, and an auto-strainer is disposed in the pretreatment device 2 to remove impurities in the raw water. The specifications and operating conditions of the first and second film processing apparatuses 3 and 4 are as shown in Table 1.
[0035]
[Table 1]

[0036]
The physical washing wastewater having a solid concentration of 0.1% discharged from the second membrane processing apparatus 4 is passed through a membrane concentrating apparatus 9 having the specifications shown in Table 2 to perform membrane filtration processing, and as a result, membrane filtration water is recovered. A rate of 95% was obtained and the solids concentration of the concentrated sludge was 2%. Table 3 shows the results of water quality analysis of the obtained membrane filtered water. From Table 3, it was found that the membrane filtered water obtained in this example satisfies the tap water quality standard, and was sent to a chlorination apparatus and sterilized to be supplied as tap water. As a result, the purified water recovery rate of the entire system was 99.98%.
[0037]
[Table 2]

[0038]
[Table 3]

[0039]
【The invention's effect】
As described above, according to the water purification membrane treatment device of the present invention, the purified water recovery rate of the entire system can be improved to 99.9% or more without adding a flocculant. Further, sludge having a solid concentration of 1 to 6% can be introduced into the dehydrator, and the dehydration speed in the dehydrator can be improved. Furthermore, since aluminum is not contained in the dewatered sludge, industrially useful effects such as reducing adverse effects on the effective use of the dewatered sludge are provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a processing flow by a water purification membrane processing apparatus of the present invention.
FIG. 2 is a diagram showing a processing flow by another water purification membrane processing apparatus of the present invention.
FIG. 3 is a diagram showing a processing flow by still another water purification membrane processing apparatus of the present invention.
FIG. 4 is a diagram showing a conventional processing flow in a water purification plant performing a membrane filtration process.
FIG. 5 is a diagram showing another conventional processing flow in a water purification plant performing a membrane filtration process.
[Explanation of symbols]
1: Landing well 2: Pretreatment unit 3: First membrane treatment unit 4: Second membrane treatment unit 5: Concentration unit 6: Dehydrator 7: Sterilization treatment units 8a and 8b: Channel 9: Membrane concentration unit 20: Landing well 21: Pretreatment device 22: Membrane treatment device 23: Drain pond 24: Concentration tank 25: Dehydrator 26: Inorganic coagulant 27: Coagulation mixing device 28: Membrane treatment device 29: Thickener 30: Dehydrator 31: Sterilization treatment device

Claims (7)

When raw water taken from rivers and the like is used as tap water by membrane filtration without adding a coagulant thereto, the raw water is subjected to primary membrane filtration, and then the physical washing wastewater after primary membrane filtration is used. A method for treating a water purification membrane, comprising performing a secondary membrane filtration treatment, and concentrating the physical washing wastewater after the secondary membrane filtration treatment. The method for treating a water purification membrane according to claim 1, wherein the physical washing wastewater after the secondary membrane filtration treatment is concentrated until the solid concentration of sludge becomes 1 to 6%. In a water purification membrane treatment device using raw water taken from rivers or the like as tap water by membrane filtration treatment using a membrane treatment device without adding a coagulant thereto, a first membrane treatment device for performing primary membrane filtration of the raw water, A second membrane treatment device for performing secondary membrane filtration of the physical cleaning wastewater from the first membrane treatment device. A landing well for receiving raw water taken from a river or the like, a pretreatment device for pretreating the raw water from the landing well, and a first membrane treatment device for performing membrane filtration of the raw water pretreated by the pretreatment device. A second membrane treatment device for further membrane-filtering the physical washing wastewater from the first membrane treatment device, a sterilization treatment device for sterilizing membrane filtration water from the first membrane treatment device, and the second membrane treatment device 1. A water purification membrane treatment apparatus comprising: a concentrator for concentrating physical washing wastewater from water; and a dehydrator for dewatering sludge concentrated by the concentrator. The membrane filtered water from the second membrane treatment device is sent to the sterilization treatment device, and the treated water from the concentration device is returned to the second membrane treatment device, The method according to claim 4, wherein The described water purification membrane treatment device. The membrane filtered water from the second membrane treatment device is returned to the first membrane treatment device, and the treated water from the concentration device is returned to the second membrane treatment device. 4. The water purification membrane treatment device according to 4. The concentrator comprises a membrane concentrator, membrane filtered water from the membrane concentrator is sent to the sterilization device, and membrane filtered water from the second membrane device is sent to the sterilization device. The water purification membrane treatment device according to claim 4, characterized in that:

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