JP2001259313A - Backwashing method for filter - Google Patents
Backwashing method for filterInfo
- Publication number
- JP2001259313A JP2001259313A JP2000073301A JP2000073301A JP2001259313A JP 2001259313 A JP2001259313 A JP 2001259313A JP 2000073301 A JP2000073301 A JP 2000073301A JP 2000073301 A JP2000073301 A JP 2000073301A JP 2001259313 A JP2001259313 A JP 2001259313A
- Authority
- JP
- Japan
- Prior art keywords
- water
- backwashing
- filter medium
- filter
- flocculant
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Filtration Of Liquid (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、凝集剤を添加した
凝集処理を行った後、ろ過処理を行うろ過装置における
逆洗方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backwashing method in a filtration apparatus for performing a filtration treatment after a coagulation treatment to which a coagulant is added.
【０００２】[0002]
【従来の技術】河川水などを原水として浄水や工業用水
を製造する場合や、排水処理等において、懸濁物質の分
離のために凝集沈殿処理およびろ過処理が広く採用され
ている。すなわち、凝集沈殿処理では、まず原水に対し
アルミ系の凝集剤等を添加混合して、原水中の懸濁物質
を粗大フロック化する。そして、この粗大フロックを沈
殿池に導入して沈殿処理することで、懸濁質の大部分を
除去する。次に、この沈殿池で得られた上澄み水（凝集
沈殿処理水）をろ過装置でさらに処理し、残留する微細
懸濁物をさらに除去する。このようにして、清澄な処理
水を得ている。2. Description of the Related Art In the case of producing purified water or industrial water using river water or the like as raw water, or in wastewater treatment, coagulation sedimentation and filtration are widely used for separating suspended substances. That is, in the coagulation-sedimentation treatment, first, an aluminum-based coagulant or the like is added to and mixed with the raw water to coarsely floculate the suspended substance in the raw water. Then, the coarse flocs are introduced into a sedimentation basin and subjected to a sedimentation treatment, thereby removing most of the suspended solids. Next, the supernatant water (coagulated sedimentation-treated water) obtained in the sedimentation basin is further processed by a filtration device to further remove the remaining fine suspension. In this way, clear treated water is obtained.
【０００３】ここで、ろ過装置においては、ろ材が所定
量の懸濁質を捕捉すると、ろ過抵抗が上昇し、またフロ
ックの流出が大きくなるため、ろ材を再生するための逆
洗を行う。この逆洗は、逆洗水（通常は処理水）をろ過
装置に逆流させ、捕捉した懸濁質を除去することによっ
て行う。[0003] In the filtration device, when the filter medium captures a predetermined amount of suspended solids, the filtration resistance increases and the outflow of flocs increases. Therefore, backwashing is performed to regenerate the filter medium. This backwashing is performed by flowing backwashing water (usually treated water) back through a filtration device to remove trapped suspended matter.
【０００４】ところが、この逆洗を行った直後におい
て、処理水中の懸濁物質（微細フロック）が増加し、十
分なろ過が行えない場合が多い。However, immediately after the backwashing, the suspended solids (fine flocs) in the treated water increase, and sufficient filtration cannot be performed in many cases.
【０００５】これは、通常のろ過処理においてアルミ系
の凝集剤を用いた場合は、ろ材の表面に薄く水酸化アル
ミニウムが付着し、これが微細な凝集フロックの除去に
貢献しているが、逆洗によってこの付着物が除去される
ため、逆洗直後の処理水が悪化するものと考えられる。[0005] This is because when an aluminum-based flocculant is used in a normal filtration treatment, aluminum hydroxide adheres thinly to the surface of the filter medium, and this contributes to the removal of fine floc. It is thought that the treated water immediately after the backwashing is deteriorated because of the removal of the deposits.
【０００６】そこで、逆洗水に凝集剤を添加して逆洗を
行うことが提案されている。このような逆洗により、逆
洗の際に凝集剤がろ材中に供給され、ろ材表面のたとえ
ば、水酸化アルミニウムの付着が助長される。従って、
逆洗直後においても、微細フロックの除去を十分なもの
にできると考えられる。Accordingly, it has been proposed to add a flocculant to backwash water to perform backwash. By such backwashing, a coagulant is supplied into the filter medium at the time of backwashing, and adhesion of, for example, aluminum hydroxide on the surface of the filter medium is promoted. Therefore,
It is considered that fine flocs can be sufficiently removed even immediately after backwashing.
【０００７】[0007]
【発明が解決しようとする課題】ところが、この逆洗水
に凝集剤を添加した場合においても、逆洗終了直後の処
理水中の懸濁物質量はそれほど改善できないことがわか
った。これは、凝集剤をろ材全体に付着させるための条
件が十分考慮されていないからである。However, it has been found that even when a coagulant is added to the backwash water, the amount of suspended solids in the treated water immediately after the completion of the backwash cannot be significantly improved. This is because conditions for causing the flocculant to adhere to the entire filter medium have not been sufficiently considered.
【０００８】本発明は、上記課題に鑑みなされたもので
あり、逆洗直後から良好なろ過処理が行えるろ過装置の
逆洗方法を提供することを目的とする。[0008] The present invention has been made in view of the above problems, and has as its object to provide a backwashing method for a filtration device that can perform a good filtration treatment immediately after backwashing.
【０００９】[0009]
【課題を解決するための手段】本発明は、凝集剤を添加
した凝集処理を行った後、ろ過処理を行うろ過装置にお
ける逆洗方法において、その逆洗工程において、ポリ塩
化アルミニウムを４０〜８０ｍｇ／ｌとなるように添加
され、そのｐＨが５．０±０．５の範囲内に制御された
逆洗水を用いて逆洗を行うことを特徴とする。According to the present invention, there is provided a backwashing method in a filtration device for performing a filtration treatment after performing a flocculation treatment by adding a flocculant, wherein 40 to 80 mg of polyaluminum chloride is used in the backwashing step. / L, and backwashing is performed using backwash water whose pH is controlled within a range of 5.0 ± 0.5.
【００１０】このように、本発明によれば、ポリ塩化ア
ルミニウム（ＰＡＣという）を４０〜８０ｍｇ／ｌとな
るように逆洗水に添加し、逆洗水のｐＨを５．０±０．
５の範囲内に制御し、逆洗を行う。これによって、ろ層
全体のろ材の表面に凝集剤が付着して、ろ材の表面状態
をろ過に好適なもの、例えばろ材表面の酸化還元電位を
０〜−１０ｍＶ程度にできる。そこで、逆洗後のろ過に
おいて、当初より微細フロックの流出を防止して、良好
な水質の処理水を得ることができる。なおＰＡＣは、通
常Ａｌ２Ｏ３として１０％を含むものが市販されている
が、本発明における４０〜８０ｍｇ／ｌというのは、上
述した濃度のＰＡＣを逆洗水１リットルあたり４０〜８
０ｍｇの割合で添加する意味であり、この場合Ａｌとし
ては２．１２〜４．２４ｍｇ／ｌの添加量となる。As described above, according to the present invention, polyaluminum chloride (referred to as PAC) is added to the backwashing water at a concentration of 40 to 80 mg / l, and the pH of the backwashing water is 5.0 ± 0.5.
Control within 5 and backwash. As a result, the flocculant adheres to the surface of the filter medium in the entire filter layer, and the surface state of the filter medium is suitable for filtration, for example, the oxidation-reduction potential of the filter medium surface can be set to about 0 to -10 mV. Therefore, in the filtration after the backwash, it is possible to prevent the outflow of the fine floc from the beginning, and to obtain treated water having good water quality. The PAC is usually commercially available containing 10% as Al 2 O 3 , but the content of 40 to 80 mg / l in the present invention means that the PAC having the above-mentioned concentration is used in an amount of 40 to 8 mg / l of backwash water.
It means adding at a rate of 0 mg, and in this case, the addition amount of Al is 2.12 to 4.24 mg / l.
【００１１】また、前記逆洗水の通水量をろ過装置にお
けるろ材の空隙体積の１．５〜２．５倍量とすることが
好適である。このような水量により、好適なろ材への凝
集剤のコーティングが行え、かつ凝集剤および酸の消費
量を適切なものに維持することができる。It is preferable that the flow rate of the backwash water is 1.5 to 2.5 times the void volume of the filter medium in the filtration device. With such an amount of water, a suitable filter medium can be coated with a flocculant, and the consumption of the flocculant and acid can be maintained at an appropriate level.
【００１２】[0012]
【発明の実施の形態】以下、本発明の実施の形態（以下
実施形態という）について、図面に基づいて説明する。Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.
【００１３】図１は、本実施形態に係る凝集分離装置の
全体構成を示す図である。河川水、湖沼水などの原水
は、まず混和槽１０に流入される。この混和槽１０に
は、凝集剤貯槽１２からの凝集剤が凝集剤ポンプ１４に
よって供給される。凝集剤は、無機アルミニウム系の凝
集剤が好ましく、特にＰＡＣ（ポリ塩化アルミニウム）
が好ましい。そして、混和槽１０には、攪拌機１６が設
けられており、原水と凝集剤が急速攪拌される。この混
和槽１０において、凝集剤が混和された凝集剤混和水
は、凝集槽１８に流入する。この凝集槽１８には、緩速
攪拌機２０が配置されており、凝集剤混和水が緩速攪拌
され、凝集フロックの合体、粗大化が図られる。FIG. 1 is a diagram showing the overall configuration of the coagulation / separation apparatus according to the present embodiment. Raw water, such as river water and lake water, flows into the mixing tank 10 first. A flocculant from a flocculant storage tank 12 is supplied to the mixing tank 10 by a flocculant pump 14. As the coagulant, an inorganic aluminum-based coagulant is preferable, and in particular, PAC (polyaluminum chloride).
Is preferred. The mixing tank 10 is provided with a stirrer 16 for rapidly stirring the raw water and the coagulant. In the mixing tank 10, the coagulant-mixed water mixed with the coagulant flows into the coagulation tank 18. The flocculation tank 18 is provided with a slow stirring machine 20, which slowly mixes the flocculant-mixed water so that the flocculated floc is united and coarsened.
【００１４】次に、凝集槽１８からの緩速攪拌後の凝集
剤混和水は、傾斜板沈殿槽２２に流入する。この傾斜板
沈殿槽２２は、仕切板２２ａにより入口側と出口側に仕
切られており、入口側に槽深の深い沈殿部２２ｂが形成
されている。そして、この沈殿部２２ｂの下部は、沈殿
汚泥を貯留する汚泥貯留部２２ｃになっている。また、
出口側には多数の傾斜板２２ｄが配置されて傾斜板沈殿
部２２ｅが形成されている。凝集剤混和水は沈殿部２２
ｂに流入され、ここで沈殿処理された後、仕切板２２ａ
の下を通過して、傾斜板沈殿部２２ｅを上向流で通過す
る。そして、この傾斜板沈殿部２２ｅの傾斜板２２ｄを
通過する際にさらに沈殿処理がなされ、スラッジが槽底
へ向けて沈殿する。傾斜板沈殿部２２ｅの槽底は、汚泥
貯留部２２ｃに向けて深くなるように傾斜しているた
め、沈殿スラッジは重力により汚泥貯留部２２ｃに移動
する。そして、傾斜板沈殿部２２ｅを通過した上澄みが
傾斜板沈殿槽２２から排出される。なお、傾斜板沈殿槽
２２の汚泥貯留部２２ｃに沈殿した汚泥は、適宜引き抜
かれ別途処分される。Next, the coagulant-mixed water after the slow stirring from the coagulation tank 18 flows into the inclined plate sedimentation tank 22. The inclined plate sedimentation tank 22 is divided into an inlet side and an outlet side by a partition plate 22a, and a sedimentation part 22b having a deep tank depth is formed on the inlet side. The lower part of the sedimentation part 22b is a sludge storage part 22c for storing the sedimentation sludge. Also,
A large number of inclined plates 22d are arranged on the outlet side to form inclined plate settling portions 22e. The coagulant-mixed water is transferred to the sediment
b, and after being settled, the partition plate 22a
And passes through the inclined plate sedimentation section 22e in an upward flow. Then, when passing through the inclined plate 22d of the inclined plate sedimentation section 22e, further sedimentation processing is performed, and sludge settles toward the tank bottom. Since the tank bottom of the inclined plate sedimentation part 22e is inclined so as to become deeper toward the sludge storage part 22c, the sedimentation sludge moves to the sludge storage part 22c by gravity. Then, the supernatant passing through the inclined plate sedimentation section 22 e is discharged from the inclined plate sedimentation tank 22. Note that the sludge settled in the sludge storage section 22c of the inclined plate settling tank 22 is appropriately pulled out and separately disposed.
【００１５】このような凝集沈殿処理により、傾斜板沈
殿槽２２からの沈殿処理水は、懸濁固形物のかなりの部
分は除去されたものになっている。この沈殿処理水は、
ろ過器２４に流入される。このろ過器２４は、アンスラ
サイトのろ過層２４ｂと、砂のろ過層２４ａの二層のろ
過層を有する重力式の急速ろ過器である。なお、場合に
よっては、沈殿処理水に追加の凝集剤注入あるいは凝集
助剤注入を行いラインミキサーにて撹拌し、ろ過器２４
に供給してもよく、またろ過器は圧力式ろ過器であって
もよい。By such a coagulating sedimentation treatment, the sedimentation treatment water from the inclined plate sedimentation tank 22 has a considerable amount of suspended solids removed. This settling water is
It flows into the filter 24. The filter 24 is a gravity type quick filter having two anthracite filtration layers 24b and a sand filtration layer 24a. In some cases, an additional coagulant or coagulant is injected into the sedimentation water, and the mixture is stirred with a line mixer.
And the filter may be a pressure filter.
【００１６】ろ過層２４ｂのろ材としてアンスラサイト
以外のろ材を使用してもよいし、またこのろ過層２４ｂ
自体を省略してもよい。また、ろ過層２４ａについて、
砂に代えガーネットなどを利用したり、砂及びガーネッ
トを多層とすることも好適である。A filter medium other than anthracite may be used as the filter medium of the filter layer 24b.
It may be omitted itself. Also, regarding the filtration layer 24a,
It is also preferable to use garnet or the like instead of sand, or to use a multilayer of sand and garnet.
【００１７】そして、このろ過器２４のろ過処理水は、
処理水タンク２６に貯留された後、配水される。The filtered water of the filter 24 is
After being stored in the treated water tank 26, water is distributed.
【００１８】また、この処理水タンク２６内の処理水
は、逆洗ポンプ２８によりろ過器２４の底部に供給でき
るようになっている。そこで、ろ過器２４に処理水を上
向流で供給し、ろ過器２４内のろ過層を逆洗できるよう
になっている。The treated water in the treated water tank 26 can be supplied to the bottom of the filter 24 by the backwash pump 28. Therefore, the treated water is supplied to the filter 24 in an upward flow so that the filtration layer in the filter 24 can be backwashed.
【００１９】すなわち、通水を継続していくと、次第に
ろ過層に捕捉される懸濁物質が増加しろ材が飽和して、
ろ過器２４はそれ以上懸濁物質を捕捉できなくなる。こ
れは、ろ過抵抗の上昇や、処理水濁度の上昇等によって
検出できる。そこで、ろ材が完全に飽和する前に、洗浄
によりろ材の再生を行う。That is, when water is continuously passed, the suspended matter trapped in the filtration layer gradually increases, and the filter medium is saturated.
Filter 24 can no longer capture suspended material. This can be detected by an increase in filtration resistance, an increase in turbidity of the treated water, and the like. Therefore, before the filter medium is completely saturated, the filter medium is regenerated by washing.
【００２０】この洗浄のタイミングは、経験的に得られ
る時間に基づくタイマー設定や、差圧計によるろ過抵抗
の設定により行われる。さらに、逆洗は、ろ過水を用い
た逆流水洗浄や、逆流水洗浄に表面洗浄あるいは空気洗
浄を組み合わせて行われる。The timing of this cleaning is set by setting a timer based on the time obtained empirically or by setting a filtration resistance using a differential pressure gauge. Furthermore, backwashing is performed by backwashing with filtered water, or by combining backwashing with surface washing or air washing.
【００２１】ここで、本実施形態においては、この逆洗
ポンプ２８からろ過器２４に至る逆洗水のラインに、凝
集剤貯槽３０からの凝集剤が凝集剤ポンプ３２により添
加される。この凝集剤としては、上述の凝集剤貯槽１２
と同様にＰＡＣが利用され、凝集剤貯槽１２からの凝集
剤を添加するように構成してもよい。さらに、酸貯槽３
４からの酸（酸性溶液、例えば硫酸）が酸ポンプ３６に
よって添加されるように構成されている。In this embodiment, a flocculant from a flocculant storage tank 30 is added to a backwash water line from the backwash pump 28 to the filter 24 by a flocculant pump 32. The coagulant includes the coagulant storage tank 12 described above.
The PAC may be used in the same manner as described above, and the flocculant from the flocculant storage tank 12 may be added. Furthermore, acid storage tank 3
The acid from 4 (acid solution, eg sulfuric acid) is configured to be added by the acid pump 36.
【００２２】このようにして、本実施形態においては、
通常の逆洗に加え、凝集剤を含む逆洗水による逆洗が行
われ、これによってろ材表面に凝集剤の被膜が構成され
る。すなわち、所定ｐＨに調整され、所定量の凝集剤が
添加された逆洗水を所定量だけろ過器２４に通水し、こ
れによってろ材表面に水酸化アルミニウムの被膜が形成
される。Thus, in this embodiment,
In addition to the usual backwashing, backwashing with backwash water containing a flocculant is performed, thereby forming a film of the flocculant on the surface of the filter medium. That is, a predetermined amount of backwash water adjusted to a predetermined pH and to which a predetermined amount of a coagulant has been added is passed through the filter 24 by a predetermined amount, whereby a film of aluminum hydroxide is formed on the surface of the filter medium.
【００２３】特に、本実施形態においては、逆洗ライン
にｐＨメータ３８および流量計４０が設けられており、
その検出結果がコントローラ４２に供給されるようにな
っている。そして、コントローラ４２は、これら検出結
果に基づいて、凝集剤ポンプ３２および酸ポンプ３６の
駆動を制御し、逆洗水のｐＨ、凝集剤の添加量が所定量
となるように制御するとともに、凝集剤および酸を添加
する逆洗水の水量を制御する。In particular, in the present embodiment, a pH meter 38 and a flow meter 40 are provided in the backwash line,
The detection result is supplied to the controller 42. The controller 42 controls the driving of the coagulant pump 32 and the acid pump 36 based on the detection results, and controls the pH of the backwash water and the amount of the coagulant to be a predetermined amount. Control the amount of backwash water to which the agent and acid are added.
【００２４】このような所定ｐＨに調整され、所定量の
凝集剤が添加された逆洗水を所定量だけろ過器２４に通
水することによってろ材表面に適切な凝集剤の被膜が形
成され、ろ過器２４におけるろ過層２４ａのろ材のゼー
タ電位が０〜−１０ｍＶになるように制御される。すな
わち、水酸化アルミニウムがろ材表面上に付着すること
で、ろ材のゼータ電位が上昇する。また、酸の添加によ
ってもゼータ電位が変化するため酸の添加量も調整す
る。これによって、ろ材表面のゼータ電位が０〜−１０
ｍＶに制御される。By passing a predetermined amount of backwash water adjusted to such a predetermined pH and to which a predetermined amount of a coagulant has been added, through a filter 24, an appropriate coagulant film is formed on the surface of the filter medium. The zeta potential of the filter medium of the filter layer 24a in the filter 24 is controlled to be 0 to -10 mV. That is, the zeta potential of the filter medium rises because aluminum hydroxide adheres to the surface of the filter medium. In addition, since the zeta potential also changes with the addition of an acid, the amount of the acid added is adjusted. Thereby, the zeta potential on the surface of the filter medium is 0 to -10.
It is controlled to mV.
【００２５】ここで、ろ材のゼータ電位は、ろ材表面へ
の水酸化アルミニウムの付着状態を示している。そこ
で、このろ材のゼータ電位を所定値（０〜−１０ｍＶ）
とすることによって、ろ材の表面状態を微細フロックを
捕捉しやすい状態に調整することができる。そして、上
述のようにして調整した逆洗水によりろ材の表面に水酸
化アルミニウムを確実に付着させることで、逆洗後のろ
過において、当初より微細フロックの流出を防止して、
良好な水質の処理水を得ることができる。Here, the zeta potential of the filter medium indicates the state of adhesion of aluminum hydroxide to the surface of the filter medium. Therefore, the zeta potential of this filter medium is set to a predetermined value (0 to -10 mV).
By doing so, the surface state of the filter medium can be adjusted to a state in which fine flocs can be easily captured. And, by reliably attaching aluminum hydroxide to the surface of the filter medium with the backwash water adjusted as described above, in the filtration after the backwash, to prevent the outflow of fine floc from the beginning,
It is possible to obtain treated water of good quality.
【００２６】また、本実施形態では、次のような手順で
逆洗を行う。（ｉ）まずろ過処理水をそのままで逆流さ
せる逆洗を行う。例えば、ＬＶ（空塔線速度）＝４０ｍ
／ｈ×８分。なお、上述したように、空気逆洗を組み合
わせてもよい。（ｉｉ）次に凝集剤（ＰＡＣ）および酸
を添加した逆洗水による逆洗を行う。ＬＶ＝４０ｍ／ｈ
×１分。（ｉｉｉ）次に、３０秒静置状態で休止する。In this embodiment, backwashing is performed in the following procedure. (I) First, backwashing is performed by back-flowing the filtered water as it is. For example, LV (superficial linear velocity) = 40 m
/ H × 8 minutes. Note that, as described above, air backwash may be combined. (Ii) Next, backwashing is performed with backwash water to which a flocculant (PAC) and an acid have been added. LV = 40m / h
X 1 minute. (Iii) Next, the apparatus is rested for 30 seconds.
【００２７】このようにして、ゼータ電位調整剤として
の凝集剤および酸を添加した逆洗水による逆洗を短時間
行い、その後休止時間をおくという逆洗を行う。これに
よって、凝集剤とろ材が十分混合するとともに、接触の
ための時間が得られ、ろ材表面に水酸化アルミニウムが
十分に付着される。In this manner, backwashing is performed for a short time with backwashing water to which a flocculant as a zeta potential regulator and an acid are added, and then backwashing is performed after a pause. As a result, the coagulant and the filter medium are sufficiently mixed, a time for contact is obtained, and aluminum hydroxide is sufficiently adhered to the surface of the filter medium.
【００２８】特に、本実施形態の凝集剤および酸を添加
した逆洗水は、凝集剤としてＰＡＣ（有効成分Ａｌ２Ｏ
３を１０％含む液体）を利用し、その添加量を４０〜８
０ｍｇ／Ｌとする。そして、その逆洗水のｐＨは５．０
±０．５とし、これをトータルの水量として、ろ過器２
４におけるろ材の空隙体積の１．５〜２．５倍量とす
る。このような逆洗水のろ材への流通によって、上述し
たようなろ材のゼータ電位を０〜−１０ｍＶに調整する
処理を行うことができる。すなわち、この程度のＰＡＣ
の濃度することによって、ろ材表面への適切な水酸化ア
ルミニウムの被膜形成が行える。濃度の高い凝集剤を通
水しても、凝集剤の拡散効率が悪くなり、効果的な被膜
形成が行えず、また濃度が低いと通水量が多くなるとと
もに十分な被膜形成ができない。なお、逆洗水をさらに
多くしてもろ材のゼータ電位制御に悪影響はない。しか
し、意味のない逆洗を行うことになり、エネルギーおよ
び凝集剤などの浪費となるため上述のような範囲に制御
することが好ましい。In particular, the backwash water to which the coagulant and the acid of the present embodiment are added is a PAC (active ingredient Al 2 O)
3 containing 10%) and the amount of addition is 40 to 8
0 mg / L. And the pH of the backwash water is 5.0.
± 0.5 and this as the total amount of water
The volume is 1.5 to 2.5 times the void volume of the filter medium in 4. By the flow of the backwash water to the filter medium, a process for adjusting the zeta potential of the filter medium to 0 to -10 mV as described above can be performed. That is, this level of PAC
, A suitable aluminum hydroxide film can be formed on the surface of the filter medium. Even if water having a high concentration is passed through, the diffusion efficiency of the flocculant deteriorates, and an effective film cannot be formed. On the other hand, if the concentration is low, the amount of water flow increases and a sufficient film cannot be formed. Incidentally, even if the backwash water is further increased, there is no adverse effect on the zeta potential control of the filter medium. However, meaningless backwashing is performed and energy and a coagulant are wasted, so that it is preferable to control to the above range.
【００２９】上述のように、本実施形態では、ろ材のゼ
ータ電位が０〜−１０ｍＶになるように逆洗水への凝集
剤添加量を調整する。このゼータ電位は、固体と液体の
界面を横切って存在する電気的ポテンシャルを示すもの
であり、水中の懸濁物質についての表面荷電を示す。通
常、河川水等に含まれる懸濁物質（粘度成分や藻類等）
は負に帯電しており、懸濁物質が各々負に帯電している
ことから電気的に反発し、凝集しにくい状態になってい
る。凝集剤は、この電位の中和をまず行い反発力を弱
め、その後に集塊化つまり凝集を行う。従って、凝集フ
ロックのゼータ電位は中和点つまりゼロに近い方が望ま
しい。通常、原水中の懸濁物質のゼータ電位は−２０ｍ
Ｖ以下で、凝集フロックのゼータ電位は−１０ｍＶ以上
となっている。As described above, in the present embodiment, the amount of the flocculant added to the backwash water is adjusted so that the zeta potential of the filter medium becomes 0 to -10 mV. This zeta potential indicates the electrical potential that exists across the solid-liquid interface and indicates the surface charge for suspended matter in water. Suspended substances (viscosity components, algae, etc.) usually contained in river water, etc.
Are negatively charged, and are electrically repelled because the suspended substances are each negatively charged, so that they are hardly aggregated. The coagulant neutralizes this potential first to weaken the repulsion, and then agglomerates, that is, agglomerates. Therefore, it is desirable that the zeta potential of the aggregated floc be close to the neutralization point, that is, zero. Normally, the zeta potential of suspended matter in raw water is -20 m
V or less, the zeta potential of the aggregated floc is -10 mV or more.
【００３０】ここで、浄水処理で一般に用いられる凝集
沈殿・急速ろ過法において、急速ろ過器より、特にろ過
開始直後に微小なフロックが流出することが知られてい
る。この微小なフロックのゼータ電位は、−１５ｍＶ以
下と低く、凝集が十分に行われていないことが知られて
いる。Here, in the coagulation sedimentation / rapid filtration method generally used in the water purification treatment, it is known that a minute floc flows out of the rapid filter, particularly immediately after the filtration is started. It is known that the zeta potential of these minute flocs is as low as −15 mV or less, and aggregation is not sufficiently performed.
【００３１】ろ材も水中の懸濁物質と同様にそのままで
は負に帯電しており、ろ材のゼータ電位を−１０ｍＶ以
上にすることによって、ろ材表面への凝集剤水酸化物の
付着を十分なものにできる。そして、この付着物を形成
することで、フロックの捕捉能力を改善し、処理水中の
懸濁物質濃度の上昇を防止することができる。なお、ゼ
ータ電位を０ｍＶ以上にするのは、経済的ではなく、ま
た洗浄排水中のアルミニウム濃度が高くなるので、好ま
しくない。The filter medium is negatively charged as it is in the same manner as the suspended substance in water. By setting the zeta potential of the filter medium to -10 mV or more, sufficient adhesion of the flocculant hydroxide to the surface of the filter medium is achieved. Can be. Then, by forming the deposits, the ability to capture flocs can be improved, and an increase in the concentration of suspended solids in the treated water can be prevented. It is not preferable to set the zeta potential to 0 mV or more because it is not economical and the aluminum concentration in the washing wastewater increases.
【００３２】本実施形態においては、凝集剤としてＰＡ
Ｃ（有効成分Ａｌ２Ｏ３を１０％含む液体）を利用し、
その添加量を４０〜８０ｍｇ／Ｌとする。そして、その
逆洗水のｐＨは５．０±０．５とし、これをトータルの
水量として、ろ過器２４におけるろ材の空隙体積の１．
５〜２．５倍量とする。このような逆洗水のろ材への流
通によって、ろ材のゼータ電位を０〜−１０ｍＶに調整
する処理を行っている。In this embodiment, PA is used as a flocculant.
Utilizing C (liquid containing 10% of active ingredient Al 2 O 3 ),
The added amount is 40 to 80 mg / L. Then, the pH of the backwash water is set to 5.0 ± 0.5, and this is defined as a total amount of water, which is 1.50 of the pore volume of the filter medium in the filter 24.
The amount is 5 to 2.5 times. A process of adjusting the zeta potential of the filter medium to 0 to -10 mV is performed by such a distribution of the backwash water to the filter medium.
【００３３】[0033]
【実施例】図１の装置を用いて実験を行った。EXAMPLE An experiment was conducted using the apparatus shown in FIG.
【００３４】「実験条件」 ・原水流量：３０００ｍ３/Ｄ ・混和槽：滞留時間４分、Ｇ値２５０〜４００ｓ−１ ・沈殿池：上向流式傾斜板付き沈殿池、滞留時間４０
分、上昇速度５ｃｍ／ｍｉｎ ・ろ過池仕様：φ５０００ｍｍ×５０００ｍｍ×Ｈ４０
００ｍｍ（ろ過面積２５ｍ２） ・ろ過速度（ＬＶ）：５ｍ／ｈ（１２０ｍ／ｄ） ・ろ材：ケイ砂 比重２．５ｍ、空隙率４５％、有効径
０．６ｍｍ、均等係数１ ．４、ろ層高６００ｍｍ ・通水時間：４８時間（タイマーにより洗浄開始） ・原水濁度：８〜３０度 ・原水ｐＨ：７．２〜７．５ ・凝集剤：ＰＡＣ１０〜３０ｍｇ／ｌ ・目標処理水濁度：０．１度未満 ・洗浄条件：水逆洗 ＬＶ＝４０ｍ／ｈ×８分 水量＝２５ｍ２×４０ｍ／ｈ×（８÷６０）＝１３３．
３ｍ３／回 ＰＡＣ＋硫酸水逆洗 ＬＶ＝４０ｍ／ｈ×１分 水量＝２５ｍ２×４０ｍ／ｈ×（１÷６０）＝１６．７
ｍ３／回 ろ材空隙容量＝２５ｍ２×０．６ｍ×０．４５＝６．７
５ｍ３ ２．５倍量通水として、６．７５ｍ３×２．５＝１６．
９ｍ３／回 逆洗水：ろ過水を用いる。ｐＨは、５．０±０．５に調
整。 ＰＡＣ：４０〜８０ｍｇ／Ｌとなるように調整。"Experimental conditions" Raw water flow rate: 3000 m 3 / D Mixing tank: residence time 4 minutes, G value 250-400 s -1 Sedimentation basin: sedimentation basin with upflow type inclined plate, residence time 40
Min, ascending speed 5cm / min ・ Filter specifications: φ5000mm × 5000mm × H40
00 mm (filtration area 25 m 2 ) Filtration speed (LV): 5 m / h (120 m / d) Filter material: silica sand Specific gravity 2.5 m, porosity 45%, effective diameter 0.6 mm, uniformity coefficient 1. 4. Filtration height 600 mm ・ Water flow time: 48 hours (washing started by timer) ・ Raw turbidity: 8 to 30 degrees ・ Raw water pH: 7.2 to 7.5 ・ Flocculant: PAC 10 to 30 mg / l ・ Target treated water turbidity: 0.1 degrees less than and washing conditions: Mizugyakuarai LV = 40m / h × 8 minutes water = 25m 2 × 40m / h × (8 ÷ 60) = 133.
3 m 3 / time PAC + sulfuric acid aqueous backwash LV = 40 m / h × 1 minute Water amount = 25 m 2 × 40 m / h × (1 ÷ 60) = 16.7
m 3 / filter medium void volume = 25 m 2 × 0.6 m × 0.45 = 6.7
As 5 m 3 2.5 times water passage, 6.75m 3 × 2.5 = 16.
9 m 3 / time Backwash water: Use filtered water. pH adjusted to 5.0 ± 0.5. PAC: adjusted to be 40 to 80 mg / L.
【００３５】「実験結果」濁度８度の原水に凝集剤とし
てＰＡＣを１０ｍｇ／Ｌ添加し、ｐＨを７．０に調整す
るために酸として硫酸を加え、混和槽１０にて攪拌機１
６を用いて混和を行い、凝集槽１８にて緩速撹拌を行
い、傾斜板沈殿槽（傾斜板無しでもよい）２２にて沈殿
処理を行った後、ろ過器２４に供給して処理水を得た。[Experimental Result] PAC was added to raw water having a turbidity of 8 ° C. as a coagulant at a concentration of 10 mg / L, and sulfuric acid was added as an acid to adjust the pH to 7.0.
6, the mixture is slowly stirred in the flocculation tank 18, and the sedimentation treatment is performed in the inclined plate sedimentation tank 22 (there may be no inclined plate). Obtained.
【００３６】ところで、ろ過器２４は、ある程度通水を
行っていくと、濁質によりろ材の間隙が飽和し、通水を
継続できなくなる。このろ過が継続できなくなるまでの
時間は、ろ過器流入水中の濁質濃度や通水速度などによ
って異なり、通常は２４〜７２時間程度であるが、本実
験では４８時間毎に逆洗を行った。By the way, when water is passed through the filter 24 to some extent, the gap between the filter media is saturated by the turbidity, and it becomes impossible to continue the water flow. The time until the filtration cannot be continued varies depending on the turbidity concentration in the inflow water of the filter, the flow rate, and the like, and is usually about 24 to 72 hours. In this experiment, the backwash was performed every 48 hours. .
【００３７】この逆洗条件は、水逆洗をＬＶ＝４０ｍ／
ｈ×８分、（ｉ）ＰＡＣ６０ｍｇ／Ｌと７５％硫酸を２
０ｍＬ／ｍ３注入したｐＨ５±０．５の凝集剤添加水に
よる水逆洗をＬＶ＝４０ｍ／ｈ×１分（ろ材空隙容量
６．７５ｍ３に対し２．５倍）として行った。なお、こ
の凝集剤を添加した水逆洗の後、３０秒程度静止時間を
おき、凝集剤のろ材表面への付着を促進した。The backwashing conditions are as follows: water backwashing is performed at LV = 40 m /
h × 8 minutes, (i) PAC 60 mg / L and 75% sulfuric acid 2
Backwashing with 0 mL / m 3 injected coagulant-added water of pH 5 ± 0.5 was performed at LV = 40 m / h × 1 minute (2.5 times the filter medium void capacity of 6.75 m 3 ). After the water backwashing with the addition of the flocculant, a rest time of about 30 seconds was allowed to promote the adhesion of the flocculant to the surface of the filter medium.
【００３８】このような処理により、逆洗直後において
も、処理水の悪化はなく、目標濁度を継続して維持でき
ることが確認できた。By such treatment, it was confirmed that the target turbidity could be maintained continuously without deterioration of the treated water immediately after the backwashing.
【００３９】[0039]
【発明の効果】以上説明したように、本発明によれば、
逆洗水への凝集剤およびｐＨ調整剤の添加量を予め設定
した値に制御する。これによって、ろ材の表面に凝集剤
が付着して、ろ材の表面状態をろ過に好適なものにでき
る。そこで、逆洗後のろ過において、当初より微細フロ
ックの流出を防止して、良好な水質の処理水を得ること
ができる。As described above, according to the present invention,
The amounts of the flocculant and the pH adjuster added to the backwash water are controlled to predetermined values. Thereby, the flocculant adheres to the surface of the filter medium, and the surface state of the filter medium can be made suitable for filtration. Therefore, in the filtration after the backwash, it is possible to prevent the outflow of the fine floc from the beginning, and to obtain treated water having good water quality.
【００４０】特に、凝集剤は、ポリ塩化アルミニウム
（ＰＡＣという）とし、このＰＡＣ（１０％Ａｌ
２Ｏ３）を４０〜８０ｍｇ／ｌとなるように逆洗水に添
加し、逆洗水のｐＨを５．０±０．５の範囲内に制御
し、かつこの調整した逆洗水の通水量はろ過装置におけ
るろ材の空隙体積の１．５〜２．５倍量とすることによ
って、好適なろ材への凝集剤のコーティングが行える。In particular, the coagulant is polyaluminum chloride (PAC), and the PAC (10% Al
2 O 3 ) is added to the backwash water to a concentration of 40 to 80 mg / l, the pH of the backwash water is controlled within the range of 5.0 ± 0.5, and the flow of the adjusted backwash water is controlled. By setting the amount of water to 1.5 to 2.5 times the void volume of the filter medium in the filtration device, a suitable filter medium can be coated with a flocculant.
【図１】 実施形態の装置の構成を示す図である。FIG. 1 is a diagram illustrating a configuration of an apparatus according to an embodiment.
１０ 混和槽、１８ 凝集槽、２２ 傾斜板沈殿槽、２
４ ろ過器、３０ 凝集剤貯槽、３２ 凝集剤ポンプ、
３８ ｐＨメータ、４０ 流量計、４２ コントロー
ラ。10 mixing tank, 18 coagulation tank, 22 inclined plate sedimentation tank, 2
4 filter, 30 flocculant storage tank, 32 flocculant pump,
38 pH meter, 40 flow meter, 42 controller.
Claims (2)
ろ過処理を行うろ過装置における逆洗方法において、 その逆洗工程において、 ポリ塩化アルミニウムを４０〜８０ｍｇ／ｌとなるよう
に添加され、そのｐＨが５．０±０．５の範囲内に制御
された逆洗水を用いて逆洗を行うことを特徴とするろ過
装置における逆洗方法。After performing a coagulation treatment to which a coagulant is added,
In a back washing method in a filtration device for performing a filtration treatment, in the back washing step, polyaluminum chloride is added so as to be 40 to 80 mg / l, and its pH is controlled within a range of 5.0 ± 0.5. A backwash method in a filtration device, wherein the backwash is performed using backwash water.
の１．５〜２．５倍量とすることを特徴とするろ過装置
における逆洗方法。2. The method according to claim 1, wherein the flow rate of the backwash water is 1.5 to 2.5 times the pore volume of the filter medium in the filtration device. Washing method.
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|---|---|---|---|
| JP2000073301A JP4800461B2 (en) | 2000-03-16 | 2000-03-16 | Backwashing method in filtration equipment |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000073301A JP4800461B2 (en) | 2000-03-16 | 2000-03-16 | Backwashing method in filtration equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001259313A true JP2001259313A (en) | 2001-09-25 |
| JP4800461B2 JP4800461B2 (en) | 2011-10-26 |
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ID=18591561
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009090253A (en) * | 2007-10-11 | 2009-04-30 | Japan Organo Co Ltd | Filter |
| JP2010227836A (en) * | 2009-03-27 | 2010-10-14 | Toray Ind Inc | Method for operating film module |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02164406A (en) * | 1988-12-19 | 1990-06-25 | Merusu Giken:Kk | Pretreatment of granular filter medium |
| JPH1119421A (en) * | 1997-07-07 | 1999-01-26 | Kurita Water Ind Ltd | Method of backwashing filter |
-
2000
- 2000-03-16 JP JP2000073301A patent/JP4800461B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02164406A (en) * | 1988-12-19 | 1990-06-25 | Merusu Giken:Kk | Pretreatment of granular filter medium |
| JPH1119421A (en) * | 1997-07-07 | 1999-01-26 | Kurita Water Ind Ltd | Method of backwashing filter |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009090253A (en) * | 2007-10-11 | 2009-04-30 | Japan Organo Co Ltd | Filter |
| JP2010227836A (en) * | 2009-03-27 | 2010-10-14 | Toray Ind Inc | Method for operating film module |
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| Publication number | Publication date |
|---|---|
| JP4800461B2 (en) | 2011-10-26 |
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