JP3973967B2

JP3973967B2 - Coagulation separation device

Info

Publication number: JP3973967B2
Application number: JP2002139162A
Authority: JP
Inventors: 正美大浦; 良行菅原; 司品田; 博子間瀬
Original assignee: Nishihara Environmental Technology Co Ltd
Current assignee: Nishihara Environment Co Ltd
Priority date: 2002-05-14
Filing date: 2002-05-14
Publication date: 2007-09-12
Anticipated expiration: 2022-05-14
Also published as: JP2003326109A

Description

【０００１】
【発明の属する技術分野】
本発明は、水処理分野において、懸濁物質等を含んだ被処理液に添加する添加物量を管理して安定した水質を得る凝集分離装置に関するものである。
【０００２】
【従来の技術】
水処理分野において、下水流入水量の極端な増加時には、処理場流入前および処理場での一次処理（最初沈殿池越流）程度で簡易放流される場合がある。この場合、高濁度の汚水が直接公共用水域へ放流されるという問題があった。このような状況から、公共用水域の更なる水質保全、即ち濁質などの改善を目的に下水での雨天時等における越流水処理の必要性が叫ばれている。
その対策として、下水処理場では汚濁物質の除去を目的に凝集沈殿処理が試みられている。
【０００３】
特に、合流式下水道の場合、雨天時には路面等の落ち葉や土砂が雨で洗い流され、短時間に大量の落ち葉や土砂が下水処理場に流入してくる。そこで、合流式下水道の流入下水を凝集沈殿処理する場合、最初沈殿池の前段に沈砂池を設けているが、雨天時の極端な流入水量の多いときには流入土砂を沈砂池で取り除くことは出来ない。その後段で、凝集沈殿を適応すると沈砂池で取り除けない砂は、凝集反応槽内に溜まり沈殿槽に移流しない場合があり、凝集反応槽に余剰な砂が増え、凝集効果に影響を与え、処理が困難になる場合がある。
【０００４】
図１０は従来の凝集沈殿処理装置を概略的に示すフロー図である。
同図において、１は原水導入管、２はその原水導入管１から汚泥等の懸濁物質等を含んだ被処理液（原水）を導入する凝集反応槽であり、この凝集反応槽２内の被処理液には、無機凝集剤供給手段３および高分子凝集剤供給手段４のそれぞれから凝集剤が供給されるようになっている。５は前記凝集反応槽２からの流出水を流入して分離物と処理水とに分離する固液分離槽、６はその固液分離槽５から分離物を引き抜く分離物引抜手段、７は返送管、８は添加物回収器であり、この添加物回収器８は、分離物引抜手段６から返送管７を介して返送された分離物に含まれる添加物を分離回収し、その回収添加物を凝集反応槽２に返送し且つ分離汚泥を排出するものである。
【０００５】
次に、上記従来の凝集沈殿処理装置の動作について説明する。
原水導入管１から凝集反応槽２内に導入された被処理液（原水）に無機凝集剤と高分子凝集剤および添加物が添加されることにより、凝集反応槽２では、被処理液と凝集剤と添加物とが混合され、これによって凝集フロックが生成される。その凝集フロックを含んだ混和液は次の固液分離槽５に移流し、この固液分離槽５で添加物を含んだ沈降汚泥と処理水とに分離され、処理水は系外に排出され、沈降汚泥は分離物引抜手段６で引き抜かれた後、返送管７を介して添加物回収器８に返送される。この添加物回収器８では、返送汚泥に含まれた添加物が分離され、その添加物は凝集反応槽２内に返送され、添加物が分離された汚泥は系外に排出される。
【０００６】
【発明が解決しようとする課題】
従来の凝集沈殿処理装置は以上のように構成されているので、添加物回収器８によって、返送汚泥から分離された添加物の濃度を測定・管理することは可能であるが、しかし、凝集反応槽２内の混合物には次段の固液分離槽５に移流しない重たい砂等が含まれているため、添加物回収器８による返送汚泥からの分離添加物の濃度測定では、例えば雨天時等に流入水量が極端に多くなって凝集反応槽２での重たい砂量が増加しても、その砂量に応じた添加物濃度を測定することはできず、このため、凝集反応槽２の砂量が増加して処理水質が悪化しても適正な対応処理ができないという課題があった。
【０００７】
本発明は上記のような課題を解決するためになされたもので、凝集反応槽に流入する被処理液に含まれた砂等のように比重の大きな混合物量が増えた場合でも、その混合物濃度に応じた添加物供給量および／または混合物引抜量を適正に制御することができ、常に安定した水質を得ることができる凝集分離装置を提供することを目的とする。
【０００８】
また、本発明は、凝集反応槽の混合物濃度に応じて凝集反応槽への添加物供給量および／または混合物引抜量を適正に自動制御することができる凝集分離装置を提供することを目的とする。
【０００９】
【課題を解決するための手段】
本発明に係る凝集分離装置は、被処理液に含まれた懸濁物質等を凝集処理する凝集反応槽と、この凝集反応槽からの流出水を固液分離する固液分離槽と、添加物を回収し排出する添加物回収器とからなる凝集分離装置において、前記凝集反応槽の混合物濃度を測定する混合物濃度測定器と、前記凝集反応槽から混合物を引き抜く添加物濃度調整用の混合物引抜手段と、前記凝集反応槽に添加物を供給する添加物供給手段とを備え、前記混合物濃度測定器による測定濃度に応じ混合物引抜手段および／または添加物供給手段を適正に制御するものである。
【００１０】
本発明に係わる凝集分離装置は、前記混合物濃度測定器に演算器を連結し、その演算器からの出力信号によって、混合物引抜手段および／または添加物供給手段を適正に自動制御するものである。
【００１１】
【発明の実施の形態】
以下、この発明の実施の一形態を説明する。
実施の形態１．
図１はこの発明の実施の形態１による凝集分離装置を示すフロー図であり、図１０と同一または相当部分には同一符号を付して重複説明を省略する。
図１において、６ａは固液分離槽５から分離物を引き抜いて添加物回収器８に返送する分離物引抜手段としてのポンプ、１０は凝集反応槽２内に砂等の添加物（分離促進用の不溶性微粒物質）を供給する添加物供給手段、１１は凝集反応槽２から混合物を引き抜く混合物引抜手段、１２は凝集反応槽２内の混合物濃度を測定するための混合物濃度測定器であり、この混合物濃度測定器１２としては、超音波式濃度計や赤外線濃度計を適用するが、混合物濃度を測定できるものであれば、いかなる計測器であってもよい。なお、添加物供給手段としては、定量フィダー供給やスラリー供給あるいはドライ供給が挙げられるが、凝集反応層２内に添加物を速やかに供給できるものであれば、如何なるものでもよい。混合物引抜手段１１としては、凝集反応層２内に掻寄機を設置し、混合物をかき寄せてポンプで引き抜く手段、あるいは凝集反応層２の底部および／または側面下部に取り付けたバルブの開閉による混合物を引き抜く手段など、速やかに混合物が引き抜けるものであれば、如何なるものでもよい。
なお、凝集処理の対象となる物質は、懸濁物質、ＣＯＤ成分、リン成分など凝集反応する物質が挙げられる。
また、前記混合物とは、被処理液と凝集剤と添加物とが混ざった物（凝集フロック）を指すものである。
【００１２】
次に動作について説明する。
混合物引抜手段１１によって凝集反応槽２から混合物を引き抜き、その引き抜き混合物濃度を混合物濃度測定器１２によって測定する。その混合物濃度測定値を設定濃度値（混合物濃度設定値）と比較し、その結果、混合物濃度測定値が設定濃度値よりも大であれば、混合物引抜手段１１に濃度過剰信号を送って混合物引抜手段１１を稼動させることにより、凝集反応槽２から混合物を引き抜く。この場合、その混合物引き抜きによって凝集反応槽２内の混合物濃度が設定濃度値に達した時点で混合物引抜手段１１が停止する。また、混合物濃度測定値が設定濃度値よりも小であれば、添加物供給手段１０に濃度不足信号を送って添加物供給手段１０を稼動させることにより、凝集反応槽２内に添加物を供給する。これにより、凝集反応槽２内の混合物濃度が設定濃度値に達すると、その時点で添加物供給手段１０が停止する。
【００１３】
なお、前記添加物としては、砂に近似する比重２〜８の範囲である有機系や無機系の物質、例えば、微粒砂や酸化ジルコニウムやガーネットなどが挙げられる。また、前記添加物供給手段１０および／または混合物引抜手段１１への制御信号は、手動によるスイッチ操作等によって送られるようにすればよい。
【００１４】
以上説明した実施の形態１によれば、凝集反応槽２内の混合物濃度を測定し、その濃度測定値を設定濃度値と比較して濃度測定値が設定濃度値よりも大のときには、凝集反応槽２内の混合物濃度が設定濃度値となるまで凝集反応槽２の混合物を引き抜き、濃度測定値が設定濃度値よりも小のときは、凝集反応槽２内の混合物濃度が設定濃度値となるまで凝集反応槽２内に添加物を供給するように構成したので、凝集反応槽２に流入する被処理液に含まれた砂等のように比重の大きな混合物量が増えた場合でも、その混合物濃度に応じた添加物供給量および／または混合物引抜量を適正に制御して凝集反応槽２内の混合物濃度を常に一定に確保することが可能となり、このため、常に安定した水質を得ることができる。
【００１５】
実施例１．
次に、上記実施の形態１による凝集分離装置の実験運転を行った結果について説明する。
なお、実施条件は、
原水；下水処理場の最初沈殿池の流入水
原水流量；２８８０ｍ^３／日（１２０ｍ^３／ｈ）
固液分離槽の上昇速度；１２０ｍ／ｈ
無機凝集剤；ＰＡＣ添加率１０ｍｇ／Ｌ（ＡＬ_２Ｏ_３として）
高分子凝集剤；アニオン系高分子凝集剤添加率１ｍｇ／Ｌ
本発明の凝集分離装置内微粒砂量；０〜３８０ｋｇ
とし、添加物としては微粒砂を用いた。
【００１６】
凝集反応槽２の砂量と混合物濃度測定器１２の指示値との関係を図４に示す。混合物濃度測定器１２として超音波式濃度計を用いた。凝集反応槽２の砂量と超音波式濃度計１２の指示値は比例関係にあることがわかる。このことから、凝集反応槽２の砂量の予測に混合物濃度測定器（超音波式濃度計）１２が適応できることがわかる。
また、混合物濃度測定器１２の指示値が５，０００ｍｇ／Ｌ以下と１４，０００ｍｇ／Ｌ以上では処理水質の悪化が見られ、凝集反応槽２内の砂濃度で適正に管理すれば良好な処理水が得られることが予測された。
【００１７】
次に、凝集反応槽２内の砂量と原水ＳＳ、処理水ＳＳ、ＳＳ除去率の実施例を図５に示す。凝集反応槽２内の砂量０〜６０ｋｇまでは原水ＳＳ１７６〜２６６ｍｇ／Ｌの範囲で処理水ＳＳ２５６〜４２６ｍｇ／Ｌ、ＳＳ除去率−９３〜−４５％であった。
凝集反応槽２内の砂量６０〜２００ｋｇまでは原水ＳＳ１４１〜２２０ｍｇ／Ｌの範囲で処理水ＳＳ２８〜３３ｍｇ／Ｌ、ＳＳ除去率８０〜８５％であった。凝集反応槽２内の砂量２００〜３８０ｋｇで原水ＳＳ１３８〜２１３ｍｇ／Ｌの範囲で処理水ＳＳ３９〜９０ｍｇ／Ｌ、ＳＳ除去率５３〜７７％であった。この結果から原水ＳＳによらず処理水ＳＳは凝集反応槽の砂量で変化することがわかった。
【００１８】
図１に示す本発明の凝集分離装置において、添加物供給手段１０と混合物引抜手段１１を手動操作で動かし、流入水量は一定とした。運転時間と混合物濃度測定器１２の指示値およびＳＳ除去率の関係を図６に示す。
混合物濃度測定器１２の指示値６，０００ｍｇ／Ｌで添加物供給手段１０を作動させ、１３，０００ｍｇ／Ｌで混合物引抜手段１１を作動させた。その結果、ＳＳ除去率８０％以上で安定した処理水質が得られた。
なお、制御の指標とする指示値は、実施例１，２では、６，０００ｍｇ／Ｌと１３，０００ｍｇ／Ｌで行ったが、要求される処理水質、装置の構造、流入水質、流入水量など加味されるので、現場によって違う値になることもある。
【００１９】
実施の形態２．
図２はこの発明の実施の形態２による凝集分離装置を概略的に示すフロー図であり、図１と同一部分には同一符号を付して重複説明を省略する。
図２において、１３は混合物濃度測定器１２から混合物濃度測定信号を入力する演算器である。この演算器１３は、凝集反応槽２内の混合物の適正濃度値が予め設定されており、その設定濃度値に対して前記混合物濃度測定器１２からの入力信号による混合物濃度測定値を比較演算し、その演算結果の制御信号を添加物供給手段１０および／または混合物引抜手段１１に出力するものである。
【００２０】
すなわち、この実施の形態２では、前記実施の形態１の混合物濃度測定器１２の系統に演算器１３を加え、この演算器１３からの出力信号で添加物供給手段１０および／または混合物引抜手段１１を自動制御する構成としたものである。
【００２１】
次に動作について説明する。
混合物濃度測定器１２が凝集反応槽２内の混合物濃度を測定し、その濃度測定を演算器１３に出力することにより、演算器１３は、これに予め設定された設定濃度値と混合物濃度測定器１２からの入力信号による濃度測定値とを比較演算する。その演算の結果、濃度測定値が設定濃度値よりも大きい場合には、演算器１３からの出力信号で混合物引抜手段１１が稼動して凝集反応槽２内の混合物が引き抜かれる。その引き抜き中においても、混合物濃度測定器１２によって凝集反応槽２内の混合物濃度が連続測定され、その濃度測定値が設定濃度値に達した時点で混合物引抜手段１１が自動的に停止する。
【００２２】
また、演算器１３による演算結果の濃度測定値が設定濃度値よりも小さい場合には、演算器１３から添加物供給手段１０への出力信号で添加物供給手段１０が稼動して凝集反応槽２内に添加物が供給される。その添加物供給中においても、混合物濃度測定器１２によって凝集反応槽２内の混合物濃度が連続測定され、その濃度測定値が設定濃度値に達した時点で添加物供給手段１０が自動的に停止する。
【００２３】
以上説明した実施の形態２によれば、混合物濃度測定器１２による凝集反応槽内混合物の濃度測定信号を演算器１３が入力して設定濃度値と比較演算し、その演算の結果、濃度測定値と設定濃度値とに差があるとき、その差がなくなるように演算器１３から出力信号で混合物引抜手段１１または添加物供給手段１０を選択的に稼動させるように構成したので、凝集反応槽２内の混合物濃度を自動制御して適正化することができ、常に安定した水質を得ることができる。
【００２４】
実施例２．
次に、上記実施の形態２による凝集分離装置の自動運転を行った結果について説明する。なお、この実施例２では、演算器１３および自動運転以外の実施条件は前記実施例１の場合と同様にした。
混合物濃度測定器１２と混合物引抜手段１１および／または添加物供給手段１０を連動させて自動運転を行った際の運転時間と混合物濃度測定器１２の指示値およびＳＳ除去率の関係を図７に示す。なお、流入水量は一定とした。
混合物濃度測定器１２の指示値６，０００ｍｇ／Ｌで添加物供給手段１０が作動し、１３，０００ｍｇ／Ｌで混合物引抜手段１１を作動させた。その結果、混合物濃度測定器１２と混合物引抜手段１１および／または添加物供給手段１０を連動させて自動運転しても、ＳＳ除去率は８０％以上で安定した処理水質が得られた。
【００２５】
実施の形態３．
図３はこの発明の実施の形態３による凝集分離装置を概略的に示すフロー図であり、図１および図２と同一部分には同一符号を付して重複説明を省略する。
図３において、１４は原水導入管１の系統に組み付けた流量計（流入水量測定手段）であり、この流量計１４は、流量測定値信号を演算器１３に出力するようになっている。すなわち、この実施の形態３では、前記実施の形態２の構成に流量計１４を加えることで、凝集反応槽２内への流入水量の変動に応じて凝集反応槽２内の混合物濃度を適正に自動制御するものである。なお、前記流量計１４の設置箇所は、原水導入管１に限定されるものではなく、凝集反応槽２内への流入水量を測定できる箇所であれば、どこでも良い。
【００２６】
以上説明した実施の形態３によれば、混合物濃度測定器１２による濃度測定値信号と流量計１４による流入水量測定値信号を演算器１３が入力し、この演算器１３によって、凝集反応槽２内の流入水量の変動に応じた適正な混合物濃度制御値を算出し、それに基づく演算器１３からの制御信号によって添加物供給手段１０または混合物引抜手段１１を選択的に稼動させるように構成したので、凝集反応槽２内への流入水量が変動しても、その変動に応じて凝集反応槽２内の混合物濃度分布が一様となるように自動制御することができ、したがって、より安定した水質を得ることができる。
【００２７】
実施例３．
次に、前記実施の形態３による凝集分離装置を自動運転した結果について説明する。なお、流量計１４以外の実験条件は前記実施例１と同様にした。
流入水量を変動させたときの混合物濃度指示値と処理性能の関係を表１に示す。流入水量を減少させると混合物濃度指示値は増加し、流入水量を増加させると混合物濃度指示値は減少したが、ＳＳ除去率は８０％以上の処理性能を得た。これは、流入水量を変動させた場合、流入水量を１２０ｍ^３／ｈで一定にした場合の良好な処理水質が得られる混合物濃度指示値と異なることを示している。
以上のことから、流入水量が変動する場合は流入水量によっても凝集反応槽の砂量を管理すると、より安定した水質を得ることができる。
【表１】

【００２８】
そこで、混合物濃度指示値と流入水量を乗算した結果の演算値とＳＳ除去率の関係を図８に示す。図８から明らかなように、演算値４８０〜１，１００ｇ／ｈの範囲でＳＳ除去率は８０％以上であった。したがって、その範囲で制御すれば、ＳＳ除去率を８０％以上にできることがわかる。
【００２９】
以上の結果をもとに、混合物濃度測定器１２と混合物引抜手段１１と添加物供給手段１０および流量計１４を連動させて自動運転を行った際の装置運転時間と混合物濃度測定器１２の指示値およびＳＳ除去率の関係を図９に示す。流入水量は４０〜１６０ｍ^３／ｈまで任意に変化させた。また、演算値は５００ｇ／ｈで添加物供給手段１０が作動し、演算値１，０００ｇ／ｈで混合物引抜手段１１を作動させた。その結果、混合物濃度測定器１２と混合物引抜手段１１と添加物供給手段１０および流量計１４を連動させることにより、ＳＳ除去率８０％以上で安定した処理水質が得られた。
【００３０】
【発明の効果】
以上のように本発明によれば、凝集反応槽に混合物濃度測定器と混合物引抜手段と添加物供給手段を設けるように構成したので、混合物濃度測定器による混合物濃度測定値に基づいて凝集反応槽の混合物濃度が常時適正に維持されるように混合物引抜手段または添加物供給手段を選択的に稼動させることができる。
したがって、従来装置では、雨天時など凝集反応槽内に流入水量が極端に多くなったときに沈砂池では取り除けない砂等が凝集反応槽内に溜まって固液分離槽に移流せず、凝集反応槽内には余剰な混合物が増えることで、凝集反応槽での凝集効果に影響を及ぼし、処理水質が悪化しても適正な対応処理ができない場合があるが、本発明では、凝集反応槽内の余剰な混合物を除去できて凝集効果を安定させることができる。その凝集効果の安定化によって、公共用水域の更なる水質保全、即ち濁質などの改善を安定して実現でき、高濁度の汚水が直接公共用水域に流されるのを防ぐことができる。
【００３１】
また、本発明によれば、混合物濃度測定器による測定濃度に基づいて添加物供給手段および／または混合物引抜手段の適正制御値を算出するための演算器を設け、この演算器からの出力信号によって、凝集反応槽内への添加物供給量および／または混合物引抜量を自動制御するように構成したので、無人運転によって、凝集反応槽内の混合物濃度を適正に自動制御することができ、安定した処理水質を得ることができる。
【００３２】
さらに本発明によれば、凝集反応槽への流入水量を測定する流入水量測定手段を設け、この流入水量測定手段からの流入水量測定信号を演算器に入力することにより、凝集反応槽内への流入水量に応じて凝集反応槽内への添加物供給量および／または混合物引抜量を自動制御することもできるので、凝集反応槽内への流入水量が大きく変動した場合であっても、その変動に応じて凝集反応槽内の混合物濃度を適正に自動制御することができ、より安定した処理水質を得ることができると共に、維持管理をさらに容易化できる。
【図面の簡単な説明】
【図１】この発明の実施の形態１による凝集分離装置を概略的に示すフロー図である。
【図２】この発明の実施の形態２による凝集分離装置を概略的に示すフロー図である。
【図３】この発明の実施の形態３による凝集分離装置を概略的に示すフロー図である。
【図４】この発明の実施の形態１による凝集反応槽の砂量と混合物濃度測定器指示値との関係を示す図である。
【図５】凝集反応槽の砂量と処理水質の関係を示す図である。
【図６】混合物濃度測定器指示値とＳＳ除去率の経時変化を示す図である。
【図７】混合物濃度測定器指示値とＳＳ除去率の経時変化を示す図である。
【図８】混合物濃度測定器指示値と流入水量の演算値とＳＳ除去率との関係を示す図である。
【図９】流入水量と演算値およびＳＳ除去率の経時変化を示す図である。
【図１０】従来の凝集沈殿処理装置を概略的に示すフロー図である。
【符号の説明】
１原水導入管
２凝集反応槽
３無機凝集剤供給手段
４高分子凝集剤供給手段
５固液分離槽
６ａポンプ（分離物引抜手段）
７返送管
８添加物回収器
１０添加物供給手段
１１混合物引抜手段
１２混合物濃度測定器
１３演算器
１４流量計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flocculation / separation apparatus that obtains stable water quality by controlling the amount of additive added to a liquid to be treated containing suspended substances and the like in the field of water treatment.
[0002]
[Prior art]
In the water treatment field, when the amount of sewage inflow water increases extremely, it may be discharged easily before the treatment plant inflow and in the primary treatment (first settling tank overflow) at the treatment plant. In this case, there is a problem that highly turbid sewage is discharged directly into public water bodies. From such a situation, the necessity of the overflow water treatment in the rainy weather etc. in the sewage is called out for the purpose of further water quality conservation of public water areas, that is, improvement of turbidity.
As a countermeasure, coagulation sedimentation treatment has been tried for the purpose of removing pollutants in sewage treatment plants.
[0003]
In particular, in the case of a combined sewer, fallen leaves and earth and sand on the road surface are washed away by rain when it rains, and a large amount of fallen leaves and earth and sand flows into the sewage treatment plant in a short time. Therefore, when coagulating sedimentation of the inflowing sewage from the combined sewerage system, a sedimentation basin is provided before the first sedimentation basin, but the inflowing earth and sand cannot be removed by the sedimentation basin when there is a large amount of inflowing water in rainy weather. . In the latter stage, sand that cannot be removed in the sand basin when coagulation sedimentation is applied may accumulate in the agglomeration reaction tank and may not be transferred to the sedimentation tank, and excess sand will increase in the aggregation reaction tank, affecting the agglomeration effect and processing. May be difficult.
[0004]
FIG. 10 is a flowchart schematically showing a conventional coagulation sedimentation treatment apparatus.
In this figure, 1 is a raw water introduction pipe, 2 is a coagulation reaction tank for introducing a liquid to be treated (raw water) containing suspended substances such as sludge from the raw water introduction pipe 1. The liquid to be treated is supplied with a flocculant from each of the inorganic flocculant supply means 3 and the polymer flocculant supply means 4. 5 is a solid-liquid separation tank that flows into the effluent water from the agglomeration reaction tank 2 and separates it into a separated product and treated water, 6 is a separation product extracting means for extracting the separated product from the solid-

liquid separation vessel

5, and 7 is a return. A pipe 8 is an additive collecting device. The additive collecting device 8 separates and collects the additive contained in the separated material returned from the separated material pulling means 6 through the returning tube 7, and collects the collected additive. Is returned to the agglomeration reaction tank 2 and the separated sludge is discharged.
[0005]
Next, the operation of the conventional coagulation sedimentation processing apparatus will be described.
By adding an inorganic flocculant, a polymer flocculant, and an additive to the liquid to be treated (raw water) introduced into the agglomeration reaction tank 2 from the raw water introduction pipe 1, the liquid to be treated and agglomerate in the agglomeration reaction tank 2. Agents and additives are mixed, thereby producing agglomerated flocs. The admixture containing the coagulated floc is transferred to the next solid-liquid separation tank 5 where it is separated into the precipitated sludge containing the additive and the treated water, and the treated water is discharged out of the system. Then, the settled sludge is pulled out by the separation pulling means 6 and then returned to the additive collecting device 8 through the return pipe 7. In the additive recovery device 8, the additive contained in the returned sludge is separated, the additive is returned into the agglomeration reaction tank 2, and the sludge from which the additive has been separated is discharged out of the system.
[0006]
[Problems to be solved by the invention]
Since the conventional coagulation sedimentation processing apparatus is configured as described above, it is possible to measure and control the concentration of the additive separated from the returned sludge by the additive recovery device 8, but the coagulation reaction Since the mixture in the tank 2 contains heavy sand or the like that does not flow to the solid-liquid separation tank 5 in the next stage, in the concentration measurement of the separated additive from the returned sludge by the additive collector 8, for example, in the rain Even if the amount of inflow water becomes extremely large and the amount of heavy sand in the agglomeration reaction tank 2 increases, the additive concentration according to the amount of sand cannot be measured. There was a problem that even if the amount increased and the quality of the treated water deteriorated, proper treatment could not be performed.
[0007]
The present invention has been made in order to solve the above problems, and even when the amount of a mixture having a large specific gravity such as sand contained in the liquid to be treated flowing into the agglomeration reaction tank is increased, the concentration of the mixture is increased. It is an object of the present invention to provide an aggregating and separating apparatus capable of appropriately controlling the additive supply amount and / or the drawing amount of the mixture in accordance with the above, and always obtaining a stable water quality.
[0008]
Another object of the present invention is to provide a flocculation / separation apparatus that can appropriately and automatically control the amount of additive supply to the flocculation reaction tank and / or the amount of mixture withdrawn according to the mixture concentration in the flocculation reaction tank. .
[0009]
[Means for Solving the Problems]
Coagulation and separation apparatus according to the present invention, a flocculation reaction tank for flocculation treatment of suspended solids or the like contained in the liquid to be treated, and the solid-liquid separation tank for solid-liquid separating effluent from the flocculation reactor, additives In an aggregating / separating apparatus comprising an additive collecting device for collecting and discharging the mixture, a mixture concentration measuring device for measuring the mixture concentration in the agglomeration reaction tank, and a mixture drawing means for adjusting the additive concentration for extracting the mixture from the agglomeration reaction tank And an additive supply means for supplying an additive to the agglomeration reaction tank, and appropriately controls the mixture drawing means and / or the additive supply means according to the concentration measured by the mixture concentration measuring device.
[0010]
The aggregating / separating apparatus according to the present invention is configured such that a calculator is connected to the mixture concentration measuring device, and the mixture drawing means and / or the additive supplying means are appropriately and automatically controlled by an output signal from the calculator.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a flow chart showing an aggregating / separating apparatus according to Embodiment 1 of the present invention. The same or corresponding parts as those in FIG.
In FIG. 1, 6a is a pump as a separator pulling means for pulling out the separated substance from the solid-liquid separation tank 5 and returning it to the additive collector 8, and 10 is an additive such as sand (for separation promotion in the agglomeration reaction tank 2). An insoluble fine particulate material), 11 is a mixture extraction means for extracting the mixture from the

agglomeration reaction tank

2, and 12 is a mixture concentration measuring device for measuring the concentration of the mixture in the aggregation reaction tank 2. An ultrasonic densitometer or an infrared densitometer is applied as the mixture concentration measuring device 12, but any measuring device may be used as long as it can measure the mixture concentration. Examples of the additive supply means include quantitative feeder supply, slurry supply, and dry supply, but any means may be used as long as the additive can be rapidly supplied into the aggregation reaction layer 2. As the mixture drawing means 11, a scraping machine is installed in the agglomeration reaction layer 2, and the mixture is drawn up by a pump, or a mixture by opening and closing a valve attached to the bottom and / or the lower side of the agglomeration reaction layer 2. Any means may be used as long as the mixture can be quickly pulled out, such as a drawing means.
Examples of the substance to be agglomerated include substances that undergo agglomeration reaction, such as suspended substances, COD components, and phosphorus components.
Moreover, the said mixture refers to the thing (aggregation floc) with which the to-be-processed liquid, the coagulant | flocculant, and the additive were mixed.
[0012]
Next, the operation will be described.
The mixture is extracted from the agglomeration reaction tank 2 by the mixture extraction means 11, and the concentration of the extracted mixture is measured by the mixture concentration measuring device 12. The mixture concentration measurement value is compared with a set concentration value (mixture concentration set value). As a result, if the mixture concentration measurement value is larger than the set concentration value, an overconcentration signal is sent to the mixture extraction means 11 to extract the mixture. By operating the means 11, the mixture is withdrawn from the aggregation reaction tank 2. In this case, the mixture extraction means 11 stops when the mixture concentration in the agglomeration reaction tank 2 reaches the set concentration value due to the extraction of the mixture. If the measured concentration of the mixture is smaller than the set concentration value, an additive is supplied into the agglomeration reaction tank 2 by sending an insufficient concentration signal to the additive supply means 10 and operating the additive supply means 10. To do. Thus, when the mixture concentration in the agglomeration reaction tank 2 reaches the set concentration value, the additive supply means 10 stops at that point.
[0013]
Examples of the additive include organic and inorganic substances having a specific gravity in the range of 2 to 8 that is similar to sand, such as fine sand, zirconium oxide, and garnet. The control signal to the additive supply means 10 and / or the mixture extraction means 11 may be sent by manual switch operation or the like.
[0014]
According to Embodiment 1 described above, the concentration of the mixture in the agglomeration reaction tank 2 is measured, and the concentration measurement value is compared with the set concentration value. When the concentration measurement value is larger than the set concentration value, the aggregation reaction is performed. The mixture in the agglomeration reaction tank 2 is withdrawn until the mixture concentration in the tank 2 reaches the set concentration value, and when the measured concentration value is smaller than the set concentration value, the mixture concentration in the agglomeration reaction tank 2 becomes the set concentration value. Since the additive is supplied to the agglomeration reaction tank 2 until the amount of the mixture having a large specific gravity increases, such as sand contained in the liquid to be treated flowing into the agglomeration reaction tank 2, the mixture It is possible to always keep the concentration of the mixture in the agglomeration reaction tank 2 constant by appropriately controlling the amount of additive supply and / or the amount of withdrawal of the mixture according to the concentration. it can.
[0015]
Example 1.
Next, the results of the experimental operation of the flocculation / separation apparatus according to Embodiment 1 will be described.
The implementation conditions are as follows:
Raw water; influent raw water flow rate of the primary sedimentation of sewage treatment plant; 2880m ³ / day (120m ³ / h)
Ascending speed of solid-liquid separation tank: 120 m / h
Inorganic flocculant; PAC addition rate 10 mg / L (as AL ₂ O ₃ )
Polymer flocculant; anionic polymer flocculant addition rate 1 mg / L
Amount of fine sand in the coagulation / separation apparatus of the present invention; 0 to 380 kg
In addition, fine sand was used as an additive.
[0016]
The relationship between the amount of sand in the agglomeration reaction tank 2 and the indicated value of the mixture concentration measuring device 12 is shown in FIG. An ultrasonic densitometer was used as the mixture concentration measuring device 12. It can be seen that the amount of sand in the agglomeration reaction tank 2 and the indicated value of the ultrasonic densitometer 12 are in a proportional relationship. From this, it is understood that the mixture concentration measuring device (ultrasonic concentration meter) 12 can be applied to the prediction of the sand amount in the agglomeration reaction tank 2.
In addition, when the indicated value of the mixture concentration measuring device 12 is 5,000 mg / L or less and 14,000 mg / L or more, the quality of the treated water is deteriorated, and if the sand concentration in the agglomeration reaction tank 2 is appropriately controlled, a good treatment is obtained. It was predicted that water would be obtained.
[0017]
Next, FIG. 5 shows an example of the amount of sand in the agglomeration reaction tank 2, the raw water SS, the treated water SS, and the SS removal rate. The amount of sand in the agglomeration reactor 2 was 0 to 60 kg, and the treated water SS was 256 to 426 mg / L and the SS removal rate was −93 to −45% in the range of raw water SS 176 to 266 mg / L.
The amount of sand in the agglomeration reaction tank 2 was within the range of raw water SS141 to 220 mg / L and the treated water SS was 28 to 33 mg / L and the SS removal rate was 80 to 85%. The amount of sand in the agglomeration reaction tank 2 was 200 to 380 kg and the raw water SS was 138 to 213 mg / L, and the treated water SS was 39 to 90 mg / L, and the SS removal rate was 53 to 77%. From this result, it was found that the treated water SS changed with the amount of sand in the agglomeration reaction tank regardless of the raw water SS.
[0018]
In the flocculation / separation apparatus of the present invention shown in FIG. 1, the additive supply means 10 and the mixture drawing means 11 are moved manually, and the inflow water amount is constant. FIG. 6 shows the relationship between the operation time, the indicated value of the mixture concentration measuring instrument 12, and the SS removal rate.
The additive supply means 10 was operated at the indicated value of 6,000 mg / L of the mixture concentration measuring device 12, and the mixture extraction means 11 was operated at 13,000 mg / L. As a result, a stable treated water quality was obtained with an SS removal rate of 80% or more.
In addition, in Example 1, 2, although the instruction value used as the parameter | index of control was performed with 6,000 mg / L and 13,000 mg / L, the required treatment water quality, the structure of an apparatus, inflow water quality, inflow water amount, etc. Because it is taken into account, it may be different depending on the site.
[0019]
Embodiment 2. FIG.
FIG. 2 is a flowchart schematically showing an aggregating / separating apparatus according to Embodiment 2 of the present invention. The same parts as those in FIG.
In FIG. 2, reference numeral 13 denotes an arithmetic unit for inputting a mixture concentration measurement signal from the mixture concentration measuring device 12. This calculator 13 is set in advance with an appropriate concentration value of the mixture in the agglomeration reaction tank 2, and compares and calculates the mixture concentration measurement value based on the input signal from the mixture concentration measuring device 12 with respect to the set concentration value. The control signal of the calculation result is output to the additive supply means 10 and / or the mixture extraction means 11.
[0020]
That is, in the second embodiment, a computing unit 13 is added to the system of the mixture concentration measuring device 12 of the first embodiment, and the additive supply means 10 and / or the mixture extracting means 11 are output from the computing unit 13. It is set as the structure which controls automatically.
[0021]
Next, the operation will be described.
When the mixture concentration measuring device 12 measures the concentration of the mixture in the agglomeration reaction tank 2 and outputs the concentration measurement to the computing device 13, the computing device 13 can set the preset concentration value and the mixture concentration measuring device set in advance. 12 is compared with the concentration measurement value by the input signal from 12. As a result of the calculation, when the concentration measurement value is larger than the set concentration value, the mixture extraction means 11 is operated by the output signal from the calculator 13 and the mixture in the aggregation reaction tank 2 is extracted. Even during the drawing, the mixture concentration measuring device 12 continuously measures the mixture concentration in the agglomeration reaction tank 2, and the mixture drawing means 11 automatically stops when the measured concentration value reaches the set concentration value.
[0022]
Further, when the concentration measurement value of the calculation result by the calculator 13 is smaller than the set concentration value, the additive supply means 10 is operated by an output signal from the calculator 13 to the additive supply means 10, and the agglomeration reaction tank 2. Additives are fed into the interior. During the supply of the additive, the mixture concentration meter 12 continuously measures the concentration of the mixture in the agglomeration reaction tank 2, and the additive supply means 10 automatically stops when the measured concentration value reaches the set concentration value. To do.
[0023]
According to the second embodiment described above, the calculator 13 inputs the concentration measurement signal of the mixture in the agglomeration reaction tank by the mixture concentration measuring device 12 and compares it with the set concentration value. As a result of the calculation, the concentration measurement value Since the mixture extraction means 11 or the additive supply means 10 is selectively operated by the output signal from the calculator 13 so that the difference is eliminated, the agglomeration reaction tank 2 The concentration of the mixture can be automatically controlled and optimized, and a stable water quality can always be obtained.
[0024]
Example 2
Next, the result of the automatic operation of the flocculation / separation apparatus according to the second embodiment will be described. In the second embodiment, implementation conditions other than the calculator 13 and automatic operation are the same as those in the first embodiment.
FIG. 7 shows the relationship between the operation time, the indicated value of the mixture concentration measuring instrument 12, and the SS removal rate when the mixture concentration measuring instrument 12, the mixture extracting means 11 and / or the additive supplying means 10 are operated automatically. Show. The amount of inflow water was constant.
The additive supply means 10 was activated at the indicated value of 6,000 mg / L of the mixture concentration measuring device 12, and the mixture extraction means 11 was activated at 13,000 mg / L. As a result, even when the mixture concentration measuring device 12, the mixture drawing means 11 and / or the additive supply means 10 were automatically operated, the SS removal rate was 80% or more and a stable treated water quality was obtained.
[0025]
Embodiment 3 FIG.
FIG. 3 is a flowchart schematically showing an aggregating / separating apparatus according to Embodiment 3 of the present invention. The same parts as those in FIGS.
In FIG. 3, reference numeral 14 denotes a flow meter (inflow water amount measuring means) assembled in the system of the raw water introduction pipe 1, and this flow meter 14 outputs a flow rate measurement value signal to the calculator 13. That is, in the third embodiment, by adding the flow meter 14 to the configuration of the second embodiment, the concentration of the mixture in the agglomeration reaction tank 2 is appropriately adjusted according to the fluctuation of the amount of water flowing into the agglomeration reaction tank 2. It is for automatic control. The place where the flow meter 14 is installed is not limited to the raw water introduction pipe 1 and may be any place as long as the amount of water flowing into the agglomeration reaction tank 2 can be measured.
[0026]
According to the third embodiment described above, the calculator 13 inputs the concentration measurement value signal from the mixture concentration meter 12 and the inflow water amount measurement value signal from the flow meter 14, and the calculator 13 allows the inside of the agglomeration reaction tank 2 to be input. Since an appropriate mixture concentration control value corresponding to the fluctuation of the inflow water amount is calculated, and the additive supply means 10 or the mixture extraction means 11 is selectively operated by a control signal from the computing unit 13 based on the calculated mixture concentration control value. Even if the amount of inflow water into the agglomeration reaction tank 2 fluctuates, the mixture concentration distribution in the agglomeration reaction tank 2 can be automatically controlled according to the fluctuation, so that more stable water quality can be achieved. Obtainable.
[0027]
Example 3
Next, the result of automatically operating the aggregating / separating apparatus according to the third embodiment will be described. The experimental conditions other than the flow meter 14 were the same as in Example 1.
Table 1 shows the relationship between the mixture concentration instruction value and the treatment performance when the inflow water amount is changed. When the inflow water amount was decreased, the mixture concentration instruction value increased. When the inflow water amount was increased, the mixture concentration instruction value decreased, but the SS removal rate was 80% or more. This indicates that when the inflowing water amount is changed, the mixture concentration is different from the mixture concentration indicating value for obtaining a good treated water quality when the inflowing water amount is kept constant at 120 m ³ / h.
From the above, when the inflowing water amount fluctuates, more stable water quality can be obtained by managing the sand amount in the agglomeration reaction tank also by the inflowing water amount.
[Table 1]

[0028]
Therefore, FIG. 8 shows the relationship between the calculated value obtained by multiplying the mixture concentration instruction value and the inflow water amount and the SS removal rate. As is apparent from FIG. 8, the SS removal rate was 80% or more in the range of calculated values from 480 to 1,100 g / h. Therefore, it can be seen that the SS removal rate can be increased to 80% or more by controlling within this range.
[0029]
Based on the above results, the apparatus operating time and the instructions of the mixture concentration measuring instrument 12 when the automatic operation is performed by interlocking the mixture concentration measuring instrument 12, the mixture extracting means 11, the additive supplying means 10 and the flow meter 14 with each other. The relationship between the value and the SS removal rate is shown in FIG. The amount of inflow water was arbitrarily changed from 40 to 160 m ³ / h. Further, the additive supply means 10 was operated at a calculated value of 500 g / h, and the mixture drawing means 11 was operated at a calculated value of 1,000 g / h. As a result, a stable treated water quality with an SS removal rate of 80% or more was obtained by interlocking the mixture concentration measuring device 12, the mixture drawing means 11, the additive supply means 10 and the flow meter 14.
[0030]
【The invention's effect】
As described above, according to the present invention, the agglomeration reaction tank is provided with the mixture concentration measuring device, the mixture drawing means, and the additive supply means, so that the agglomeration reaction vessel is based on the mixture concentration measurement value by the mixture concentration measuring device. It is possible to selectively operate the mixture drawing means or the additive supply means so that the concentration of the mixture is always properly maintained.
Therefore, in the conventional system, sand that cannot be removed in the sedimentation basin when the amount of water flowing into the agglomeration reaction tank becomes extremely large, such as in rainy weather, accumulates in the agglomeration reaction tank and does not transfer to the solid-liquid separation tank. An excess of the mixture in the tank may affect the agglomeration effect in the agglomeration reaction tank, and even if the treated water quality deteriorates, proper handling may not be possible. The excess mixture can be removed and the agglomeration effect can be stabilized. By stabilizing the agglomeration effect, further water quality conservation of public water areas, that is, improvement of turbidity can be stably realized, and high turbidity sewage can be prevented from flowing directly into public water areas.
[0031]
Further, according to the present invention, there is provided an arithmetic unit for calculating an appropriate control value of the additive supply means and / or the mixture extraction means based on the concentration measured by the mixture concentration measuring device, and an output signal from the arithmetic unit is used. Since it is configured to automatically control the additive supply amount and / or the amount of mixture withdrawn into the agglomeration reaction tank, the mixture concentration in the agglomeration reaction tank can be appropriately and automatically controlled by unattended operation. Treated water quality can be obtained.
[0032]
Further, according to the present invention, the inflow water amount measuring means for measuring the inflow water amount to the agglomeration reaction tank is provided, and the inflow water amount measurement signal from the inflow water amount measurement means is input to the computing unit, whereby Depending on the amount of influent water, the amount of additive supply and / or the amount of mixture withdrawn into the agglomeration reactor can be automatically controlled, so even if the amount of influent water into the agglomeration reactor greatly fluctuates Accordingly, the concentration of the mixture in the agglomeration reaction tank can be automatically and appropriately controlled, a more stable treated water quality can be obtained, and maintenance can be further facilitated.
[Brief description of the drawings]
FIG. 1 is a flowchart schematically showing an aggregating / separating apparatus according to Embodiment 1 of the present invention;
FIG. 2 is a flowchart schematically showing an aggregating / separating apparatus according to Embodiment 2 of the present invention.
FIG. 3 is a flowchart schematically showing an aggregating / separating apparatus according to Embodiment 3 of the present invention.
FIG. 4 is a diagram showing the relationship between the amount of sand in the agglomeration reaction tank and the indicated value of the mixture concentration measuring device according to Embodiment 1 of the present invention.
FIG. 5 is a diagram showing the relationship between the amount of sand in the agglomeration reaction tank and the quality of treated water.
FIG. 6 is a diagram showing a change with time of a mixture concentration measuring device indicating value and an SS removal rate.
FIG. 7 is a diagram showing a change with time of a mixture concentration measuring instrument indicating value and an SS removal rate.
FIG. 8 is a diagram showing a relationship among a mixture concentration measuring device indicating value, a calculated value of the influent water amount, and an SS removal rate.
FIG. 9 is a diagram showing changes over time in the inflow water amount, the calculated value, and the SS removal rate.
FIG. 10 is a flowchart schematically showing a conventional coagulation sedimentation processing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Raw water introduction pipe 2 Aggregation reaction tank 3 Inorganic flocculant supply means 4 Polymer flocculant supply means 5 Solid-liquid separation tank 6a Pump (separate extraction means)
7 Return pipe 8 Additive collector 10 Additive supply means 11 Mixture withdrawal means 12 Mixture concentration measuring instrument 13 Calculator 14 Flow meter

Claims

An agglomeration reaction tank for aggregating suspended substances, etc .;
A solid-liquid separation tank for solid-liquid separation of the effluent water from the agglomeration reaction tank;
In an aggregating and separating apparatus comprising an additive collector for collecting and discharging an additive,
A mixture concentration measuring device for measuring the mixture concentration of the agglomeration reaction tank;
A mixture extraction means for adjusting the additive concentration for extracting the mixture from the agglomeration reaction tank ;
An aggregating and separating apparatus, comprising: an additive supplying means for supplying an additive to the aggregating reaction tank .

The aggregating and separating apparatus according to claim 1, wherein a calculator is connected to the mixture concentration measuring device.