JP4150119B2

JP4150119B2 - Sludge concentration method

Info

Publication number: JP4150119B2
Application number: JP02950699A
Authority: JP
Inventors: 勝博平林; 正行高橋
Original assignee: Organo Corp
Current assignee: Organo Corp
Priority date: 1999-02-08
Filing date: 1999-02-08
Publication date: 2008-09-17
Anticipated expiration: 2019-02-08
Also published as: JP2000229300A

Description

【０００１】
【発明の属する技術分野】
本発明は、濾過膜を用いた汚泥濃縮装置による汚泥濃縮方法に関する。本発明に係る汚泥濃縮方法は、例えば、浄水場で発生する汚泥水の濃縮を行う汚泥濃縮装置に好適に適用される。
【０００２】
【従来の技術】
浄水場では、図３に示すように、各処理設備（例えば凝集沈殿装置等）で発生した汚泥水を沈降分離式汚泥濃縮槽である程度濃縮し、濃縮後の汚泥水５０を汚泥水貯槽５２に貯留し、この汚泥水貯槽５２内の汚泥水を濾過方式の汚泥濃縮装置５４に導入して汚泥の濃縮処理（予備濃縮）を行った後、汚泥濃縮装置５４で生成した濃縮汚泥を濃縮汚泥貯槽５６に貯留し、さらに濃縮汚泥貯槽５６内の濃縮汚泥を加圧式、真空式等の汚泥脱水装置５８に導入して汚泥の脱水処理を行うのが一般的である。
【０００３】
図４は、前述した汚泥濃縮装置５４の一例を示す拡大図である。本装置において２は濃縮容器を示す。濃縮容器２は、下側部分４と上側部分６とをその間に仕切板８を介在させた状態で連結することにより作製されており、したがって濃縮容器２の内部は仕切板８によって下室１０と上室１２とに区画されている。なお、下側部分４の下部は逆円錐形をなしている。
【０００４】
濃縮容器２の下端部には下室１０に連通するヘッダー管１４が連結されているとともに、このヘッダー管１４には、汚泥水貯槽５２に接続された第１汚泥水導入管１６、第２汚泥水導入管１８及び未濃縮汚泥水返送管２０と、濃縮汚泥貯槽５６に接続された濃縮汚泥排出管２２とが連結されている。これらの管１６，１８，２０，２２にはそれぞれ自動操作弁２４が介装されている。
【０００５】
濃縮容器２の内部には多数の濾過筒２６が設置されている。この濾過筒２６は、多数の通孔（図示せず）を有する支持筒２８の外側面に濾過膜３０を被装してなるものである。濾過膜３０としては、通常、織布製や不織布製の濾過膜（濾布）が使用される。また、濃縮容器２の上部には上室１２に連通する処理水流出管３２、濃縮容器２内を減圧して濾過筒２６から付着汚泥が脱落することを防止するための脱気管３４、及び、濃縮容器２内に空気を供給して濾過筒２６から付着汚泥を剥離するための剥離空気導入管３６が接続されている。
【０００６】
本例の汚泥濃縮装置５４によって浄水場等の汚泥水の処理を行う場合、下記工程を行う。
▲１▼汚泥水張り込み工程
本工程では、例えばポンプ６０を用いて汚泥水貯槽５２内の汚泥水を第１汚泥水導入管１６を通して汚泥濃縮装置５４の濃縮容器２の下室１０内に導入し、下室１０内を汚泥水で満たす。
【０００７】
▲２▼汚泥濃縮工程
本工程では、例えば加圧空気６２により汚泥水貯槽５２内の汚泥水に圧力を加え、この圧力によって汚泥水貯槽５２内の汚泥水を第２汚泥水導入管１８を通して濃縮容器２の下室１０内に連続的に導入する。これにより、汚泥水は濾過筒２６の外部から内部に流通して濾過膜３０で濾過され、汚泥水中の懸濁物は濾滓として濾過膜３０の外側面に捕捉されるとともに、処理水は支持筒２８内の上端部から上室１２内に流出し、さらに処理水流出管３２から濃縮容器２外に排出される。
【０００８】
▲３▼未濃縮汚泥水排出工程
汚泥濃縮装置５４ヘの汚泥水の導入を続行するにしたがい、濾過膜３０の外側面に汚泥が付着し圧力損失が増大する。よって、予め規定しておいた圧力損失の値になった時点あるいは予め規定した汚泥水の導入量に達した際に汚泥濃縮装置５４ヘの汚泥水の供給を止め、重力により、あるいはポンプ等を用いて下室１０内の未濃縮汚泥水を未濃縮汚泥水返送管２０を通して汚泥水貯槽５２に戻す。このとき、脱気管３４から空気を排出して濃縮容器２内を減圧することにより、濾過筒２６から付着汚泥が脱落することを防止する。
【０００９】
▲４▼濃縮汚泥剥離工程
剥離空気導入管３６から濃縮容器２の上室１２内に加圧空気を供給し、この加圧空気を濾過筒２６の内側から外側に通すことにより、濾過膜３０の外側面に付着した汚泥を剥離して濃縮容器２の底部に落下させる。
【００１０】
▲５▼濃縮汚泥排出工程
重力により、あるいはポンプ等を用いて下室１０内の濃縮汚泥を濃縮汚泥排出管２２を通して濃縮汚泥貯槽５６に排出する。
【００１１】
汚泥濃縮装置５４を用いた処理では、前記の一連の工程を繰り返して汚泥水の濃縮を行うものであり、各工程の所要時間は、汚泥水張り込み工程は２〜８分程度、汚泥濃縮工程は２０〜１００分程度、未濃縮汚泥水排出工程は２〜８分程度、濃縮汚泥剥離工程は３０秒〜３分程度、濃縮汚泥排出工程２〜８分程度である。
【００１２】
【発明が解決しようとする課題】
前述した汚泥水貯槽５２は、浄水場の各処理設備からの汚泥水が集合するところであり、この汚泥水貯槽５２には例えば浄水場への流入水中に含まれる濁質分が凝集剤と反応して生成したアルミニウムフロックなどが濃縮されて流入する。また、汚泥水貯槽５２内の汚泥水中には、上記アルミニウムフロックだけでなく、沈砂池等で除去できなかった砂分や、浄水場のコンクリート水槽から発生した脱離砂や落ち葉等の固形分も含まれる。
【００１３】
一方、前記汚泥濃縮工程▲２▼では、汚泥水にある程度の圧力を加え、２０〜１００分程度という比較的長い時間をかけて静的に濃縮を行うため、汚泥濃縮工程において第２汚泥水導入管１８を介してヘッダー管１４から濃縮容器２内に流入する汚泥水の流量はそれほど大きくない。通常、ヘッダー管１４から下室１０内に流入する汚泥水の流体速度は０．１〜０．４ｍ／秒程度である。したがって、汚泥の濃縮は濾過筒２６によってアルミニウムフロックを主体に行われるが、アルミニウムフロックより比重が大きい砂等の固形分の下室１０内での沈降速度は汚泥水の流体速度を上回っているため、汚泥水中に含まれる砂等の固形分は下室１０内を沈降してヘッダー管１４内に沈下・集積してしまう。
【００１４】
そのため、汚泥濃縮工程の次の未濃縮汚泥水排出工程▲３▼で汚泥濃縮装置５４内の未濃縮汚泥水をいったん汚泥水貯槽５２に返すときに、ヘッダー管１４内に沈下・集積した砂等の固形分も汚泥水貯槽５２に一緒に戻る。この汚泥水貯槽５２に戻された砂等の固形分は、汚泥水貯槽５２に堆積したり、次の汚泥水張り込み工程や汚泥濃縮工程で汚泥濃縮装置５４に送られた後に再度汚泥水貯槽５２に戻ったりするため、汚泥水貯槽５２内の砂等の固形分の堆積量は徐々に増加する。１回の未濃縮汚泥水排出工程で汚泥水貯槽５２に戻される砂等の固形分の量はそれほど多くないが、汚泥濃縮の一連の工程を数多く繰り返すと、汚泥水貯槽５２に堆積する砂等の固形分はかなり多量となる。したがって、従来の濾過膜を用いた汚泥濃縮装置による処理では、汚泥水貯槽５２を定期的に清掃して内部に堆積した砂等の固形分を除去する作業が必要となり、汚泥水処理の省力化を図る上での妨げになっていた。
【００１５】
本発明は、前記事情に鑑みてなされたもので、濾過方式の汚泥濃縮装置を用いて汚泥の濃縮を行う場合に、汚泥濃縮装置に導入された汚泥水中に含まれる砂等の固形分が未濃縮汚泥水排出工程で汚泥水貯槽に戻ることを防ぎ、汚泥水貯槽内に砂等の固形分が堆積することを防止することにより、汚泥水貯槽の定期的な清掃の必要性をなくして汚泥水処理を省力化できるようにした汚泥濃縮方法を提供することを目的とする。
【００１６】
【課題を解決するための手段】
本発明は、前記目的を達成するため、濾過膜を用いて汚泥の濃縮を行う汚泥濃縮装置による汚泥濃縮方法であって、前記汚泥濃縮装置の濾過膜に汚泥水を通水して汚泥を濃縮する汚泥濃縮工程と、汚泥濃縮工程終了後に汚泥濃縮装置内に残留する未濃縮汚泥水を排出する未濃縮汚泥水排出工程と、汚泥濃縮工程で濾過膜に付着した濃縮汚泥を未濃縮汚泥水排出工程後に剥離する濃縮汚泥剥離工程と、濃縮汚泥剥離工程により剥離した濃縮汚泥を排出する濃縮汚泥排出工程とを実施して汚泥の濃縮を行うに当たり、汚泥濃縮工程において汚泥濃縮装置の底部に沈下・集積した砂等の固形分を、未濃縮汚泥水排出工程における未濃縮汚泥水の排出先とは異なる排出先に排出することを特徴とする汚泥濃縮方法を提供する。
【００１７】
すなわち、濾過膜を用いた汚泥濃縮装置による汚泥濃縮工程は２０〜１００分程度という比較的長い時間をかけて行うものであり、この時濾過膜上では汚泥の濃縮が進行し、同時に汚泥濃縮装置の底部では砂等の比重の大きな固形分の沈下・集積が進行する。本発明は、汚泥濃縮工程、未濃縮汚泥水排出工程、濃縮汚泥剥離工程若しくは濃縮汚泥排出工程の途中又はこれらの工程の間に、汚泥濃縮装置の底部に沈下・集積した砂等の固形分を未濃縮汚泥水排出工程における未濃縮汚泥水の排出先とは異なる排出先に排出することにより、汚泥水中に含まれる砂等の固形分が汚泥水貯槽に戻ることを防ぎ、汚泥水貯槽内に砂等の固形分が堆積することを防止するものである。
【００１８】
この場合、前記砂等の固形分の排出は、汚泥濃縮工程と未濃縮汚泥排出工程との間に行うことが好ましい。その理由は以下のごとくである。すなわち、汚泥濃縮工程は、前述のように比較的長い時間をかけて行われるので、この間に砂等の固形分の沈下・集積が十分に進行する。したがって、該汚泥濃縮工程において固形分の沈下・集積が十分に行われた後に、沈下・集積した固形分を排出するようにすれば、濃縮容器内の汚泥水中に含まれている砂等の固形分の大部分を系外に排出することができ、これにより、該汚泥濃縮工程終了後に行われる未濃縮汚泥排出工程において、未濃縮汚泥と共に汚泥水貯槽に戻される砂等の固形分の量を極めて少なくすることができるからである。
【００１９】
また、砂等の固形分は、沈降性が極めて良いために濃縮装置の底部に比較的容易に沈下・集積するものであって、汚泥濃度的には汚泥濃縮工程で濾過膜に付着した濃縮汚泥と同等のものであるため、濃縮汚泥の排出先に排出しても、例えば脱水等の後段の処理における問題は生じない。また、濃縮汚泥の排出先と砂等の固形分の排出先とを個別に設置することは経済的に好ましくない。したがって、本発明では、砂等の固形分の排出先を濃縮汚泥排出工程における濃縮汚泥の排出先と同じとすることが適当である。
【００２０】
本発明を適用する汚泥濃縮装置は、汚泥水を濾過膜に通して汚泥の濃縮を行うものである。このような汚泥濃縮装置としては、例えば、多数の通孔を有する支持筒の外側面に濾過膜を被装してなる濾過筒（エレメント）を濃縮容器内に設置し、汚泥水を上記濾過筒の外部から内部に流通させて汚泥水中の懸濁物を濾滓として上記濾過膜の外側面に捕捉させるとともに、濾過液を濾過筒内部から濃縮容器外に流出させるエレメント方式の汚泥濃縮装置を挙げることができるが、これに限定されるものではない。また、本発明を適用する汚泥濃縮装置の濾過膜の種類に限定はないが、例えば、各種合成繊維のマルチフィラメント糸、ステープルファイバー糸や各種天然繊維の糸によって形成された織布、不織布等からなる濾過膜が挙げられる。
【００２１】
【発明の実施の形態】
図１は本発明を適用する汚泥濃縮装置の一例を示す。本装置７０は、図４に示した汚泥濃縮装置において、ヘッダー管１４に砂等の固形分を集積するための固形分集積管３８を連結するとともに、この固形分集積管３８に自動操作弁４０が介装された固形分排出管４２を接続したものである。その他の構成は図４に示した汚泥濃縮装置と同じであるから、図１において図４と同一の部分には同一の参照符号を付してその説明を省略する。
【００２２】
本装置７０では、汚泥水中に含まれる砂等の固形分は、濃縮容器２の出入口４４を通ってヘッダー管１４内に沈降する。そのため、前記固形分集積管３８は濃縮容器２の出入口４４の真下に設け、固形分集積管３８内に砂等の固形分が良好に沈下・集積するようにしてある。なお、固形分集積管３８の内径はヘッダー管１４の内径と同程度で十分であり、固形分集積管３８をあまり大きくすることは設備的に得策でない。また、固形分集積管３８の形状は適宜選択することができ、例えばコーン状、エンドキャップ状、エンドプレート状等の様々な形状とすることができる。
【００２３】
固形分排出管４２の流出端は濃縮汚泥排出管２２に連結されており、したがって本装置７０では沈下・集積された砂等の固形分は濃縮汚泥貯槽５６に排出されるようになっている。なお、固形分排出管４２は排出対象の固形分の大部分が砂であるためあまり大きくする必要はなく、例えば口径５０ｍｍ程度の管で十分である。
【００２４】
本例の汚泥濃縮装置７０を用い、本発明を適用して浄水場等の汚泥水の濃縮処理を行う場合、前述した工程▲１▼〜▲５▼を行うものであるが、さらに汚泥濃縮工程▲２▼と未濃縮汚泥水排出工程▲３▼との間において次の固形分排出工程を行う。すなわち、汚泥濃縮工程終了後に固形分排出管４２の自動操作弁４０を開、その他の自動操作弁２４を閉とし、重力により、あるいはポンプ等を用いて固形分集積管３８内の砂等の固形分を固形分排出管４２及び濃縮汚泥排出管２２を通して濃縮汚泥貯槽５６に排出する。その後、未濃縮汚泥水排出工程を行うものである。なお、排出される固形分には、濃縮過程中に濾過膜に付着した濃縮汚泥が濾過膜から脱離した汚泥塊が一部含まれることもある。
【００２５】
図２は本発明を適用する汚泥濃縮装置の他の例を示す。本装置８０は、ヘッダー管を設けていないもので、本発明はこのようなタイプの汚泥濃縮装置にも適用できる。本装置８０では、濃縮容器２の下部に下室１０に連通する汚泥水入口４６及びドレン口４８が設けられている。その他の構成は図４に示した汚泥濃縮装置と同じであるから、図２において図４と同一の部分には同一の参照符号を付してその説明を省略する。なお、図２では脱気管及び剥離空気導入管を省略してある。
【００２６】
本例の汚泥濃縮装置８０では、汚泥水中に含まれる砂等の固形分は、濃縮容器２の底部のドレン口４８内に沈下・集積する。したがって、本装置８０を用い、本発明を適用して浄水場等の汚泥水の濃縮処理を行う場合、下記工程を行う。なお、本装置８０は前述した汚泥張り込み工程を行わない方式のものであるが、本発明はこのような方式の汚泥濃縮装置にも適用できる。
【００２７】
（１）汚泥濃縮工程
本工程では、ポンプ８２等を用い、汚泥水貯槽５２内の汚泥水を汚泥水導入管８４を通して汚泥水入口４６から濃縮容器２の下室１０内に所定圧力で連続的に導入する。これにより、汚泥水は濾過筒２６の外部から内部に流通して濾過膜３０で濾過され、汚泥水中の懸濁物は濾滓として濾過膜３０の外側面に捕捉されるとともに、処理水は支持筒２８内の上端部から上室１２内に流出し、さらに処理水流出管３２から濃縮容器２外に排出される。
【００２８】
（２）固形分排出工程
汚泥濃縮装置８０ヘの汚泥水の導入を続行するにしたがい、濾過膜３０の外側面に汚泥が付着し圧力損失が増大する。よって、予め規定しておいた圧力損失の値になった時点あるいは予め規定した汚泥水の導入量に達した際に汚泥濃縮装置８０ヘの汚泥水の供給を止め、重力により、あるいはポンプ等を用いてドレン口４８内に沈下・集積した砂等の固形分を濃縮汚泥排出管８６を通して濃縮汚泥貯槽５６に排出する。この場合、実質的にドレン口４８内に溜まった砂等の固形分のみを濃縮汚泥貯槽５６に排出する。
【００２９】
（３）未濃縮汚泥水排出工程
重力により、あるいはポンプ等を用いて下室１０内の未濃縮汚泥水を未濃縮汚泥水返送管８８を通して汚泥水貯槽５２に戻す。このとき、脱気管から空気を排出して濃縮容器２内を減圧することにより、濾過筒２６から付着汚泥が脱落することを防止する。
【００３０】
（４）濃縮汚泥剥離工程
剥離空気導入管から濃縮容器２の上室１２内に加圧空気を供給し、この加圧空気を濾過筒２６の内側から外側に通すことにより、濾過膜３０の外側面に付着した汚泥を剥離して濃縮容器２の底部に落下させる。
【００３１】
（５）濃縮汚泥排出工程
重力により、あるいはポンプ等を用いて下室１０内の濃縮汚泥を濃縮汚泥排出管８６を通して濃縮汚泥貯槽５６に排出する。
【００３２】
なお、前記各例では砂等の固形分の排出を汚泥濃縮工程と未濃縮汚泥排出工程との間に行ったが、図１に示した汚泥濃縮装置のように砂等の固形分を集積するための専用の固形分集積管３８を設けた装置の場合は、砂等の固形分の排出を、汚泥濃縮工程、未濃縮汚泥水排出工程、濃縮汚泥剥離工程あるいは濃縮汚泥排出工程の途中や、未濃縮汚泥水排出工程と濃縮汚泥剥離工程との間あるいは濃縮汚泥剥離工程と濃縮汚泥排出工程との間に行うことも可能である。さらに、砂等の固形分の排出は、必ずしも前記の一連の工程からなる１サイクルの濾過処理毎に行う必要はなく、例えば２〜３サイクルに一回というように間欠的に行なってもよい。
【００３３】
【発明の効果】
以上のように、本発明によれば、濾過膜による汚泥濃縮装置を用いて汚泥の濃縮を行う場合に、汚泥濃縮装置に導入された汚泥水中に含まれる砂等の固形分が未濃縮汚泥水排出工程で汚泥水貯槽に戻ることを防ぎ、汚泥水貯槽内に砂等の固形分が堆積することを防止することにより、汚泥水貯槽の定期的な清掃の必要性をなくして汚泥水処理を省力化することができる。
【図面の簡単な説明】
【図１】本発明を適用する汚泥濃縮装置の一例を示す概略断面図である。
【図２】本発明を適用する汚泥濃縮装置の他の例を示す概略断面図である。
【図３】浄水処理場における汚泥処理設備の一例を示すフロー図である。
【図４】濾過膜を用いた汚泥濃縮装置の一例を示す概略断面図である。
【符号の説明】
２濃縮容器
１４ヘッダー管
１６第１汚泥水導入管
１８第２汚泥水導入管
２０未濃縮汚泥水返送管
２２濃縮汚泥排出管
２６濾過筒
３０濾過膜
３２処理水流出管
３８固形分集積管
４２固形分排出管
４６汚泥水入口
４８ドレン口
５０汚泥水
５２汚泥水貯槽
５６濃縮汚泥貯槽
７０汚泥濃縮装置
８０汚泥濃縮装置
８４汚泥水導入管
８６濃縮汚泥排出管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sludge concentration method using a sludge concentrator using a filtration membrane. The sludge concentration method according to the present invention is suitably applied to, for example, a sludge concentration apparatus that concentrates sludge water generated at a water purification plant.
[0002]
[Prior art]
In the water purification plant, as shown in FIG. 3, sludge water generated in each treatment facility (for example, a coagulating sedimentation apparatus) is concentrated to some extent in a sedimentation-type sludge concentration tank, and the concentrated sludge water 50 is stored in a sludge water storage tank 52. After storing and introducing the sludge water in the sludge water storage tank 52 into the sludge concentrator 54 of the filtration method and performing the sludge concentration treatment (preliminary concentration), the concentrated sludge generated by the sludge concentrator 54 is concentrated in the sludge storage tank. In general, the sludge is stored in the sludge storage tank 56 and the sludge in the concentrated sludge storage tank 56 is introduced into a sludge dewatering device 58 such as a pressure type or a vacuum type to perform sludge dewatering treatment.
[0003]
FIG. 4 is an enlarged view showing an example of the sludge concentrating device 54 described above. In this apparatus, 2 indicates a concentration container. The concentration container 2 is produced by connecting the lower part 4 and the upper part 6 with a partition plate 8 interposed therebetween. Therefore, the interior of the concentration container 2 is separated from the lower chamber 10 by the partition plate 8. It is partitioned into an upper chamber 12. Note that the lower portion of the lower portion 4 has an inverted conical shape.
[0004]
A header pipe 14 communicating with the lower chamber 10 is connected to the lower end portion of the concentration container 2, and the first sludge water introduction pipe 16 and the second sludge connected to the sludge water storage tank 52 are connected to the header pipe 14. The water introduction pipe 18 and the unconcentrated sludge water return pipe 20 are connected to the concentrated sludge discharge pipe 22 connected to the concentrated sludge storage tank 56. These pipes 16, 18, 20 and 22 are each provided with an automatic operation valve 24.
[0005]
A large number of filter cylinders 26 are installed inside the concentration container 2. The filter cylinder 26 is formed by covering the outer surface of a support cylinder 28 having a large number of through holes (not shown) with a filter membrane 30. As the filter membrane 30, a filter membrane (filter fabric) made of woven fabric or nonwoven fabric is usually used. Further, an upper portion of the concentration container 2 has a treated water outflow pipe 32 communicating with the upper chamber 12, a degassing pipe 34 for reducing the inside of the concentration container 2 and preventing the attached sludge from dropping from the filter cylinder 26, and A separation air introduction pipe 36 is connected to supply air into the concentration container 2 to separate the attached sludge from the filter cylinder 26.
[0006]
When processing sludge water such as a water purification plant by the sludge concentrating device 54 of this example, the following steps are performed.
(1) Sludge water filling process In this process, for example, the pump 60 is used to introduce the sludge water in the sludge water storage tank 52 into the lower chamber 10 of the concentration container 2 of the sludge concentrator 54 through the first sludge water introduction pipe 16. The lower chamber 10 is filled with sludge water.
[0007]
(2) Sludge concentration process In this process, for example, pressure is applied to the sludge water in the sludge water storage tank 52 by the pressurized air 62, and the sludge water in the sludge water storage tank 52 is concentrated through the second sludge water introduction pipe 18 by this pressure. It is continuously introduced into the lower chamber 10 of the container 2. Thereby, the sludge water flows from the outside to the inside of the filter cylinder 26 and is filtered by the filter membrane 30, and the suspension in the sludge water is trapped on the outer surface of the filter membrane 30 as a filter cake and the treated water is supported. It flows out into the upper chamber 12 from the upper end in the cylinder 28, and is further discharged out of the concentration container 2 from the treated water outflow pipe 32.
[0008]
(3) Unconcentrated sludge water discharge process As the introduction of sludge water into the sludge concentrator 54 continues, sludge adheres to the outer surface of the filtration membrane 30 and the pressure loss increases. Therefore, the supply of sludge water to the sludge concentrator 54 is stopped when the pressure loss value specified in advance or when the introduction amount of sludge water reaches a predetermined value, and the gravity or pump is turned off. The unconcentrated sludge water in the lower chamber 10 is returned to the sludge water storage tank 52 through the unconcentrated sludge water return pipe 20. At this time, the air is discharged from the deaeration pipe 34 and the inside of the concentration container 2 is depressurized, thereby preventing the attached sludge from dropping off from the filter cylinder 26.
[0009]
(4) Concentrated sludge stripping process Pressurized air is supplied from the stripping air introduction pipe 36 into the upper chamber 12 of the concentration container 2, and this pressurized air is passed from the inside to the outside of the filter cylinder 26, thereby The sludge adhering to the outer surface is peeled off and dropped to the bottom of the concentration container 2.
[0010]
(5) Concentrated sludge discharge process Concentrated sludge in the lower chamber 10 is discharged to the concentrated sludge storage tank 56 through the concentrated sludge discharge pipe 22 by gravity or by using a pump or the like.
[0011]
In the treatment using the sludge concentrator 54, the above-described series of steps are repeated to concentrate the sludge water. The time required for each step is about 2 to 8 minutes for the sludge water filling step, and the sludge concentration step is About 20 to 100 minutes, unconcentrated sludge water discharge process is about 2 to 8 minutes, concentrated sludge stripping process is about 30 seconds to 3 minutes, and concentrated sludge discharge process is about 2 to 8 minutes.
[0012]
[Problems to be solved by the invention]
The sludge water storage tank 52 described above is a place where sludge water from each treatment facility of the water purification plant gathers. In the sludge water storage tank 52, for example, turbid components contained in the inflow water to the water purification plant react with the flocculant. The aluminum flocs produced in this way are concentrated and flowed in. In addition, the sludge water in the sludge water storage tank 52 includes not only the above-mentioned aluminum floc, but also sand content that could not be removed by a sand basin, etc., and solid content such as detached sand and fallen leaves generated from a concrete water tank of a water purification plant. included.
[0013]
On the other hand, in the sludge concentration step (2), a certain amount of pressure is applied to the sludge water, and static concentration is performed over a relatively long time of about 20 to 100 minutes. The flow rate of the sludge water flowing into the concentration container 2 from the header pipe 14 via the pipe 18 is not so large. Usually, the fluid velocity of sludge water flowing from the header pipe 14 into the lower chamber 10 is about 0.1 to 0.4 m / sec. Therefore, the sludge is concentrated mainly on the aluminum floc by the filter cylinder 26, but the sedimentation speed in the lower chamber 10 of the solid content such as sand having a specific gravity larger than that of the aluminum floc exceeds the fluid speed of the sludge water. Solid matter such as sand contained in the sludge water settles in the lower chamber 10 and sinks and accumulates in the header pipe 14.
[0014]
Therefore, when the unconcentrated sludge water in the sludge concentrator 54 is once returned to the sludge water storage tank 52 in the unconcentrated sludge water discharge step (3) next to the sludge concentration step, the sand that has settled and accumulated in the header pipe 14 or the like. The solid content is also returned to the sludge water storage tank 52 together. The solid content such as sand returned to the sludge water storage tank 52 is accumulated in the sludge water storage tank 52 or sent to the sludge concentrator 54 in the next sludge water filling process or sludge concentration process, and then the sludge water storage tank 52 again. The amount of solid content such as sand in the sludge water storage tank 52 gradually increases. The amount of solids such as sand returned to the sludge water storage tank 52 in one unconcentrated sludge water discharge process is not so much, but if a series of sludge concentration processes are repeated many times, sand accumulated in the sludge water storage tank 52, etc. The solid content of is considerably large. Therefore, in the treatment by the conventional sludge concentrating device using the filtration membrane, it is necessary to periodically clean the sludge water storage tank 52 and remove the solid content such as sand accumulated therein, thereby saving the labor of the sludge water treatment. It was an obstacle to plan.
[0015]
The present invention has been made in view of the above circumstances, and when the sludge is concentrated using a filtration-type sludge concentrator, solid content such as sand contained in the sludge water introduced into the sludge concentrator is not present. By preventing the sludge water storage tank from returning to the sludge water storage process and preventing the accumulation of solids such as sand in the sludge water storage tank, the sludge water storage tank eliminates the need for regular cleaning. An object of the present invention is to provide a method for concentrating sludge that can save water treatment.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is a sludge concentration method using a sludge concentrating device that concentrates sludge using a filtration membrane, and concentrates sludge by passing sludge water through the filtration membrane of the sludge concentration device. Sludge concentration process, unconcentrated sludge water discharge process that discharges unconcentrated sludge water remaining in the sludge concentrator after completion of the sludge concentration process, and concentrated sludge that adheres to the filtration membrane in the sludge concentration process In the sludge concentration process, the concentrated sludge stripping process that peels after the process and the concentrated sludge discharge process that discharges the concentrated sludge stripped in the concentrated sludge stripping process, sinks to the bottom of the sludge concentrator. Provided is a sludge concentration method characterized in that solid content such as accumulated sand is discharged to a discharge destination different from a discharge destination of unconcentrated sludge water in a non-concentrated sludge water discharge step.
[0017]
That is, the sludge concentration process by the sludge concentrator using a filtration membrane is performed over a relatively long time of about 20 to 100 minutes. At this time, the sludge concentration proceeds on the filter membrane, and at the same time, the sludge concentrator. At the bottom of the basin, settlement and accumulation of solids with high specific gravity such as sand proceed. In the present invention, solid content such as sand that has settled and accumulated at the bottom of the sludge concentrator is obtained during or during the sludge concentration process, the unconcentrated sludge water discharge process, the concentrated sludge stripping process, or the concentrated sludge discharge process. By discharging the unconcentrated sludge water to a different destination from the unconcentrated sludge water discharge process, solids such as sand contained in the sludge water are prevented from returning to the sludge water storage tank. It prevents solids such as sand from accumulating.
[0018]
In this case, it is preferable to discharge the solids such as sand between the sludge concentration step and the unconcentrated sludge discharge step. The reason is as follows. That is, since the sludge concentration step is performed over a relatively long time as described above, the settlement and accumulation of solids such as sand sufficiently proceed during this time. Therefore, if the settled and accumulated solids are discharged after the solids are sufficiently settled and accumulated in the sludge concentration step, the solids such as sand contained in the sludge water in the concentration container are discharged. The amount of solids such as sand returned to the sludge water storage tank together with the unconcentrated sludge in the unconcentrated sludge discharge step performed after the end of the sludge concentration step can be reduced. This is because it can be extremely reduced.
[0019]
In addition, solids such as sand settle down and accumulate relatively easily at the bottom of the concentrator because of their very good sedimentation. Concentrated sludge adhered to the filtration membrane during the sludge concentration process. Therefore, even if the concentrated sludge is discharged to the destination, there is no problem in the subsequent processing such as dehydration. In addition, it is economically undesirable to separately install a destination for concentrated sludge and a destination for solids such as sand. Therefore, in the present invention, it is appropriate that the discharge destination of the solid content such as sand is the same as the discharge destination of the concentrated sludge in the concentrated sludge discharge step.
[0020]
The sludge concentrating apparatus to which the present invention is applied concentrates sludge by passing sludge water through a filtration membrane. As such a sludge concentrating apparatus, for example, a filter cylinder (element) formed by covering a filter membrane on the outer surface of a support cylinder having a large number of through holes is installed in a concentration container, and sludge water is supplied to the filter cylinder. An element-type sludge concentrating device that causes the suspension in the sludge water to be trapped on the outer surface of the filtration membrane as a filter cake and flows out from the inside of the filter cylinder to the outside of the concentration container. However, the present invention is not limited to this. Further, the type of filtration membrane of the sludge concentrator to which the present invention is applied is not limited, but for example, from multifilament yarns of various synthetic fibers, staple fiber yarns, woven fabrics formed from various natural fibers, nonwoven fabrics, etc. A filtration membrane.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of a sludge concentration apparatus to which the present invention is applied. In the sludge concentrating apparatus shown in FIG. 4, the present apparatus 70 is connected to the header pipe 14 with a solid content collecting pipe 38 for collecting solid contents such as sand, and the solid content collecting pipe 38 has an automatic operation valve 40. Is connected to the solid content discharge pipe 42. Since the other structure is the same as the sludge concentration apparatus shown in FIG. 4, the same reference numerals are given to the same parts in FIG.
[0022]
In the present apparatus 70, solid content such as sand contained in the sludge water settles in the header pipe 14 through the inlet / outlet 44 of the concentration container 2. Therefore, the solid content collection tube 38 is provided directly below the inlet / outlet 44 of the concentration container 2 so that solid content such as sand is well settled and accumulated in the solid content collection tube 38. It is sufficient that the inner diameter of the solid content collecting tube 38 is approximately the same as the inner diameter of the header tube 14, and it is not advantageous in terms of equipment to make the solid content collecting tube 38 too large. Moreover, the shape of the solid content collection tube 38 can be selected as appropriate, and can be various shapes such as a cone shape, an end cap shape, and an end plate shape.
[0023]
The outflow end of the solid content discharge pipe 42 is connected to the concentrated sludge discharge pipe 22, and therefore the solid content such as the subsidized and accumulated sand is discharged into the concentrated sludge storage tank 56 in this apparatus 70. The solid content discharge pipe 42 does not need to be so large because most of the solid content to be discharged is sand. For example, a pipe having a diameter of about 50 mm is sufficient.
[0024]
When the sludge concentration apparatus 70 of this example is used to concentrate the sludge water of a water purification plant or the like by applying the present invention, the steps {circle around (1)} to {circle around (5)} are performed. The next solid content discharge process is performed between (2) and the unconcentrated sludge water discharge process (3). That is, after completion of the sludge concentration process, the automatic operation valve 40 of the solid content discharge pipe 42 is opened and the other automatic operation valves 24 are closed, and solids such as sand in the solid content collection pipe 38 are applied by gravity or using a pump or the like. The portion is discharged to the concentrated sludge storage tank 56 through the solid content discharge pipe 42 and the concentrated sludge discharge pipe 22. Thereafter, an unconcentrated sludge water discharge step is performed. The discharged solid content may include a part of the sludge mass from the concentrated sludge adhering to the filtration membrane during the concentration process.
[0025]
FIG. 2 shows another example of the sludge concentration apparatus to which the present invention is applied. The present apparatus 80 is not provided with a header pipe, and the present invention can be applied to such a type of sludge concentrating apparatus. In the present apparatus 80, a sludge water inlet 46 and a drain port 48 communicating with the lower chamber 10 are provided in the lower part of the concentration container 2. Since the other structure is the same as that of the sludge concentrating device shown in FIG. 4, the same reference numerals are given to the same parts in FIG. In FIG. 2, the deaeration pipe and the separation air introduction pipe are omitted.
[0026]
In the sludge concentrating device 80 of this example, solids such as sand contained in the sludge water sink and accumulate in the drain port 48 at the bottom of the concentration container 2. Therefore, when the present invention is applied and the sludge water concentration process of a water purification plant or the like is performed using the apparatus 80, the following steps are performed. In addition, although this apparatus 80 is a thing of the system which does not perform the sludge pouring process mentioned above, this invention is applicable also to the sludge concentration apparatus of such a system.
[0027]
(1) Sludge concentration step In this step, the sludge water in the sludge water storage tank 52 is continuously supplied from the sludge water inlet 46 to the lower chamber 10 of the concentration container 2 through the sludge water introduction pipe 84 at a predetermined pressure using the pump 82 or the like. To introduce. Thereby, the sludge water flows from the outside to the inside of the filter cylinder 26 and is filtered by the filter membrane 30, and the suspension in the sludge water is trapped on the outer surface of the filter membrane 30 as a filter cake and the treated water is supported. It flows out into the upper chamber 12 from the upper end in the cylinder 28, and is further discharged out of the concentration container 2 from the treated water outflow pipe 32.
[0028]
(2) Solid content discharge process As the introduction of the sludge water into the sludge concentrator 80 continues, sludge adheres to the outer surface of the filtration membrane 30 and the pressure loss increases. Therefore, the supply of sludge water to the sludge concentrator 80 is stopped at the time when the pressure loss value specified in advance or when the introduction amount of sludge water reaches a predetermined value, and by gravity or by using a pump, etc. The solid matter such as sand that has settled and accumulated in the drain port 48 is discharged to the concentrated sludge storage tank 56 through the concentrated sludge discharge pipe 86. In this case, substantially only solid content such as sand accumulated in the drain port 48 is discharged to the concentrated sludge storage tank 56.
[0029]
(3) Unconcentrated sludge water discharge process The unconcentrated sludge water in the lower chamber 10 is returned to the sludge water storage tank 52 through the unconcentrated sludge water return pipe 88 by gravity or using a pump or the like. At this time, air is discharged from the deaeration pipe and the inside of the concentration container 2 is depressurized, thereby preventing the attached sludge from dropping off from the filter cylinder 26.
[0030]
(4) Concentrated sludge stripping step Pressurized air is supplied from the stripping air introduction pipe into the upper chamber 12 of the concentration container 2, and this pressurized air is passed from the inside to the outside of the filter cylinder 26, thereby The sludge adhering to the side surface is peeled off and dropped to the bottom of the concentration container 2.
[0031]
(5) Concentrated sludge discharge process The concentrated sludge in the lower chamber 10 is discharged to the concentrated sludge storage tank 56 through the concentrated sludge discharge pipe 86 by gravity or using a pump or the like.
[0032]
In each of the above examples, the solid content such as sand is discharged between the sludge concentration process and the unconcentrated sludge discharge process. However, the solid content such as sand is accumulated as in the sludge concentration apparatus shown in FIG. In the case of an apparatus provided with a dedicated solid content collecting pipe 38 for the purpose of discharging solid content such as sand, the sludge concentration process, the unconcentrated sludge water discharge process, the concentrated sludge stripping process or the concentrated sludge discharge process, It is also possible to carry out between the unconcentrated sludge water discharge process and the concentrated sludge stripping process or between the concentrated sludge stripping process and the concentrated sludge discharge process. Furthermore, it is not always necessary to discharge the solid content such as sand every time one cycle of filtration treatment including the above-described series of steps, and may be performed intermittently, for example, once every two to three cycles.
[0033]
【The invention's effect】
As described above, according to the present invention, when sludge is concentrated using a sludge concentrator using a filtration membrane, solids such as sand contained in the sludge water introduced into the sludge concentrator are unconcentrated sludge water. Prevents the sludge water storage tank from returning to the sludge water storage tank and prevents the accumulation of solids such as sand in the sludge water storage tank, eliminating the need for regular cleaning of the sludge water storage tank. It can save labor.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of a sludge concentration apparatus to which the present invention is applied.
FIG. 2 is a schematic sectional view showing another example of the sludge concentrating device to which the present invention is applied.
FIG. 3 is a flowchart showing an example of a sludge treatment facility in a water purification plant.
FIG. 4 is a schematic sectional view showing an example of a sludge concentrating device using a filtration membrane.
[Explanation of symbols]
2 Concentration container 14 Header pipe 16 First sludge water introduction pipe 18 Second sludge water introduction pipe 20 Unconcentrated sludge water return pipe 22 Concentrated sludge discharge pipe 26 Filtration cylinder 30 Filtration membrane 32 Treated water outflow pipe 38 Solid content collection pipe 42 Solid Discharge pipe 46 Sludge water inlet 48 Drain port 50 Sludge water 52 Sludge water storage tank 56 Concentrated sludge storage tank 70 Sludge concentration apparatus 80 Sludge concentration apparatus 84 Sludge water introduction pipe 86 Concentrated sludge discharge pipe

Claims

A sludge concentrating method using a sludge concentrating device for concentrating sludge using a filtration membrane, wherein the sludge concentrating step of passing sludge water through the filtering membrane of the sludge concentrating device to concentrate the sludge, and after the sludge concentrating step is completed Unconcentrated sludge water discharge process for discharging unconcentrated sludge water remaining in the sludge concentrator, concentrated sludge stripping process for stripping concentrated sludge adhering to the filtration membrane in the sludge concentration process after the unconcentrated sludge water discharge process, and concentration When the sludge is concentrated by performing the concentrated sludge discharge process that discharges the concentrated sludge separated in the sludge stripping process, solids such as sand that has settled and accumulated at the bottom of the sludge concentrator in the sludge concentration process are not concentrated. A method for concentrating sludge, characterized in that it is discharged to a destination different from the destination of unconcentrated sludge water in the sludge water discharge step.

The sludge concentration method according to claim 1, wherein the solid content such as sand is discharged between the sludge concentration step and the unconcentrated sludge discharge step.

The sludge concentration method according to claim 1 or 2, wherein a discharge destination of the solid content such as sand is the same as a discharge destination of the concentrated sludge in the concentrated sludge discharge step.