JP4199369B2

JP4199369B2 - Sludge volume reduction method

Info

Publication number: JP4199369B2
Application number: JP10762399A
Authority: JP
Inventors: 哲三枝
Original assignee: Mitsubishi Kakoki Kaisha Ltd
Current assignee: Mitsubishi Kakoki Kaisha Ltd
Priority date: 1999-04-15
Filing date: 1999-04-15
Publication date: 2008-12-17
Anticipated expiration: 2019-04-15
Also published as: JP2000301198A

Description

【０００１】
【発明の属する技術分野】
本発明は、有機性排水を生物学的に処理し、発生した有機性汚泥（以下単に汚泥という。）を減容化する汚泥減容化処理方法に関する。
【０００２】
【従来の技術】
従来、下水、食品排水、厨房排水又は浄化槽汚泥などの有機性排水の処理方法としては、活性汚泥処理法、ＵＡＳＢ法（上向流嫌気性自己造粒生物床式処理法）、固定床式接触酸化法又は流動床式接触酸化法などの生物処理方法が用いられている。
【０００３】
活性汚泥法にあっては、好気性微生物である活性汚泥の浮遊する処理槽内に排水（以下原水という。）を供給し、空気で曝気することにより、活性汚泥の生物学的作用で原水中の有機物を酸化分解処理する方法であり、また、ＵＡＳＢ法にあっては、嫌気性のメタン生成菌を自己造粒させた微生物粒子で流動床を形成させ、原水を上向流で流通させてメタン生成菌の生物学的作用で原水中の有機物を分解処理する方法である。
【０００４】
更に、固定床式接触酸化法にあっては、処理槽内に生物担体の固定床を設け、空気を散気することにより微生物を担体の表面に付着増殖させ、付着した微生物の生物学的作用で原水中の有機物を酸化分解処理する方法であり、また、流動床式接触酸化法は、好気性生物処理槽内の液中に流動可能に生物担体を充填し、原水を供給して空気で曝気することにより、生物担体の表面に付着増殖した微生物の生物学的作用で原水中の有機物を酸化分解処理する方法である。
【０００５】
前記生物処理方法では、いずれも有機物を生物学的に分解処理するのに伴い、増殖した微生物が汚泥として大量に発生する。発生した汚泥の一部は生物処理工程に循環されるが、残部は余剰汚泥として適宜な方法で処分されている。なお、その余剰汚泥量は生物処理工程に導入された原水中の有機物量（ＢＯＤ）の３０〜４０％といわれている。それら余剰汚泥の処分方法としては、汚泥を濃縮、脱水したのち焼却や埋め立てにより処分したり、又は嫌気性消化処理により減容化されている。
【０００６】
【発明が解決しようとする課題】
前記従来の余剰汚泥の処分方法で、汚泥を濃縮、脱水したのち焼却又は埋め立て処分する方法にあっては、汚泥の濃縮、脱水後においても含水率が７０〜８０ｗｔ％と高いため嵩が大きく、廃棄物業者に処分を依頼する場合には、引き取りコストが高くなり、排水処理全体にかかるコストの多くを占めているのが現状である。更に、埋め立て処分においては、産業廃棄物埋立処分場の残余年数が少なくなっており、引き取りコストも年々高騰している。また、焼却処分においては、含水率が高いため燃料消費量が多く燃料費が嵩み、更に、排出ガスや焼却灰の処理が必要であり、近年はダイオキシン問題等から焼却処理自体が困難になってきている状況である。
【０００７】
また、嫌気性消化法により減容化処理する方法にあっては、メタン菌等の嫌気性微生物が浮遊する処理槽内に汚泥を供給し、嫌気性ガスで曝気することにより、嫌気性微生物の生物学的作用で汚泥中の有機物をメタンガスや炭酸ガス等に分解処理する方法であるが、メタンガスを燃料等に有効活用できるため好ましいが、処理に時間がかかり、消化槽等の設備が過大となり、また、最終的に発生する汚泥量も多く、その処分には前記の問題点が付き纏うことになる。
【０００８】
本発明は、前記従来の汚泥処分及び処理における問題点に鑑みて成されたものであり、比較的小型で容易な運転操作の設備を付設することで効率の高い汚泥の減容化を図ることができ、運転コストや設備コストなどが低廉となり、最終処分コストも低廉化できる汚泥減容化処理方法を提供する目的で成されたものである。
【０００９】
【課題を解決するための手段】
前記目的を達成するための本発明の要旨は、請求項１に記載した発明においては、生物処理工程からの低濃度有機性汚泥を沈降分離により濃縮する沈殿槽での沈降分離工程とは別工程に、生物処理工程からの低濃度有機性汚泥の一部を濾過膜で濾過処理して濃縮汚泥と清澄水を得る汚泥濃縮工程と、汚泥濃縮工程で濃縮された濃縮汚泥を高温好気性生物処理して汚泥を可溶化処理する可溶化処理工程と、可溶化処理された汚泥を生物処理工程に循環する汚泥循環工程を設けたことを特徴とする汚泥減容化処理方法である。
【００１０】
また、請求項２に記載した発明においては、請求項１記載の汚泥減容化処理方法において、生物処理工程が活性汚泥処理工程であり、低濃度有機性汚泥が活性汚泥処理工程からの汚泥であることを特徴とする汚泥減容化処理方法である。
【００１１】
請求項３に記載した発明においては、ＵＡＳＢ処理工程の後段に活性汚泥処理工程を設けて排水処理する排水処理方法において、活性汚泥処理工程からの汚泥を濾過膜で濾過処理して濃縮汚泥と清澄水を得る汚泥濃縮工程と、汚泥濃縮工程で濃縮された濃縮汚泥及びＵＡＳＢ処理工程からの余剰な自己造粒汚泥を高温好気性生物処理して汚泥を可溶化処理する可溶化処理工程と、可溶化処理された汚泥を活性汚泥処理装置に循環する汚泥循環工程を設けたことを特徴とする汚泥減容化処理方法である。
【００１２】
請求項４に記載した発明においては、生物処理工程の後段に嫌気性消化工程を設けて排水処理する排水処理方法において、生物処理工程からの汚泥を濾過膜で濾過処理して濃縮汚泥と清澄水を得る汚泥濃縮工程と、汚泥濃縮工程で濃縮された濃縮汚泥及び嫌気性消化工程からの循環汚泥を高温好気性生物処理して汚泥を可溶化処理する可溶化処理工程と、可溶化処理された汚泥を嫌気性消化工程に循環する汚泥循環工程を設けたことを特徴とする汚泥減容化処理方法である。
【００１３】
請求項５に記載した発明においては、請求項１〜請求項４のいずれか１項に記載の汚泥減容化処理方法において、汚泥濃縮工程で濃縮された汚泥のＭＬＳＳが３００００〜１０００００ｍｇ／Ｌであることを特徴とし、請求項６に記載した発明においては、請求項１〜請求項５のいずれか１項に記載の汚泥減容化処理方法において、可溶化処理工程の液温が５５〜８０℃であることを特徴とする汚泥減容化処理方法である。
【００１４】
前記構成の装置において汚泥を処理する作用について述べると、活性汚泥処理工程からの汚泥等のＭＬＳＳが１０００〜２００００ｍｇ／Ｌである低濃度有機性汚泥を濾過膜で濾過処理する汚泥濃縮工程により、ＭＬＳＳが３００００〜１０００００ｍｇ／Ｌに濃縮された濃縮汚泥と清澄水を得ることができる。汚泥のＭＬＳＳが３００００〜１０００００ｍｇ／Ｌであることにより、装置を小型化でき、可溶化処理も効率よく行うことができる。
【００１５】
濃縮された濃縮汚泥、ＵＡＳＢ処理工程からの自己造粒汚泥や嫌気性消化処理工程からの汚泥を可溶化処理工程に供給し、５５〜８０℃の液温、滞留時間が１２〜７２時間で高温好気性生物処理し可溶化処理することにより、汚泥の１０〜４０ｖｏｌ％が液化される。可溶化された汚泥を汚泥循環工程で生物処理工程に循環することにより、液化された有機物は再度生物学的作用で処理され、最終的に汚泥の２０〜５０ｖｏｌ％が減容化されるとともに、汚泥自体も沈降し易く濾過膜の目詰まりがし難い汚泥とすることができる。また、液温を５５〜８０℃に保持して可溶化処理することにより、常温で成育する活性汚泥微生物を殺菌し、高温状態で成育する微生物を優位に繁殖させることができ、汚泥を効率よく液化することができる。
【００１６】
【発明の実施の形態】
以下に本発明の実施の形態について図面に基づいて説明する。図１は本発明の一実施の形態である活性汚泥処理装置における系統図、図２は本発明の他の実施の形態であるＵＡＳＢ処理装置における系統図、図３は本発明の他の実施の形態である嫌気性消化処理装置における系統図、図４は本発明の要部である汚泥濃縮工程と可溶化処理工程の系統図である。
【００１７】
図１において、１は好気性微生物である活性汚泥が浮遊し空気で曝気することにより、活性汚泥の生物学的作用で原水中の有機物を酸化分解処理する生物処理工程の活性汚泥処理槽であり、該活性汚泥処理槽１は、一般的な活性汚泥処理槽であるが、処理槽内に生物担体の固定床を設け、空気を散気することにより微生物を担体の表面に付着増殖させ、付着した微生物の生物学的作用で原水中の有機物を酸化分解処理する固定床式接触酸化処理槽や好気性生物処理槽内の液中に流動可能に生物担体を充填し、原水を供給して空気で曝気することにより、生物担体の表面に付着増殖した微生物の生物学的作用で原水中の有機物を酸化分解処理する流動床式接触酸化処理槽であってもよい。更に、排水中の窒素分を生物学的に硝化脱窒処理する硝化脱窒処理槽であってもよく、また、処理槽１内に濾過膜装置を配置し、汚泥を濾過して処理水を排出する構成であってもよい。
【００１８】
２は汚泥濃縮工程の濾過膜式汚泥濃縮槽、３は可溶化処理工程の可溶化処理槽であるが、それらを図５により詳述する。濾過膜式汚泥濃縮槽２の内部には濾過膜装置５が内設されており、濾過膜式汚泥濃縮槽２の形状は、上面が開放された槽や密閉構造の槽のいずれでもよいが、構造が簡易となる開放槽が好ましい。また、内設される濾過膜装置５は、濾過体が不織布成形体の表面に、セルロ−スアセテ−ト系、芳香族ポリアミド系及びポリスフォン系等の孔径が０．１〜数μの精密濾過膜や分画分子量数万〜数１０万程度の限外濾過膜等を貼着して成るモジュ−ルや不織布成形体のみから成るダイナミック膜モジュ−ルが用いられるが、精密濾過膜を用いるのが好ましい。
【００１９】
また、濾過体の形状は円盤状や矩形板状の平膜が複数水平方向に所定の間隔で併設された平膜形状が好ましいが、円筒状であってもよく、本発明はそれらには限定されない。また、濾過膜装置５の濾過体の下方には、図示しないが、気体を被処理液流路に散気する散気手段が配置されている。
【００２０】
可溶化処理槽３は汚泥濃縮工程で濃縮された濃縮汚泥を高温好気性生物処理して汚泥を可溶化処理する処理槽であり、上面が開放された槽や密閉構造の槽のいずれでもよいが、加熱効果や防臭効果をあげるためには密閉構造槽が好ましい。
【００２１】
また、可溶化処理槽３は、外側面がジャケット７構造となり、ジャケット７内部に蒸気や温水等を流通させて槽を加熱する構造となっているのが好ましいが、電気ヒ−タを内設又は外部に付設して加熱する構造であってもよい。更に、可溶化処理槽３内には、下部に空気や高濃度酸素を吹き込む散気手段６が設けられ、軸心部には攪拌手段８が付設されている。また、可溶化処理槽３内に流動可能に生物担体を充填して流動床式槽とすることにより、酸素と汚泥の接触効率が高まるため、より一層の可溶化処理を行なうことができる。なお、種菌としては、他の同一装置から発生した汚泥を用いるのが好ましいが、コンポスト汚泥を用いることもできる。
【００２２】
図２は、嫌気性のメタン生成菌を自己造粒させた微生物粒子で流動床を形成させ、原水を上向流で流通させてメタン生成菌の生物学的作用で原水中の有機物を分解処理するＵＡＳＢ処理工程のＵＡＳＢ処理槽１０を設け、後段に活性汚泥処理工程の活性汚泥処理槽１ａを設けた構成であり、図３は生物処理工程等で発生した余剰汚泥を、メタン菌等の嫌気性微生物が浮遊する処理槽内に汚泥を供給し、嫌気性ガスで曝気することにより、嫌気性微生物の生物学的作用で汚泥中の有機物をメタンガスや炭酸ガス等に分解処理する嫌気性消化工程の嫌気性消化槽１１を設けた構成である。
【００２３】
前記構成の装置により有機性排水を処理する方法について以下詳述する。図１の生物処理工程として活性汚泥処理槽１を設けた方法にあっては、原水供給管ａから活性汚泥処理槽１に供給された有機性排水の原水は、好気性微生物である活性汚泥が浮遊し空気で曝気されることにより、活性汚泥の生物学的作用で原水中の有機物が酸化分解される。この活性汚泥処理におけるＭＬＳＳは、一般的に１０００〜２００００ｍｇ／Ｌである。
【００２４】
生物処理工程で処理された低濃度汚泥である汚泥混合液は汚泥混合液排出管ｂから後段の沈殿槽４に供給されるが、一部は汚泥混合液供給管ｃから汚泥濃縮工程の濾過膜式汚泥濃縮槽２に供給されて、汚泥が濃縮処理される。なお、濃縮処理された濃縮汚泥のＭＬＳＳは３００００〜１０００００ｍｇ／Ｌであり、濃縮汚泥は濃縮汚泥供給管ｄから汚泥減容化処理工程の可溶化処理槽３に供給され、濾過膜を透過した濾過水は処理水として濾過水排出管ｆから系外に排出される。なお、汚泥のＭＬＳＳが３００００〜１０００００ｍｇ／Ｌであることにより、装置を小型化でき、可溶化処理も効率よく行うことができる。
【００２５】
前記沈殿槽４に供給された汚泥混合液は汚泥が沈降分離され、上澄水は処理水として処理水排出管ｈから系外に排出され、沈降汚泥は活性汚泥処理槽１の汚泥濃度を維持するため沈降汚泥供給管ｇから循環される。なお、前記濾過膜式汚泥濃縮槽２に供給される汚泥混合液に換えて、沈降汚泥供給管ｇに分岐管を設け、分岐管を濾過膜式汚泥濃縮槽２に接続して活性汚泥処理槽１に循環される低濃度汚泥である沈降汚泥の一部を供給してもよい。
【００２６】
可溶化処理槽３に供給された濃縮汚泥は、液温が５５〜８０℃に保持されて滞留時間を１２〜７２時間として、高温好気性生物の生物学的な酸化作用で可溶化処理される。これにより、汚泥の１０〜４０ｖｏｌ％が液化され、可溶化された汚泥を汚泥循環工程の可溶化処理汚泥供給管ｅから活性汚泥処理槽１に循環することにより、液化された有機物は再度生物学的作用で処理され、最終的に汚泥の２０〜５０ｖｏｌ％が減容化されるとともに、汚泥自体も沈降し易く濾過膜の目詰まりがし難い汚泥とすることができる。また、液温を５５〜８０℃に保持して可溶化処理することにより、常温で成育する活性汚泥微生物を殺菌し、高温状態で成育する微生物を優位に繁殖させることができ、汚泥を効率よく液化することができる。
【００２７】
図２のＵＡＳＢ処理槽１０の後段に活性汚泥処理槽１ａを設けて排水処理する排水処理方法において、活性汚泥処理槽１ａからの汚泥を汚泥濃縮工程の濾過膜式汚泥濃縮槽２に供給して汚泥が濃縮処理され、濃縮された濃縮汚泥及びＵＡＳＢ処理工程からの余剰な自己造粒汚泥は汚泥減容化処理工程の可溶化処理槽３に供給され、濾過膜を透過さた濾過水は処理水として系外に排出される。可溶化処理槽３に供給された濃縮汚泥は、高温好気性生物の生物学的な酸化作用で可溶化処理されて汚泥の１０〜４０ｖｏｌ％が液化され、可溶化された汚泥を汚泥循環工程から活性汚泥処理槽１ａに循環することにより、液化された有機物は再度生物学的作用で処理され、最終的に汚泥の２０〜５０ｖｏｌ％が減容化される。
【００２８】
図３の生物処理工程等で発生した余剰汚泥を嫌気性消化処理する嫌気性消化槽１１を設け設けて排水処理する排水処理方法において、生物処理工程からの低濃度汚泥である余剰汚泥を汚泥濃縮工程の濾過膜式汚泥濃縮槽２に供給して汚泥が濃縮処理され、濃縮された濃縮汚泥及び嫌気性消化工程の嫌気性消化槽１１からの循環汚泥は汚泥減容化処理工程の可溶化処理槽３に供給され、濾過膜を透過さた濾過水は処理水として系外に排出される。可溶化処理槽３に供給された濃縮汚泥は、高温好気性生物の生物学的な酸化作用で可溶化処理されて汚泥の１０〜４０ｖｏｌ％が液化され、可溶化された汚泥を汚泥循環工程から嫌気性消化槽１１に循環することにより、液化された有機物は再度生物学的作用で処理され、最終的に汚泥の２０〜５０ｖｏｌ％が減容化される。
【００２９】
前記汚泥濃縮工程及び可溶化処理工程について図５により更に詳述する。汚泥濃縮槽２に供給された汚泥は、汚泥濃縮槽２の内部に設けられた濾過膜装置５により減圧された濾過膜により濾過処理され、濾過膜を透過した濾過水は処理水として濾過水排出管ｆから系外に排出され、非透過側に濃縮された濃縮汚泥は濃縮汚泥供給管ｄから汚泥減容化処理工程の可溶化処理槽３に供給される。
【００３０】
可溶化処理槽３に供給された濃縮汚泥は、ジャケット７に蒸気や温水を流通させて処理槽を加熱することにより加熱され、攪拌機８で攪拌されるとともに、散気手段６から空気や高濃度酸素が供給され、液温が５５〜８０℃に保持されて、滞留時間を１２〜７２時間として、高温好気性生物の生物学的な酸化作用で可溶化処理される。なお、余分な気体は排気管ｊから排気する。これにより、汚泥の１０〜４０ｖｏｌ％が液化され、可溶化された汚泥を汚泥循環工程の可溶化処理汚泥供給管ｅから生物処理工程の活性汚泥処理槽１等に循環することにより、液化された有機物は再度生物学的作用で処理され、最終的に汚泥の２０〜５０ｖｏｌ％が減容化されるとともに、汚泥自体も沈降し易く濾過膜の目詰まりがし難い汚泥とすることができる。
【００３１】
以下に本発明の一実施の形態の汚泥減容化処理方法を用いて有機性排水を処理した実施例について詳述する。
【００３２】
（実施例１）
図１の装置を用いて食品系有機排水（ＢＯＤ：１４００ｍｇ／Ｌ）を活性汚泥処理槽に供給して処理し、ＭＬＳＳが１０００〜２００００ｍｇ／Ｌである汚泥混合液を汚泥濃縮槽に供給し、ＭＬＳＳが４００００〜６００００ｍｇ／Ｌに濃縮された濃縮汚泥が得られた。その濃縮汚泥を可溶化処理槽に供給し、６０℃の液温で２４時間可溶化処理した結果、汚泥の１０〜４０ｖｏｌ％が液化された。可溶化された汚泥を活性汚泥処理槽に循環して再度生物学的処理した結果、最終的に汚泥の２０〜５０ｖｏｌ％が減容化され、沈殿槽から引き抜く余剰汚泥は殆ど発生しなかった。また、沈殿槽の上澄水である処理水はＢＯＤが１０ｍｇ／Ｌ以下であった。
【００３３】
【発明の効果】
本発明は、比較的小型で容易な運転操作の設備を付設することにより汚泥の減容化効果が高い方法であり、運転コストや設備コストなどが低廉で、最終処分コストも低廉化できる汚泥減容化処理方法である。
請求項１に記載の発明においては、汚泥濃縮工程の濾過膜で濾過処理して濃縮汚泥を得て濃縮汚泥を可溶化処理し、生物処理工程に循環することにより、汚泥の２０〜５０ｖｏｌ％を減容化することができる。
【００３４】
請求項２に記載の発明においては、請求項１記載の汚泥減容化処理方法において生物処理工程が活性汚泥処理工程であり、低濃度有機性汚泥が活性汚泥処理工程からの汚泥であることにより、活性汚泥処理工程から排出される余剰汚泥を殆どなくすことができる。
【００３５】
請求項３に記載の発明においては、ＵＡＳＢ処理工程の後段に活性汚泥処理工程を設けて排水処理する排水処理方法において、活性汚泥処理工程の汚泥を汚泥濃縮工程の濾過膜で濾過処理して濃縮汚泥を得て濃縮汚泥を及びＵＡＳＢ処理工程からの余剰な自己造粒汚泥を可溶化処理し、生物処理工程に循環することにより、汚泥の２０〜５０ｖｏｌ％を減容化することができる。
【００３６】
請求項４に記載の発明においては、生物処理工程の後段に嫌気性消化工程を設けて排水処理する排水処理方法において、活性汚泥処理工程の汚泥を汚泥濃縮工程の濾過膜で濾過処理して濃縮汚泥を得て濃縮汚泥及び嫌気性消化工程からの循環汚泥を可溶化処理し、生物処理工程に循環することにより、汚泥の２０〜５０ｖｏｌ％を減容化することができる。
【００３７】
請求項５に記載の発明においては、請求項１〜請求項４のいずれか１項に記載の汚泥減容化処理方法で、汚泥濃縮工程で濃縮された汚泥のＭＬＳＳが３００００〜１０００００ｍｇ／Ｌであることにより、装置を小型化でき、可溶化処理も効率よく行うことができる。
【００３８】
請求項６に記載の発明においては、請求項１〜請求項５のいずれか１項に記載の汚泥減容化処理方法で、可溶化処理工程の液温が５５〜８０℃であることにより、装置を小型化でき、可溶化処理も効率よく行うことができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態である活性汚泥処理装置における系統図
【図２】本発明の他の実施の形態であるＵＡＳＢ処理装置における系統図
【図３】本発明の他の実施の形態である嫌気性消化処理装置における系統図
【図４】本発明の要部である汚泥濃縮工程と可溶化処理工程の系統図
【符号の説明】
１：活性汚泥処理槽
２：濾過膜式汚泥濃縮槽
３：可溶化処理槽
４：沈殿槽
５：濾過膜装置
６：散気手段
７：ジャケット
８：攪拌機
１０：ＵＡＳＢ処理槽
１１：嫌気性消化槽[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sludge volume reducing treatment method for biologically treating organic waste water to reduce the volume of generated organic sludge (hereinafter simply referred to as sludge).
[0002]
[Prior art]
Conventionally, as an organic wastewater treatment method such as sewage, food wastewater, kitchen wastewater or septic tank sludge, activated sludge treatment method, UASB method (upward flow anaerobic self-granulating biological bed treatment method), fixed bed contact method Biological treatment methods such as an oxidation method or a fluidized bed contact oxidation method are used.
[0003]
In the activated sludge method, wastewater (hereinafter referred to as raw water) is supplied into a treatment tank in which activated sludge, which is an aerobic microorganism, floats, and aerated with air. In the UASB method, a fluidized bed is formed with microbial particles obtained by self-granulating anaerobic methanogens, and raw water is circulated in an upward flow. It is a method of decomposing organic matter in raw water by biological action of methanogens.
[0004]
Further, in the fixed bed type contact oxidation method, a fixed bed of a biological carrier is provided in the treatment tank, and air is diffused so that microorganisms adhere to the surface of the carrier and the biological action of the attached microorganisms. In this method, the organic matter in the raw water is oxidatively decomposed, and the fluidized bed catalytic oxidation method fills the liquid in the aerobic biological treatment tank with a flowable biological carrier, supplies the raw water, and supplies it with air. In this method, organic matter in raw water is oxidatively decomposed by the biological action of microorganisms that have adhered and proliferated on the surface of the biological carrier by aeration.
[0005]
In any of the above biological treatment methods, a large amount of the grown microorganisms are generated as sludge as the organic matter is biologically decomposed. A part of the generated sludge is circulated in the biological treatment process, but the remainder is disposed of as an excess sludge by an appropriate method. The amount of excess sludge is said to be 30 to 40% of the amount of organic matter (BOD) in the raw water introduced into the biological treatment process. As a method for disposing the surplus sludge, the sludge is concentrated and dehydrated and then disposed of by incineration or landfill, or the volume is reduced by anaerobic digestion.
[0006]
[Problems to be solved by the invention]
In the conventional surplus sludge disposal method, the sludge is concentrated, dewatered and then incinerated or landfilled, and the water content is high at 70 to 80 wt% even after the sludge concentration and dewatering, and the bulk is large. In the case of requesting disposal to a waste supplier, the pick-up cost becomes high, and the current situation is that it accounts for most of the cost for the entire wastewater treatment. Furthermore, in landfill disposal, the remaining years of the industrial waste landfill site are decreasing, and the collection cost is also rising year by year. Also, incineration disposal has a high water content, so fuel consumption is large and fuel costs are high. In addition, it is necessary to treat exhaust gas and incineration ash. In recent years, incineration treatment itself has become difficult due to dioxin problems. It is a situation that is coming.
[0007]
In addition, in the method of volume reduction treatment by anaerobic digestion method, sludge is supplied into a treatment tank in which anaerobic microorganisms such as methane bacteria are suspended, and aerobic gas is aerated to remove anaerobic microorganisms. It is a method of decomposing organic matter in sludge into methane gas, carbon dioxide gas, etc. by biological action, but it is preferable because methane gas can be effectively used as fuel, etc., but it takes time to process, and the equipment such as digestion tank becomes excessive. Also, the amount of sludge that is finally generated is large, and the above-mentioned problems are attached to its disposal.
[0008]
The present invention has been made in view of the problems in the conventional sludge disposal and treatment, and is intended to reduce sludge volume with high efficiency by installing relatively small and easy operation equipment. The purpose of the present invention is to provide a sludge volume reduction method that can reduce operating costs and equipment costs, and can reduce final disposal costs.
[0009]
[Means for Solving the Problems]
The gist of the present invention for achieving the above object is that, in the invention described in claim 1, a step separate from the sedimentation step in the sedimentation tank in which the low-concentration organic sludge from the biological treatment step is concentrated by sedimentation. In addition, a part of the low-concentration organic sludge from the biological treatment process is filtered with a filtration membrane to obtain concentrated sludge and clarified water, and the concentrated sludge concentrated in the sludge concentration process is subjected to high-temperature aerobic biological treatment. Thus, there is provided a solubilization treatment step for solubilizing sludge and a sludge reduction treatment method characterized by providing a sludge circulation step for circulating the solubilized sludge to the biological treatment step.
[0010]
Moreover, in invention described in Claim 2, in the sludge volume reduction processing method of Claim 1, a biological treatment process is an activated sludge treatment process, and a low concentration organic sludge is sludge from an activated sludge treatment process. It is the sludge volume reduction processing method characterized by being.
[0011]
In the invention described in claim 3, in the wastewater treatment method in which the activated sludge treatment process is provided after the UASB treatment process, the sludge from the activated sludge treatment process is filtered through a filtration membrane and concentrated sludge and clarified. A sludge concentrating step for obtaining water, a solubilizing step for solubilizing sludge by subjecting the concentrated sludge concentrated in the sludge concentrating step and excess self-granulated sludge from the UASB processing step to high-temperature aerobic biological treatment; It is a sludge volume reduction processing method provided with the sludge circulation process which circulates solubilized sludge to an activated sludge processing apparatus.
[0012]
In the invention described in claim 4, in the wastewater treatment method in which an anaerobic digestion step is provided after the biological treatment step, the sludge from the biological treatment step is filtered through a filtration membrane and concentrated sludge and clarified water. A solubilization process for solubilizing sludge by subjecting the concentrated sludge concentrated in the sludge concentration process and the circulating sludge from the anaerobic digestion process to high temperature aerobic biological treatment It is a sludge volume reduction processing method characterized by providing the sludge circulation process which circulates sludge to an anaerobic digestion process.
[0013]
In invention described in Claim 5, in the sludge volume reduction processing method of any one of Claims 1-4, MLSS of the sludge concentrated by the sludge concentration process is 30000-100000 mg / L. The invention according to claim 6 is characterized in that, in the sludge volume reduction treatment method according to any one of claims 1 to 5, the liquid temperature of the solubilization treatment step is 55 to 80. It is a sludge volume reduction processing method characterized by being ℃.
[0014]
Describing the action of treating sludge in the apparatus having the above-described configuration, the MLSS is subjected to the sludge concentration step of filtering low-concentration organic sludge having a MLSS of 1000 to 20000 mg / L, such as sludge from the activated sludge treatment step, through a filtration membrane. Can be concentrated sludge and clear water concentrated to 30000-100,000 mg / L. When the MLSS of sludge is 30,000 to 100,000 mg / L, the apparatus can be miniaturized and the solubilization treatment can be performed efficiently.
[0015]
Concentrated concentrated sludge, self-granulating sludge from the UASB treatment process and sludge from the anaerobic digestion treatment process are supplied to the solubilization treatment process, and the liquid temperature at 55 to 80 ° C. and the residence time are high at 12 to 72 hours. 10-40 vol% of sludge is liquefied by aerobic biological treatment and solubilization treatment. By circulating the solubilized sludge to the biological treatment process in the sludge circulation process, the liquefied organic matter is treated again by biological action, and finally 20-50 vol% of the sludge is reduced in volume, The sludge itself can be easily settled, and the sludge can be prevented from clogging the filtration membrane. In addition, by maintaining the liquid temperature at 55 to 80 ° C. and solubilizing, the activated sludge microorganisms that grow at room temperature can be sterilized, and the microorganisms that grow at high temperatures can be preferentially propagated, and sludge can be efficiently produced. It can be liquefied.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 is a system diagram of an activated sludge treatment apparatus according to an embodiment of the present invention, FIG. 2 is a system diagram of a UASB treatment apparatus according to another embodiment of the present invention, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a system diagram of a sludge concentration process and a solubilization process which are the main parts of the present invention.
[0017]
In FIG. 1, reference numeral 1 denotes an activated sludge treatment tank for a biological treatment process in which activated sludge, which is an aerobic microorganism, floats and aerated with air to oxidatively decompose organic matter in raw water by the biological action of activated sludge. The activated sludge treatment tank 1 is a general activated sludge treatment tank. However, a fixed bed of a biological carrier is provided in the treatment tank, and air is diffused so that microorganisms adhere to and grow on the surface of the carrier. The biological carrier is filled with a biological carrier in a fluidized manner in a fixed-bed catalytic oxidation treatment tank or an aerobic biological treatment tank that oxidizes and decomposes organic matter in the raw water, and the raw water is supplied to the air. It may be a fluidized bed catalytic oxidation treatment tank that oxidizes and decomposes organic matter in raw water by the biological action of microorganisms that adhere and grow on the surface of the biological carrier by aeration. Further, it may be a nitrification / denitrification treatment tank that biologically nitrifies and denitrifies the nitrogen content in the waste water. Also, a filtration membrane device is disposed in the treatment tank 1 to filter the sludge and treat the treated water. The structure which discharges | emits may be sufficient.
[0018]
2 is a filtration membrane type sludge concentration tank in the sludge concentration process, and 3 is a solubilization process tank in the solubilization process, which will be described in detail with reference to FIG. A filtration membrane device 5 is installed inside the filtration membrane type sludge concentration tank 2, and the shape of the filtration membrane type sludge concentration tank 2 may be either a tank with an open top surface or a tank with a closed structure. An open tank with a simple structure is preferred. In addition, the filtration membrane device 5 provided therein is a microfiltration having a filter body on the surface of the nonwoven fabric molded body and having a pore diameter of 0.1 to several μ such as cellulose acetate type, aromatic polyamide type and polysphonic type. A membrane or an ultrafiltration membrane with a molecular weight cut off of several tens of thousands to several hundred thousand or a dynamic membrane module consisting only of a nonwoven fabric molded body is used. Is preferred.
[0019]
Further, the shape of the filter body is preferably a flat membrane shape in which a plurality of flat membranes having a disk shape or a rectangular plate shape are arranged at predetermined intervals in the horizontal direction, but may be cylindrical, and the present invention is not limited thereto. Not. Further, although not shown, an air diffuser that diffuses gas into the liquid passage to be treated is disposed below the filter body of the filter membrane device 5.
[0020]
The solubilization treatment tank 3 is a treatment tank for solubilizing sludge by subjecting the concentrated sludge concentrated in the sludge concentration step to high temperature aerobic biological treatment, and may be either a tank having an open upper surface or a tank having a closed structure. In order to increase the heating effect and the deodorizing effect, a sealed structure tank is preferred.
[0021]
The solubilization tank 3 preferably has a jacket 7 structure on the outer surface and a structure in which steam, hot water, etc. are circulated inside the jacket 7 to heat the tank. Or the structure attached to the exterior and heating may be sufficient. Further, in the solubilization treatment tank 3, a diffuser means 6 for blowing air or high-concentration oxygen is provided at the lower part, and an agitating means 8 is provided at the axial center. Moreover, since the contact efficiency of oxygen and sludge increases by filling the biological support | carrier so that it can flow in the solubilization processing tank 3 and making it a fluid bed type tank, a further solubilization process can be performed. In addition, as the inoculum, it is preferable to use sludge generated from another same apparatus, but compost sludge can also be used.
[0022]
Fig. 2 shows the formation of a fluidized bed with microbial particles that are self-granulated anaerobic methanogens, and the raw water is circulated in an upward flow to decompose organic matter in the raw water by the biological action of the methanogens. The UASB treatment tank 10 for the UASB treatment process is provided, and the activated sludge treatment tank 1a for the activated sludge treatment process is provided in the latter stage. FIG. 3 shows the excess sludge generated in the biological treatment process, etc. Anaerobic digestion process that decomposes organic matter in sludge into methane gas, carbon dioxide gas, etc. by biological action of anaerobic microorganisms by supplying sludge into an aerobic microorganism and aeration with anaerobic gas The anaerobic digester 11 is provided.
[0023]
A method for treating organic wastewater with the apparatus having the above-described configuration will be described in detail below. In the method of providing the activated sludge treatment tank 1 as the biological treatment process of FIG. 1, the raw water of the organic wastewater supplied to the activated sludge treatment tank 1 from the raw water supply pipe a is activated sludge which is an aerobic microorganism. By floating and aerated with air, organic matter in the raw water is oxidatively decomposed by the biological action of activated sludge. The MLSS in this activated sludge treatment is generally 1000 to 20000 mg / L.
[0024]
The sludge mixed liquid, which is a low-concentration sludge treated in the biological treatment process, is supplied to the subsequent sedimentation tank 4 from the sludge mixed liquid discharge pipe b, but a part of the filtration membrane in the sludge concentration process from the sludge mixed liquid supply pipe c. The sludge is supplied to the type sludge concentration tank 2 and concentrated. The MLSS of the concentrated sludge subjected to the concentration treatment is 30,000 to 100,000 mg / L, and the concentrated sludge is supplied from the concentrated sludge supply pipe d to the solubilization treatment tank 3 in the sludge volume reduction treatment step and filtered through the filtration membrane. Water is discharged out of the system from the filtered water discharge pipe f as treated water. In addition, when MLSS of sludge is 30000-100000 mg / L, an apparatus can be reduced in size and a solubilization process can also be performed efficiently.
[0025]
The sludge mixed solution supplied to the settling tank 4 is settled and separated, and the supernatant water is discharged out of the system from the treated water discharge pipe h as treated water, and the precipitated sludge maintains the sludge concentration in the activated sludge treatment tank 1. Therefore, it is circulated from the sedimentation sludge supply pipe g. In addition, instead of the sludge mixed solution supplied to the filtration membrane type sludge concentration tank 2, a branch pipe is provided in the settling sludge supply pipe g, and the branch pipe is connected to the filtration membrane type sludge concentration tank 2 to activate the activated sludge treatment tank. You may supply a part of sedimentation sludge which is the low concentration sludge circulated to 1.
[0026]
The concentrated sludge supplied to the solubilization tank 3 is solubilized by the biological oxidizing action of the high temperature aerobic organism with the liquid temperature maintained at 55 to 80 ° C. and the residence time being 12 to 72 hours. . As a result, 10 to 40 vol% of the sludge is liquefied and the solubilized sludge is circulated from the solubilized sludge supply pipe e in the sludge circulation process to the activated sludge treatment tank 1 so that the liquefied organic matter is once again biological. Thus, the sludge itself can be easily settled and the filtration membrane is not easily clogged. In addition, by maintaining the liquid temperature at 55 to 80 ° C. and solubilizing, the activated sludge microorganisms that grow at room temperature can be sterilized, and the microorganisms that grow at high temperatures can be preferentially propagated, and sludge can be efficiently produced. It can be liquefied.
[0027]
In the wastewater treatment method in which the activated sludge treatment tank 1a is provided at the subsequent stage of the UASB treatment tank 10 in FIG. 2, the sludge from the activated sludge treatment tank 1a is supplied to the filtration membrane sludge concentration tank 2 in the sludge concentration step. The sludge is concentrated, the concentrated concentrated sludge and the excess self-granulated sludge from the UASB treatment process are supplied to the solubilization tank 3 of the sludge volume reduction process, and the filtered water that has passed through the filtration membrane is treated. It is discharged out of the system as water. The concentrated sludge supplied to the solubilization tank 3 is solubilized by biological oxidation of high-temperature aerobic organisms to liquefy 10 to 40 vol% of the sludge, and the solubilized sludge is removed from the sludge circulation step. By circulating to the activated sludge treatment tank 1a, the liquefied organic matter is treated again by biological action, and finally 20-50 vol% of the sludge is reduced in volume.
[0028]
In the wastewater treatment method in which an anaerobic digestion tank 11 for anaerobically digesting surplus sludge generated in the biological treatment process of FIG. 3 is provided, the excess sludge from the biological treatment process is sludge concentrated. The sludge is supplied to the filtration membrane sludge concentration tank 2 in the process, and the sludge is concentrated. The concentrated sludge and the circulating sludge from the anaerobic digestion tank 11 in the anaerobic digestion process are solubilized in the sludge volume reduction process. The filtered water supplied to the tank 3 and permeated through the filtration membrane is discharged out of the system as treated water. The concentrated sludge supplied to the solubilization tank 3 is solubilized by biological oxidation of high-temperature aerobic organisms to liquefy 10 to 40 vol% of the sludge, and the solubilized sludge is removed from the sludge circulation step. By circulating to the anaerobic digestion tank 11, the liquefied organic matter is treated again by biological action, and finally 20-50 vol% of the sludge is reduced.
[0029]
The said sludge concentration process and solubilization process process are further explained in full detail with FIG. The sludge supplied to the sludge concentration tank 2 is filtered by the filtration membrane reduced in pressure by the filtration membrane device 5 provided inside the sludge concentration tank 2, and the filtrate water that has permeated the filtration membrane is discharged as treated water. The concentrated sludge discharged out of the system from the pipe f and concentrated on the non-permeate side is supplied from the concentrated sludge supply pipe d to the solubilization treatment tank 3 in the sludge volume reduction treatment process.
[0030]
The concentrated sludge supplied to the solubilization treatment tank 3 is heated by circulating steam and hot water through the jacket 7 and heating the treatment tank, and is stirred by the stirrer 8 and is also air and high concentration from the air diffuser 6. Oxygen is supplied, the liquid temperature is maintained at 55 to 80 ° C., the residence time is 12 to 72 hours, and solubilization is performed by the biological oxidizing action of the high temperature aerobic organism. Excess gas is exhausted from the exhaust pipe j. Thereby, 10 to 40 vol% of the sludge was liquefied and liquefied by circulating the solubilized sludge from the solubilized sludge supply pipe e in the sludge circulation step to the activated sludge treatment tank 1 or the like in the biological treatment step. The organic matter is treated again by biological action, and finally, 20 to 50 vol% of the sludge is reduced, and the sludge itself can easily be settled to make it difficult to clog the filtration membrane.
[0031]
The Example which processed the organic waste water using the sludge volume reduction processing method of one embodiment of this invention below is explained in full detail.
[0032]
(Example 1)
Using the apparatus of FIG. 1, food-based organic wastewater (BOD: 1400 mg / L) is supplied to the activated sludge treatment tank and processed, and a sludge mixed solution having MLSS of 1000 to 20000 mg / L is supplied to the sludge concentration tank. A concentrated sludge having an MLSS concentration of 40,000 to 60,000 mg / L was obtained. The concentrated sludge was supplied to a solubilization tank and solubilized at a liquid temperature of 60 ° C. for 24 hours. As a result, 10-40 vol% of the sludge was liquefied. The solubilized sludge was circulated to the activated sludge treatment tank and biologically treated again. As a result, 20 to 50 vol% of the sludge was finally reduced, and surplus sludge withdrawn from the settling tank was hardly generated. Moreover, the treated water which is the supernatant water of the precipitation tank had a BOD of 10 mg / L or less.
[0033]
【The invention's effect】
The present invention is a method of reducing sludge volume by installing equipment for relatively small and easy operation, reducing sludge that can reduce operating costs and equipment costs, and reduce final disposal costs. This is a treatment method.
In invention of Claim 1, it filters with the filter membrane of a sludge concentration process, obtains concentrated sludge, solubilizes concentrated sludge, and circulates in a biological treatment process, 20-50 vol% of sludge is obtained. Volume can be reduced.
[0034]
In invention of Claim 2, in the sludge volume reduction processing method of Claim 1, a biological treatment process is an activated sludge treatment process, and low concentration organic sludge is sludge from an activated sludge treatment process. The surplus sludge discharged from the activated sludge treatment process can be almost eliminated.
[0035]
In the invention described in claim 3, in the wastewater treatment method in which the activated sludge treatment process is provided after the UASB treatment process, the sludge in the activated sludge treatment process is filtered by the filtration membrane of the sludge concentration process and concentrated. By obtaining sludge, solubilizing the concentrated sludge and surplus self-granulated sludge from the UASB treatment step, and circulating in the biological treatment step, the volume of sludge can be reduced by 20 to 50 vol%.
[0036]
In the invention according to claim 4, in the wastewater treatment method in which an anaerobic digestion step is provided after the biological treatment step, the sludge in the activated sludge treatment step is filtered through a filtration membrane in the sludge concentration step and concentrated. By obtaining sludge and solubilizing the concentrated sludge and the circulating sludge from the anaerobic digestion process and circulating them to the biological treatment process, the volume of sludge can be reduced by 20 to 50 vol%.
[0037]
In invention of Claim 5, MLSS of the sludge concentrated by the sludge concentration process by the sludge volume reduction processing method of any one of Claims 1-4 is 30000-100000 mg / L. As a result, the apparatus can be miniaturized and the solubilization process can be performed efficiently.
[0038]
In invention of Claim 6, in the sludge volume reduction processing method of any one of Claims 1-5, when the liquid temperature of a solubilization process is 55-80 degreeC, The apparatus can be miniaturized and solubilization can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a system diagram of an activated sludge treatment apparatus according to an embodiment of the present invention. FIG. 2 is a system diagram of a UASB treatment apparatus according to another embodiment of the present invention. Fig. 4 is a system diagram of an anaerobic digestion treatment apparatus in the form of the present invention.
1: Activated sludge treatment tank 2: Filtration membrane type sludge concentration tank 3: Solubilization treatment tank 4: Precipitation tank 5: Filtration membrane device 6: Aeration means 7: Jacket 8: Stirrer 10: UASB treatment tank 11: Anaerobic digestion Tank

Claims

A part of the low-concentration organic sludge from the biological treatment process is filtered with a filtration membrane in a separate process from the sedimentation separation process in the sedimentation tank that concentrates the low-concentration organic sludge from the biological treatment process by sedimentation separation. The sludge concentration process to obtain concentrated sludge and clarified water, the solubilization process to solubilize sludge by high-temperature aerobic biological treatment of the concentrated sludge concentrated in the sludge concentration process, and biological treatment of the solubilized sludge A sludge volume reduction method characterized by providing a sludge circulation step for circulation to the process.

The sludge volume reduction processing method according to claim 1, wherein the biological treatment step is an activated sludge treatment step, and the low-concentration organic sludge is sludge from the activated sludge treatment step.

In a wastewater treatment method in which an activated sludge treatment process is provided after the UASB treatment process, the sludge concentration process in which sludge from the activated sludge treatment process is filtered through a filtration membrane to obtain concentrated sludge and clarified water, and sludge concentration. Solubilized sludge concentrated in the process and surplus self-granulated sludge from the UASB treatment process treated with high-temperature aerobic biological treatment to solubilize sludge, and activated sludge treatment equipment for the solubilized sludge The sludge volume reduction processing method characterized by providing the sludge circulation process circulated in the inside.

In a wastewater treatment method in which an anaerobic digestion step is provided after the biological treatment step, the sludge concentration step in which sludge from the biological treatment step is filtered through a filtration membrane to obtain concentrated sludge and clarified water, and the sludge concentration step Concentrated sludge and solubilized sludge that solubilizes sludge by high-temperature aerobic biological treatment of concentrated sludge and anaerobic digestion process from anaerobic digestion process, and sludge that circulates solubilized sludge to anaerobic digestion process A sludge volume reduction method characterized by providing a circulation step.

The sludge volume reduction processing method according to any one of claims 1 to 4, wherein MLSS of the sludge concentrated in the sludge concentration step is 30,000 to 100,000 mg / L.

The liquid temperature of a solubilization process process is 55-80 degreeC, The sludge volume reduction processing method of any one of Claims 1-5.