JP3831002B2

JP3831002B2 - High concentration organic waste liquid treatment apparatus and method

Info

Publication number: JP3831002B2
Application number: JP4270096A
Authority: JP
Inventors: 英樹横山; 健治桂; 雅彦三浦; 進長谷川
Original assignee: Kobelco Eco Solutions Co Ltd
Current assignee: Shinko Pantec Co Ltd
Priority date: 1996-02-29
Filing date: 1996-02-29
Publication date: 2006-10-11
Anticipated expiration: 2016-02-29
Also published as: JPH09234495A

Description

【０００１】
【発明の属する技術分野】
本発明は、有機性汚泥、例えば、下水処理場、屎尿処理場などの下水処理プロセスから排出される生汚泥及び生物性汚泥、食品工場、化学工場などの排水処理プロセスなどから排出される有機性高濃度汚泥などの、生物分解性有機性固形物を含む、高濃度有機性廃液の処理装置及び処理方法に関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
従来より、でんぷん工場廃液、ビール工場廃液、酸発酵廃液等の生物分解性有機性固形物を含む高濃度有機性廃液を処理する場合には、活性汚泥法などの好気性消化処理も可能であるが、通常、省エネルギー、創エネルギーの観点より、メタン発酵によりメタン等のガスに転換する嫌気性消化方法が採用されている。
【０００３】
好気性消化処理方法の最大の問題点は大量の余剰汚泥発生にあり、この発生量を抑制すべく種々の努力がなされているが、コスト、安全性、所要時間、労力などの種々の面からかかる問題点を充分に満足できるまで解決することのできた方法は見出されえない。
【０００４】
メタン発酵による嫌気性消化は、上向流嫌気性汚泥床処理装置(以下「UASB」と称する)及び固定床式処理装置などにおいて行われる。UASBは、微生物の自己造粒作用を利用して形成されたグラニュールによって処理する装置である。このUASBでは、投入される有機性廃液に固形分が多量に含まれるとグラニュールが固形物に同伴して流出してしまい、グラニュールを系内に維持できない場合があるので、通常は高濃度有機性廃液を沈殿槽で分離した後の上澄液が処理対象とされる。しかしながらこの場合、沈殿槽で沈殿分離した有機性固形物を含む沈殿固形物濃縮液（汚泥）の、濃縮、消化、脱水、コンポスト化及び焼却といった工程を経る処理に手間や費用を要するので好ましくなかった。従って、有機性廃液に固形分が多量に含まれる場合の嫌気性消化には固定床式処理装置が汎用される。固定床式処理装置は、ビーズなどの担体に微生物を固定して処理する装置であるが、槽内廃液の線流速が極端に遅いために、沈降性の高い固形物が担体の間隙に捕捉されて目詰まりを起こし、液体分の通路を塞いでしまいがちである。この目詰まり箇所が増えるに伴って液体分の通路が減少し、目詰まりのない箇所しか液体分が流れなくなり、液体と担体との接触が十分に行われなくなる「液体分の短絡現象」が生じることとなる。この液体分の短絡現象のためにメタン発酵槽での廃液の滞留時間が短くなり処理効率の極端な低下が惹起こされる。そこで目詰まりを解消するために逆洗などが行われるが、逆洗には多大な経費や時間が必要とされるという現状にある。
【０００５】
このため、有機性固形物含有廃液を熱アルカリ法や酵素添加法などの物理化学的方法によって可溶化する方法も提案されてはいるが、薬品費用などが嵩んでかえってコスト高となり、好ましいとはいえない。
【０００６】
そこで、本発明者らは、生物分解性有機性固形物を含む高濃度有機性廃液を処理する場合に、有機性廃液に含まれる固形分を可溶化処理することにより、接触効率が良好で処理能の高いUASBを用いた処理に好適な、高濃度有機性廃液の嫌気性消化処理方法及びそのための処理装置を提案した（特願平７−１５７８７５号）。さらに特願平７−１５７８７５号によれば、生物分解性有機性固形物を含む高濃度有機性廃液の処理に際して有機性廃液に含まれる固形分を可溶化処理することにより、固定床式処理装置を用いる場合に少ない逆洗頻度にて処理することが可能となった。
【０００７】
しかしながら、特願平７−１５７８７５号の発明では、沈殿槽で得られた沈殿固形物濃縮液に高濃度の有機性可溶化物が含まれる場合には、可溶化槽に有機性可溶化物が多量に流入することとなる結果、可溶化工程においてかかる可溶化物を栄養源とする微生物の増殖が活発に行われ、菌体量の増大が惹起こされる。従って、可溶化が高率に行われたとしても、菌体量が増大するに伴い有機性固形物の除去率は低値に抑えられてしまうという問題点があった。また、本来は嫌気性消化装置で処理されるべき有機性可溶化物が可溶化槽へ流入して、可溶化槽において分解されるために、消化処理に至る有機物が減少し、消化処理槽でのメタン生成量やエネルギー発生量が低減するという望ましくない結果も生じていた。
【０００８】
【課題を解決するための手段】
本発明の高濃度有機性廃液の処理装置及び方法は、前記の課題を達成するために成し遂げられたものであって、下記の（１）〜（１１）をその要旨とする。
【０００９】
（１）有機性固形物を含む高濃度有機性廃液の処理装置であって、
有機性固形物含有廃液を沈殿分離するための沈殿槽、
該沈殿槽で沈殿した有機性固形物を含む沈殿固形物含有液Ａをさらに固液分離するための機械的分離手段、
該機械的分離手段で得られる有機性可溶化物含量の少ない有機性固形物濃縮液Ｃを高温条件で可溶化処理するための可溶化槽、
及び前記沈殿槽で得られる有機性固形物の少ない上澄液ｂ及び／または前記機械的分離手段により得られる有機性可溶化物溶液ｄを消化処理するための上向流嫌気性汚泥床処理装置を含み、前記可溶化槽で得られる可溶化処理液Ｅが該上向流嫌気性汚泥床処理装置に導入されるように構成されていることを特徴とする高濃度有機性廃液の処理装置。
【００１０】
（２）有機性固形物含有廃液とともに、前記可溶化槽で得られる可溶化処理液が前記沈殿槽にて沈殿分離されるように構成された、前記（１）の高濃度有機性廃液の処理装置。
【００１２】
（３）前記機械的分離手段で得られる有機性固形物濃縮液Ｃを前記可溶化槽で得られる可溶化処理液によって加温するための熱交換器が、前記機械的分離手段から前記可溶化槽に至る還流経路にさらに設けられた、前記（１）または（２）記載の高濃度有機性廃液の処理装置。
【００１４】
（４）前記上向流嫌気性汚泥床処理装置で発生したメタンガスを燃焼するためのメタンガス燃焼装置、及び、該メタンガス燃焼装置で生じた熱によって前記可溶化槽を加温するための加温経路をさらに含む、前記（１）から（３）のいずれかに記載の高濃度有機性廃液の処理装置。
【００１６】
（５）前記機械的分離手段が遠心分離器である、前記（１）から（４）のいずれかに記載の高濃度有機性廃液の処理装置。
【００１７】
（６）有機性固形物を含む高濃度有機性廃液の処理方法であって、有機性固形物含有廃液を沈殿槽にて沈殿分離する工程、該沈殿分離工程で沈殿した有機性固形物を含む沈殿固形物含有液Ａをさらに固液分離するための機械的分離手段での機械的分離工程、該機械的分離工程で得られる有機性可溶化物含量の少ない有機性固形物濃縮液Ｃを高温条件で可溶化処理するための可溶化槽における可溶化工程、及び前記沈殿工程で得られる有機性固形物の少ない上澄液ｂ及び前記機械的分離工程で得られる有機性可溶化物溶液ｄを消化するための上向流嫌気性汚泥床処理装置における消化処理工程を含み、前記可溶化工程で得られる可溶化処理液が該消化処理工程に付されることを特徴とする高濃度有機性廃液の処理方法。
【００１８】
（７）有機性固形物含有廃液とともに、前記可溶化工程で得られる可溶化処理液が前記沈殿槽にて沈殿分離される、前記（６）記載の高濃度有機性廃液の処理方法。
【００２０】
（８）前記機械的分離工程で得られる有機性固形物濃縮液が、前記可溶化工程で得られる可溶化処理液によって加温される、前記（６）または（７）記載の高濃度有機性廃液の処理方法。
【００２２】
（９）前記消化処理工程において発生したメタンガスを燃焼するためのメタンガス燃焼工程をさらに含み、該メタンガス燃焼工程で生じた熱によって前記可溶化槽が加温される、前記（６）から（８）のいずれかに記載の高濃度有機性廃液の処理方法。
【００２４】
（１０）前記機械的分離手段が遠心分離である、前記（６）から（９）のいずれかに記載の高濃度有機性廃液の処理方法。
【００２５】
（１１）前記可溶化工程が５０〜９０℃の温度範囲となるような条件下で行われる、前記（６）から（１０）のいずれかに記載の高濃度有機性廃液の処理方法。
【００２６】
すなわち、本発明者らは鋭意研究を行った結果、有機性固形物含有廃液を沈殿槽にて分離して沈殿固形物含有液を得た後、さらに、機械的分離手段によって有機性可溶化物溶液と有機性固形物濃縮液に分離し、可溶化槽にてその有機性固形物濃縮液を処理する構成とすることにより、可溶化槽に流入する有機性可溶化物を可能な限り少量となるようにすれば、有機性固形物除去率が格段に向上することを知見して、本発明を完成したものである。本発明者らはまた、このように可溶化槽に流入する有機性可溶化物の量を減じれば、消化処理に付される有機物量を高値に保つことが可能となるので、嫌気性消化処理を行った場合に消化処理槽でのメタン生成量やエネルギー発生量を高めうることを見出して、本発明を完成した。
【００２７】
以下の発明の実施の形態において、図面を参照しつつ本発明の高濃度有機性廃液の処理装置及び方法の実施態様を説明するが、本発明はもとよりこれらの実施態様に限定されるものではない。
【００２８】
【発明の実施の形態】
本発明においては、有機性汚泥、例えば、下水処理場、屎尿処理場などの下水処理プロセスから排出される生汚泥及び生物性汚泥、または食品工場、化学工場などの排水処理プロセスから排出されるでんぷん工場廃液、ビール工場廃液、酸発酵廃液等の、生物分解性有機性固形物を含む高濃度有機性廃液が処理の対象とされる。
【００２９】
本発明の第１の実施態様の概略図である図１に示すように、有機性固形物含有廃液は沈殿槽1に導入され、ここで沈殿分離により得られる有機性固形物の少ない上澄液ｂは、廃棄先に応じた基準値にまで適宜処理した後、下水または河川などに放流することができる。
【００３０】
一方、前記沈殿槽1において沈殿分離した沈殿固形物含有液Ａは、機械的分離手段2に供され、固液分離が行われた結果、有機性可溶化物溶液ｄと有機性固形物濃縮液Ｃとが得られる。機械的分離手段2は、前記沈殿固形物含有液Ａから有機性可溶化物をできる限り除去しうる手段であればよく、遠心分離、膜分離、重力分離、常圧浮上濃縮、加圧浮上濃縮、砂濾過逆洗及びそれらの組合せよりなる群より選択されるが、特に遠心分離が好適に採用される。遠心分離は、例えば1,000〜2,000 × gにて3〜10分間実施されるとよい。
【００３１】
前記機械的手段2において得られた有機性可溶化物溶液ｄは、前記沈殿槽1で得られた上澄液ｂと共に処理に付され放流、廃棄しうる。一方、有機性固形物濃縮液Ｃは、還流経路21を介して可溶化槽3に導入され、高温条件で嫌気的または好気的微生物反応により、固形物の可溶化が行われる。この高温条件において用いられる嫌気性または好気性微生物（好熱菌）は、例えば、従来の好気性もしくは嫌気性消化槽または下水処理場活性汚泥の余剰汚泥由来の微生物などを培養することによって得ることができる。
【００３２】
可溶化槽3は、好ましくは、50〜90℃の温度範囲で操作するとよいが、かかる条件はその処理対象である有機性固形物濃縮液Ｃ中に含まれる有機性固形物の種類及び濃度ならびに該固形物を分解する微生物の種類に依存して変動可能である。例えば、下水余剰汚泥から分離した微生物を用いる場合には、可溶化反応と熱による物理化学的な熱分解の双方が同時に効率良く充分に生じうるように、60〜80℃の範囲、好ましくは約70℃にて操作するとよい。可溶化の時間は、可溶化対象となる有機性固形物の分解性、濃度、達成すべき可溶化率などに応じて選択すべきであるが、好ましくは6〜48時間、最も好ましくは約24時間程度行う。可溶化は常圧下で撹拌しながら行うとよい。基本的に、可溶化槽3の操作条件は、微生物による可溶化反応と熱による物理化学的な熱分解の双方が同時に効率良く充分に生じうるように設定することが好ましい。
【００３３】
可溶化槽3において好気的に可溶化を行うためには、従来の曝気装置及び撹拌手段を備えることができる。また嫌気的な可溶化に際しては、(1)槽内の液を循環することによる攪拌手段、(2)生成ガスの循環曝気による攪拌手段、(3)攪拌翼などの攪拌機による撹拌手段、または(4)活性微生物固定手段を配するなど、処理対象に含まれる有機性固形物と微生物とを効率的に接触させるための手段を具備したものが使用可能である。可溶化槽3としては、バッチ式及び連続方式のいずれでも使用できる。
【００３４】
このように、可溶化槽3で可溶化された可溶化処理液Ｅは、有機性固形物含有廃液とともに沈殿槽1に導入後沈殿分離され、その後、これまでに記載した処理工程がサイクルとして繰り返され、固形物が所望の程度にまで減容化される。
【００３５】
また、有機物の分解に伴い系内に生物難分解性固形物又は無機性固形物が蓄積する場合には、前記サイクルを経た後に沈殿槽1で沈殿分離した有機性固形物を含む沈殿固形物含有液Ａの一部である汚泥Ｆを、排出経路23を介して適宜排出し、濃縮及び脱水処理を行った後、別途廃棄してもよい。この場合、排出経路23から排出される汚泥Ｆは、可溶化槽3を通過たものであるために、概して溶存ガスが少なく沈降性の優れた汚泥であるので、濃縮及び脱水処理を容易に行うことができる。
【００３６】
図示しないが、可溶化槽3における可溶化が充分に行われて可溶化処理液中の固形分が所望の濃度にまで減容化された場合には、沈殿槽1に戻さずに、前記上澄み液ｂ及び有機性可溶化物溶液ｄと共に処理に付し、放流、廃棄することができる。
【００３７】
図２には、図１に示した実施態様に加え、沈殿槽1での沈殿分離により得られる有機性固形物の少ない上澄液ｂ及び有機性可溶化物溶液ｄ及び／または可溶化処理液Ｅを消化するための消化処理装置4、ならびに、有機性固形物濃縮液Ｃを昇温するため熱交換器5を含む、本発明の第２の実施態様の概略を示す。
【００３８】
消化処理装置4は、例えば活性汚泥法などを行う好気性消化処理装置、またはメタン発酵などを行う嫌気性消化処理装置（UASB及び固定床式処理装置等）に代表され、消化が充分に行われるものであればよいが、特に、メタンガスとしてエネルギーを回収することができる嫌気性消化処理装置が好ましい。消化処理装置4において好気的な反応を行う場合は、旧来の曝気手段を具備すればよく、他の撹拌手段を備えてもよい。消化処理装置4もまた、バッチ式または連続式のいずれでも使用可能である。
【００３９】
さらに、図２に記載の実施態様では、機械的分離手段2により得られる有機性固形物濃縮液Ｃを、可溶化処理液Ｅを用いて昇温するための熱交換器5が具備されている。有機性固形物濃縮液Ｃは、還流経路21に設けられた熱交換器5を経由して昇温された後に、可溶化槽3に導入され、ここで可溶化された可溶化処理液Ｅは前記と同様のサイクル処理に付される。このような構成とすることによって、熱損失が抑制されるという好ましい効果が達成される。
【００４０】
また、消化処理装置4にUASBや固定床式処理装置を採用して嫌気的にメタン発酵を行う場合、消化処理装置4で発生したメタンガスをメタンガス燃焼装置6に導入し、メタンガスを燃焼することにより生じる熱を、加温経路22を介して可溶化槽3に導いて可溶化槽3を加温するような構成とすることができる。メタンガス燃焼装置6としては、特に限定されるものではなく、通常のガスバーナーを具備した自然通風式炉内燃焼型燃焼塔などの燃焼装置が使用可能である。このような構成により、可溶化槽3で放出されるエネルギーが嫌気性消化処理によって発生するメタンの燃焼エネルギーで補充されることになるので、非常に良好なエネルギー効率となる。
【００４１】
【実施例】
（実施例）
でんぷん工場廃液を処理対象の有機性固形物含有廃液として用い、沈殿槽にて30分間沈殿分離（沈殿率SV30＝10％）して、沈殿固形物含有液（固形物濃度SS＝1.3％、揮発性有機物質含有割合VSS/SS＝98％）を得た。この沈殿固形物含有液を3,000 rpm（1,300 × g）にて5分間遠心分離することにより得られた有機性固形物濃縮液を水道水で希釈して有機性固形物濃度を1％に調整した液体を、可溶化処理の材料として用いた。
【００４２】
内径100mm、高さ1mの耐熱塩化ビニル製の熱媒を循環させるジャケット方式の円筒型反応槽に前記調整済みの液体を導入し、温度70℃、通気量0.1vvm、反応液量4Lで運転した。反応槽における水理学的滞留時間が５日になるよう、液体を連続的に供給し、その後最終的な有機性固形物及び全有機物の除去率を測定した。
【００４３】
（比較例）
比較例として、前記沈殿固形物含有液を沈殿上澄液で有機性固形物濃度が1％となるように調整した液体を用い、実施例と同様の処理を行った。
【００４４】
有機性固形物濃縮液（実施例の可溶化材料）及び沈殿固形物含有液（比較例の可溶化材料）双方の、有機性可溶化物及び有機性固形物の含有濃度を表１に示す。
【００４５】
【表１】

【００４６】
表１より、沈殿固形物含有液を遠心分離することにより得られる有機性固形物濃縮液中の有機性可溶化物濃度は、8.0 g/lから2.5 g/lになり、約30％程度にまで減じられることが示された。
【００４７】
次に、実施例及び比較例における有機性固形物及び全有機物の除去率の測定結果を表２に示す。
【００４８】
【表２】

【００４９】
表２より明らかなように、実施例では比較例よりも有機性固形物の除去率が26ポイント上昇した。従って、本発明の方法を採用して沈殿固形物含有液中の有機性可溶化物を低減させることで、反応槽内で有機性可溶化物を栄養源として生育する微生物の増殖が抑制された結果、良好な有機性固形物の除去が達成されることが示唆された。
【００５０】
また、全有機物の除去率は実施例と比較例とで大差はないが、有機物含有量は比較例の方が50％程度高いため、除去（ガス化）された有機物の絶対量は比較例の方が高いので、反応に伴って比較例の槽で増殖した生物によって、固形物除去率に負の効果がもたらされたものと考えられる。
【００５１】
【発明の効果】
本発明の高濃度有機性廃液の消化処理装置及び方法は、有機性固形物含有廃液を沈殿槽にて分離して沈殿固形物含有液を得た後、さらに、機械的分離手段によって有機性可溶化物溶液と有機性固形物濃縮液に分離し、可溶化槽においてその有機性固形物濃縮液を処理する構成としたので、以下のような顕著で特有な作用効果を奏する極めて優れた発明である。
【００５２】
（１）可溶化槽に流入する有機性可溶化物を可能な限り少量となるようにすることによって、かかる有機性可溶化物を栄養源として生育する微生物の可溶化槽内における増殖が抑制され、従って、有機性固形物除去率が格段に向上する。
【００５３】
（２）このように可溶化槽に流入する有機性可溶化物の量を減じれば、可溶化槽における過剰の有機物除去には至らないので、消化処理に付される有機物量を高値に保つことが可能となり、嫌気性消化処理を行う場合のメタン生成量やエネルギー発生量を高めうる。
【図面の簡単な説明】
【図１】図１は、本発明の高濃度有機性廃液の消化処理装置及び方法の第１の実施態様の概略を示す図である。
【図２】図２は、本発明の高濃度有機性廃液の消化処理装置及び方法の第２の実施態様の概略を示す図である。
【符号の説明】
１・・・沈殿槽
２・・・機械的分離手段
３・・・可溶化槽
４・・・消化処理装置
５・・・熱交換器
６・・・メタンガス燃焼装置
２１・・・還流経路
２２・・・加温経路
２３・・・排出経路
Ａ・・・沈殿固形物含有液
ｂ・・・上澄液
Ｃ・・・有機性固形物濃縮液
ｄ・・・有機性可溶化物溶液
Ｅ・・・可溶化処理液
Ｆ・・・汚泥[0001]
BACKGROUND OF THE INVENTION
The present invention relates to organic sludge, for example, raw sludge discharged from sewage treatment processes such as sewage treatment plants and sewage treatment plants, biological sludge, organic waste discharged from wastewater treatment processes such as food factories and chemical factories. The present invention relates to a treatment apparatus and treatment method for high concentration organic waste liquid containing biodegradable organic solids such as high concentration sludge.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, when processing high concentration organic waste liquid containing biodegradable organic solids such as starch factory waste liquid, beer factory waste liquid, acid fermentation waste liquid, etc., aerobic digestion treatment such as activated sludge process is also possible. However, from the viewpoint of energy saving and energy creation, an anaerobic digestion method is generally adopted in which the gas is converted into a gas such as methane by methane fermentation.
[0003]
The biggest problem of the aerobic digestion treatment method is the generation of a large amount of excess sludge, and various efforts have been made to suppress this generation amount, but from various aspects such as cost, safety, required time, and labor. No method could be found that could solve such problems until they were fully satisfied.
[0004]
Anaerobic digestion by methane fermentation is performed in an upflow anaerobic sludge bed treatment device (hereinafter referred to as “UASB”), a fixed bed treatment device, or the like. The UASB is a device for processing with granules formed by utilizing the self-granulating action of microorganisms. In this UASB, if the organic waste liquid to be added contains a large amount of solids, the granules may flow out with the solids, and the granules may not be maintained in the system. The supernatant liquid after separating the organic waste liquid in the sedimentation tank is treated. However, in this case, it is not preferable because it requires labor and cost for the processing of the concentrated solid solution (sludge) containing the organic solid precipitated and separated in the settling tank through the steps of concentration, digestion, dehydration, composting and incineration. It was. Therefore, a fixed bed processing apparatus is widely used for anaerobic digestion when the organic waste liquid contains a large amount of solids. A fixed bed processing device is a device that fixes and processes microorganisms on a carrier such as a bead, but because the linear flow rate of waste liquid in the tank is extremely slow, solid matter with high sedimentation is trapped in the gap between the carriers. This can cause clogging and block the liquid passage. As the number of clogged portions increases, the liquid passage decreases, and the liquid portion flows only in the clogged portions, resulting in a “liquid short circuit phenomenon” in which contact between the liquid and the carrier is not sufficiently performed. It will be. Due to the short circuit phenomenon of the liquid, the residence time of the waste liquid in the methane fermentation tank is shortened, causing an extreme decrease in processing efficiency. In order to eliminate clogging, backwashing or the like is performed. However, backwashing requires a large amount of money and time.
[0005]
For this reason, a method of solubilizing organic solid-containing waste liquid by a physicochemical method such as a hot alkali method or an enzyme addition method has been proposed, but it is preferable because it increases the cost of the chemical and increases the cost. I can't say that.
[0006]
In view of this, the present inventors treated the solid content contained in the organic waste liquid with a good contact efficiency when treating the high concentration organic waste liquid containing the biodegradable organic solid. A high-concentration organic waste liquid anaerobic digestion treatment method suitable for treatment with high-performance UASB and a treatment apparatus therefor have been proposed (Japanese Patent Application No. 7-157875). Further, according to Japanese Patent Application No. 7-157875, a fixed-bed processing apparatus is provided by solubilizing a solid content contained in an organic waste liquid when processing a high concentration organic waste liquid containing a biodegradable organic solid. It is possible to process with less frequent backwashing when using.
[0007]
However, in the invention of Japanese Patent Application No. 7-157875, when a high concentration organic solubilizate is contained in the precipitated solid concentrate obtained in the precipitation tank, the organic solubilizate is contained in the solubilization tank. As a result of the inflow of a large amount, microorganisms using such a solubilizate as a nutrient source are actively propagated in the solubilization step, thereby causing an increase in the amount of cells. Therefore, even if the solubilization is performed at a high rate, there is a problem that the removal rate of the organic solid matter is suppressed to a low value as the amount of bacterial cells increases. In addition, the organic solubilizate that should be processed in the anaerobic digester flows into the solubilization tank and is decomposed in the solubilization tank. There was also an undesirable result that the amount of methane produced and the amount of energy generated were reduced.
[0008]
[Means for Solving the Problems]
The high concentration organic waste liquid treatment apparatus and method of the present invention have been accomplished in order to achieve the above-mentioned problems, and the following (1) to (11) are summarized.
[0009]
(1) A processing apparatus for high concentration organic waste liquid containing organic solids,
A sedimentation tank for separating and separating organic solid-containing waste liquid;
Mechanical separation means for further solid-liquid separation of the precipitated solid-containing liquid A containing the organic solid precipitated in the settling tank ;
Solubilization tank for solubilizing less organic solids concentrate C of organic solubilized matter content obtained in the mechanical separation means at high temperature,
And an upflow anaerobic sludge bed treatment apparatus for digesting the supernatant b with less organic solids obtained in the settling tank and / or the organic lysate solution d obtained by the mechanical separation means And a solubilization treatment liquid E obtained in the solubilization tank is introduced into the upward flow anaerobic sludge bed treatment apparatus.
[0010]
(2) The treatment of the high-concentration organic waste liquid according to (1), wherein the solubilization treatment liquid obtained in the solubilization tank is precipitated and separated in the precipitation tank together with the organic solid-containing waste liquid. apparatus.
[0012]
(3) A heat exchanger for heating the organic solid concentrate C obtained by the mechanical separation means with the solubilization treatment liquid obtained in the solubilization tank is solubilized from the mechanical separation means. The high-concentration organic waste liquid treatment apparatus according to (1) or (2) , further provided in a reflux path leading to a tank.
[0014]
(4) A methane gas combustion apparatus for combusting methane gas generated in the upward flow anaerobic sludge bed treatment apparatus , and a heating path for heating the solubilization tank by heat generated in the methane gas combustion apparatus The high concentration organic waste liquid processing apparatus according to any one of (1) to (3) , further including:
[0016]
(5) The high concentration organic waste liquid treatment apparatus according to any one of (1) to (4) , wherein the mechanical separation means is a centrifuge.
[0017]
(6) A method for treating a high-concentration organic waste liquid containing organic solids, comprising a step of precipitating and separating an organic solid-containing waste liquid in a precipitation tank, and an organic solid precipitated in the precipitation separation step mechanical separation step at the mechanical separation means for further solid-liquid separation of the precipitate solids containing liquid a, less organic solids concentrate C of organic solubilized matter content obtained in the mechanical separation process hot A solubilization step in a solubilization tank for solubilization treatment under conditions , and a supernatant b with less organic solids obtained in the precipitation step and an organic lysate solution d obtained in the mechanical separation step A high-concentration organic waste liquid comprising a digestion treatment step in an upflow anaerobic sludge bed treatment apparatus for digestion, wherein the solubilization treatment liquid obtained in the solubilization step is subjected to the digestion treatment step Processing method.
[0018]
(7) The method for treating a high-concentration organic waste liquid according to (6) , wherein the solubilized treatment liquid obtained in the solubilization step is precipitated and separated in the precipitation tank together with the organic solid-containing waste liquid.
[0020]
(8) The high-concentration organic material according to (6) or (7) , wherein the organic solid concentrate obtained in the mechanical separation step is heated by the solubilization treatment solution obtained in the solubilization step. Waste liquid treatment method.
[0022]
(9) before Symbol further comprising a methane combustion process for burning methane gas generated in digestion step, the solubilization tank is warmed by the heat generated in the methane combustion process, from the (6) ( The processing method of the high concentration organic waste liquid in any one of 8) .
[0024]
(10) The method for treating a high concentration organic waste liquid according to any one of (6) to (9) , wherein the mechanical separation means is centrifugation.
[0025]
(11) The method for treating a high concentration organic waste liquid according to any one of (6) to (10) , wherein the solubilization step is performed under a temperature range of 50 to 90 ° C.
[0026]
That is, as a result of earnest research, the present inventors separated the organic solid-containing waste liquid in a precipitation tank to obtain a precipitated solid-containing liquid, and further, an organic solubilizate by mechanical separation means. By separating the solution into an organic solid concentrate and treating the organic solid concentrate in a solubilization tank, the organic solubilization product flowing into the solubilization tank can be reduced as little as possible. As a result, the inventors have found that the organic solid removal rate is remarkably improved, and have completed the present invention. The present inventors can also keep the amount of organic matter subjected to digestion treatment at a high value by reducing the amount of organic solubilized product flowing into the solubilization tank. The present invention has been completed by finding that the amount of methane produced and the amount of energy produced in the digestion tank can be increased when the treatment is performed.
[0027]
In the following embodiments of the present invention, embodiments of the apparatus and method for treating highly concentrated organic waste liquid according to the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments. .
[0028]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, organic sludge, for example, raw sludge and biological sludge discharged from sewage treatment processes such as sewage treatment plants and manure treatment plants, or starch discharged from wastewater treatment processes such as food factories and chemical factories. High concentration organic waste liquids containing biodegradable organic solids such as factory waste liquids, beer factory waste liquids, and acid fermentation waste liquids are targeted for treatment.
[0029]
As shown in FIG. 1, which is a schematic diagram of the first embodiment of the present invention, an organic solid-containing waste liquid is introduced into a sedimentation tank 1, where a supernatant liquid with a small amount of organic solids obtained by precipitation separation is obtained. b can be discharged into sewage or a river after appropriately processing to a reference value according to the disposal destination.
[0030]
On the other hand, the precipitated solid-containing liquid A precipitated and separated in the precipitation tank 1 is supplied to the mechanical separation means 2 and subjected to solid-liquid separation. As a result, the organic solubilizate solution d and the organic solid concentrate C is obtained. The mechanical separation means 2 may be any means as long as it can remove the organic solubilizate from the precipitated solid-containing liquid A as much as possible. Centrifugation, membrane separation, gravity separation, atmospheric pressure levitation concentration, pressure levitation concentration , Selected from the group consisting of sand filtration backwash and combinations thereof, in particular, centrifugal separation is preferably employed. Centrifugation is preferably performed at 1,000 to 2,000 × g for 3 to 10 minutes, for example.
[0031]
The organic lysate solution d obtained in the mechanical means 2 can be subjected to treatment together with the supernatant b obtained in the precipitation tank 1 and discharged or discarded. On the other hand, the organic solid concentrate C is introduced into the solubilization tank 3 through the reflux path 21, and the solid is solubilized by an anaerobic or aerobic microbial reaction under high temperature conditions. The anaerobic or aerobic microorganisms (thermophilic bacteria) used in this high temperature condition can be obtained, for example, by culturing microorganisms derived from surplus sludge from conventional aerobic or anaerobic digesters or sewage treatment plant activated sludge. Can do.
[0032]
The solubilization tank 3 is preferably operated in the temperature range of 50 to 90 ° C., but such conditions are the type and concentration of the organic solid contained in the organic solid concentrate C to be treated, and It can vary depending on the type of microorganism that degrades the solid. For example, in the case of using a microorganism separated from sewage surplus sludge, a temperature range of 60 to 80 ° C., preferably about so that both the solubilization reaction and physicochemical thermal decomposition by heat can occur efficiently and sufficiently simultaneously. It is recommended to operate at 70 ℃. The solubilization time should be selected according to the decomposability, concentration, solubilization rate to be achieved, etc. of the organic solid to be solubilized, but is preferably 6 to 48 hours, most preferably about 24. Do about hours. Solubilization may be performed with stirring under normal pressure. Basically, it is preferable to set the operation conditions of the solubilization tank 3 so that both the solubilization reaction by microorganisms and the physicochemical thermal decomposition by heat can occur efficiently and sufficiently.
[0033]
In order to solubilize aerobically in the solubilization tank 3, a conventional aeration apparatus and stirring means can be provided. In anaerobic solubilization, (1) stirring means by circulating the liquid in the tank, (2) stirring means by circulating aeration of the product gas, (3) stirring means by a stirrer such as a stirring blade, or ( 4) Those equipped with means for efficiently bringing the organic solid matter contained in the treatment target into contact with the microorganisms, such as arranging active microorganism fixing means, can be used. As the solubilization tank 3, either a batch type or a continuous type can be used.
[0034]
Thus, the solubilized treatment liquid E solubilized in the solubilization tank 3 is introduced into the precipitation tank 1 together with the organic solid-containing waste liquid, and then separated by precipitation. Thereafter, the processing steps described so far are repeated as a cycle. And the solids are reduced to the desired extent.
[0035]
In addition, in the case where a hard-to-decompose solid or inorganic solid accumulates in the system with the decomposition of the organic matter, it contains a precipitated solid containing an organic solid that has been separated by precipitation in the sedimentation tank 1 after passing through the cycle. The sludge F, which is a part of the liquid A, may be appropriately discharged through the discharge path 23, concentrated and dehydrated, and then discarded separately. In this case, since the sludge F discharged from the discharge path 23 has passed through the solubilization tank 3, it is generally a sludge having a small amount of dissolved gas and an excellent sedimentation property, so that concentration and dehydration treatment are easily performed. be able to.
[0036]
Although not shown in the drawings, when the solubilization in the solubilization tank 3 is sufficiently performed and the solid content in the solubilization treatment liquid is reduced to a desired concentration, the supernatant is not returned to the precipitation tank 1. The liquid b and the organic lysate solution d can be treated, discharged and discarded.
[0037]
In addition to the embodiment shown in FIG. 1, FIG. 2 shows a supernatant b and an organic lysate solution d and / or a solubilization treatment liquid with a small amount of organic solids obtained by precipitation separation in the precipitation tank 1. An outline of a second embodiment of the present invention including a digestion processing apparatus 4 for digesting E and a heat exchanger 5 for raising the temperature of the organic solid concentrate C is shown.
[0038]
The digestion treatment apparatus 4 is represented by, for example, an aerobic digestion treatment apparatus that performs an activated sludge method or an anaerobic digestion treatment apparatus (such as a UASB and a fixed bed type treatment apparatus) that performs methane fermentation or the like, and digestion is sufficiently performed. Any anaerobic digestion treatment apparatus capable of recovering energy as methane gas is preferable. In the case of performing an aerobic reaction in the digestion processing apparatus 4, it is only necessary to have the conventional aeration means, and other stirring means may be provided. The digester 4 can also be used either batchwise or continuously.
[0039]
Further, in the embodiment shown in FIG. 2, a heat exchanger 5 for raising the temperature of the organic solid concentrate C obtained by the mechanical separation means 2 using the solubilizing treatment liquid E is provided. . The organic solid concentrate C is heated through the heat exchanger 5 provided in the reflux path 21 and then introduced into the solubilization tank 3, where the solubilized solution E is solubilized. The same cycle processing as described above is applied. By setting it as such a structure, the preferable effect that a heat loss is suppressed is achieved.
[0040]
In addition, when UASB or fixed bed processing equipment is used for digestion treatment equipment 4 to perform anaerobic methane fermentation, methane gas generated in digestion treatment equipment 4 is introduced into methane gas combustion equipment 6, and methane gas is burned. The generated heat can be guided to the solubilization tank 3 via the heating path 22 to heat the solubilization tank 3. The methane gas combustion apparatus 6 is not particularly limited, and a combustion apparatus such as a naturally ventilated in-furnace combustion type combustion tower equipped with a normal gas burner can be used. With such a configuration, the energy released in the solubilization tank 3 is supplemented with the combustion energy of methane generated by the anaerobic digestion process, so that the energy efficiency is very good.
[0041]
【Example】
(Example)
Starch factory waste liquid is used as waste liquid containing organic solids to be treated and settled and separated for 30 minutes (precipitation rate SV30 = 10%) in a sedimentation tank. Liquid containing precipitated solids (solids concentration SS = 1.3%, volatile The organic organic substance content ratio VSS / SS = 98%) was obtained. The organic solid concentration obtained by centrifuging the precipitated solid-containing liquid at 3,000 rpm (1,300 × g) for 5 minutes was diluted with tap water to adjust the organic solid concentration to 1%. The liquid was used as the material for the solubilization process.
[0042]
The adjusted liquid was introduced into a jacket-type cylindrical reaction tank that circulates a heat-resistant vinyl chloride heating medium with an inner diameter of 100 mm and a height of 1 m, and was operated at a temperature of 70 ° C., an air flow of 0.1 vvm, and a reaction liquid volume of 4 L. . The liquid was continuously fed so that the hydraulic residence time in the reaction tank was 5 days, and then the final organic solids and the total organic matter removal rate were measured.
[0043]
(Comparative example)
As a comparative example, the same treatment as in the example was performed using a liquid in which the above-described precipitated solid-containing liquid was adjusted with a precipitate supernatant so that the organic solid concentration was 1%.
[0044]
Table 1 shows the concentrations of the organic solubilized product and the organic solid contained in both the organic solid concentrate (the solubilized material of the example) and the precipitated solid-containing solution (the solubilized material of the comparative example).
[0045]
[Table 1]

[0046]
From Table 1, the concentration of the organic lysate in the organic solid concentrate obtained by centrifuging the precipitated solid-containing liquid is 8.0 g / l to 2.5 g / l, about 30%. It was shown to be reduced to.
[0047]
Next, Table 2 shows the measurement results of the removal rates of organic solids and total organics in Examples and Comparative Examples.
[0048]
[Table 2]

[0049]
As is apparent from Table 2, the removal rate of organic solids increased by 26 points in Examples compared to Comparative Examples. Therefore, by adopting the method of the present invention and reducing the organic solubilizate in the precipitated solid-containing liquid, the growth of microorganisms that grow using the organic solubilizate as a nutrient source in the reaction vessel was suppressed. The results suggested that good organic solid removal was achieved.
[0050]
Moreover, the removal rate of all organic substances is not much different between Examples and Comparative Examples, but the organic substance content is about 50% higher in Comparative Examples, so the absolute amount of removed (gasified) organic substances is the same as that in Comparative Examples. Therefore, it is considered that a negative effect on the solids removal rate was brought about by the organisms that grew in the tank of the comparative example with the reaction.
[0051]
【The invention's effect】
The high-concentration organic waste liquid digestion treatment apparatus and method of the present invention, after separating the organic solid-containing waste liquid in a sedimentation tank to obtain a precipitated solid-containing liquid, is further made organic by mechanical separation means. Since it is separated into a lysate solution and an organic solid concentrate, and the organic solid concentrate is treated in a solubilization tank, it is an extremely excellent invention that has the following remarkable and unique effects. is there.
[0052]
(1) By reducing the amount of organic lysate flowing into the solubilization tank as much as possible, the growth of microorganisms that grow using such organic lysate as a nutrient source is suppressed. Therefore, the organic solid removal rate is remarkably improved.
[0053]
(2) If the amount of organic solubilizate flowing into the solubilization tank is reduced in this way, excess organic substances in the solubilization tank will not be removed, so the amount of organic matter subjected to digestion is kept at a high value. It is possible to increase the amount of methane produced and the amount of energy generated when anaerobic digestion is performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a first embodiment of an apparatus and method for digesting high-concentration organic waste liquid according to the present invention.
FIG. 2 is a diagram showing an outline of a second embodiment of the digestion apparatus and method for high-concentration organic waste liquid according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Sedimentation tank 2 ... Mechanical separation means 3 ... Solubilization tank 4 ... Digestion processing apparatus 5 ... Heat exchanger 6 ... Methane gas combustion apparatus 21 ... Reflux path | route 22. ··· Heating route 23 ··· Discharge route A ··· Precipitated solid-containing solution b ··· Supernatant C ··· Organic solid concentrate d · · Organic lysate solution E ···・ Solubilization treatment solution F ... sludge

Claims

A processing apparatus for high-concentration organic waste liquid containing organic solids, a precipitation tank (1) for precipitating and separating organic solid-containing waste liquid, and an organic solid precipitated in the precipitation tank (1) A mechanical separation means (2) for further solid-liquid separation of the precipitated solid-containing liquid A , and an organic solid concentrate C having a low organic solubilized product content obtained by the mechanical separation means (2). Obtained by solubilization tank (3) for solubilization under high temperature conditions, and supernatant b with less organic solids obtained in the precipitation tank (1) and / or the mechanical separation means (2) An upstream anaerobic sludge bed treatment device for digesting the organic solubilizate solution d is included, and the solubilized treatment liquid E obtained in the solubilization tank (3) is treated with the upward flow anaerobic sludge bed treatment. Treatment of highly concentrated organic waste liquid, characterized in that it is configured to be introduced into the equipment apparatus.

The high-concentration organic substance according to claim 1, wherein the solubilized treatment liquid E obtained in the solubilization tank (3) is precipitated and separated in the precipitation tank (1) together with the organic solid-containing waste liquid. Waste liquid treatment equipment.

The heat exchanger (5) for heating the organic solid concentrate C obtained by the mechanical separation means (2) with the solubilized treatment liquid E obtained by the solubilization tank (3) comprises the machine The processing apparatus of the high concentration organic waste liquid of Claim 1 or 2 further provided in the recirculation | reflux path | route (21) from the automatic separation means (2) to the said solubilization tank (3).

A methane gas combustion device (6) for combusting methane gas generated in the upward flow anaerobic sludge bed treatment device , and the solubilization tank (3) is heated by heat generated in the methane gas combustion device (6) The processing apparatus of the high concentration organic waste liquid in any one of Claim 1 to 3 which further contains the heating path | route (22) for carrying out.

The processing apparatus of the high concentration organic waste liquid in any one of Claim 1 to 4 whose said mechanical separation means (2) is a centrifuge.

A method for treating high-concentration organic waste liquid containing organic solids, comprising a step of precipitating and separating organic solid-containing waste liquid in a precipitation tank (1), and an organic solid precipitated in the precipitation separation step mechanical separation process, small organic solid concentrate of organic solubilized matter content obtained in the mechanical separation process in the mechanical separation means for further solid-liquid separation of the precipitate solids containing solution a (2) The solubilization step in the solubilization tank (3) for solubilizing C under high temperature conditions , and the supernatant b with less organic solids obtained in the precipitation step and the organicity obtained in the mechanical separation step Including a digestion treatment step in an upflow anaerobic sludge bed treatment apparatus for digesting the solubilizate solution d, wherein the solubilization treatment liquid E obtained in the solubilization step is subjected to the digestion treatment step. The processing method of high concentration organic waste liquid.

The processing method of the high concentration organic waste liquid of Claim 6 by which the solubilization process liquid E obtained at the said solubilization process is settled and separated in the said precipitation tank (1) with an organic solid containing waste liquid.

The processing method of the high concentration organic waste liquid of Claim 6 or 7 with which the organic solid concentrate C obtained by the said mechanical separation process is heated by the solubilization processing liquid E obtained by the said solubilization process. .

Before Symbol further comprising a methane combustion process for burning methane gas generated in digestion step, the solubilization tank by the heat generated in said methane combustion process (3) is warmed, from claims 6 8 The processing method of the high concentration organic waste liquid in any one .

The processing method of the high concentration organic waste liquid in any one of Claim 6 to 9 whose said mechanical separation means (2) is centrifugation.

The processing method of the high concentration organic waste liquid in any one of Claim 6 to 10 performed on the conditions that the said solubilization process becomes a temperature range of 50-90 degreeC.