JP4466815B2 - Organic waste disposal methods - Google Patents

Organic waste disposal methods Download PDF

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Publication number
JP4466815B2
JP4466815B2 JP2003082097A JP2003082097A JP4466815B2 JP 4466815 B2 JP4466815 B2 JP 4466815B2 JP 2003082097 A JP2003082097 A JP 2003082097A JP 2003082097 A JP2003082097 A JP 2003082097A JP 4466815 B2 JP4466815 B2 JP 4466815B2
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methane fermentation
waste
carbonization
dry
fermentation residue
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JP2004284917A (en
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宝鋼 劉
雅一 安田
光昭 黒島
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Kurita Water Industries Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A40/00Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
    • Y02A40/10Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
    • Y02A40/20Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00Technologies for the production of fuel of non-fossil origin
    • Y02E50/30Fuel from waste, e.g. synthetic alcohol or diesel
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00Technologies relating to chemical industry
    • Y02P20/10Process efficiency
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/40Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/50Reuse, recycling or recovery technologies
    • Y02W30/78Recycling of wood or furniture waste

Description

【0001】
【発明の属する技術分野】
本発明は、乾式メタン発酵と炭化処理及び堆肥化処理を組み合わせて有機系廃棄物を資源化処理するエネルギー自立型の有機系廃棄物の処理方法に関する。
【0002】
【従来の技術】
家畜糞尿、木質、食品残渣、水産加工残渣、可燃ゴミ、生ゴミ等の有機系廃棄物を焼却することなく資源化する方法の1つとして、有機系廃棄物を発酵させてコンポスト化し、これを農地に戻す方法は既に知られ、実用に供されている。
【0003】
又、有機系廃棄物をコンポスト化し、これを炭化処理して得られた炭化物を土壌改良材等として有効利用する方法も知られており、この方法において、炭化物を発酵槽に返送することによってこれを副資材として利用し、減容率の向上を図る提案がなされている(例えば、特開2000−205096参照)。
【0004】
【発明が解決しようとする課題】
ところが、有機系廃棄物の発酵方式として湿式メタン発酵を採用する場合、発酵残渣には多量の水分が含まれるため、脱水及び廃水処理が必要となり、これらの処理に膨大なコストと労力を要していた。
【0005】
そこで、発酵方式として乾式メタン発酵を採用し、この乾式メタン発酵と炭化処理を組み合わせる処理方法が考えられる。この方法では廃水処理が不要となるが、メタン発酵残渣の全量を炭化処理すると加熱蒸気中の水分が炭化工程に入り、又、炭化の廃熱を有効利用することができない等のため、エネルギーの利用効率が悪いという問題があった。
【0006】
又、乾式メタン発酵と堆肥化処理を組み合わせた処理方法では、多量の水分調整材が必要であるとともに、堆肥生産量が多くなって減量率が悪いという問題があった。
【0007】
本発明は上記問題に鑑みてなされたもので、その目的とする処は、エネルギーの利用効率を高めてエネルギー自立型を実現するとともに、堆肥製品生成量を低く抑えて減量率を高め、更には堆肥化処理から脱臭工程を省略することができる有機系廃棄物の処理方法を提供することにある。
【0008】
【課題を解決するための手段】
上記目的を達成するため、本発明は、廃棄物量に対して10%以下の水蒸気を加えて家畜糞尿及び食品残渣から成る有機系廃棄物の乾式メタン発酵を行った後、得られたメタン発酵残渣70〜90%を炭化処理する一方、残りの10〜30%のメタン発酵残渣に、前記炭化処理で得られた炭化物の一部又は全部を添加し、その混合物を堆肥化処理する有機系廃棄物の処理方法として、
前記メタン発酵残渣と前記炭化物との混合物の含水率を70%以下とし、
前記乾式メタン発酵によって発生するメタンガスの一部を燃料として前記蒸気を得るとともに、熱源として発電し、前記炭化処理における燃料として利用し、燃焼脱臭の燃料として利用し、
前記メタン発酵残渣に対して10〜40%の木質廃材、木材主体の建設廃材、おが屑、間伐材及び/又はコーヒー粕から成る非生分解性廃棄物を炭化工程に加えて炭化処理し、
メタン発酵残渣の予熱乾燥処理に供された乾留ガスの燃焼排ガスを前記堆肥化処理における熱源として利用し、
予熱乾燥処理された含水率15〜30%の前記メタン発酵残渣と炭化工程に加えられる含水率30%以下の前記非生分解性廃棄物の比率を4:1〜1:5(乾燥固形物として)とすることを特徴とする。
【0010】
発明によれば、乾式メタン発酵によって得られたメタン発酵残渣の全てではなく、その70%〜90%を炭化処理するようにしたため、炭化工程に入る加熱蒸気中の水分量が低く抑えられ、水分蒸発にようする消費エネルギーが低く抑えられるとともに、堆肥物の生産量が低く抑えられて減量率が高められる。又、炭化処理で得られた炭化物の一部又は全部を残りの10〜30%のメタン発酵残渣に添加し、その混合物を堆肥化処理するようにしたため、炭化物の脱臭作用によって堆肥物の脱臭がなされ、その結果として堆肥化処理から脱臭工程を省略することができる。
【0015】
又、乾式メタン発酵によって発生するメタンガスをエネルギー源として、処理に必要な水蒸気や電力を賄うとともに、炭化処理や燃焼脱臭の燃料として利用するため、エネルギーの利用効率が高められてエネルギー自立型のシステムを構築することができる。
【0019】
更に、メタン発酵残渣に対して10〜40%の非生分解性廃棄物を炭化工程に直接加えて炭化処理し、この炭化処理によって発生する乾留ガスをメタン発酵残渣の予熱乾燥処理や堆肥化処理における熱源として利用するため、エネルギーの利用効率が高められてエネルギー自立型のシステムを実現することができる。又、堆肥化処理においてメタン発酵残渣は昇温しづらく、堆肥化しにくいが、乾留ガスの燃焼排ガスによってメタン発酵残渣の堆肥化を容易化することができる。
【0022】
【発明の実施の形態】
以下に本発明の実施の形態を添付図面に基づいて説明する。
【0023】
図1は本発明に係る有機系廃棄物の処理方法を実施するための処理装置の構成を示すブロック図である。
【0024】
図1に示す処理装置を用いて実施される本発明に係る有機系廃棄物の処理方法を説明すると、先ず、原料としての有機系廃棄物のうち、家畜糞尿、食品残渣等の生分解性廃棄物が後述のボイラー3,4にて発生した70〜90℃の水蒸気によって45〜60℃まで加熱された後、ラインL1から乾式メタン発酵槽1に投入されて発酵に好適な50〜57℃の嫌気性雰囲気の下で発酵される。
【0025】
そして、上記乾式メタン発酵槽1における有機系廃棄物の乾式メタン発酵処理によって発生したメタンガスは、ラインL2を経て発電機2に供給されるとともに、ラインL2から分岐するラインL3を通って前記ボイラー3に供給される。
【0026】
ところで、発電機2においては、不図示のガスエンジンがメタンガスを燃料として駆動され、このガスエンジンによって発電機2が駆動されて発電され、これによってシステムに必要な電力が賄われる。そして、ガスエンジンから排出される排気ガスの熱(排熱)によって前記ボイラー4が駆動されて70〜90℃の水蒸気が発生し、この水蒸気は、メタンガスを燃料とする前記ボイラー3からラインL4に排出される水蒸気にラインL5を通って合流し、合流した水蒸気は、前述のようにラインL4から乾式メタン発酵槽1に投入される生分解性廃棄物の加熱に供される。尚、生分解性廃棄物に加えられる水蒸気は、投入廃棄物量に対して10wt%以下に設定される。
【0027】
他方、乾式メタン発酵槽1からラインL6へと排出されるメタン発酵残渣は、65〜85%の水分を含んでおり、その一部(10〜30wt%)はラインL6から分岐するラインL7を経て堆肥化装置5に投入され、残りの70〜90wt%のメタン発酵残渣は、乾燥機6に投入されて含水率が15〜30%となるまで予熱乾燥処理される。
【0028】
そして、乾燥機6によって予熱乾燥処理された含水率15〜30%のメタン発酵残渣は、炭化装置(炭化炉)7に投入されて炭化処理されるが、原料としての有機系廃棄物のうち、木質廃材、建設廃材(木材主体)、おが屑、間伐材、コーヒー粕等の含水率30%以下の非生分解性廃棄物は、発酵処理されることなくラインL8を経て炭化装置7に直接投入されて前記メタン発酵残渣と共に炭化処理される。尚、このときのメタン発酵残渣(含水率65〜85%)と非生分解性廃棄物(含水率30%以下)の比率(重量比)は、4:1〜1:5(乾燥固形物として)に設定される。
【0029】
ここで、炭化装置7での炭化処理前段の予熱炉と後段の再燃炉のバーナーに供給される燃料には、前記乾式メタン発酵槽1にて発生したメタンガスの一部が利用される。即ち、乾式メタン発酵槽1からラインL2へと排出されるメタンガスの一部がラインL2からラインL9を通って炭化装置7に供給されて燃焼に供される。
【0030】
炭化装置7での炭化処理は、内部に空気を供給しないで、例えば外熱式のスクリューで600〜800℃に0.2〜1時間加熱することによってなされる。この炭化処理によって得られる炭化物の含水率は10%以下であり、本実施の形態では、その全部がラインL10を経てメタン発酵残渣に添加される。このように、含水率65〜85%のメタン発酵残渣に含水率10%以下の炭化物が添加されることによって得られる混合物の含水率は70%以下に調整され、この混合物が前記堆肥化装置5に投入され、堆肥化処理される。
【0031】
尚、本実施の形態では、炭化物の全量をメタン発酵残渣に添加するようにしたが、一部を添加し、残りを図1に破線にて示すようにラインL11から排出し、この炭化物を種々の用途に供するようにしても良い。ここで、炭化物の用途としては、脱臭や水分調整、空隙率アップによる通気性改良、粘度の低減による装置への付着抑制、粉塵の減少、陽イオン交換能力(CEC)の向上、土壌の保水性や団粒構造の向上等に資する用途が考えられる。
【0032】
ところで、炭化装置7おいて発生する800〜900℃の乾留ガス(バイオガス)は、ラインL12を通って前記乾燥機6に熱風として供給されてメタン発酵残渣の予熱乾燥に供され、予熱乾燥に供されて温度が200〜230℃に低下した乾留排ガスは、ラインL13を経て熱交換器8に供給される。
【0033】
熱交換器8においては、ラインL14から供給される大気中の新鮮空気が乾留ガスによって60〜70℃に加熱され、堆肥の通気用熱風としてラインL15を通って前記堆肥化装置5に供給される。そして、熱交換器8において空気の加熱に供された乾留ガスは、白煙が出ない程度の150℃程度まで温度が下がり、ラインL16から大気中に排出される。
【0034】
而して、上述のように熱交換器8における乾留ガスとの熱交換によって60〜70℃に加熱された新鮮空気が堆肥の通気用熱風としてラインL15を通って堆肥化装置5に供給されることによって、メタン発酵残渣と炭化物が堆肥化装置5において加熱され、これらが最適な温度60℃の好気性雰囲気の下で堆肥化処理され、含水率30〜70%(最適値60%)の堆肥物がラインL17から排出されるとともに、堆肥排ガスがラインL18から排出される。
【0035】
他方、乾式メタン発酵槽1周りにいて発生する臭気は、ラインL19を通って脱臭装置9に吸引され、ラインL9から分岐するラインL20を経て脱臭装置9に供給されるメタンガスによって燃焼脱臭される。
【0036】
以上において、図1に示す処理装置を用いて実施される本発明に係る処理方法によれば、乾式メタン発酵によって得られたメタン発酵残渣の全てではなく、その70%〜90%を炭化処理するようにしたため、炭化工程に入る加熱蒸気中の水分量が低く抑えられ、水分蒸発に要する消費エネルギーが低く抑えられるとともに、堆肥物の生産量が低く抑えられて減量率が高められる。
【0037】
又、炭化処理で得られた炭化物の一部又は全部を残りの10〜30%のメタン発酵残渣に添加し、その混合物を堆肥化処理するようにしたため、炭化物の脱臭作用によって堆肥物の脱臭がなされ、その結果として堆肥化処理から脱臭工程を省略することができる。
【0038】
更に、乾式メタン発酵によって発生するメタンガスをエネルギー源として、処理に必要な水蒸気や電力を賄うとともに、炭化処理や燃焼脱臭の燃料として利用するようにしたため、エネルギーの利用効率が高められてエネルギー自立型のシステムを構築することができる。
【0039】
又、本発明によれば、メタン発酵残渣に対して10〜40%の非生分解性廃棄物を炭化工程に直接加えて炭化処理し、この炭化処理によって発生する乾留ガスをメタン発酵残渣の予熱乾燥処理や堆肥化処理における熱源として利用するため、エネルギーの利用効率が高められてエネルギー自立型のシステムを実現することができる。
【0040】
尚、堆肥化処理においてメタン発酵残渣は昇温しづらく、堆肥化しにくいが、本発明では乾留ガスの燃焼排ガスによってメタン発酵残渣を加熱するようにしたため、前記問題を解消してメタン発酵残渣の堆肥化を容易化することができる。
【0041】
ここで、本実施の形態における有機系廃棄物の処理における乾物収支と水収支及び重量収支を図2、図3及び図4に基づいてそれぞれ具体的に説明する。
【0042】
先ず、乾物収支を図2に基づいて説明すると、投入乾物合計32.9t/dのうち、メタン発酵槽に投入される生分解性廃棄物であるメタン発酵原料乾物が23.4t/d、蒸気が0t/d、非生分解性廃棄物である木質廃材乾物が9.5t/dである場合、メタン発酵工程における乾物分解量は7.6t/d−(−は減量を意味する)、炭化及び堆肥工程における乾物分解量は17.4t/d−となり、処理工程全体における乾物分解量は26.0(=7.6+17.4)t/d−となる。
【0043】
従って、処理工程の乾物減少量は26.0t/dとなり、炭化及び堆肥工程によって得られる炭入り堆肥乾物は6.9(=32.9−26.0)t/dとなり、乾物収支は投入乾物合計=排出と分解乾物合計=32.9t/dとなる。
【0044】
次に、水収支を図3に基づいて説明すると、メタン発酵槽に投入される生分解性廃棄物であるメタン発酵原料に含まれる水分が72.8t/d、加熱に用いられる蒸気の水分が7.8t/d、非生分解性廃棄物である木質廃材に含まれる水分が4.0t/dである場合、メタン発酵工程における水分消費量は2.3t/d−(−は減量を意味する)、炭化及び堆肥工程における水分生成量は8.6t/d+(+は増量)となり、処理工程全体における水分生成量は6.3(=8.6−2.3)t/d+となる。従って、投入水と生成水の合計は90.9(=72.8+7.8+4.0+6.3)t/dとなる。
【0045】
そして、炭化及び堆肥工程によって得られる炭入り堆肥乾物に含まれる水分は3.0t/dであるため、処理工程での水分蒸発量は87.9(=90.9−3.0)t/dとなり、水収支は投入水と生成水合計=蒸発水と排出水合計=90.9t/dとなる。
【0046】
従って、図2に示す乾物収支と図3に示す水収支から、重量収支は図4に示すようになる。
【0047】
即ち、投入物合計117.5(=32.9+90.9−6.3)t/dのうち、メタン発酵槽に投入されるメタン発酵原料が96.2(=23.4+72.8)t/d、蒸気水分が7.8t/d、木質廃材が13.5(=9.5+4.0)t/dとなり、処理工程における重量変化は107.6(=26+87.9−6.3)t/d−となる。そして、炭化及び堆肥工程によって得られる炭入り堆肥乾物の重量は9.9(=6.9+3.0)t/dであるため、処理工程での水分蒸発量は107.6(=117.5−9.9)t/dとなり、重量収支は投入物合計=分解と製品合計=117.5t/dとなる。尚、本例における減量率は、100−(9.9/117.5)×100=91.5%となる。
【0048】
次に、処理装置全体の熱収支を表1に基づいて説明する。
【0049】

Figure 0004466815
表1に示すように、図1に示した処理装置においては、乾式メタン発酵槽において発生するメタン発酵ガスの熱量41,830kwh/dと炭化装置において発生する炭化乾留ガスの熱量74,860kWh/dの合計116,690kWh/dが入熱として加えられる。
【0050】
そして、装置において消費又は失われる熱量(損失熱量)としては、装置を駆動するための動力(装置動力)5,965kWh/d(熱量換算)、乾式メタン発酵槽に投入される生分解性廃棄物の加熱に用いられる蒸気(メタン加熱蒸気)の熱量8,140kWh/d、炭化工程と堆肥工程での水分蒸発熱69,502kWh/d、脱臭工程における燃料(メタンガス)の燃焼熱3,890kkWh/d、発電機やボイラーでの熱損失(メタンガス熱損失)12,698kWh/d及び炭化、堆肥熱損失(熱交換器からラインLを経て大気中に排出される乾留ガスの熱量+堆肥装置からラインLを経て大気中に排出される空気の熱量)16,495kWh/dが考えられ、これらの総計は116,690kWh/dとなり、その値は入熱に等しい。
【0051】
つまり、本実施の形態に係る処理装置において消費又は失われる熱量(損失熱量)は、装置自体において発生したメタン発酵ガス及び炭化乾留ガスの熱量によって賄われるため、本実施の形態に係る処理装置はエネルギー自立型となり、化石燃料のインプットが不要となるとともに、装置全体の電力自給が可能となる。
【0052】
【発明の効果】
以上の説明で明らかなように、本発明によれば、廃棄物量に対して10%以下の水蒸気を加えて有機系廃棄物の乾式メタン発酵を行った後、得られたメタン発酵残渣の70〜90%を炭化処理する一方、残りの10〜30%のメタン発酵残渣に、前記炭化処理で得られた炭化物の一部又は全部を添加し、その混合物を堆肥化処理するようにしたため、エネルギーの利用効率を高めてエネルギー自立型を実現するとともに、堆肥製品生成量を低く抑えて減量率を高め、更には堆肥化処理から脱臭工程を省略することができるという効果が得られる。
【図面の簡単な説明】
【図1】 本発明に係る有機系廃棄物の処理方法を実施するための処理装置の構成を示すブロック図である。
【図2】 本発明の実施の形態における有機系廃棄物の処理における乾物収支を説明する図である。
【図3】 本発明の実施の形態における有機系廃棄物の処理における水収支を説明する図である。
【図4】 本発明の実施の形態における有機系廃棄物の処理における重量収支を説明する図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process how the energy self-supporting organic waste for processing resource the organic waste in a combination of carbonization and composting process and dry methane fermentation.
[0002]
[Prior art]
One way to recycle organic waste such as livestock manure, wood, food residues, fishery processing residues, combustible waste, and garbage without incineration, fermenting organic waste into compost, Methods for returning to farmland are already known and put into practical use.
[0003]
Also known is a method of effectively composting organic waste and carbonizing it as a soil conditioner. In this method, the carbide is returned to the fermenter. A proposal has been made to improve the volume reduction rate by using as a secondary material (see, for example, Japanese Patent Laid-Open No. 2000-205096).
[0004]
[Problems to be solved by the invention]
However, when wet methane fermentation is adopted as a fermentation method for organic waste, since the fermentation residue contains a large amount of water, dehydration and wastewater treatment are required, and these treatments require enormous costs and labor. It was.
[0005]
Then, the dry methane fermentation is employ | adopted as a fermentation system, and the processing method which combines this dry methane fermentation and carbonization processing can be considered. This method eliminates the need for wastewater treatment, but if the entire amount of methane fermentation residue is carbonized, the water in the heated steam enters the carbonization process, and the waste heat of carbonization cannot be used effectively. There was a problem that usage efficiency was bad.
[0006]
Moreover, in the processing method combining dry methane fermentation and composting treatment, there is a problem that a large amount of moisture adjusting material is required and the amount of compost production increases and the weight loss rate is poor.
[0007]
The present invention has been made in view of the above problems, and the purpose of the process is to increase the efficiency of energy use and realize an energy self-sustained type, while reducing the amount of compost product generated and increasing the weight loss rate. and to provide a process how the organic waste can be omitted deodorization step from composting process.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present invention is, after the dry methane fermentation of organic waste by the addition of 10% or less of water vapor with respect to waste amounts consisting manure and food residues, resulting methane fermentation An organic system in which 70 to 90% of the residue is carbonized, and a part or all of the carbide obtained by the carbonization is added to the remaining 10 to 30% methane fermentation residue, and the mixture is composted. As a waste disposal method,
The water content of the mixture of the methane fermentation residue and the carbide is 70% or less,
Together to obtain the water vapor a part of the methane gas generated by the dry methane fermentation as a fuel, and power generation as a heat source, use as a fuel in the carbonization process, used as fuel in the combustion deodorization,
Non-biodegradable waste consisting of 10-40% wood waste, construction waste mainly composed of wood, sawdust, thinned wood and / or coffee lees is added to the carbonization step and carbonized,
Utilizing combustion exhaust gas of dry distillation gas subjected to preheating drying treatment of methane fermentation residue as a heat source in the composting treatment,
The ratio of the methane fermentation residue having a water content of 15 to 30% that has been preheated and dried to the non-biodegradable waste having a water content of 30% or less added to the carbonization step is 4: 1 to 1: 5 (as a dry solid) ).
[0010]
According to the present invention, not all of the methane fermentation residue obtained by dry methane fermentation, but 70% to 90% of the methane fermentation residue is carbonized, so that the amount of water in the heated steam entering the carbonization process is kept low, The energy consumption for evaporation of moisture is kept low, and the production amount of compost is kept low and the weight loss rate is increased. In addition, part or all of the carbide obtained by carbonization treatment is added to the remaining 10-30% methane fermentation residue, and the mixture is composted. As a result, the deodorization action of the carbide reduces the deodorization of the compost. As a result, the deodorizing step can be omitted from the composting process.
[0015]
In addition, methane gas generated by dry methane fermentation is used as an energy source to supply steam and electric power necessary for processing, and also as carbonization and combustion deodorization fuel. Can be built.
[0019]
Furthermore, 10 to 40% of non-biodegradable waste is directly added to the carbonization process and carbonized with respect to the methane fermentation residue, and the carbonized gas generated by this carbonization is preheated and composted to the methane fermentation residue. Since it is used as a heat source in the energy, the energy use efficiency can be improved and an energy self-supporting system can be realized. Further, in the composting process, the temperature of the methane fermentation residue is difficult to increase and it is difficult to compost, but composting of the methane fermentation residue can be facilitated by the combustion gas of dry distillation gas.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0023]
FIG. 1 is a block diagram showing the configuration of a processing apparatus for carrying out the organic waste processing method according to the present invention.
[0024]
The organic waste processing method according to the present invention implemented using the processing apparatus shown in FIG. 1 will be described. First, among organic wastes as raw materials, biodegradable waste such as livestock manure, food residues, etc. After the product is heated to 45-60 ° C. by 70-90 ° C. steam generated in boilers 3, 4 described later, it is introduced into the dry methane fermentation tank 1 from line L 1 and is suitable for fermentation at 50-57 ° C. Fermented under anaerobic atmosphere.
[0025]
And the methane gas generated by the dry methane fermentation treatment of the organic waste in the dry methane fermenter 1 is supplied to the generator 2 through the line L2 and passes through the line L3 branched from the line L2 to the boiler 3. To be supplied.
[0026]
By the way, in the generator 2, a gas engine (not shown) is driven by using methane gas as a fuel, and the generator 2 is driven by the gas engine to generate electric power, thereby supplying electric power necessary for the system. Then, the boiler 4 is driven by the heat (exhaust heat) of the exhaust gas discharged from the gas engine to generate water vapor at 70 to 90 ° C., and this water vapor passes from the boiler 3 using methane gas as fuel to the line L4. The discharged steam joins through the line L5, and the joined steam is used for heating the biodegradable waste put into the dry methane fermentation tank 1 from the line L4 as described above. In addition, the water vapor | steam added to biodegradable waste is set to 10 wt% or less with respect to input waste amount.
[0027]
On the other hand, the methane fermentation residue discharged from the dry methane fermenter 1 to the line L6 contains 65 to 85% of water, and a part (10 to 30 wt%) thereof passes through the line L7 branched from the line L6. The remaining 70 to 90 wt% methane fermentation residue is put into the composting apparatus 5 and is put into the dryer 6 and preheated and dried until the water content becomes 15 to 30%.
[0028]
And the methane fermentation residue with a water content of 15 to 30% that has been preheated and dried by the dryer 6 is put into a carbonization device (carbonization furnace) 7 and carbonized, but among organic wastes as raw materials, Non-biodegradable waste with a moisture content of 30% or less, such as wood waste, construction waste (mainly wood), sawdust, thinned wood, coffee grounds, etc., is directly fed into the carbonization device 7 via the line L8 without being fermented. And carbonized together with the methane fermentation residue. In addition, the ratio (weight ratio) of the methane fermentation residue (water content 65 to 85%) and non-biodegradable waste (water content 30% or less) at this time is 4: 1 to 1: 5 (as a dry solid) ).
[0029]
Here, a part of the methane gas generated in the dry methane fermentation tank 1 is used as the fuel supplied to the burner of the preheating furnace and the subsequent reburning furnace in the carbonization apparatus 7. That is, a part of the methane gas discharged from the dry methane fermenter 1 to the line L2 is supplied from the line L2 through the line L9 to the carbonizer 7 for combustion.
[0030]
Carbonization treatment in the carbonization apparatus 7 is performed by heating to 600 to 800 ° C. for 0.2 to 1 hour, for example, with an externally heated screw without supplying air to the inside. The moisture content of the carbide obtained by the carbonization treatment is 10% or less, and in the present embodiment, the entire content is added to the methane fermentation residue via the line L10. Thus, the moisture content of the mixture obtained by adding a carbide having a moisture content of 10% or less to a methane fermentation residue having a moisture content of 65 to 85% is adjusted to 70% or less, and this mixture is adjusted to the composting apparatus 5. To be composted.
[0031]
In the present embodiment, the entire amount of the carbide is added to the methane fermentation residue, but a part of the carbide is added, and the remainder is discharged from the line L11 as indicated by a broken line in FIG. You may make it use for. Here, carbide applications include deodorization, moisture adjustment, improved air permeability by increasing porosity, reduced adhesion to equipment by reducing viscosity, reduced dust, improved cation exchange capacity (CEC), water retention of soil Applications that contribute to the improvement of the aggregate structure.
[0032]
By the way, 800-900 degreeC dry distillation gas (biogas) which generate | occur | produces in the carbonization apparatus 7 is supplied to the said dryer 6 as a hot air through the line L12, and is used for the preheating drying of a methane fermentation residue, and is used for preheating drying. The dry distillation exhaust gas that has been supplied and has a temperature lowered to 200 to 230 ° C. is supplied to the heat exchanger 8 via a line L13.
[0033]
In the heat exchanger 8, fresh air in the atmosphere supplied from the line L14 is heated to 60 to 70 ° C. by dry distillation gas, and supplied to the composting apparatus 5 through the line L15 as hot air for aeration of compost. . The temperature of the dry distillation gas used for heating the air in the heat exchanger 8 is lowered to about 150 ° C. at which white smoke is not emitted, and is discharged into the atmosphere from the line L16.
[0034]
Thus, as described above, fresh air heated to 60 to 70 ° C. by heat exchange with the dry distillation gas in the heat exchanger 8 is supplied to the composting apparatus 5 through the line L15 as hot air for compost ventilation. As a result, the methane fermentation residue and carbide are heated in the composting device 5 and composted in an aerobic atmosphere at an optimal temperature of 60 ° C., and compost having a moisture content of 30 to 70% (optimum value 60%). A thing is discharged | emitted from the line L17, and compost waste gas is discharged | emitted from the line L18.
[0035]
On the other hand, odor generated have you to dry methane fermentation tank 1 around is sucked into the deodorizing device 9 through line L19, is burned deodorized by methane gas to be supplied to the deodorizing device 9 via which the line L20 branched from the line L9 .
[0036]
In the above, according to the processing method according to the present invention implemented using the processing apparatus shown in FIG. 1, not all of the methane fermentation residue obtained by dry methane fermentation, but 70% to 90% thereof is carbonized. As a result, the amount of water in the heated steam entering the carbonization step is kept low, energy consumption required for water evaporation is kept low, and the production amount of compost is kept low, thereby increasing the weight loss rate.
[0037]
In addition, part or all of the carbide obtained by carbonization treatment is added to the remaining 10-30% methane fermentation residue, and the mixture is composted. As a result, the deodorization action of the carbide reduces the deodorization of the compost. As a result, the deodorizing step can be omitted from the composting process.
[0038]
In addition, methane gas generated by dry methane fermentation is used as an energy source to supply steam and electric power necessary for processing, and as carbonization and combustion deodorization fuel. System can be built.
[0039]
Moreover, according to the present invention, 10 to 40% of non-biodegradable waste is directly added to the carbonization process and carbonized with respect to the methane fermentation residue, and the dry distillation gas generated by the carbonization process is preheated to the methane fermentation residue. Since it is used as a heat source in the drying process and composting process, the energy utilization efficiency can be improved and an energy self-supporting system can be realized.
[0040]
In the composting process, the temperature of the methane fermentation residue is difficult to increase, and composting is difficult. Can be facilitated.
[0041]
Here, the dry matter balance, the water balance and the weight balance in the treatment of the organic waste in the present embodiment will be specifically described based on FIG. 2, FIG. 3 and FIG.
[0042]
First, the dry matter balance will be described with reference to FIG. 2. Of the total input dry matter of 32.9 t / d, 23.4 t / d of methane fermentation raw material dry matter, which is biodegradable waste put into the methane fermentation tank, is steam. Is 0 t / d, and wood waste dry matter that is non-biodegradable waste is 9.5 t / d, the dry matter decomposition amount in the methane fermentation process is 7.6 t / d- (-means weight loss), carbonization In addition, the dry matter decomposition amount in the composting process is 17.4 t / d-, and the dry matter decomposition amount in the entire treatment process is 26.0 (= 7.6 + 17.4) t / d-.
[0043]
Therefore, the dry matter reduction amount in the treatment process is 26.0 t / d, and the carbonized compost dry matter obtained by the carbonization and composting process is 6.9 (= 32.9-26.0) t / d, and the dry matter balance is input. Total dry matter = discharge and total dry matter = 32.9 t / d.
[0044]
Next, the water balance will be described with reference to FIG. 3. The moisture contained in the methane fermentation raw material, which is biodegradable waste put into the methane fermentation tank, is 72.8 t / d, and the moisture of the steam used for heating is 7.8 t / d, when the water content in non-biodegradable wood waste is 4.0 t / d, the water consumption in the methane fermentation process is 2.3 t / d- (-means weight loss) The water generation amount in the carbonization and composting process is 8.6 t / d + (+ is an increase), and the water generation amount in the entire treatment process is 6.3 (= 8.6-2.3) t / d +. . Therefore, the sum of the input water and the generated water is 90.9 (= 72.8 + 7.8 + 4.0 + 6.3) t / d.
[0045]
And since the water | moisture content contained in the carbonized compost dry matter obtained by a carbonization and composting process is 3.0 t / d, the water evaporation amount in a process process is 87.9 (= 90.9-3.0) t /. d, and the water balance is the sum of input water and generated water = evaporated water and discharged water = 90.9 t / d.
[0046]
Accordingly, the weight balance is as shown in FIG. 4 from the dry matter balance shown in FIG. 2 and the water balance shown in FIG.
[0047]
That is, out of the total input 117.5 (= 32.9 + 90.9-6.3) t / d, the methane fermentation raw material charged into the methane fermentation tank is 96.2 (= 23.4 + 72.8) t / d. d, steam moisture is 7.8 t / d, wood waste is 13.5 (= 9.5 + 4.0) t / d, and the weight change in the treatment process is 107.6 (= 26 + 87.9-6.3) t. / D-. And since the weight of the charcoal-containing compost dry matter obtained by a carbonization and composting process is 9.9 (= 6.9 + 3.0) t / d, the water evaporation amount in a process process is 107.6 (= 117.5). -9.9) t / d, and the weight balance is total input = decomposition and total product = 117.5 t / d. The weight loss rate in this example is 100− (9.9 / 117.5) × 100 = 91.5%.
[0048]
Next, the heat balance of the whole processing apparatus will be described based on Table 1.
[0049]
Figure 0004466815
As shown in Table 1, in the processing apparatus shown in FIG. 1, the calorific value 41,830 kWh / d of the methane fermentation gas generated in the dry methane fermentation tank and the calorific value 74,860 kWh / d of the carbonized dry distillation gas generated in the carbonization apparatus. A total of 116,690 kWh / d is added as heat input.
[0050]
The amount of heat consumed or lost in the device (loss of heat) is power for driving the device (device power) 5,965 kWh / d (calorie conversion), biodegradable waste put into the dry methane fermentation tank Heat of steam (methane heating steam) used for heating of steam is 8,140 kWh / d, moisture evaporation heat is 69,502 kWh / d in carbonization process and composting process, combustion heat of fuel (methane gas) in deodorization process is 3,890 kWh / d , Heat loss in generators and boilers (methane gas heat loss) 12,698 kWh / d and carbonization, compost heat loss (heat amount of dry distillation gas discharged from the heat exchanger through the line L to the atmosphere + line L from the composting device The amount of heat of the air discharged into the atmosphere via the air) is considered to be 16,495 kWh / d, and the total of these is 116,690 kWh / d, which is equivalent to the heat input. There.
[0051]
That is, the amount of heat consumed or lost in the processing apparatus according to the present embodiment (loss of heat) is covered by the amount of heat of the methane fermentation gas and carbonized carbonization gas generated in the apparatus itself, so the processing apparatus according to the present embodiment is The energy self-sustained type eliminates the need for fossil fuel input and allows the entire device to be self-sufficient in power.
[0052]
【The invention's effect】
As is clear from the above description, according to the present invention, after 10% or less of water vapor is added to the amount of waste and dry methane fermentation of organic waste is performed, 70 to 70 to methane fermentation residue obtained. While 90% carbonization treatment was performed, a part or all of the carbide obtained in the carbonization treatment was added to the remaining 10-30% methane fermentation residue, and the mixture was composted. In addition to increasing the efficiency of use and realizing an energy self-supporting type, it is possible to increase the weight loss rate by reducing the amount of compost product produced, and to eliminate the deodorizing step from the composting process.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a treatment apparatus for carrying out a method for treating organic waste according to the present invention.
FIG. 2 is a diagram for explaining a dry matter balance in the treatment of organic waste in the embodiment of the present invention.
FIG. 3 is a diagram for explaining a water balance in the treatment of organic waste in the embodiment of the present invention.
FIG. 4 is a diagram for explaining the weight balance in the treatment of organic waste in the embodiment of the present invention.

Claims (1)

廃棄物量に対して10%以下の水蒸気を加えて家畜糞尿及び食品残渣から成る有機系廃棄物の乾式メタン発酵を行った後、得られたメタン発酵残渣70〜90%を炭化処理する一方、残りの10〜30%のメタン発酵残渣に、前記炭化処理で得られた炭化物の一部又は全部を添加し、その混合物を堆肥化処理する有機系廃棄物の処理方法であって、
前記メタン発酵残渣と前記炭化物との混合物の含水率を70%以下とし、
前記乾式メタン発酵によって発生するメタンガスの一部を燃料として前記蒸気を得るとともに、熱源として発電し、前記炭化処理における燃料として利用し、燃焼脱臭の燃料として利用し、
前記メタン発酵残渣に対して10〜40%の木質廃材、木材主体の建設廃材、おが屑、間伐材及び/又はコーヒー粕から成る非生分解性廃棄物を炭化工程に加えて炭化処理し、
メタン発酵残渣の予熱乾燥処理に供された乾留ガスの燃焼排ガスを前記堆肥化処理における熱源として利用し、
予熱乾燥処理された含水率15〜30%の前記メタン発酵残渣と炭化工程に加えられる含水率30%以下の前記非生分解性廃棄物の比率を4:1〜1:5(乾燥固形物として)とすることを特徴とする有機系廃棄物の処理方法。
After dry methane fermentation of organic waste consisting of manure and food residues by the addition of 10% or less of water vapor with respect to waste amount, while carbonizing the 70% to 90% of the resulting methane fermentation residue In addition, the remaining 10 to 30% of the methane fermentation residue is a method for treating organic waste by adding a part or all of the carbide obtained in the carbonization treatment and composting the mixture.
The water content of the mixture of the methane fermentation residue and the carbide is 70% or less,
Together to obtain the water vapor a part of the methane gas generated by the dry methane fermentation as a fuel, and power generation as a heat source, use as a fuel in the carbonization process, used as fuel in the combustion deodorization,
Non-biodegradable waste consisting of 10-40% wood waste, construction waste mainly composed of wood, sawdust, thinned wood and / or coffee lees is added to the carbonization step and carbonized,
Utilizing combustion exhaust gas of dry distillation gas subjected to preheating drying treatment of methane fermentation residue as a heat source in the composting treatment,
The ratio of the methane fermentation residue having a water content of 15 to 30% that has been preheated and dried to the non-biodegradable waste having a water content of 30% or less added to the carbonization step is 4: 1 to 1: 5 (as a dry solid) And a method for treating organic waste.
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KR101312618B1 (en) * 2012-06-20 2013-09-30 (주) 동명기계 Methods for processing organic waste and carbonized fuel or fetilizer prepared therefrom
CN111233290A (en) * 2020-01-23 2020-06-05 重庆市渝西水务有限公司 Sludge treatment system for sewage treatment plant

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