JP3619726B2

JP3619726B2 - Method for producing algae culture medium

Info

Publication number: JP3619726B2
Application number: JP32328499A
Authority: JP
Inventors: 龍明佐藤; 真哉宮本; 尚実豊原; 優岡本; 義成高松
Original assignee: Toshiba Corp; Toshiba Plant Systems and Services Corp
Current assignee: Toshiba Corp; Toshiba Plant Systems and Services Corp
Priority date: 1998-11-13
Filing date: 1999-11-12
Publication date: 2005-02-16
Anticipated expiration: 2019-11-12
Also published as: JP2000245278A

Description

【０００１】
【発明の属する技術分野】
本発明は、海洋や湖において大規模に藻類を培養するための藻類培養媒体の製造方法に関し、特に火力発電所や焼却炉から発生する石炭灰や焼却灰を有効利用し、あるいは砂や貝殻粉砕物を利用して、藻類培養用養分供給媒体を大量に製造するための製造方法に関する。
【０００２】
【従来の技術】
微細藻類は単位面積当たりの太陽光利用率、すなわちＣＯ_２を固定能が陸上植物に比べ高く、増殖の速度も速いことから、大気中のＣＯ_２を固定するための有力な選択肢と考えられている。このため、地球温暖化防止を目的として、微細藻類によってＣＯ_２を吸収・固定し、さらにこれらを原料として石油代替燃料などの有用物を製造する研究が行われている。
【０００３】
たとえば太陽光を集光し、これを効率的に照射可能なフォトリアクターを設け、このフォトリアクター内にＣＯ_２に富んだ火力発電所の排ガスを導入し、微細藻類を培養する研究が多くの研究機関で実施されている。
【０００４】
【発明が解決しようとする課題】
ところで地球温暖化防止に貢献する程の膨大なＣＯ_２を固定するためには、広大な面積での微細藻類の培養が必要となる。試算によると日本で発生するＣＯ_２の１０％を固定するためには、３００ｋｍ四方の面積が必要となる。
【０００５】
日本国内の内陸部ではこのような広大な面積を確保することは困難であり、海洋での大規模な培養が必要となるが、従来は海洋での養分の効率的な供給が困難であった。すなわち、海洋で養分を散布すると養分は急速に海洋中に拡散するので、ほとんどの養分は藻類の培養に利用されないばかりか、海洋全体が富栄養化してしまい、海洋汚染を引き起こすことになる。
【０００６】
このため、何らかの方法で養分を海面に固定し、藻類の増殖に合わせて養分を供給する媒体が必要となる。先に本発明者らの内のある者達は鋭意研究の結果、水に浮遊可能でしかも養分を供給可能な媒体の製造に関する提案を行った（特願平１０−５２０５０）。
【０００７】
この発明により、海洋等で微細藻類が増殖するための養分を供給することのできる媒体の製造が可能となった。しかしながら、特願平１０−５２０５０の発明では、水への浮遊を維持するために、多量の撥水剤を添加していた。撥水剤はこのような媒体の製造原料のうち、最も高価であり、しかも長期に亘る浮遊において次第に撥水剤が不十分となり、やがて沈降してしまうという問題があった。
【０００８】
本発明は前述の課題を解決するためになされたもので、、本発明の目的は、水に浮く藻類増殖の核となる藻類培養媒体を火力発電所の石炭灰、焼却灰等の産業廃棄物、砂、貝殻粉砕物から大量に、しかも安価に製造する方法を提供し、それによって大量生産された藻類培養媒体を広大な海域に散布することによって、大規模かつクリーンに藻類の増殖を行うことを可能にするものである。
【０００９】
【課題を解決するための手段】
本発明は、無機質材料と硬化材と藻類培養養分とを含む原料を混合物にする混合工程と、前記混合物を型枠に投入して予備成形体とする予備成形工程と、この予備成形体を解砕して微細な成形体とする解砕成形工程と、この成形体を養生する養生工程とを少なくとも有し、この成形体の密度を１ｇ／ｃｍ ^３以下とすることを特徴とする藻類培養媒体の製造方法である。
【００１１】
本発明によれば、海水および淡水に浮遊する藻類培養媒体を大量に製造することができる。
【００１２】
この場合、型枠にて成形したのち解砕する前の段階では解砕に適する程度に養生を行っておき、解砕後にさらに養生を行うことができる。この方法によれば、一個ずつ型枠に混合物を投入する必要がないので、大量の成形体を迅速に製造することができる。
【００１３】
本発明は、混合工程において、混合槽中に高速で回転する撹拌翼を有する高速撹拌翼混合機を用いれば、短時間で均一に混合を行うことができるので、好ましく用いることができる。そして混合層槽をほぼ円筒状の形状にし、撹拌翼を底部に配置することによって、非常に効率的に撹拌、混合を行うことができる。撹拌翼としては、ブレード型が上記混合を迅速に行うことができるので特に好ましく用いられる。
【００１４】
また本発明は成形工程として、上記混合物を攪拌しながら水もしくは硬化材水溶液を散布して成形体に成形する攪拌成形工程を用いることができる。この成形体は成形後に養生して成形体の強度を高めることができる。この方法によれば、大量の粒状成形体をまとめて成形することができる。
【００１５】
上記の混合物を攪拌しながら水もしくは硬化材水溶液を散布して成形体に成形する工程では、混合工程で使用される高速撹拌翼混合機とは別の混合機を用意して用いてもよいが、混合工程で使用の高速撹拌翼混合機をそのまま継続して用いることができる。こうすることによって移送の手間やロスを省くことができる。
また、本発明は、成形工程として上記混合物を押出機に供給するなどして、ダイスで押出して成形体とする工程を用いることができる。この方法によれば、所定の形状の成形体を生産性良く大量に製造することができる。
【００１６】
そして本発明においては、混合物をダイスから押出して成形する上記工程において、２重の管からなるダイスを用い、混合物を２重の管の外側管内壁と内側管外壁との間に移送して入れ、押出成形後にその両端を圧縮し封じきることにより、外部に多孔質層を有し、その内部に中空部を有する成形体とすることができる。ここに中空部とは出入口がなく閉じられた空洞である。このようにして製造を行うことによって、成形体のみかけ比重を小さくすることができ、藻類培養媒体として水面に浮上させる上で有利となる。
【００１７】
さらに混合物をダイスから押し出して成形する上記工程において３重の管からなるダイスの最外側の管と中間の管との間に多孔質性の材料を、中間の管と最内側の管との間に低透水性の材料を入れることによって、多孔質層と中空部との間に多孔質層よりも低透水性の層を設けることにより、中空部の浸水が防止できるので、成形体の浮上状態が一層安定化する。
【００１８】
上記の低透水層には、石炭灰、焼却灰、モンモリロナイト、カオリナイト、セメント、水ガラス、石灰、石膏のうち、少なくとも一種を含むものを用いることができる。これらを用いることによって、中空部の周囲を気密に形成することができる。そして中空部を設けることによってみかけ比重を小さくできるので、軽量化材を含有しなくても水に浮遊可能にすることができる。
【００１９】
また、本発明は成形工程として、上記混合物を圧縮して成形体とする工程を用いることができる。この方法によれば所定の形状の成形体を生産性良く大量に製造することができる。
【００２０】
本発明の藻類媒体の製造方法に用いる無機質材料としては、石炭灰、焼却灰、砂、貝殻粉砕物、および珪藻から選択された少なくとも１種を含むものを好ましく用いることができる。これらのうち、石炭灰や焼却灰は多量に生成される産業廃棄物であり、その再利用が可能になるため、特に好ましい。
【００２１】
そしてこれら石炭灰、焼却灰、砂、貝殻粉砕物、および珪藻から選択された少なくとも１種を含む無機質材料は、環境を汚染する成分、即ち、重金属や有害な有機物質などの成分を低減もしくは除去処理したものが環境汚染の恐れがないので好ましく用ることができる。石炭灰はシリカとアルミナを主成分とし、成分的にも比較的安定しており、環境を汚染する成分を含まないように管理して用いることが可能である。また、焼却灰についても、分別収集の段階あるいは焼却灰の後処理の段階で、環境を汚染する成分を除去して用いることが可能である。
【００２２】
また、本発明に用いる硬化材としては、セメント、水ガラス、石灰、および石膏から選択された少なくとも１種を含むものが好ましく用いられる。そしてセメントまたは水ガラスから選択された少なくとも１種を含む硬化材には、その構成成分として、藻類培養養分、例えばリン酸化合物を含むものを用いることができる。
【００２３】
また、本発明に用いる藻類培養養分としては、リン分、窒素分、および鉄分から選択された少なくとも１種を含むものが好ましい。これらを含むことによって藻類の培養に必要な養分の供給が可能になる。
【００２４】
また、本発明に用いる軽量化材としては、粉末アルミナ、パーライト、シラス、シラスバルーン、または粒状軽石から選択された少なくともｌ種を含むものを好ましく用いることができる。これらを含有させることによって藻類培養媒体の比重を小さくすることができ、水に浮遊させることが可能になる。
【００２５】
そして本発明において、硬化材、藻類培養養分および軽量化材の添加量は、無機質材料の重量１００重量部に対して、硬化材を少なくとも５重量部、そして藻類培養養分は２０重量部を超えないことが好ましい。硬化材の量が５重量部以上であれば望ましい硬度が得られる。
【００２６】
また本発明においては、混合物に撥水剤を含有させてもよい。それによって、藻類培養媒体の水面への浮上の安定化に役立てることができる。
【００２７】
本発明の混合工程において、混合機として混合槽の底部をその排出口に向かって傾斜させた高速攪拌翼混合機を用いることが好ましい。この底部の傾斜によって混合体の排出が良好になり、生産性が向上する。
【００２８】
本発明においては、成形体を養生する養生工程として、加熱養生を用いることができる。そして加熱養生は、温度１００℃以上の加熱養生を好ましく用いることができる。また加熱養生の熱源として、火力発電所もしくは廃棄物焼却場の廃熱を好ましく用いることができる。これらの廃熱を用いれば、加熱養生のための新たな熱源を用意する必要がなく、しかも廃熱が有効利用できる。
【００２９】
【発明の実施の形態】
以下に本発明の実施の形態を実施例に基づき具体的に説明する。
【００３０】
（実施例１）
図１に本実施例１における藻類培養媒体の標準成形工程を示す。無機質材料として石炭灰、焼却灰、砂、貝殻粉砕物のいずれかについて、硬化材と軽量化材および藻類培養養分を添加し、さらに水を加えて混合した。混合は、大量の材料を短時間で均一にする観点から、撹拌翼がブレード型の高速撹拌翼混合機の一種であるヘンシェルミキサにより行った。図２に高速撹拌翼混合機の一種であるヘンシェルミキサの模式的断面図を示す。図２において、符合１は攪拌槽、２は攪拌翼、３は槽の蓋部、４は排出口、５は駆動手段、そして６は台である。
【００３１】
こうして得た混合物を型枠に入れて養生（温湿度を保って硬化）して成形体を作製する。
【００３２】
続いて、脱型した成形体の硬化反応促進（強度向上）のために成形体を加熱養生（１１０℃、２４時間）してぺレット状の藻類培養媒体を作製した。なお、製造した成形体がアルカリ分を多く含み、ｐＨが高くなる場合には、必要に応じて水に浸漬して成形体のｐＨを下げることも行った。また、無機質材料については、環境に影響する重金属や有機物が含有していることが考えられるため、本試験ではこのような重金属や有機物を予め除去し、かつ乾燥処理したものを用いた。
【００３３】
表１に実施例１における実施条件およびその結果を示す。表１において、藻類培養媒体成形体の製作には、無機質材料として石炭灰、焼却灰、砂、貝殻粉砕物を用い、硬化材として珪酸ナトリウムを用い、軽量化材としてパーライトを用い、さらに藻類培養養分にはリン酸ナ卜リウムとリン酸鉄および硝酸ナトリウムを重量比５：１：５で用いた。
【００３４】
【表１】

【００３５】
これらの成形体を、藻の入った海水を貯えた水槽の中に入れて試験した。表１に示したように、いずれの無機質材料を用いた場合でも、硬化材として珪酸ナトリウムを用い、さらに軽量化材としてパーライトを用いることによって、成形体の密度が１ｇ／ｃｍ３以下で水に浮遊させることができること、そして藻類の増殖が得られることが確認された。
【００３６】
（実施例２）
図３に実施例２における藻類培養媒体の解砕成形工程を示す。実施例１と同様の条件で無機質材料に硬イヒ材と軽量化材および藻類培養養分さらに水を加えて高速ブレード型混合機であるヘンシェルミキサにより混合を行った。こうして得た混合物を大型の型枠に入れて３００ｍｍ□×３０ｍｍｔ大の成形体を作製した。これを、脱型および加熱養生（１１０℃、２４時間）後に解砕造粒機に投入し、直径約５ｍｍの角張った成形体を得た。この成形体について、実施例１と同じ方法で試験を行った。その結果を表２に示す。
【００３７】
【表２】

【００３８】
表２から明らかなように、解砕成形法で作製した成形体も標準成形工程による場合と同様に、密度が１ｇ／ｃｍ^３以下で水に浮遊し、藻類の増殖が得られることを確認した。本成形方法によれば、混合物を型枠に入れる操作回数が標準方法よりも低減できるため、より大量の成形体を作製する際は有利であることが明確となった。
【００３９】
（実施例３）
図４に実施例３における藻類培養媒体の攪拌成形の工程を示す。実施例１と同様に無機質材料に硬化材と軽量化材および藻類培養養分を添加して高速ブレード型混合機であるヘンシエルミキサにより混合した。この後、この混合物を撹拌翼によって撹拌して成形する撹拌成形を行った。撹拌成形は回転翼による撹拌の速さによって次に述べるように転動成形と混合成形とに区分される。転動成形方法では、ミキサの回転羽根を低速で回しながら粉末材料混合物に水を投入して、直径が約５〜１５ｍｍの球状の成形体とした。一方、混合成形方法では、ミキサの回転羽根を高速で回して粉末材料混合物を乱流状態にして、この中にスプレーを用いて水を噴射して供給することで、直径が約５〜１９ｍｍの球状の成形体を得た。これら成形体について、ミキサのジャケットに蒸気を供給することで加熱養生（１１０℃、２４時間）して藻類培養媒体を作製した。なお、実施例１と同様に作製した成形体がアルカリ分を多く含み、ｐＨが高くなる場合には、必要に応じて水に浸漬して成形体のｐＨを下げることも行った。結果を表３に示す。
【００４０】
【表３】

【００４１】
表３の結果から明らかになったように、攪拌成形方法で作製した成形体も標準成形工程により成形し養生した場合と同様に、密度が１ｇ／ｃｍ３以下で水に浮遊し、藻類の増殖が得られることを確認した。本成形方法によれば、成形体の必要量に応じて、ミキサの大きさを変えることで、大量の球状成形体として藻類培養媒体が得られることが明確となった。また、本実施例で明らかなように、本成形方法によれば、材料の混合と成形および加熱養生の各工程を同一のミキサ内で行えることも分かった。だだし、成形工程専用のドラム型やパン型造粒機を用いた転動成形方法、あるいは、フレキソミックス装置を用いた混合成形方法により、各工程を単独で行っても、もちろん構わない。
【００４２】
（実施例４）
図５に実施例４における藻類培養媒体の押出成形工程を示す。実施例１と同様の条件で無機質材料に硬化材と軽量化材および藻類培養養分さらに水を加えてヘンシェルミキサにより混合を行った。こうして得た混合物をスクリュー式押出造粒機に供給し、直径約１０ｍｍで長さが約１０ｍｍの円柱状の成形体を作製した。この成形体を加熱養生（１１０℃、２４時間）して藻類培養媒体を作製した。結果を表４に示す。
【００４３】
【表４】

【００４４】
なお、実施例１と同様に作製した成形体がアルカリ分を多く含み、ｐＨが高くなる場合には、必要に応じて水に浸漬して成形体のｐＨを下げることも行った。表４の結果から明らかなように、押出成形で作製した成形体も標準成形工程で成形し養生した場合と同様に、密度が１ｇ／ｃｍ^３以下で水に浮遊し、藻類の増殖が得られることを確認した。
【００４５】
（実施例５）
図６に実施例５における藻類培養媒体の圧縮成形工程を示す。実施例１と同様の条件で無機質材料に硬化材と軽量化材および藻類培養養分さらに水を加えてヘンシェルミキサにより混合を行った。こうして得た混合物を油圧式の圧縮造粒機に供給し、直径約１０ｍｍで長さが約１０ｍｍの円柱状の成形体を作製した。この成形体を加熱養生（１１０℃、２４時間）して藻類培養媒体を作製した。なお、実施例１と同様に作製した成形体がアルカリ分を多く含み、ｐＨが高くなる場合には、必要に応じて水に浸漬して成形体のｐＨを下げることも行った。結果を表５に示す。
【００４６】
【表５】

【００４７】
表５の結果から明らかなように、圧縮成形方法で作製した成形体も標準成形工程で成形し養生した場合と同様に、密度が１ｇ／ｃｍ３以下で水に浮遊し、藻類の増殖が得られることを確認した。
【００４８】
（実施例６）
無機質材料を石炭灰に限定した上で、硬化材を各種変えた他は上記実施例と同じ方法で試験を行った。その結果を表６に示す。
【００４９】
【表６】

【００５０】
表６から明らかなように、硬化材として、セメントの他に珪酸ナトリウム、珪酸カリウム、珪酸リチウム、およびシリカゾルを用いた場合にも、水に浮遊し、藻類の増殖が得られる成形体、すなわち、藻類培養媒体が得られることが確認された。
【００５１】
また、硬化材をセメントと珪酸ナトリウムに限定して、上記実施例２〜５と同じ方法で試験を行い、成形方法の違いによる影響も確認した。得られた結果は標準成形工程による場合とほぼ同等であり、成形体の密度がｌｇ／ｃｍ^３以下で水に浮遊し、藻類の増殖が確認された。この結果から、本発明における無機質材料の成形工程、即ち、標準成形、解砕成形、撹拌成形（転動成形、混合成形）、押出成形、圧縮成形のいずれにおいても、いずれの硬化剤でも標準成形工程の場合と同等の結果が得られる藻類培養媒体を作製できることを確認した。
【００５２】
（実施例７）
藻類培養養分としても有効なリン酸塩化合物を、硬化材として用いた。また、他の藻類培養養分はリン酸鉄もしくは水酸化酸化鉄（鉄分）および硝酸ナトリウム（窒素分）とした藻類培養媒体の成形体を作製した。その結果を表７に示す。
【表７】

【００５３】
この結果から明らかなように、標準成形方法においてリン酸ナ卜リウム、リン酸２水素ナトリウム、リン酸アルミニウムおよびリン酸水素アルミニウムは、いずれも硬イヒ材としても有効であり、これらを用いた場合に水に浮遊し、藻類の増殖が得られる成形体が作製できることを確認した。
【００５４】
また、リン酸塩としてリン酸ナトリウムとリン酸アルミニウムをそれぞれ添加した条件について、上記実施例２〜５と同じ方法で試験を行い、成形工程の違いによる影響も確認した。この結果、得られた結果は標準成形方法の場合とほぼ同等であり、成形体の密度が１ｇ／ｃｍ^３以下で水に浮遊し、藻類の増殖が確認された。本結果から、本発明における無機質材料の成形方法、即ち、標準成形工程、解砕成形工程、撹拌成形工程（転動成形工程、混合成形工程）、押出成形工程、圧縮成形工程のいずれでも、藻類培養養分としても有効なリン酸塩化合物を、硬化材として適用できることを確認した。
【００５５】
図７は、上記実施例６−１、６−２および７−１の条件で、硬化材添加量をそれぞれ変化させた場合について、作製した成形体の圧縮強度の変イヒを調べた結果を示す。この結果から、硬化材は無機質材料の重量１００重量部に対して５重量部以上において、強度が基準値を満たすことが分かつた。
【００５６】
また図８には、硬化材として珪酸ナトリウムに固定した場合について、成形工程の違いによる影響も確認した結果を示す。この結果から、成形工程の違いによる強度への大きな変化は見られず、いずれも硬化材が５重量部以上において強度の基準値を満たすことが分かった。
【００５７】
（実施例８）
無機質材料を石炭灰に限定し、さらに硬化材を珪酸ナトリウムに限定した上で、藻類培養養分を各種変えた他は、実施例１と同じ標準成形条件で藻類培養媒体を製作し、実施例１と同じ方法で試験を行った。その結果を表８に示す。
【００５８】
【表８】

【００５９】
表８から明らかなように、藻類培養養分としてリン酸鉄、水酸化酸化鉄、リン酸アルミニウム、およびリン酸ナトリウムを用いた場合に、水に浮遊し、藻類の増殖が得られる藻類培養媒体が得られることが確認できた。
【００６０】
また、藻類培養養分としてリン酸鉄と水酸化酸化鉄（鉄分）、およびリン酸アルミニウムとリン酸ナトリウム（リン分）、さらに硝酸ナトリウム（窒素分）を複合添加した場合について、上記実施例２〜５と同じ方法で試験を行い、成形工程の違いによる影響をも調べた結果を併せて表８に示す。この結果から明らかなように、得られた成形体はいずれも標準成形工程の場合とほぼ同等であり、成形体の密度が１ｇ／ｃｍ３以下で水に浮遊し、藻類の増殖が確認された。この結果から、成形工程の違いに関わらず、藻類培養養分添加の効果が確認された。
【００６１】
図９は、実施例８−１の条件で藻類培養養分であるリン酸鉄＋リン酸ナトリウム＋硝酸ナトリウムの添加量を変えた場合の、藻類成長速度の変化を調べた結果を示す。この図９から、無機質材料１００重量部に対して藻類培養養分が２０重量部以下であれば、藻類培養養分の増加に対して藻類成長速度が飽和せず、添加量として適切であることが分かる。
【００６２】
（実施例９）
無機質材料を石炭灰に、硬化材を珪酸ナトリウムに限定した他は、実施例１と同様の標準成形工程で藻類培養媒体成形体を作製し、実施１と同じ条件で試験を行い、各種軽量化材の有効性を調べた。その結果を表９に示す。この結果から、パーライトの他、シラスおよびその化合物、粒状軽石、さらにこれらの混合物を利用することにより、水に浮遊し、かつ、藻類の増殖が得られる藻類培養媒体成形体が得られることが確認された。また、軽量化材としてパーライトおよびシラスをぞれぞれ添加した条件について、上記実施例２〜５と同じ方法で試験を行い、成形工程の違いによる影響について確認した結果も併せて表９に示す。
【００６３】
【表９】

【００６４】
この結果から明らかなように、得られた成形体はいずれも標準成形工程の場合とほぼ同等であり、成形体の密度がｌｇ／ｃｍ^３以下で水に浮遊し、藻類の増殖が確認された。この結果から、成形工程の違いに関わらず、軽量化材添加の効果が確認された。
【００６５】
図１０には、上記実施例９−２、９−３、および９−５のそれぞれの条件で、軽量化材であるパーライト、シラスおよび粉末アルミニウムの添加量を変化させた場合について、成形体の密度変化を調べた結果を示す。この結果から、無機質材料の１００重量部に対して、軽量化材を１０重量部以上添加することで、成形体の密度をｌｇ／ｃｍ３以下にでき、水に浮遊させることができることが分かった。
【００６６】
また、図１１には軽量化材としてパーライトを用いた場合について、成形工程の違いによる影響も確認した結果を示す。この結果から、成形工程に違いによる成形体密度の大きな変化は見られず、いすれも軽量化材が１０重量部以上において、基準である１ｇ／ｃｍ^３以下の密度となることが分かった。
【００６７】
（実施例１０）
上記実施例１のＲＵＮ１−１と同じ条件で、石炭灰に硬化材と軽量化材および藻類培養養分、さらに水を混合する混合工程について、ミキサの違いによる影響を調べた。混合槽の容量は２０Ｌ（リットル）で混合物の量は１０Ｌとなるようにした。混合機は周速５ｍ／秒以上の高速攪拌翼混合機と、周速５ｍ／秒で使用する高速ブレ−ド型ミキサと周速５ｍ／秒で使用する中速ブレード型ミキサであって、それぞれについて図２に示した標準タイプと、図１２に模式的断面図を示した高速攪拌翼混合機の混合槽の底部が排出口に向かって傾斜しているタイプの各２種類、計４種類について行い、さらにこれらブレード型との比較のために、低速のホイール型混合機を用いた場合についても行った。ここに図１２の高速攪拌翼混合機において、符合１は攪拌槽、２は攪拌翼、３は槽の蓋部、４は排出口、５は駆動手段、６は台、そして７が攪拌槽の傾斜している底部である。
【００６８】
結果を表１０に示す。高速ブレード型および中速ミキサでは５分間の混合で混合がなされた混合物が得られたのに対して、ホイール型ミキサでは３０分以上の時間を要し、しかも混合が不均一であり、また凝集塊が見られた。
【００６９】
【表１０】

【００７０】
また、混合物をミキサーから排出し、この排出重量と投入重量から排出率を求めた結果、高速および中速いずれのブレード型ミキサにおいても、標準タイプの排出率が９５重量％であるのに対して、混合槽の底部が排出口に向かって傾斜しているタイプの排出率は９９．５重量％であった。これは標準タイプが回転羽根下部のクリアランス部の混合物を押し出せずに残るのに対して、傾斜型は自重で混合物が排出できるため極めて排出率が高いものと考えられる。一方、ホイール型では塊が回転羽根に固着するなどして排出率が低く、８０重量％であった。
【００７１】
続いて、混合槽に１０Ｌの水を加えて１分間回転させた後に洗浄水を排出し、洗浄状況を目視で確認した。この結果、高速ブレード型ミキサは良好に洗浄できていた。ただし、標準タイプでは、回転羽根下部のクリアランス部に洗浄水が残留していた。これに対して、中速ブレード型ミキサでは、混合槽の壁面や回転羽根の表面に張り付くように若干の混合物が残留していた。このため、５ＭＰａ程度の高圧水を吹きかけることを試みたところ、良好に洗い落とすことができた。ホイール型ミキサについては、初期洗浄後もかなりの混合物が残留し、なおかつ高圧水の吹きかけでも落としきれずに、人力で掻き落とす操作を併用することで洗浄できた。
【００７２】
以上の結果から、大量の混合物を短時問で均−に混合するには高速攪拌翼混合機である高速ブレード型および中速ブレード型混合機が適しており、その中でも高速ブレード型で混合槽底部が排出口に向かって傾斜しているタイプが、排出性や洗浄性からみて特に好ましいことを確認した。
【００７３】
（実施例１１）
本発明の内部に中空部を有する成形体を作製する押出成形方法の一実施例を、図１３を参照して説明する。本実施例では、実施例４に示した押出成形工程に沿い、実施例４において軽量化材を含まず、他は同じ配合で無機質材料（石炭灰）に硬化材（珪酸ナトリウム）、藻類培養養分（リン酸ナトリウム、リン酸鉄、硝酸ナトリウム）および水を添加して高速ブレード型混合機により混合し、押出成形機で成形後、１１０℃の温度で２４時間養生することにより成形体の内部に中空部を有する成形体を作製した。本実施例では、まず２重の管の外側の管１１と内側の管１２の間に多孔質層１３の原料の混合物を挿入形成し、押出成形によって円柱状に成形する。これを圧縮機１４によって押出成形体の両端を圧迫し、内部に中空部１５を有する成形体を作製した。成形体の大きさは、中空部の直径約２ｍｍ、多孔質層の外径約５ｍｍ、成形体長約１ｃｍとなるようにした。本実施例による成形体の水への浮遊日数は約２００日であった。
【００７４】
続いて、成形体内部に中空部と低透水層を有してなる成形体の成形方法についての実施例を、図１４を参照して説明する。図１４において、図１３と同じ部分は同一番号を付している。上記図１３を参照として示した実施例においては、成形体内を浸透した水が中空部内に入った場合、中空部内に水が蓄積すると成形体は沈降する。しかし、図１４を参照として示す本実施例では、低透水性層６を形成するために、３重の管からなるダイスの最外側の管と中間の管との間に多孔質の材料を、中間の管と最内側の管との間に低透水性の材料を入れて押し出し成形によって円筒状に成形する。低透水層６には石炭灰、焼却灰、モンモリオナイト、カオリナイト、セメント、水ガラス、石灰、石膏のうち少なくとも１つを用いる。本実施例では、中空部は直径２ｍｍ、低透水層１ｍｍ、多孔質層外径約６ｍｍ、成形体長約１ｃｍとなるように成形し、その他工程は上記図１３の場合と同等とした。このような構造とすることにより、多孔質層を通過した水は低透水層で著しく透過速度が低下するので、微細藻類などの水性生物の養分を供給可能な期間、水に浮遊させておくことが可能であることがわかった。
【００７５】
本実施例による成形体の水への浮遊期間は１年を過ぎ、まだ浮遊中である。
【００７６】
（実施例１２）
実施例１と同じ標準成形工程により成形した成形体を、硬化させる際に加熱養生した場合、および蒸気中で加熱しで養生した場合のそれぞれについて、硬化の進行を調べた。その結果を表１１に示す。
【００７７】
【表１１】

【００７８】
この結果から、加熱養生した場合、および蒸気中で加熱養生した場合には、これらの措置をしない場合に比べて硬化が速くなり、製造時間の短縮がえられることが分かった。また、上記実施例２〜５ど同じ方法で試験し、成形方法の違いによる影響を確認した結果も、併せて表１１に示す。この結果からも明らかなように、成形方法の違いに関わらず、１００℃以上に加熱した場合は１日以内に硬化し、製造時間の短縮を確認した。また、本実施例では貫流ボイラーの蒸気を用いたが、火力発電所や廃棄物焼却場に成形設備を設ける際は、この廃熱を利用するのがコスト的に有利である。
【００７９】
なお、本発明に示された上記の実施例は例示に過ぎず、発明を限定するものではない。発明の範囲はクレームによって示されたものであって、クレームの内容に含まれるすべての変形例は本発明に含まれるものである。
【００８０】
【発明の効果】
本発明の無機質材料を主原料とする藻類培養媒体の製造方法によれば、海面などの水面に浮遊させて藻類を繁殖・増殖させることができる成形体を、短時間、かつ、大量にしかも安価に製造することか可能となる。これにより、主原料として石炭灰や焼却灰等の産業廃棄物を有効利用して、これを藻類の培養媒体として海洋などに散布することで、海洋などの富栄養化や汚染を防止して藻類を大量に培養でき、これにより大気中のＣＯ_２削減による地球温暖化防止に貢献できる。また、培養した藻類はアルコール等の有効物の原料となることから、これを化石燃料の代替エネルギーの供給等に貢献できる。従って、本発明は今後の人類が当面する環境とエネルギーの問題解決に大きく役立つものである。
【図面の簡単な説明】
【図１】実施例１に記載の標準成形方法による無機質材料を主原料とする藻類培養媒体の製造工程の流れ図である。
【図２】実施例１に記載の藻類培養媒体の製造工程における高速攪拌翼混合機であるヘンシェルミキサの模式的断面図を示す。
【図３】実施例２に記載の解砕成形方法による無機質材料を主原料とする藻類培養媒体の製造工程の流れ図を示す。
【図４】実施例３に記載の攪拌混合成形方法による無機質材料を主原料とする藻類培養媒体の成形工程の流れ図を示す。
【図５】実施例４に記載の押出成形方法による無機質材料を主原料とする藻類培養媒体の製造工程の流れ図を示す。
【図６】実施例５に記載の圧縮成形方法による無機質材料を主原料とする藻類培養媒体の製造工程を示す図である。
【図７】実施例７に記載の標準成形方法による藻類培養媒体における硬化材添加量と藻類培養媒体強度の関係を示す。
【図８】実施例７に記載の各種成形方法における硬化材添加量と藻類培養媒体強度の関係を示す。
【図９】実施例８に記載の藻類培養媒体における養分・供給剤の添加量と藻類の成長速度との関係を示す。
【図１０】実施例９に記載の標準成形方法における軽量化材添加量と藻類培養媒体密度の関係を示す。
【図１１】実施例９に記載の各種成形方法における軽量化材添加量と藻類培養媒体密度の関係を示す。
【図１２】実施例１０に記載の藻類培養媒体の製造工程における混合槽の底部が排気口に向かって傾斜しているヘンシェルミキサの模式的断面図を示す。
【図１３】実施例１１に記載の内部に中空部を有する成形体を作製する押出成形方法の概要を模式的に示す図である。
【図１４】実施例１１に記載の内部に中空部と低透水層を有する成形体を作製する押出成形方法の概要を模式的に示す図である。
【符号の説明】
１……攪拌槽、２……攪拌翼、３……槽の蓋部、４……排出口、
５……駆動源、６……台、７……底部、１１……外側の管、
１２……内側の管、１２’……中間の管、１３……多孔質層、
１４……圧迫機、１５……空孔部、１６……低透水層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an algae culture medium for culturing algae on a large scale in the ocean or a lake, and in particular, effectively uses coal ash or incineration ash generated from a thermal power plant or an incinerator, or pulverizes sand or shells. The present invention relates to a production method for producing a large amount of a nutrient supply medium for algae culture using a product.
[0002]
[Prior art]
Microalgae are the solar utilization rate per unit area, that is, CO₂CO2 in the atmosphere because of its higher ability to fix and higher growth speed than land plants₂It is considered as a powerful option for fixing. For this reason, for the purpose of global warming prevention, CO₂Research is being conducted to produce useful materials such as petroleum alternative fuels by using these as raw materials.
[0003]
For example, a photoreactor capable of concentrating sunlight and irradiating it efficiently is provided, and CO is provided in the photoreactor.₂Many research institutes are conducting research on introducing microalgae by introducing exhaust gas from abundant thermal power plants.
[0004]
[Problems to be solved by the invention]
By the way, the huge amount of CO that contributes to the prevention of global warming₂In order to fix the bacterium, it is necessary to culture microalgae in a large area. According to estimates, CO generated in Japan₂In order to fix 10% of the area, an area of 300 km square is required.
[0005]
It is difficult to secure such a vast area in the inland area of Japan, and large-scale culture in the ocean is required, but in the past it was difficult to efficiently supply nutrients in the ocean. . That is, when nutrients are sprayed in the ocean, the nutrients diffuse rapidly into the ocean, so that most of the nutrients are not used for algae culture, but the entire ocean is eutrophied, causing ocean pollution.
[0006]
For this reason, the medium which fixes a nutrient to the sea surface with a certain method and supplies a nutrient according to algae growth is needed. As a result of diligent research, some of the present inventors previously proposed a method for producing a medium that can float in water and supply nutrients (Japanese Patent Application No. 10-52050).
[0007]
According to the present invention, it is possible to produce a medium capable of supplying nutrients for growing microalgae in the ocean or the like. However, in the invention of Japanese Patent Application No. 10-52050, a large amount of water repellent is added in order to maintain floating in water. The water-repellent agent is the most expensive among the raw materials for producing such a medium, and the water-repellent agent gradually becomes insufficient in the long-term floating, so that there is a problem that it eventually settles.
[0008]
The present invention has been made in order to solve the above-mentioned problems. The object of the present invention is to use an algae culture medium as a nucleus for algae growth floating in water as industrial waste such as coal ash and incineration ash of a thermal power plant. Providing a large-scale and inexpensive method for producing large quantities of sand and shell crushed materials, and spreading the algae culture medium mass-produced thereby to a large area of the sea, allowing large-scale and clean growth of algae Is possible.
[0009]
[Means for Solving the Problems]
The present invention includes a mixing step of mixing a raw material containing an inorganic material, a hardener, and an algal culture nutrient,A preforming step in which the mixture is put into a mold to form a preform, a crushing and molding step in which the preform is crushed into a fine molded body,And at least a curing process for curing the molded body,The density of this compact is 1 g / cm ³ Be as followsThis is a method for producing an algae culture medium.
[0011]
ADVANTAGE OF THE INVENTION According to this invention, the algae culture medium which floats in seawater and fresh water can be manufactured in large quantities.
[0012]
ThisIn this case, curing is performed to an extent suitable for crushing at the stage after being molded in the mold and before crushing, and further curing can be performed after crushing. According to this method, since it is not necessary to put the mixture into the mold one by one, a large number of molded articles can be quickly produced.
[0013]
In the mixing step, if a high-speed stirring blade mixer having a stirring blade rotating at a high speed in a mixing tank is used in the mixing step, uniform mixing can be performed in a short time, and therefore it can be preferably used. And by making the mixing layer tank into a substantially cylindrical shape and disposing the stirring blade at the bottom, stirring and mixing can be performed very efficiently. As the stirring blade, a blade type is particularly preferably used because it can rapidly perform the above mixing.
[0014]
In addition, the present invention can use a stirring molding process in which water or a hardening material aqueous solution is sprayed and molded into a molded body while stirring the mixture. This molded body can be cured after molding to increase the strength of the molded body. According to this method, a large amount of granular compacts can be molded together.
[0015]
In the step of sprinkling water or a hardening material aqueous solution while stirring the above mixture to form a molded body, a mixer different from the high-speed stirring blade mixer used in the mixing step may be prepared and used. The high-speed stirring blade mixer used in the mixing step can be continuously used as it is. By doing so, it is possible to save the labor and loss of transfer.
Moreover, this invention can use the process of extruding with a die | dye, such as supplying the said mixture to an extruder as a shaping | molding process, and making it a molded object. According to this method, a molded body having a predetermined shape can be produced in large quantities with high productivity.
[0016]
In the present invention, in the above-described process of extruding the mixture from the die, a die consisting of a double tube is used, and the mixture is transferred between the outer wall of the double tube and the outer wall of the inner tube. By compressing and sealing both ends after extrusion molding, a molded body having a porous layer outside and a hollow part inside can be obtained. Here, the hollow portion is a closed cavity without an entrance / exit. By producing in this way, it is possible to reduce the apparent specific gravity of the molded body, which is advantageous for floating on the water surface as an algae culture medium.
[0017]
Further, in the above-described process of forming the mixture by extruding the mixture from the die, a porous material is placed between the outermost tube and the intermediate tube of the triple die, and the intermediate tube is placed between the intermediate tube and the innermost tube. By placing a low water permeability material in the porous layer and the hollow part, a lower water permeability layer than the porous layer can be provided, so that the hollow part can be prevented from being flooded. Is further stabilized.
[0018]
As the low water permeability layer, a material containing at least one of coal ash, incinerated ash, montmorillonite, kaolinite, cement, water glass, lime, and gypsum can be used. By using these, the periphery of the hollow portion can be formed airtight. And since an apparent specific gravity can be made small by providing a hollow part, even if it does not contain a weight reducing material, it can be made to float in water.
[0019]
Moreover, this invention can use the process of compressing the said mixture into a molded object as a formation process. According to this method, a molded body having a predetermined shape can be produced in large quantities with high productivity.
[0020]
As the inorganic material used in the method for producing an algal medium of the present invention, a material containing at least one selected from coal ash, incinerated ash, sand, crushed shells, and diatoms can be preferably used. Among these, coal ash and incineration ash are industrial wastes produced in large quantities, and are particularly preferable because they can be reused.
[0021]
And these inorganic materials containing at least one selected from coal ash, incinerated ash, sand, shell crushed materials, and diatoms reduce or remove components that pollute the environment, that is, components such as heavy metals and harmful organic substances. Since the treated product has no fear of environmental pollution, it can be preferably used. Coal ash is composed mainly of silica and alumina, and is relatively stable in terms of components, and can be managed and used so as not to contain components that pollute the environment. Incineration ash can also be used after removing components that pollute the environment at the stage of separate collection or after-treatment of incineration ash.
[0022]
Moreover, as a hardening | curing material used for this invention, what contains at least 1 sort (s) selected from cement, water glass, lime, and gypsum is used preferably. And the hardened material containing at least 1 sort (s) selected from cement or water glass can use the thing containing algae culture nutrients, for example, a phosphate compound, as the structural component.
[0023]
Moreover, as algae culture nutrient used for this invention, what contains at least 1 sort (s) selected from phosphorus content, nitrogen content, and iron content is preferable. By including these, it becomes possible to supply nutrients necessary for algae culture.
[0024]
Moreover, as a weight reducing material used for this invention, the thing containing at least 1 sort (s) selected from powder alumina, pearlite, shirasu, shirasu balloon, or granular pumice can be used preferably. By containing these, the specific gravity of the algal culture medium can be reduced, and it can be suspended in water.
[0025]
And in this invention, the addition amount of a hardening | curing material, algae culture nutrient, and a weight reduction material is at least 5 weight part of hardening | curing material with respect to 100 weight part of weight of an inorganic material, and algae culture nutrient does not exceed 20 weight part. It is preferable. If the amount of the hardener is 5 parts by weight or more, a desired hardness can be obtained.
[0026]
In the present invention, the mixture may contain a water repellent. Thereby, it can be used to stabilize the floating of the algal culture medium to the water surface.
[0027]
In the mixing step of the present invention, it is preferable to use a high-speed stirring blade mixer in which the bottom of the mixing tank is inclined toward the discharge port as the mixer. This slope of the bottom improves the discharge of the mixture and improves productivity.
[0028]
In the present invention, heat curing can be used as a curing process for curing the molded body. And heat curing can use preferably the heat curing of the temperature of 100 degreeC or more. Moreover, the waste heat of a thermal power plant or a waste incineration plant can be preferably used as a heat source for heat curing. If these waste heats are used, it is not necessary to prepare a new heat source for heat curing, and the waste heat can be effectively used.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below based on examples.
[0030]
Example 1
FIG. 1 shows a standard molding process of the algal culture medium in Example 1. For any one of coal ash, incinerated ash, sand, and shell pulverized material as an inorganic material, a hardening material, a lightening material, and an algal culture nutrient were added, and water was further added and mixed. The mixing was performed by a Henschel mixer, which is a kind of blade type high-speed stirring blade mixer, from the viewpoint of making a large amount of material uniform in a short time. FIG. 2 shows a schematic cross-sectional view of a Henschel mixer, which is a kind of high-speed stirring blade mixer. In FIG. 2, reference numeral 1 is a stirring tank, 2 is a stirring blade, 3 is a lid of the tank, 4 is a discharge port, 5 is a driving means, and 6 is a table.
[0031]
The mixture thus obtained is placed in a mold and cured (cured while maintaining temperature and humidity) to produce a molded body.
[0032]
Subsequently, the pellet was heated and cured (110 ° C., 24 hours) in order to accelerate the curing reaction (improvement of strength) of the demolded molded body, thereby producing a pellet-like algal culture medium. In addition, when the manufactured molded object contained much alkali content and pH became high, it was also immersed in water as needed and the pH of the molded object was also performed. In addition, since it is considered that the inorganic material contains heavy metals and organic substances that affect the environment, in this test, such heavy metals and organic substances were previously removed and dried.
[0033]
Table 1 shows implementation conditions and results in Example 1. In Table 1, the algae culture medium molded body is manufactured by using coal ash, incinerated ash, sand and shell pulverized material as inorganic materials, sodium silicate as a hardener, pearlite as a weight reducing material, and algal culture. As nutrients, sodium phosphate, iron phosphate and sodium nitrate were used at a weight ratio of 5: 1: 5.
[0034]
[Table 1]

[0035]
These molded bodies were tested by placing them in a water tank containing seawater containing algae. As shown in Table 1, even when any inorganic material is used, by using sodium silicate as a curing material and further using pearlite as a weight reducing material, the density of the molded body floats in water at 1 g / cm 3 or less. It was confirmed that algae growth can be obtained.
[0036]
(Example 2)
FIG. 3 shows the crushing and forming step of the algal culture medium in Example 2. Under the same conditions as in Example 1, hard baboon material, light weight material, algae culture nutrients and water were added to the inorganic material and mixed with a Henschel mixer which is a high-speed blade type mixer. The mixture thus obtained was placed in a large mold to produce a molded body having a size of 300 mm □ × 30 mmt. This was put into a pulverizing granulator after demolding and heat curing (110 ° C., 24 hours) to obtain an angular shaped product having a diameter of about 5 mm. This molded body was tested in the same manner as in Example 1. The results are shown in Table 2.
[0037]
[Table 2]

[0038]
As is clear from Table 2, the density of the molded body produced by the crushing molding method is 1 g / cm as in the case of the standard molding process.³In the following, it floated in water and confirmed that algae growth was obtained. According to this molding method, since the number of operations for putting the mixture into the mold can be reduced as compared with the standard method, it has become clear that it is advantageous when producing a larger amount of the molded body.
[0039]
(Example 3)
FIG. 4 shows the step of stirring and forming the algal culture medium in Example 3. In the same manner as in Example 1, a hardener, a lightening material, and algae culture nutrients were added to the inorganic material and mixed with a Henschel mixer, which is a high-speed blade type mixer. Thereafter, the mixture was stirred by a stirring blade and molded. Agitation molding is classified into rolling molding and mixed molding as described below according to the speed of stirring by the rotary blades. In the rolling molding method, water was added to the powder material mixture while rotating the rotating blades of the mixer at a low speed to obtain a spherical molded body having a diameter of about 5 to 15 mm. On the other hand, in the mixing molding method, the rotating blades of the mixer are rotated at a high speed to make the powder material mixture in a turbulent state, and water is sprayed and supplied into the pulverized material mixture so that the diameter is about 5 to 19 mm. A spherical shaped body was obtained. These molded bodies were heated and cured (110 ° C., 24 hours) by supplying steam to the jacket of the mixer to produce an algae culture medium. In addition, when the molded object produced similarly to Example 1 contained many alkalis and pH became high, it immersed in water as needed and also performed pH reduction of the molded object. The results are shown in Table 3.
[0040]
[Table 3]

[0041]
As is clear from the results in Table 3, the molded body produced by the stirring molding method floats in water at a density of 1 g / cm 3 or less, and algae grows in the same manner as when molded and cured by the standard molding process. It was confirmed that it was obtained. According to this molding method, it became clear that the algal culture medium can be obtained as a large amount of spherical molded body by changing the size of the mixer according to the required amount of the molded body. Further, as is clear from this example, it has also been found that according to this molding method, the steps of mixing and molding materials and heating and curing can be performed in the same mixer. However, it is of course possible to carry out each process independently by a rolling molding method using a drum mold or a bread granulator dedicated to the molding process, or a mixing molding method using a flexomix device.
[0042]
Example 4
FIG. 5 shows an extrusion process of the algal culture medium in Example 4. Under the same conditions as in Example 1, a hardening material, a lightening material, an algae culture nutrient, and water were further added to the inorganic material, and mixing was performed using a Henschel mixer. The mixture thus obtained was supplied to a screw-type extrusion granulator to produce a cylindrical shaped body having a diameter of about 10 mm and a length of about 10 mm. This molded body was heat-cured (110 ° C., 24 hours) to prepare an algal culture medium. The results are shown in Table 4.
[0043]
[Table 4]

[0044]
In addition, when the molded object produced similarly to Example 1 contained many alkalis and pH became high, it immersed in water as needed and also performed pH reduction of the molded object. As is clear from the results in Table 4, the density of the molded body produced by extrusion molding was 1 g / cm as in the case of molding and curing in the standard molding process.³In the following, it floated in water and confirmed that algae growth was obtained.
[0045]
(Example 5)
FIG. 6 shows the compression molding process of the algal culture medium in Example 5. Under the same conditions as in Example 1, a hardening material, a lightening material, an algae culture nutrient, and water were further added to the inorganic material, and mixing was performed using a Henschel mixer. The mixture thus obtained was supplied to a hydraulic compression granulator to produce a cylindrical molded body having a diameter of about 10 mm and a length of about 10 mm. This molded body was heat-cured (110 ° C., 24 hours) to prepare an algal culture medium. In addition, when the molded object produced similarly to Example 1 contained many alkalis and pH became high, it immersed in water as needed and also performed pH reduction of the molded object. The results are shown in Table 5.
[0046]
[Table 5]

[0047]
As is clear from the results in Table 5, the molded body produced by the compression molding method is also floated in water at a density of 1 g / cm 3 or less, and algae can be grown, as in the case of molding and curing in the standard molding process. It was confirmed.
[0048]
(Example 6)
The test was carried out in the same manner as in the above example except that the inorganic material was limited to coal ash and the hardener was changed in various ways. The results are shown in Table 6.
[0049]
[Table 6]

[0050]
As is apparent from Table 6, when a hardener is used, in addition to cement, sodium silicate, potassium silicate, lithium silicate, and silica sol, a molded body that floats in water and obtains algae growth, that is, It was confirmed that an algae culture medium was obtained.
[0051]
Moreover, the hardener was limited to cement and sodium silicate, and the test was conducted by the same method as in Examples 2 to 5, and the influence due to the difference in the molding method was also confirmed. The obtained results are almost the same as those obtained by the standard molding process, and the density of the molded body is lg / cm.³Below, it floated in water and algae growth was confirmed. From this result, in any molding process of the inorganic material in the present invention, that is, standard molding, crush molding, stirring molding (roll molding, mixed molding), extrusion molding, compression molding, any curing agent is standard molding. It was confirmed that an algae culture medium capable of obtaining results equivalent to those in the process can be produced.
[0052]
(Example 7)
A phosphate compound that is also effective as an algae culture nutrient was used as a curing material. In addition, other algae culture nutrients were formed as algae culture medium molded bodies containing iron phosphate or iron hydroxide oxide (iron content) and sodium nitrate (nitrogen content). The results are shown in Table 7.
[Table 7]

[0053]
As is clear from this result, sodium phosphate, sodium dihydrogen phosphate, aluminum phosphate and aluminum hydrogen phosphate are all effective as hard baboon materials in the standard molding method. It was confirmed that a molded body that floated on water and could grow algae could be produced.
[0054]
Moreover, about the conditions which added sodium phosphate and aluminum phosphate as a phosphate, the test was done by the same method as the said Examples 2-5, and the influence by the difference in a shaping | molding process was also confirmed. As a result, the obtained result is almost the same as that of the standard molding method, and the density of the molded body is 1 g / cm.³Below, it floated in water and algae growth was confirmed. From these results, the method for molding the inorganic material in the present invention, that is, the standard molding process, the crushing molding process, the stirring molding process (rolling molding process, the mixing molding process), the extrusion molding process, and the compression molding process are all algae. It was confirmed that a phosphate compound effective as a culture nutrient can be applied as a curing material.
[0055]
FIG. 7 shows the result of investigating the change in compression strength of the produced molded body in the case where the amount of addition of the hardener was changed under the conditions of Examples 6-1 6-2, and 7-1. . From this result, it was found that the strength satisfies the standard value when the curing material is 5 parts by weight or more with respect to 100 parts by weight of the inorganic material.
[0056]
Moreover, in FIG. 8, the result of having confirmed the influence by the difference in a formation process about the case where it fixes to sodium silicate as a hardening | curing material is shown. From this result, it was found that there was no significant change in strength due to the difference in the molding process, and in all cases, the cured material satisfied the strength standard value at 5 parts by weight or more.
[0057]
(Example 8)
Example 1 The algae culture medium was produced under the same standard molding conditions as Example 1, except that the inorganic material was limited to coal ash and the hardener was limited to sodium silicate, and various algae culture nutrients were changed. The test was carried out in the same way. The results are shown in Table 8.
[0058]
[Table 8]

[0059]
As is apparent from Table 8, when using iron phosphate, iron hydroxide oxide, aluminum phosphate, and sodium phosphate as the algal culture nutrient, there is an algae culture medium that floats in water and allows the growth of algae. It was confirmed that it was obtained.
[0060]
Moreover, about the case where iron phosphate and iron hydroxide oxide (iron content), aluminum phosphate and sodium phosphate (phosphorus content), and sodium nitrate (nitrogen content) are added together as algae culture nutrients, the above Examples 2 to 2 are added. Table 8 shows the results of the test conducted by the same method as in No. 5 and the investigation of the influence of the difference in the molding process. As is apparent from the results, all of the obtained molded bodies were almost the same as those in the standard molding step, and the molded bodies floated in water at a density of 1 g / cm 3 or less, and the growth of algae was confirmed. From this result, the effect of adding algal culture nutrients was confirmed regardless of the difference in the molding process.
[0061]
FIG. 9: shows the result of having investigated the change of the algal growth rate at the time of changing the addition amount of iron phosphate + sodium phosphate + sodium nitrate which is an algal culture nutrient on the conditions of Example 8-1. From FIG. 9, it can be seen that if the algal culture nutrient is 20 parts by weight or less with respect to 100 parts by weight of the inorganic material, the algal growth rate is not saturated with respect to the increase of the algal culture nutrient, and the addition amount is appropriate. .
[0062]
Example 9
Except that the inorganic material is coal ash and the hardener is sodium silicate, an algae culture medium molded body is produced in the same standard molding process as in Example 1, and tested under the same conditions as in Example 1 to reduce various weights. The effectiveness of the material was investigated. The results are shown in Table 9. From this result, it is confirmed that by using shirasu and its compound, granular pumice, and a mixture thereof in addition to pearlite, an algae culture medium molded body that floats in water and can grow algae can be obtained. It was done. Moreover, about the conditions which each added pearlite and shirasu as a weight reduction material, it tested by the same method as the said Examples 2-5, and also the result confirmed about the influence by the difference in a formation process is also shown in Table 9 together .
[0063]
[Table 9]

[0064]
As is apparent from the results, all of the obtained molded bodies were almost the same as in the standard molding process, and the density of the molded bodies was lg / cm.³Below, it floated in water and algae growth was confirmed. From this result, the effect of adding the weight reducing material was confirmed regardless of the difference in the molding process.
[0065]
FIG. 10 shows the case of the molded body in the case where the addition amount of pearlite, shirasu, and powdered aluminum as lightening materials was changed under the conditions of Examples 9-2, 9-3, and 9-5. The result of examining the density change is shown. From this result, it was found that by adding 10 parts by weight or more of the weight reducing material to 100 parts by weight of the inorganic material, the density of the molded body can be reduced to lg / cm 3 or less and can be suspended in water.
[0066]
FIG. 11 shows the result of confirming the influence of the difference in the molding process when pearlite is used as the weight reducing material. From this result, there is no significant change in the density of the molded body due to the difference in the molding process, and in any case, when the weight reduction material is 10 parts by weight or more, the standard is 1 g / cm.³The following density was found.
[0067]
(Example 10)
Under the same conditions as RUN 1-1 in Example 1 above, the influence of the difference in the mixer was investigated in the mixing step of mixing the hardened material, the lightening material, the algal culture nutrient, and water with coal ash. The volume of the mixing tank was 20 L (liter) and the amount of the mixture was 10 L. The mixer is a high-speed agitating blade mixer with a peripheral speed of 5 m / sec or more, a high-speed blade mixer used at a peripheral speed of 5 m / sec, and a medium-speed blade mixer used at a peripheral speed of 5 m / sec. 2 types for each of the standard type shown in FIG. 2 and the type in which the bottom of the mixing tank of the high-speed stirring blade mixer shown in the schematic cross-sectional view in FIG. In addition, for comparison with these blade types, a low speed wheel type mixer was used. Here, in the high speed stirring blade mixer of FIG. 12, reference numeral 1 is a stirring tank, 2 is a stirring blade, 3 is a lid of the tank, 4 is a discharge port, 5 is a driving means, 6 is a table, and 7 is a stirring tank. An inclined bottom.
[0068]
The results are shown in Table 10. The high-speed blade type and medium-speed mixers produced a mixture that was mixed in 5 minutes, while the wheel type mixer required more than 30 minutes, and the mixing was uneven and coagulation A lump was seen.
[0069]
[Table 10]

[0070]
Further, the mixture was discharged from the mixer, and the discharge rate was calculated from the discharge weight and the input weight. As a result, the standard type discharge rate was 95% by weight in both the high-speed and medium-speed blade type mixers. The discharge rate of the type in which the bottom of the mixing tank is inclined toward the discharge port was 99.5% by weight. This is because the standard type remains without extruding the mixture in the clearance part at the lower part of the rotating blades, whereas the inclined type can discharge the mixture by its own weight, so the discharge rate is considered to be extremely high. On the other hand, in the wheel type, the lump was fixed to the rotating blades and the discharge rate was low, which was 80% by weight.
[0071]
Subsequently, 10 L of water was added to the mixing tank and rotated for 1 minute, and then the cleaning water was discharged, and the cleaning status was confirmed visually. As a result, the high-speed blade type mixer was washed well. However, in the standard type, cleaning water remained in the clearance portion below the rotary blade. On the other hand, in the medium-speed blade type mixer, some mixture remained so as to stick to the wall surface of the mixing tank and the surface of the rotary blade. For this reason, when an attempt was made to spray high-pressure water of about 5 MPa, it was possible to wash off well. As for the wheel mixer, a considerable mixture remained even after the initial cleaning, and it could not be removed even by spraying with high-pressure water, and it could be cleaned by using a manual scraping operation.
[0072]
From the above results, high-speed blade-type and medium-speed blade-type mixers, which are high-speed stirring blade mixers, are suitable for mixing a large amount of mixture uniformly in a short time. It was confirmed that the type in which the bottom portion is inclined toward the discharge port is particularly preferable from the viewpoint of dischargeability and cleanability.
[0073]
(Example 11)
One embodiment of an extrusion molding method for producing a molded body having a hollow portion inside the present invention will be described with reference to FIG. In this example, in accordance with the extrusion molding process shown in Example 4, the lightening material was not included in Example 4, and the others were the same composition and the inorganic material (coal ash) was hardened (sodium silicate), algae culture nutrient (Sodium phosphate, iron phosphate, sodium nitrate) and water are added and mixed with a high-speed blade type mixer. After molding with an extrusion molding machine, curing is performed at a temperature of 110 ° C. for 24 hours. A molded body having a hollow portion was produced. In this embodiment, first, a mixture of raw materials for the porous layer 13 is inserted between the outer tube 11 and the inner tube 12 of the double tube, and formed into a cylindrical shape by extrusion. This was compressed by the compressor 14 at both ends of the extruded molded body to produce a molded body having a hollow portion 15 inside. The size of the molded body was such that the diameter of the hollow portion was about 2 mm, the outer diameter of the porous layer was about 5 mm, and the length of the molded body was about 1 cm. The number of days in which the molded body according to this example floated in water was about 200 days.
[0074]
Next, an example of a method for forming a formed body having a hollow portion and a low water permeable layer inside the formed body will be described with reference to FIG. 14, the same parts as those in FIG. 13 are denoted by the same reference numerals. In the embodiment shown with reference to FIG. 13 above, when water that has permeated the molded body enters the hollow portion, the molded body sinks when water accumulates in the hollow portion. However, in this embodiment shown with reference to FIG. 14, in order to form the low water permeability layer 6, a porous material is used between the outermost tube and the middle tube of the triple die. A low water-permeable material is placed between the intermediate tube and the innermost tube, and is formed into a cylindrical shape by extrusion. For the low water permeability layer 6, at least one of coal ash, incinerated ash, montmorillonite, kaolinite, cement, water glass, lime, and gypsum is used. In this example, the hollow portion was formed to have a diameter of 2 mm, a low water permeability layer of 1 mm, a porous layer outer diameter of about 6 mm, and a molded body length of about 1 cm, and the other processes were the same as those in FIG. By adopting such a structure, the water that has passed through the porous layer has a low water permeability and the permeation rate is remarkably reduced. Was found to be possible.
[0075]
The floating period of the molded body according to the present example in water is over one year and is still floating.
[0076]
(Example 12)
The progress of curing was examined for each of the case where the molded body molded by the same standard molding process as in Example 1 was cured by heating when it was cured, and when it was cured by heating in steam. The results are shown in Table 11.
[0077]
[Table 11]

[0078]
From this result, it was found that when heat-cured and when heat-cured in steam, curing is faster and production time can be shortened than when these measures are not taken. Table 11 also shows the results of testing by the same method as in Examples 2 to 5 and confirming the influence due to the difference in molding method. As is clear from this result, regardless of the difference in the molding method, when heated to 100 ° C. or higher, it was cured within one day, and shortening of the production time was confirmed. In the present embodiment, the steam of the once-through boiler is used. However, when forming equipment is installed in a thermal power plant or a waste incineration plant, it is advantageous in cost to use this waste heat.
[0079]
The above-described embodiments shown in the present invention are merely examples, and do not limit the invention. The scope of the invention is indicated by the claims, and all modifications included in the content of the claims are included in the present invention.
[0080]
【The invention's effect】
According to the method for producing an algae culture medium using the inorganic material of the present invention as a main raw material, it is possible to produce a molded body that can float on the water surface such as the sea surface and propagate and propagate the algae in a short time, in a large amount, and at a low cost. It will be possible to manufacture. This effectively utilizes industrial waste such as coal ash and incinerated ash as the main raw material, and disperses it as a culture medium for algae in the ocean, thereby preventing eutrophication and contamination in the ocean, etc. Can be cultured in large quantities, so that CO in the atmosphere₂Contributing to the prevention of global warming through reduction. In addition, since cultured algae can be used as raw materials for effective substances such as alcohol, this can contribute to the supply of alternative energy for fossil fuels. Therefore, the present invention is greatly useful for solving environmental and energy problems for the future of humankind.
[Brief description of the drawings]
FIG. 1 is a flowchart of a manufacturing process of an algal culture medium using an inorganic material as a main raw material by a standard molding method described in Example 1.
FIG. 2 is a schematic cross-sectional view of a Henschel mixer that is a high-speed agitating blade mixer in the manufacturing process of the algal culture medium described in Example 1.
FIG. 3 shows a flow chart of a manufacturing process of an algal culture medium using an inorganic material as a main raw material by the crushing and forming method described in Example 2.
4 shows a flow chart of a process for forming an algae culture medium using an inorganic material as a main raw material by the stirring and mixing method described in Example 3. FIG.
FIG. 5 shows a flowchart of a manufacturing process of an algae culture medium using an inorganic material as a main raw material by the extrusion molding method described in Example 4.
6 is a diagram showing a manufacturing process of an algae culture medium using an inorganic material as a main raw material by the compression molding method described in Example 5. FIG.
7 shows the relationship between the amount of hardener added in the algal culture medium and the algal culture medium strength by the standard molding method described in Example 7. FIG.
8 shows the relationship between the amount of hardener added and the strength of the algal culture medium in the various molding methods described in Example 7. FIG.
9 shows the relationship between the added amount of nutrients / feeding agent and the growth rate of algae in the algae culture medium described in Example 8. FIG.
10 shows the relationship between the amount of lightening material added and the algal culture medium density in the standard molding method described in Example 9. FIG.
11 shows the relationship between the amount of lightening material added and the algal culture medium density in various molding methods described in Example 9. FIG.
12 is a schematic cross-sectional view of a Henschel mixer in which the bottom of the mixing tank is inclined toward the exhaust port in the manufacturing process of the algal culture medium described in Example 10. FIG.
13 is a diagram schematically showing an outline of an extrusion molding method for producing a molded body having a hollow portion therein as described in Example 11. FIG.
14 is a view schematically showing an outline of an extrusion molding method for producing a molded body having a hollow portion and a low water permeable layer therein as described in Example 11. FIG.
[Explanation of symbols]
1 ... Stirrer tank, 2 ... Stirrer blade, 3 ... Lid of tank, 4 ... Discharge port,
5 ... drive source, 6 ... stand, 7 ... bottom, 11 ... outer tube,
12 ... inner tube, 12 '... middle tube, 13 ... porous layer,
14 …… Presser, 15 …… Hole, 16 …… Low water permeability

Claims

A mixing step of mixing a raw material containing an inorganic material, a hardener, and algae culture nutrients , a preforming step in which the mixture is put into a mold to form a preform, and the preform is crushed and finely A method for producing an algae culture medium, comprising at least a crushing and forming step for forming a green body and a curing step for curing the green body, wherein the density of the green body is 1 g / cm ³ or less .

2. The method for producing an algae culture medium according to claim 1, wherein a high-speed rotary blade mixer is used for the mixing step, and the forming step forms a molded body by spraying water or an aqueous hardener solution while stirring the mixture. A method for producing an algae culture medium, comprising a stirring molding step.

The method for producing an algae culture medium according to claim 2 , wherein the agitation molding step is performed in the same high-speed agitator mixing machine as the mixing step.

2. The method for producing an algae culture medium according to claim 1, wherein the molding step includes an extrusion molding step in which the mixture is transferred to a die and extruded to form a molded body. .

5. The method for producing an algae culture medium according to claim 4, wherein the extrusion molding step is a die in which the die is a double tube, and the die is formed by a double tube between an outer tube inner wall and an inner tube outer wall. The mixture is transferred and put into, and the extruded product is compressed and sealed at both ends to form a molded body having a porous layer on the outside and a hollow portion inside. Method for producing algae culture medium.

6. The method for producing an algal culture medium according to claim 5 , further comprising a step of providing a layer having a lower water permeability than the porous layer between the porous layer and the hollow portion. Method.

7. The method for producing an algae culture medium according to claim 6 , wherein a porous material is provided between an outermost tube and an inner tube of a die composed of triple tubes, and an intermediate tube and an innermost tube of the die. A method for producing an algae culture medium, comprising: extruding a low water-permeable material between the two and then compressing and sealing both ends thereof.

The method for producing an algae culture medium according to claim 7 , wherein the low water-permeable layer contains at least one of clay-like montmorillonite, kaolinite, cement, water glass, lime, and gypsum. A method for producing an algal culture medium.

2. The method for producing an algal culture medium according to claim 1, wherein the molding step includes a compression molding step in which the mixture is compressed to form a molded body.

The method for producing an algae culture medium according to any one of claims 1 to 9 , wherein the inorganic material includes at least one selected from coal ash, incinerated ash, sand, shell pulverized material, and diatom. A method for producing an algal culture medium.

11. The method for producing an algal culture medium according to claim 10 , wherein the inorganic material is obtained by reducing or removing heavy metals and organic substances that affect the environment .

The method for producing an algal culture medium according to any one of claims 1 to 11 , wherein the hardener includes at least one selected from cement, water glass, lime, and gypsum. A method for manufacturing a medium.

The method for producing an algae culture medium according to claim 12 , wherein the curing material contains an algae culture nutrient as a constituent component.

The algal culture medium production method according to any one of claims 1 to 13 , wherein the algal culture nutrient contains at least one selected from a phosphorus content, a nitrogen content, and an iron content. A method for manufacturing a medium.

The method for producing an algal culture medium according to any one of claims 1 to 12 , 14 , wherein the amount of the hardener, the algal culture nutrient, and the lightening material added is 100 parts by weight of the inorganic material. The method for producing an algae culture medium, wherein the hardener is at least 5 parts by weight, and the algae culture nutrient does not exceed 20 parts by weight.

In the manufacturing method of the algal culture medium of any one of Claims 1 thru | or 15 , using the high-speed stirring blade mixer which inclined the mixing tank bottom part toward the discharge port as a mixer used for the said mixing process. A method for producing a characteristic algal culture medium.

The method for producing an algae culture medium according to any one of claims 1 to 16 , wherein the curing step for curing the shaped body is heat curing at a temperature of 100 ° C or higher. .

The method for producing an algae culture medium according to any one of claims 1 to 17 , wherein the curing step includes a heating curing step, and a heat source for the heating curing is waste heat from a thermal power plant or a waste incineration plant. A method for producing an algae culture medium.

The method for producing an algae culture medium according to any one of claims 1 to 18 , wherein the raw material further contains a weight-reducing material.