JP2005000121A

JP2005000121A - Biomass culture tank and biomass culture method

Info

Publication number: JP2005000121A
Application number: JP2003169493A
Authority: JP
Inventors: Kentaro Matsunaga; 健太郎松永; Tetsuo Yoshimitsu; 哲夫吉満; Michihiko Koyama; 充彦小山; Hideshige Moriyama; 英重森山; Nobukazu Suzuki; 信和鈴木
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2003-06-13
Filing date: 2003-06-13
Publication date: 2005-01-06
Anticipated expiration: 2023-06-13
Also published as: JP4284116B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biomass culture tank capable of efficiently fixing carbon dioxide in air or exhaust gas by biological means at a low cost. <P>SOLUTION: The biomass culture tank is provided with a culture tank 1 for holding photosynthesis organism 2, a culture liquid supplying means 5 for supplying a culture liquid containing carbonate ion to the culture tank, a supplemental nutrient supplying means 6 for supplying nutrients necessary for the culture of the photosynthesis organism to the culture tank, and a discharging means 7 for discharging the culture liquid from the culture tank. Efficient biological fixation of carbon dioxide is performed by using a culture liquid containing carbonate ion for the culture of the photosynthesis organism to accelerate the culture of the organism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、各種プラントから排出される排気ガス等に含まれる二酸化炭素を生物的に固定するバイオマス培養槽およびバイオマス培養方法に関する。
【０００２】
【従来の技術】
近年における地球温暖化現象の主要原因の１つとして、産業活動における化石燃料燃焼に由来する二酸化炭素の排出が指摘されている。これまでに様々な方法での対策が検討されているが、その１つに光合成生物の培養による二酸化炭素の固定が挙げられる。過去には、フォトバイオリアクターと呼ばれる外界と完全に遮断された閉鎖系システムにおける単一種植物の高効率培養等も検討されている。
【０００３】
光合成生物の培養による二酸化炭素の固定は、例えば栄養素を含む培養液を入れた培養槽中に藻体を分散させ、培養槽の底部から二酸化炭素を送り込み、太陽光や人工光を利用して藻体を増殖させることにより行われている（例えば、特許文献１参照。）。
【０００４】
また、光合成生物が浮遊性菌体であり、液中の光合成生物の濃度が低く、光合成生物単体では十分に二酸化炭素を固定できないことから、光合成生物を無機性または有機性の担持体に付着させることも検討されている（例えば、特許文献２参照。）。
【０００５】
さらに、上述したような液相中での光合成生物の培養に対して、気相中で光合成生物を培養し、二酸化炭素を固定することも検討されている（例えば、特許文献３、４参照。）。
【０００６】
しかしながら、上述したような光合成生物の培養方法においては要求される二酸化炭素の固定量とそれに必要なコストとの折り合いをつけることが容易でなく、光合成生物の培養により二酸化炭素を固定するプラントの商用的な運用は未だ実現されていない。
【０００７】
一方、一般ごみの焼却によって生じる焼却灰や、石炭火力発電により生じる石炭灰については、その処理方法が問題とされている。特に焼却灰については、その殆どが産業廃棄物として埋め立て処理されており、土地の確保や土壌汚染の問題等により、埋め立て以外の処理方法、出来れば付加価値のある製品への利用が求められている。
【０００８】
例えば、上記灰類の焼結体は植物や微細藻類、菌類の生育に適当な材料組成や表面状態を有することから、各種菌類、淡水性および海洋性植物の担持体としての応用が検討されている。
【０００９】
石炭灰については漁礁や藻類養殖の培地として既存のコンクリートブロックの代用として海中に沈める等の活用も提案されているが、より積極的な活用、例えば二酸化炭素の効率的な固定等への活用が期待されている。
【００１０】
【特許文献１】
特開２００１−２３１５３８
【特許文献２】
特願平６−３１９５２０
【特許文献３】
特開平７−２１３２７６
【特許文献４】
特開平８−３８１５８
【００１１】
【発明が解決しようとする課題】
上述したように、光合成生物を用いた二酸化炭素の生物的固定においては、単位時間、面積あたりの二酸化炭素の固定量を向上させ、稼動コストを低減することが求められている。また、産業廃棄物として処理されている焼却灰や石炭灰を資源として有効利用することも求められている。
【００１２】
本発明は上記したような課題を解決するためになされたものであり、空気中あるいは排気ガス中の二酸化炭素を効率的かつ低コストに生物固定することが可能なバイオマス培養槽およびバイオマス培養方法を提供することを目的としている。
【００１３】
【課題を解決するための手段】
本発明のバイオマス培養槽は、光合成生物および液体培地を保持する培養槽と、前記培養槽に炭酸イオンを含有する培養液を供給する培養液供給手段と、前記培養槽に前記光合成生物の培養に必要な補助栄養素を供給する補助栄養素供給手段と、前記培養槽から液体培地を排出する排出手段とを具備することを特徴とする。
【００１４】
また本発明のバイオマス培養方法は、焼却灰および石炭灰から選択される少なくとも１種と水とを接触させた後、これに二酸化炭素を接触させて炭酸イオンを含有する培養液を作製し、この培養液を用いて光合成生物の培養を行うことを特徴とする。
【００１５】
【発明の実施の形態】
以下、本発明のバイオマス培養槽について、図面を参照して説明する。
【００１６】
図１は本発明のバイオマス培養槽の一例を示した概略図である。本発明のバイオマス培養槽における培養槽１には、例えば光合成生物２、必要に応じて光合成生物２を表面に付着固定できる無機物または有機物からなる担持体３が液体培地４中に分散されている。
【００１７】
そして、培養槽１には光合成生物２の培養に主として用られる炭酸イオンを含有する培養液が培養液供給手段５より供給される。また、光合成生物２の培養に必要なその他の補助栄養素が補助栄養素供給手段６より供給される。さらに、培養槽１にはこれら培養液、補助栄養素の供給により過剰となった液体培地４を排出するための排出手段７が設けられている。
【００１８】
上述した培養槽１内の液体培地４は淡水または海水に相当するものであり、光合成生物２の種類によって適宜選択されるものである。
【００１９】
培養液供給手段５より供給される炭酸イオンを含む培養液は、例えば石炭灰または焼却灰と水とを接触させて得られる溶液に二酸化炭素を接触させて得られるものである。すなわち、石炭灰または焼却灰にはアルカリ金属またはアルカリ土類金属の酸化物が含まれており、これと水とを接触させたものにさらに二酸化炭素を接触させることで炭酸イオンを生成させることができる。
【００２０】
上述した炭酸イオンの生成は例えば以下のような反応式で表すことができる。なお、下記反応式では炭酸塩として表しているが、これらの炭酸塩は液中で電離して炭酸イオンを生成するものである。
Ｋ_２Ｏ＋Ｈ_２Ｏ → ２ＫＯＨ
２ＫＯＨ＋ＣＯ_２ → Ｋ_２ＣＯ_３＋Ｈ_２Ｏ
または
Ｎａ_２Ｏ＋Ｈ_２Ｏ → ２ＮａＯＨ
２ＮａＯＨ＋ＣＯ_２ → Ｎａ_２ＣＯ_３＋Ｈ_２Ｏ
【００２１】
具体的には例えば図２に示すように、培養液生成槽８に、一般ごみの焼却所で生じた焼却灰、石炭火力発電所で生じた石炭灰等の灰類９ａおよびこれらのものに必要に応じて重金属を除去する処理を行って得られる処理スラグ９ｂの中から選ばれる少なくとも１種を充填し、水分供給手段１０により水分を供給して溶液を調整する。さらに、この培養液生成槽８内の溶液中に焼却所や火力発電所等から排出された二酸化炭素を含む排ガスを二酸化炭素供給手段１１により放出し、炭酸イオンを生成させる。
【００２２】
上述したような方法により炭酸イオンを含む培養液を作製することで、焼却所、火力発電所から排出される二酸化炭素だけでなく、これらのものから排出される焼却灰や石炭灰を処理することもでき、二酸化炭素の効率的な生物的固定だけでなく、廃棄物量を減らし資源の有効利用が可能となる。また、このような方法により得られた炭酸イオンを含む培養液を主として用いて光合成生物２の培養を行うことで、光合成生物２の培養も促進させることができる。
【００２３】
このような培養液については微細藻類の増殖速度を高くするため、その炭酸イオン濃度、水素イオン濃度を所定の濃度に調整することが好ましい。また、炭酸イオン濃度、水素イオン濃度以外の光合成生物の成長に必要な無機成分および有機成分の濃度についても調整することが好ましい。培養液中の炭酸イオン濃度は培養する光合成生物の種類によっても異なるが、例えば最終的な調整が行われた培養液において０．００１［ｍｏｌ／ｌ］〜０．０１［ｍｏｌ／ｌ］程度であることが好ましい。
【００２４】
炭酸イオン濃度、水素イオン濃度の調整は、例えば培養液を製造する際の炭酸イオン等の生成量を調整することにより行ってもよいし、一旦培養液を作製した後、所定の成分を添加することにより調整してもよい。
【００２５】
培養液を製造する際の炭酸イオン、水素イオンの生成量を調整することにより濃度を調整する方法としては、例えば培養液生成槽８に充填する灰類９ａ、処理スラグ９ｂの量、水分供給手段１０により供給する水分の量、二酸化炭素供給手段１１により放出する二酸化炭素の量等を適宜調整することにより行う。
【００２６】
また、培養液を製造した後における炭酸イオン濃度、水素イオン濃度の調整は、例えば補助栄養素供給手段６等から炭酸イオン濃度、水素イオン濃度を上昇または低下させることのできる物質を添加して行う。
【００２７】
炭酸イオン、水素イオン以外の光合成生物の成長に必要な無機成分および有機成分の濃度についても、例えば補助栄養素供給手段６から所定の成分（補助栄養素）を供給して調整する。補助栄養素としては、例えば硫酸マグネシウム、硫酸銅および硫酸亜鉛等が挙げられる。
【００２８】
このような炭酸イオン、水素イオン、その他光合成生物の成長に必要な無機成分および有機成分の濃度の調整は、例えば培養液供給手段５の途中にこれらの濃度を測定する濃度測定手段であるセンサ１２を設け、このセンサ１２の測定結果を基に所定の濃度、組成となるように組成調整手段１３で培養液生成槽８における炭酸イオン等の生成量の調整、その後の補助栄養素供給手段６による各成分の添加量の調整を行うことによりなされる。
【００２９】
このようにして成分調整が行われた培養液は培養槽１へ供給される。この際の培養液の供給量は、例えば排出手段７に培養槽１から排出される液体培地４中の含有有機物濃度を測定する含有有機物濃度測定手段１４を設け、この含有有機物濃度測定手段１４の測定結果に応じて供給量を調整する供給量調整手段１５により行われることが好ましい。このようにして培養液の供給量を調整することで、培養液の過不足を抑制し、光合成生物２を効率的に培養することができる。
【００３０】
本発明における光合成生物２としては上述したような培養液に含まれる炭酸イオンを栄養源として培養できるものであれば特に制限されるものではなく、例えば藻類、微細藻類のような液体培地中で培養するものの他、水耕栽培により培養可能な野菜等であってもよい。二酸化炭素の効率的な処理、すなわち生物的固定という観点からは増殖速度の高いものが好ましく、このようなものとしては微細藻類が好適に用いられる。
【００３１】
微細藻類としては、例えばクロレラ、スピルリナ等の微細藻類が増殖速度が高いため好ましく、具体的にはＳｙｎｅｃｈｏｃｙｓｔｉｓｓｐ．ＰＣＣ６８０３、ＡｎａｂａｅｎａＣｙｌｉｎｄｒｉｃａ等を用いることができる。
【００３２】
上述したような光合成生物２として藻類、微細藻類を用いる場合には、これらのものが付着できるように担持体３を用いることが好ましい。担持体３は、例えば一般ごみの焼却所で生じた焼却灰もしくは石炭火力発電所で生じた石炭灰等の灰類またはこれらのものに必要に応じて重金属除去処理を施して得られる処理スラグ等から選ばれる少なくとも１種と、ポリエチレン等のバインダとを混合し、所定の形状に成形することにより得られるものである。
【００３３】
このような焼却灰や石炭灰を用いることで、廃棄物として処理されている焼却灰や石炭灰の量を減らすことができるとともに、これら焼却灰や石炭灰には光合成生物２の培養に必要な成分も含まれているため、光合成生物２の培養を促進することもできる。
【００３４】
この担持体３には予め培養対象となる光合成生物２の種子、胞子もしくは株を内部に包含または表面に付着させておくことが好ましい。光合成生物２の培養過程で担持体３には光合成生物２が付着するが、予め内部または表面に光合成生物２の種子、胞子もしくは株等を包含または付着しておくことで、より効率的に培養を行うことが可能となる。
【００３５】
また、担持体３には培養対象となる光合成生物２の生育に必要な栄養素を内部に包含または表面に付着させておくことが好ましい。光合成生物２の培養過程では培養液供給手段５および栄養素供給手段６により光合成生物２の生育に必要な栄養素が供給されるが、予め内部または表面に光合成生物２の生育に必要な栄養素を包含または付着しておくことで、より効率的に培養を行うことが可能となる。
【００３６】
上述したように担持体３の内部に光合成生物２の種子、胞子もしくは株またはその生育に必要な栄養素を含有させるには、例えば一般ごみの焼却所で生じた焼却灰もしくは石炭火力発電所で生じた石炭灰等の灰類またはこれらのものに必要に応じて重金属除去処理を施して得られる処理スラグ等から選ばれる少なくとも１種と、ポリエチレン等のバインダと、光合成生物２の種子、胞子もしくは株またはその生育に必要な栄養素とを混合した後、所定の形状に成形することにより行う。
【００３７】
また、担持体３の表面に光合成生物２の種子、胞子もしくは株またはその生育に必要な栄養素を付着させるには、例えば上述したような灰類または処理スラグ等から選ばれる少なくとも１種とポリエチレン等のバインダとを混合し所定の形状に成形した後、その表面に光合成生物２の種子、胞子もしくは株、またはその生育に必要な栄養素を付着させることにより行う。
【００３８】
このようにして得られる担持体３は、例えば最大直径２ｃｍ以下のペレット状にして培養槽１内の液体培地４に分散させてもよいし、プラスチック、植物繊維または金属等からなる網状またはかご状の構造物の内部に保持してもよいし、そのような構造物に固定してもよい。
【００３９】
担持体３をこのような網状またはかご状の構造物の内部に保持または固定することで、培養後における光合成生物２が付着した担持体３の回収が容易になると共に、培養中においても担持体３へ液体培地４を十分に循環させることができ、培養、回収を効率的に行うことができる。
【００４０】
光合成生物２の培養は、培養槽１への人工光や太陽光の照射により行われる。光合成生物２は液体培地４に分散したまま成長する他、液体培地４に担持体３が分散されている場合にはその表面でも高密度に成長する。
【００４１】
培養槽１中の液体培地４は、光合成生物２およびこれを付着した担持体３を平均的に日光や栄養分と接触させて効率的に培養するために循環させることが好ましい。このような液体培地４の循環は、例えば培養槽１への培養液の流入により、あるいは、焼却所、火力発電所等から排出される排気ガスの培養槽１内への放出により、または、モータ、ポンプ、水車等の利用により行われる。
【００４２】
循環方向は特に制限されるものではなく、例えば培養槽１の垂直方向の中心軸を中心として渦を形成するような平面方向の循環方向としてもよいし、培養槽１の底面中心から上方へ湧き上り、周辺部で底部へ沈降するような垂直方向の循環方向としてもよい。
【００４３】
また培養槽１は、例えば図３に示すように、その採光部を選択的透光性フィルムもしくはガラス１６で覆うことが好ましい。この選択的透光性フィルムもしくはガラス１６は、例えば培養槽１に入射する可視光、特に光合成生物２の光合成に用いられる波長の光を透過し、培養槽１内から培養槽１外へ向かう光は透過させず、培養槽１内に反射させるものである。このような選択的透光性フィルムもしくはガラス１６で採光部を覆うことで入射光の有効利用が可能となる。
【００４４】
また、培養槽１内の側面や底面は鏡面１７とすることが好ましい。培養槽１内の側面や底面を鏡面１７とすることで、培養槽１内に入射した光が培養槽１内の側面や底面に吸収されることを抑制し、入射光の有効利用が可能となる。
【００４５】
さらに、このような鏡面１７の表面上には光触媒層１８を設けることが好ましい。光触媒層１８としては、例えば酸化チタンからなるものが挙げられる。このような光触媒層１８を設けることで、鏡面１７における光合成生物２、汚れ等の付着を抑制し、鏡面１７の反射効率の低下を抑制することができる。
【００４６】
培養槽１の液体培地中を浮遊する光合成生物２もしくはこれが付着した担持体３は、適当な回収手段を用いて回収される。回収手段としては、例えばフィルタが好適に用いられる。
【００４７】
フィルタは、光合成生物２を担持した担持体３を回収するための比較的目の粗いフィルタと、水中に分散したまま成長した光合成生物２を回収するための目の細かいフィルタとを併用することで、より効率的に光合成生物２を回収することができる。
【００４８】
担持体３を回収するためのフィルタとしては、担持体３の最大径よりも目の細かい網目構造や格子構造を有する平面あるいは袋状の構造物が用いられる。また、光合成生物２を回収するためのフィルタとしては、光合成生物２の最大径よりも目の細かい網目・格子構造を有する平面あるいは袋状の構造物、例えば布、紙もしくはプラスチック製のろ紙、不織布、または、多孔質構造を有するスポンジもしくは軽石等を用いることができる。
【００４９】
培養槽１内におけるろ過操作により光合成生物２およびこれが付着した担持体３を捕獲したフィルタは、光合成生物２および担持体３と共に液体培地４から引き上げられる。担持体３の表面に付着した光合成生物２は、機械的処理あるいは化学的処理により分離、回収される。光合成生物２が分離され再生された担持体３は適当な返送手段を用いて再度培養槽１中に投入し、光合成生物２の培養に役立ててもよい。
【００５０】
また、ろ過操作によりフィルタに付着した光合成生物２は、担持体３の表面に付着した光合成生物２と同様、機械的処理あるいは化学的処理により回収する。フィルタが有機物の場合には、フィルタごとバイオマスとして活用してもよい。
【００５１】
【発明の効果】
本発明によれば、光合成生物の培養に炭酸イオンを含有する培養液を用いることで、光合成生物の培養を促進し二酸化炭素の効率的な生物的固定が可能になる。また、炭酸イオンを含有する培養液の製造に二酸化炭素および従来廃棄されていた石炭灰もしくは焼却灰を用いることができ、環境への負荷の低減、資源の有効利用が可能となる。
【図面の簡単な説明】
【図１】本発明のバイオマス培養槽の一例を示した概略図
【図２】本発明のバイオマス培養槽の他の例を示した概略図
【図３】本発明のバイオマス培養槽における培養槽の一例を示した断面図
【符号の説明】
１…培養槽２…光合成生物３…担持体４…液体培地５…培養液供給手段６…補助栄養素供給手段７…排出手段８…培養液生成槽９ａ…灰類９ｂ…処理スラグ１０…水分供給手段１１…二酸化炭素供給手段１２…濃度測定手段１３…組成調整手段１４…含有有機物濃度測定手段１５…供給量調整手段１６…選択的透光性フィルムまたはガラス１７…鏡面１８…光触媒層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biomass culture tank and a biomass culture method for biologically fixing carbon dioxide contained in exhaust gas discharged from various plants.
[0002]
[Prior art]
As one of the main causes of the global warming phenomenon in recent years, the emission of carbon dioxide derived from fossil fuel combustion in industrial activities has been pointed out. Various measures have been studied so far, one of which is fixing carbon dioxide by culturing photosynthetic organisms. In the past, high-efficiency culture of single-species plants in a closed system called a photobioreactor that is completely blocked from the outside world has been studied.
[0003]
For example, carbon dioxide is fixed by culturing photosynthetic organisms. For example, algal bodies are dispersed in a culture tank containing a culture solution containing nutrients, carbon dioxide is fed from the bottom of the culture tank, and sunlight or artificial light is used to algae. It is carried out by growing the body (for example, see Patent Document 1).
[0004]
In addition, the photosynthetic organism is attached to an inorganic or organic carrier because the photosynthetic organism is a floating cell, the concentration of the photosynthetic organism in the liquid is low, and the photosynthesis organism alone cannot fix carbon dioxide sufficiently. (For example, see Patent Document 2).
[0005]
Furthermore, in contrast to culturing photosynthetic organisms in the liquid phase as described above, it has been studied to culture photosynthetic organisms in the gas phase and fix carbon dioxide (see, for example, Patent Documents 3 and 4). ).
[0006]
However, in the method for culturing photosynthetic organisms as described above, it is not easy to strike a balance between the required amount of carbon dioxide to be fixed and the cost required for it, and commercial use of a plant that fixes carbon dioxide by culturing photosynthetic organisms. Operation has not been realized yet.
[0007]
On the other hand, regarding incineration ash produced by incineration of general waste and coal ash produced by coal-fired power generation, the treatment method is considered a problem. In particular, most of incineration ash is landfilled as industrial waste, and due to problems such as securing land and soil contamination, it is required to use treatment methods other than landfill, and if possible, products with added value. Yes.
[0008]
For example, since the sintered body of ash has a material composition and surface state suitable for the growth of plants, microalgae and fungi, its application as a carrier for various fungi, freshwater and marine plants has been studied. Yes.
[0009]
Coal ash has been proposed to be submerged in the sea as a substitute for existing concrete blocks as a medium for fishing reefs and algae culture, but more active use, for example, efficient fixation of carbon dioxide, etc. Expected.
[0010]
[Patent Document 1]
JP 2001-231538 A
[Patent Document 2]
Japanese Patent Application No. 6-319520
[Patent Document 3]
JP-A-7-213276
[Patent Document 4]
JP-A-8-38158
[0011]
[Problems to be solved by the invention]
As described above, in the biological fixation of carbon dioxide using a photosynthetic organism, it is required to improve the fixed amount of carbon dioxide per unit time and area and reduce the operating cost. In addition, incineration ash and coal ash treated as industrial waste are also required to be effectively used as resources.
[0012]
The present invention has been made to solve the above-described problems, and provides a biomass culture tank and a biomass culture method capable of biologically fixing carbon dioxide in air or exhaust gas efficiently and at low cost. It is intended to provide.
[0013]
[Means for Solving the Problems]
The biomass culture tank of the present invention comprises a culture tank for holding a photosynthetic organism and a liquid medium, a culture solution supply means for supplying a culture solution containing carbonate ions to the culture tank, and a culture vessel for culturing the photosynthetic organism. Supplemental nutrient supply means for supplying necessary supplemental nutrients and discharge means for discharging the liquid medium from the culture tank are provided.
[0014]
In the biomass culture method of the present invention, after bringing water into contact with at least one selected from incineration ash and coal ash, carbon dioxide is brought into contact therewith to produce a culture solution containing carbonate ions. It is characterized by culturing a photosynthetic organism using a culture solution.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the biomass culture tank of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a schematic view showing an example of a biomass culture tank of the present invention. In the culture tank 1 in the biomass culture tank of the present invention, for example, a photosynthetic organism 2 and, if necessary, a support 3 made of an inorganic substance or an organic substance capable of attaching and fixing the photosynthetic organism 2 to the surface are dispersed in a liquid medium 4.
[0017]
A culture solution containing carbonate ions mainly used for culturing the photosynthetic organism 2 is supplied from the culture solution supply means 5 to the culture tank 1. Further, other supplemental nutrients necessary for culturing the photosynthetic organism 2 are supplied from the supplemental nutrient supply means 6. Furthermore, the culture tank 1 is provided with a discharge means 7 for discharging the liquid medium 4 that has become excessive due to the supply of the culture medium and supplemental nutrients.
[0018]
The liquid medium 4 in the culture tank 1 described above corresponds to fresh water or seawater, and is appropriately selected depending on the type of the photosynthetic organism 2.
[0019]
The culture solution containing carbonate ions supplied from the culture solution supply means 5 is obtained, for example, by bringing carbon dioxide into contact with a solution obtained by bringing coal ash or incineration ash into contact with water. In other words, coal ash or incinerated ash contains an oxide of alkali metal or alkaline earth metal, and carbon dioxide can be generated by bringing carbon dioxide into contact with water in contact with this. it can.
[0020]
The production | generation of the carbonate ion mentioned above can be represented by the following reaction formula, for example. In addition, although it represents as carbonate in the following reaction formula, these carbonates ionize in a liquid and produce | generate a carbonate ion.
_{_{K 2 O + H 2 O →}} 2KOH
2KOH + CO ₂ → K ₂ CO ₃ + H ₂ O
Or Na ₂ O + H ₂ O → 2NaOH
_{_{2NaOH + CO 2 → Na 2 CO}} 3 + H 2 O
[0021]
Specifically, as shown in FIG. 2, for example, as shown in FIG. 2, ash 9a such as incineration ash generated at a general waste incineration plant, coal ash generated at a coal-fired power plant, and the like are necessary. In accordance with the above, at least one selected from the treatment slag 9b obtained by performing the treatment for removing heavy metals is filled, and moisture is supplied by the moisture supply means 10 to adjust the solution. Further, exhaust gas containing carbon dioxide discharged from an incinerator, a thermal power plant, or the like into the solution in the culture solution generation tank 8 is released by the carbon dioxide supply means 11 to generate carbonate ions.
[0022]
Treating not only carbon dioxide emitted from incinerators and thermal power plants, but also incinerated ash and coal ash emitted from these by producing a culture solution containing carbonate ions by the method described above In addition to efficient biological fixation of carbon dioxide, the amount of waste can be reduced and resources can be used effectively. Moreover, culture | cultivation of the photosynthetic organism 2 can also be promoted by culturing the photosynthetic organism 2 mainly using the culture solution containing the carbonate ion obtained by such a method.
[0023]
In order to increase the growth rate of microalgae for such a culture solution, it is preferable to adjust its carbonate ion concentration and hydrogen ion concentration to predetermined concentrations. Moreover, it is preferable to adjust also the density | concentration of the inorganic component and organic component which are required for growth of photosynthetic organisms other than carbonate ion concentration and hydrogen ion concentration. The carbonate ion concentration in the culture solution varies depending on the type of photosynthetic organism to be cultured. For example, in the culture solution in which final adjustment has been performed, Preferably there is.
[0024]
The adjustment of the carbonate ion concentration and the hydrogen ion concentration may be carried out, for example, by adjusting the production amount of carbonate ions or the like when producing the culture solution. You may adjust by.
[0025]
As a method of adjusting the concentration by adjusting the production amount of carbonate ions and hydrogen ions when producing the culture solution, for example, ashes 9a to be filled in the culture solution production tank 8, the amount of the treated slag 9b, water supply means The amount of water supplied by 10 and the amount of carbon dioxide released by the carbon dioxide supply means 11 are appropriately adjusted.
[0026]
Further, the adjustment of the carbonate ion concentration and the hydrogen ion concentration after the production of the culture solution is performed by adding a substance capable of increasing or decreasing the carbonate ion concentration and the hydrogen ion concentration from the supplementary nutrient supply means 6 or the like, for example.
[0027]
Concentrations of inorganic components and organic components necessary for the growth of photosynthetic organisms other than carbonate ions and hydrogen ions are also adjusted by, for example, supplying predetermined components (auxiliary nutrients) from the supplementary nutrient supply means 6. Examples of supplemental nutrients include magnesium sulfate, copper sulfate, and zinc sulfate.
[0028]
The adjustment of the concentrations of such carbonate ions, hydrogen ions, and other inorganic and organic components necessary for the growth of photosynthetic organisms is performed by, for example, a sensor 12 which is a concentration measuring means for measuring these concentrations in the middle of the culture solution supply means 5. And adjusting the production amount of carbonate ions and the like in the culture medium production tank 8 by the composition adjusting means 13 so as to obtain a predetermined concentration and composition based on the measurement result of the sensor 12, and each of the supplementary nutrient supplying means 6 thereafter This is done by adjusting the amount of components added.
[0029]
The culture solution whose components have been adjusted in this way is supplied to the culture tank 1. In this case, the supply amount of the culture solution is, for example, provided in the discharge means 7 with the contained organic substance concentration measuring means 14 for measuring the contained organic substance concentration in the liquid medium 4 discharged from the culture tank 1. It is preferably performed by the supply amount adjusting means 15 that adjusts the supply amount according to the measurement result. Thus, by adjusting the supply amount of a culture solution, the excess and deficiency of a culture solution can be suppressed and the photosynthetic organism 2 can be cultured efficiently.
[0030]
The photosynthetic organism 2 in the present invention is not particularly limited as long as it can be cultured using the carbonate ions contained in the culture solution as described above as a nutrient source. For example, it is cultured in a liquid medium such as algae and microalgae. In addition to what to do, it may be a vegetable that can be cultured by hydroponics. From the viewpoint of efficient treatment of carbon dioxide, that is, biological fixation, those having a high growth rate are preferred, and microalgae are preferably used as such.
[0031]
As the microalgae, for example, microalgae such as chlorella and spirulina are preferable because of their high growth rates. Specifically, Synochcystis sp. PCC6803, Anabaena Cylindrica, etc. can be used.
[0032]
When using algae or microalgae as the photosynthetic organism 2 as described above, it is preferable to use the carrier 3 so that these can adhere. The carrier 3 is, for example, incineration ash generated at a general waste incinerator or ash such as coal ash generated at a coal-fired power plant, or a processing slag obtained by subjecting these to heavy metal removal treatment as necessary. And a binder such as polyethylene are mixed and molded into a predetermined shape.
[0033]
By using such incineration ash and coal ash, the amount of incineration ash and coal ash treated as waste can be reduced, and these incineration ash and coal ash are necessary for culturing photosynthetic organisms 2. Since the component is also included, the culture of the photosynthetic organism 2 can be promoted.
[0034]
It is preferable that the carrier 3 contains seeds, spores or strains of the photosynthetic organism 2 to be cultured in advance or is attached to the surface. The photosynthetic organism 2 adheres to the carrier 3 during the cultivation process of the photosynthetic organism 2, but the seeds, spores, strains, etc. of the photosynthetic organism 2 are included or attached to the inside or the surface in advance, thereby culturing more efficiently. Can be performed.
[0035]
Moreover, it is preferable that nutrients necessary for the growth of the photosynthetic organism 2 to be cultured are contained inside or attached to the surface of the support 3. In the process of culturing the photosynthetic organism 2, nutrients necessary for the growth of the photosynthetic organism 2 are supplied by the culture medium supply means 5 and the nutrient supply means 6, and the nutrients necessary for the growth of the photosynthetic organism 2 are included in the interior or surface in advance. By adhering, it becomes possible to culture more efficiently.
[0036]
As described above, in order to contain the seeds, spores or strains of the photosynthetic organism 2 or nutrients necessary for the growth thereof in the support 3, for example, incineration ash generated in a general waste incinerator or generated in a coal-fired power plant Ashes such as coal ash, or at least one selected from treated slag obtained by subjecting these to ash as necessary, binders such as polyethylene, seeds, spores or strains of photosynthetic organisms 2 Or after mixing with nutrients necessary for the growth, it is performed by molding into a predetermined shape.
[0037]
In order to attach seeds, spores or strains of the photosynthetic organism 2 or nutrients necessary for their growth to the surface of the support 3, for example, at least one selected from ash or treated slag as described above, polyethylene and the like This is carried out by mixing with a binder and forming a predetermined shape, and then attaching seeds, spores or strains of the photosynthetic organism 2 or nutrients necessary for their growth to the surface thereof.
[0038]
The carrier 3 thus obtained may be in the form of a pellet having a maximum diameter of 2 cm or less and dispersed in the liquid medium 4 in the culture tank 1, or a net or basket made of plastic, plant fiber, metal, or the like. You may hold | maintain inside this structure, and you may fix to such a structure.
[0039]
By holding or fixing the carrier 3 inside such a net-like or basket-like structure, the carrier 3 to which the photosynthetic organisms 2 adhere after the culture can be easily recovered, and the carrier can be used even during the culture. The liquid medium 4 can be sufficiently circulated to 3, and culture and recovery can be performed efficiently.
[0040]
The photosynthetic organism 2 is cultured by irradiating the culture tank 1 with artificial light or sunlight. The photosynthetic organism 2 grows while being dispersed in the liquid medium 4, and when the carrier 3 is dispersed in the liquid medium 4, it grows at a high density on the surface.
[0041]
The liquid medium 4 in the culture tank 1 is preferably circulated in order to cultivate the photosynthetic organism 2 and the carrier 3 attached thereto in an average manner in contact with sunlight or nutrients for efficient cultivation. Such circulation of the liquid medium 4 may be caused by, for example, inflow of a culture solution into the culture tank 1, or by discharge of exhaust gas discharged from an incinerator, a thermal power plant, or the like into the culture tank 1, or a motor. , Using pumps, water wheels, etc.
[0042]
The circulation direction is not particularly limited. For example, the circulation direction may be a planar circulation direction in which a vortex is formed around the central axis in the vertical direction of the culture tank 1, or the spring flows upward from the center of the bottom of the culture tank 1. It is good also as a vertical circulation direction which goes up and sinks to a bottom part at a peripheral part.
[0043]
In addition, as shown in FIG. 3, for example, the culture tank 1 preferably covers the daylighting portion with a selective translucent film or glass 16. This selective translucent film or glass 16 transmits, for example, visible light incident on the culture tank 1, in particular, light having a wavelength used for photosynthesis of the photosynthetic organism 2, and light traveling from the culture tank 1 to the outside of the culture tank 1. Is not transmitted but is reflected in the culture tank 1. Covering the daylighting portion with such a selective light-transmitting film or glass 16 makes it possible to effectively use incident light.
[0044]
Further, the side surface and the bottom surface in the culture tank 1 are preferably mirror surfaces 17. By making the side surface and bottom surface in the culture tank 1 into the mirror surface 17, it is possible to suppress the light incident in the culture tank 1 from being absorbed by the side surface and bottom surface in the culture tank 1, and to effectively use the incident light. Become.
[0045]
Furthermore, it is preferable to provide a photocatalytic layer 18 on the surface of the mirror surface 17. Examples of the photocatalyst layer 18 include those made of titanium oxide. By providing such a photocatalyst layer 18, adhesion of the photosynthetic organism 2 and dirt on the mirror surface 17 can be suppressed, and a decrease in the reflection efficiency of the mirror surface 17 can be suppressed.
[0046]
The photosynthetic organism 2 floating in the liquid medium of the culture tank 1 or the carrier 3 to which it is attached is recovered using an appropriate recovery means. For example, a filter is preferably used as the collecting means.
[0047]
The filter uses a relatively coarse filter for recovering the carrier 3 carrying the photosynthetic organisms 2 and a fine filter for recovering the photosynthetic organisms 2 grown while dispersed in water. The photosynthetic organism 2 can be recovered more efficiently.
[0048]
As a filter for recovering the carrier 3, a flat or bag-like structure having a mesh structure or a lattice structure finer than the maximum diameter of the carrier 3 is used. Further, as a filter for recovering the photosynthetic organism 2, a planar or bag-like structure having a mesh / lattice structure finer than the maximum diameter of the photosynthetic organism 2, such as cloth, paper or plastic filter paper, non-woven fabric Alternatively, a sponge or pumice having a porous structure can be used.
[0049]
The filter that has captured the photosynthetic organisms 2 and the carrier 3 to which the photosynthetic organisms 2 are attached by the filtration operation in the culture tank 1 is pulled up from the liquid medium 4 together with the photosynthetic organisms 2 and the carriers 3. The photosynthetic organism 2 attached to the surface of the carrier 3 is separated and recovered by mechanical treatment or chemical treatment. The carrier 3 from which the photosynthetic organisms 2 have been separated and regenerated may be put into the culture tank 1 again using an appropriate return means to be useful for culturing the photosynthetic organisms 2.
[0050]
In addition, the photosynthetic organism 2 attached to the filter by the filtration operation is recovered by mechanical treatment or chemical treatment in the same manner as the photosynthetic organism 2 attached to the surface of the carrier 3. If the filter is organic, the filter may be used as biomass.
[0051]
【The invention's effect】
According to the present invention, by using a culture solution containing carbonate ions for cultivation of photosynthetic organisms, the cultivation of photosynthetic organisms can be promoted and carbon dioxide can be efficiently biologically fixed. In addition, carbon dioxide and conventionally discarded coal ash or incinerated ash can be used for the production of a culture solution containing carbonate ions, thereby reducing the burden on the environment and effectively using resources.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an example of a biomass culture tank of the present invention. FIG. 2 is a schematic diagram showing another example of a biomass culture tank of the present invention. Sectional view showing an example [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Culture tank 2 ... Photosynthesis organism 3 ... Carrier 4 ... Liquid culture medium 5 ... Culture solution supply means 6 ... Supplementary nutrient supply means 7 ... Discharge means 8 ... Culture solution production tank 9a ... Ash 9b ... Process slag 10 ... Water supply Means 11 ... Carbon dioxide supply means 12 ... Concentration measurement means 13 ... Composition adjustment means 14 ... Concentration organic substance concentration measurement means 15 ... Supply amount adjustment means 16 ... Selective translucent film or glass 17 ... Mirror surface 18 ... Photocatalyst layer

Claims

A culture tank for holding a photosynthetic organism and a liquid medium, a culture solution supply means for supplying a culture solution containing carbonate ions to the culture tank, and an auxiliary for supplying supplementary nutrients necessary for culturing the photosynthetic organism to the culture tank A biomass culture tank comprising nutrient supply means and discharge means for discharging a liquid medium from the culture tank.

The biomass culture tank according to claim 1, wherein the photosynthetic organism is dispersed in the liquid medium, and a carrier made of an inorganic substance or an organic substance capable of adhering the photosynthetic organism to the surface is dispersed.

A recovery means for recovering the photosynthetic organism and the carrier attached to the photosynthetic organism from the culture tank; and a return means for returning the carrier to the culture tank after removing the photosynthetic organism from the recovered carrier. The biomass culture tank according to claim 2, comprising:

The biomass carrier according to claim 2 or 3, wherein the carrier includes at least one selected from incineration ash, coal ash, and treated slag obtained by removing heavy metals from these.

The biomass carrier according to any one of claims 2 to 4, wherein the carrier includes or attaches seeds, spores or strains of the photosynthetic organism or nutrients necessary for the growth thereof. .

6. The carrier according to claim 2, wherein the carrier is made into a pellet having a maximum diameter of 2 cm or less, and the carrier is circulated in the culture tank by circulating a liquid medium in the culture tank. The biomass culture tank of any one of Claims.

The said support body is hold | maintained inside the net-like or cage-like structure which consists of a plastic, a vegetable fiber, or a metal, or is fixed to the said structure. Biomass culture tank.

The culture solution containing carbonate ions includes a solution obtained by bringing carbon ash into contact with a solution obtained by bringing coal ash or incineration ash into contact with water to produce carbonate ions. The biomass culture tank according to any one of 7.

Concentration measuring means for measuring at least one concentration selected from carbonate ions, hydrogen ions, and other inorganic and organic components necessary for the growth of the photosynthetic organism in the culture solution, and the results of the concentration measuring means 9. The composition adjusting device according to claim 1, further comprising: a composition adjusting unit that adjusts a supply amount of various supplemental nutrients from the supplemental nutrient supplying unit to make the culture solution have a predetermined composition. Biomass culture tank.

Contained organic matter concentration measuring means for measuring the concentration of contained organic matter in the liquid medium discharged from the culture tank in the discharging means, and supply of the culture solution from the culture solution supplying means according to the measurement result of the contained organic matter concentration measuring means The biomass culture tank according to any one of claims 1 to 9, further comprising supply amount adjusting means for adjusting the amount.

The biomass culture tank according to any one of claims 1 to 10, wherein at least one of a wall surface and a bottom surface inside the culture tank is a mirror surface, and a photocatalyst layer is provided on the mirror surface.

Selective translucency that transmits light of the wavelength used for photosynthesis from the outside to the inside of the culture tank and suppresses the transmission from the inside to the outside in the daylighting section that incorporates light used for photosynthesis of the photosynthetic organism in the culture tank The biomass culture tank according to any one of claims 1 to 11, wherein a biofilm or glass is provided.

In the cultivation of photosynthetic organisms, at least one selected from incineration ash and coal ash is brought into contact with water, and then carbon dioxide is brought into contact therewith to prepare a culture solution containing carbonate ions. A biomass culturing method comprising culturing a photosynthetic organism using the method.