JP4038772B2

JP4038772B2 - Method and apparatus for culturing photosynthetic microorganisms

Info

Publication number: JP4038772B2
Application number: JP2003512388A
Authority: JP
Inventors: 敏朗関根
Original assignee: 敏朗関根
Priority date: 2001-07-11
Filing date: 2002-07-11
Publication date: 2008-01-30
Anticipated expiration: 2022-07-11
Also published as: JPWO2003006629A1; WO2003006629A1

Description

産業上の利用分野
本発明は、微細藻類、光合成細菌等光合成微生物の培養方法に関する。
本発明は、上記藻菌体生産のほか、有機性廃水の浄化処理にも利用できる。
従来の技術
一般に光合成微生物の培養は、微細藻類の培養において見られるように、大規模なものでは酢酸やブドウ糖を炭素源とした食用クロレラ培養池や有機汚水浄化のための高率酸化池を代表とする、屋外に建設された水深２０ｃｍ程度の浅く広い平面池ｐで行なわれている。これらはいずれも水面で直接太陽光を受ける上部開放式の培養装置である。このため、
（１）寒冷地においては，広大な水面からの熱損失が大きく，特に夜間の熱損失が大きく、光合成微生物懸濁液が冷却され増殖速度が小さくなる．
（２）水温がおよそ１０℃以上となると光合成微生物を捕食するミジンコ，ワムシ等微小動物の増殖が活発となり，光合成微生物が活発に捕食され，クロレラの場合一昼夜にして全滅させられる例が多数ある。前記微小動物は，風、鳥、虫などによって運ばれるため、培養池への侵入とその繁殖を防ぐことが困難であり，この大量発生を防ぐには，大量の薬品を使用せざるを得ない。
（３）降雨により光合成微生物懸濁液が希釈され、光合成微生物濃度が低下する。さらには、培養池から光合成微生物懸濁液が流失する。この流失を防止するには、必要以上に培養池の側壁を高くする必要性や、温室が必要ない温暖地域においても透明フィルム製の上屋が必要となる。
などの問題点があった。
これらが解決されれば、光合成細菌、微細藻類等光合成微生物による、食糧生産、廃水処理、炭酸ガス固定、などが大きく進展する。このような観点から、本発明者は、平成４年９月８日に特願平４−２８２１４６（光合成微生物の培養装置とその運転方法）を、平成８年１２月２９日に特願平８−３５９９７１（微細藻類培養装置）を考案し出願した。
この結果、（１）の問題点が改善され、光合成微生物のより効率的な培養が可能となり、敷地面積が広大となる欠点も改善された。また（２）の問題点も解消され、光合成微生物の安定的連続培養が可能となった。
しかし、（１）の問題点は完全には解消されないままである。
光合成微生物の培養、特に廃水処理を目的にした場合、（１）の問題点が施設設置の障害となっている。廃水処理においては、毎日一定の処理能力が必要とされる。太陽光による光合成微生物の培養を行なう場合、その増殖が日射量や温度等気象条件に大きく左右される。光合成微生物の増殖は，冬期に最も低下するため、この冬期の増殖を基準に培養池の規模が設定される。このため，まだまだ広大な面積の敷地が必要となっている。
また、（３）の問題点のため、培養施設の建設費が高価となっている。
発明が解決しようとする課題
そこで本発明は、寒冷地での懸濁液の冷却を防ぐとともに，日照等気象条件に左右されずに一定の優れた培養成績をあげることのできる光合成微生物の培養方法及びその装置を提供することを目的とするものである。
問題を解決するための手段
微細藻類、紅色無硫黄細菌等光合成微生物は、
（Ａ）太陽光エネルギーを吸収し、このエネルギーを利用して、炭酸ガス、有機物及びその他栄養物を吸収資化し、増殖する能力
（Ｂ）吸収した有機物を異化代謝する過程（発酵、呼吸）で生成するエネルギーを利用して増殖する能力
を有する。
夜間、太陽光の照射がなくなると、光合成微生物は有機物を異化代謝する過程（発酵、呼吸）で生成するエネルギーのみを利用して、増殖する。
特願平４−２８２１４６（光合成微生物の培養装置とその運転方法）、及び特願平８−３５９９７１（微細藻類培養装置）の技術は、昼間、前記（Ａ）の性質により培養し、夜間にはこの懸濁液を上部密閉容器に収納し、液の保温及び嫌気的環境条件の創出による捕食生物の抑制を可能にした。その後、上記装置の普及に努める中で、前述の敷地問題に突き当たり、この問題をさらに改善する研究を重ね、ついに、特願平４−２８２１４６、及び特願平８−３５９９７１に記載された技術に、（Ｂ）の性質を発揮させる技術内容を付加する事を考案し、新たな技術として提案するものである。また、降雨による問題点も解消するものである。
すなわち本発明は、
第１に微細藻類、光合成細菌等光合成微生物を増殖させる方法において，有機物が溶解した液中に光合成微生物を懸濁させ、
昼間は、大気下に開放された気液接触面積の大なる浅い平面池ｐにおいて、前記光合成微生物の懸濁液ｓに太陽光を照射し、
夜間は、懸濁液ｓを、気液接触面積の小なる深い曝気槽に移し、該曝気槽内の懸濁液ｓに空気等酸素含有気体を曝気する期間、及び曝気を停止し懸濁液ｓを嫌気状態にする期間を設けて、
光合成微生物を培養することを特徴とする光合成微生物の培養方法であり、
第２に、微細藻類、光合成細菌等光合成微生物を増殖させる方法において，有機物が溶解した液中に光合成微生物を懸濁させ、
昼間は、大気下に開放された気液接触面積の大なる浅い平面池ｐにおいて、前記光合成微生物の懸濁液ｓに太陽光を照射し、
夜間は、懸濁液ｓを、気液接触面積の小なる深い曝気槽に移し、該曝気槽内の懸濁液ｓに空気を曝気する期間、及び曝気を停止し嫌気状態にする期間を設けて、光合成微生物を培養するとともに、
昼間、降雨時には懸濁液ｓを前記曝気槽に移し、該曝気槽内の懸濁液ｓに空気等酸素含有気体を曝気して光合成微生物を培養し、平面池ｐに流入する雨水は平面池ｐ外へ排出し、光合成微生物を培養することを特徴とする光合成微生物の培養方法である。
このように本発明は、昼間の太陽光エネルギーを利用した増殖を浅い平面池ｐで行なわせ、太陽光のない夜間の酸素呼吸によるエネルギーを利用した増殖を酸素溶解効率の高い深い曝気槽ａで行なわせるとともに、曝気槽ａ内において懸濁液ｓを嫌気状態にする期間も設けてワムシ等光合成微生物捕食生物の増殖を抑制するものであり、それぞれの代謝に適する場を形成した方法である。
【図面の簡単な説明】
図１は、本発明の別の一実施例を示す平面図である。
図２は、図４におけるＢ−Ｂ縦断面図であり、昼間作動中の状態を示している。
図３は、図４におけるＢ−Ｂ縦断面図であり、夜間曝気作動中の状態を示している。
図４は、図１におけるＢ−Ｂ縦断面図であり、夜間曝気停止中の状態を示している。
図５は、平面池ｐの態様を示す平面図である。
図６は、平面池ｐの態様を示す平面図である。
図７は、平面池ｐの態様を示す平面図である。
図８は、また別の実施例を示す縦断面図であり、図１乃至図４に示した実施例の図２に対応するもので、昼間作動中の状態を示している。
図９は、図８と同じ装置の縦断面図であり、図３に対応するもので、夜間曝気作動中の状態を示している。
図１０は、図８と同じ装置の縦断面図であり、図４に対応するもので、夜間曝気停止中の状態を示している。
図１１は、また別の実施例を示す平面図である。
図１２は、図１１におけるＤ−Ｄ縦断面図であり、昼間作動中の状態を示している。
図１３は、図１１におけるＤ−Ｄ縦断面図であり、昼間作動中の状態を示している。
図１４は、また別の実施例を示す平面図である。
図１５は、図１４におけるＥ−Ｅ縦断面図であり、昼間作動中の状態を示している。
図１６は、図１４におけるＥ−Ｅ縦断面図であり、昼間作動中の状態を示している。
図１７は、また別の実施例を示す平面図である。図１１に対応する。
図１８は、また別の実施例を示す平面図である。図１４に対応する。
図１９は、また別の実施例を示す平面図である。
図２０は、図１９におけるＦ−Ｆ縦断面図であり、昼間作動中の状態を示している。
図２１は、図２０におけるＨ−Ｈ横断面図であり、昼間作動中の状態を示している。
図２２は、図１９におけるＧ−Ｇ縦断面図であり、昼間作動中の状態を示している。
図２３は、図１９におけるＩ−Ｉ縦断面図であり、夜間曝気中の状態を示している。
図２４は、本発明の一実施例を示す平面図である。
図２５は、図２４におけるＪ−Ｊ縦断面図であり、昼間作動中の状態を示している。
図２６は、図２４におけるＪ−Ｊ縦断面図であり、夜間曝気作動中の状態を示している。
符号の説明
ａは上部が密閉された深い曝気槽、ｐは平面池、ｂは浮蓋付き曝気槽，ｅは残液排出管、ｆは雨水排出管，ｇは気泡、ｋは空気層、ｓは懸濁液、ｔは液面、２は弁、３は散気装置、４は流量調節弁、５はブロワー、６はポンプ、７は弁、８は管、９は管、１０は管、１１は弁、１３は弁、１４は管、１５は弁、１６は撹拌ローター、１７は整流壁、１８は管、１９はポンプ、２０は撹拌装置、２１は台車、２２は中心回転部、２４は導水管、２５は散気装置、２７は返送管、２８は整流壁、２９は噴出用導水管、３０は吸込用導水管、３１は吸込用導水管、３３は整流壁、３４は弁、３７は整流壁、３８は浮遊体、３９は支持体
破線矢印は懸濁液の流動方向を示す。
実施例と作用
図１乃至図４は、本発明の別の一実施例を示す図面である。図１は平面図、図２は昼間作動中のＢ−Ｂ縦断面図、図３は夜間曝気作動中のＢ−Ｂ縦断面図，図４は夜間曝気停止中のＢ−Ｂ縦断面図である。
装置は、太陽光の照射を受ける浅い平面池ｐと上部が密閉された深い曝気槽ａからなる。曝気槽ａの底部には散気装置３が設けてある。曝気槽ａから平面池ｐへ有機物を含む栄養液に光合成微生物を懸濁した液（以後懸濁液ｓと略す）を送るためのポンプ６及び管８、平面池ｐから曝気槽ａへ懸濁液ｓを送るための管９、により液移動機構を構成してある。平面池ｐ底面は管９設置部位に向けて低く設けられている。管９の近傍には残液排出管ｅ及び雨水排出管ｆが設けられている。曝気槽ａには空気の出し入れをする管１４及び弁１５が備えられている。
昼間（図２）、懸濁液を平面池ｐに満たして太陽光照射を受けさせる。液中の光合成微生物は、光を吸収し、このエネルギーを利用して、有機物を吸収資化し、増殖する。夜間（図３）には、弁７及び弁１５を開け、管９を介して、懸濁液を曝気槽ａへ流下させる。曝気槽ａを充満させる以上の懸濁液ｓは平面池ｐに残る。この平面池ｐに残る残液中では、残液が空気と接触しているため、ワムシ等光合成微生物捕食生物は生存、増殖できる。これを避けるため、この残液は、収穫物として、弁２を開け、残液排出管ｅを介して貯留槽等（図示せず）へ排出する。
次に、曝気槽ａに満たされた懸濁液に、ブロワ５により、流量調節弁４、管１０、散気装置３を介して、空気を通気し、酸素を供給する。光合成微生物は、この酸素を利用した呼吸により、有機物を分解かつ資化し、増殖する。その後（図４）ブロワ５を停止し、弁７、弁１３及び弁１５を閉じる。密閉された曝気槽ａ内懸濁液ｓ中の酸素は次第に消費されて嫌気状態となる。嫌気条件下ワムシ等捕食生物は次第に死滅していく。光合成微生物は、１日から２日間程度であれば、生存している。
ワムシは、嫌気条件下６時間程度で半数致死、１２時間程度で全数致死となり、半数致死のものを４８時間曝気すると元の状態に戻るという実験結果が得られている。上記夜間の曝気停止時間は、８時間以上が適当である。
昼間（図２）には、ブロワ５を停止し、弁７を閉じ、弁１３及び弁１５を開け、ポンプ６により、管８を介して、懸濁液ｓを平面池ｐへ送り、懸濁液ｓを平面池ｐに満たして太陽光照射を受けさせる。以後上記工程を繰返し、培養を行なう。
昼間降雨時には、上記夜間の場合と同様に、曝気槽ａに満たされた懸濁液ｓを曝気するとともに、平面池ｐ内に流入してくる雨水は、弁１１を開け雨水排出管ｆを介して排水路等（図示せず）へ排出する。
実験室における純粋培養は例外として、屋外における大量培養では非光合成微生物の混入・増殖は必ず存在する。平面池ｐの水深は、光合成微生物を優先的に増殖させるため、２０ｃｍ以下が適当である。水深２０ｃｍ以上では深くなるほど、光合成微生物の濃度が低下し、優先的に増殖させることが難しくなる。
夜間や降雨時に、平面池ｐに通気し、酸素を供給して、上記のように光合成微生物を呼吸代謝により増殖させることも可能であるが、平面池ｐは浅いため、単位動力当りの酸素供給能が、極めて低く、費用の点から、現実的に実施不可能である。本発明では、懸濁液ｓを深い曝気槽ａに導き、ここで曝気するので、単位動力当りの酸素供給能が高く、現実的に実施可能である。通常の活性汚泥法曝気槽で、曝気水深３−４ｍで、６−８％の酸素溶解効率が得られる。本発明の曝気槽ａ水深も２．５−４ｍに設定すればよい。
夜間懸濁液ｓが平面池ｐ内に残存しないよう、平面池ｐ底面は管９設置部位に向けて低く設けられ、管９の近傍には残液排出管ｅが設けられている。これは、必須条件ではなく、平面池ｐ底面はほぼ水平でも良い。ほぼ水平であれば、懸濁液ｓが黄変し連続培養が不可能となることはない。
このように本発明の方法及び装置によれば、夜間や昼間降雨時にも、光合成微生物を効率的に増殖させることにより、単位面積当りの増殖量を増加させることが可能となるとともに、ワムシ等の増殖が抑制されるので、毎日懸濁液ｓを収穫し、この収穫分と同量の栄養液を添加する、いわゆる連続培養が可能となる。また、毎日排出される有機性廃水を栄養液として用いる場合、光合成微生物の収穫量増加とともに、これを毎日連続して効率的に浄化処理できる。
本実施例では、夜間、曝気した後、曝気を停止し嫌気状態にしたが、順序を逆にして、嫌気状態に保持した後、曝気を行なう方式でも、同様の効果がある。
図１乃至図４に示した平面池ｐは、特に撹拌機構を設けていないが、曝気槽ａへ懸濁液ｓを毎日移動させる際の流動で光合成微生物の沈積はほとんど防止できる。また、添加した栄養液との混合は曝気槽ａで毎日行なわれるので、平面池ｐで栄養分の濃度が不均一になることも防止している。しかし、増殖をさらに速めるには、撹拌機構は必要である。
平面池ｐに関する実施例を、平面図で図５乃至図７に示した。いずれも水深１０−４０ｃｍの浅い平面池ｐである。図５の平面池ｐは、整流壁１７で区画された１つの無終端水路に、矢印の方向に懸濁液ｓを流動させるための撹拌ローター１６が設けられ、撹拌機構が構成されている。図６の平面池ｐは、整流壁１７で区画された１つの水路の下流端から上流端へポンプ１９により管１８を介して懸濁液ｓを送ることにより、矢印の方向に懸濁液ｓを流動させ、撹拌機構を構成している。図７は、円形の平面池ｐの中心回転部２２から円周側壁上端上の台車２１にかけて、下方にブラシのついた撹拌装置２０を設け、矢印の方向に、台車２１を動かし、池内を撹拌する。
図５乃至図７に示した撹拌機構を有する平面池ｐは、撹拌装置の分だけ施設費・運転費が高価となるが、本発明にも利用できる。
図８乃至図１０は、また別の実施例を示す図面であり、図１乃至図４に示した実施例に対応するものである。図２に対応する図８は昼間作動中の縦断面図、図３に対応する図９は夜間曝気作動中の縦断面図，図４に対応する図１０は夜間曝気停止中の縦断面図である。図１乃至図４に示した実施例と異なる点は、管９が曝気槽ａ底部に開口している点である。
昼間（図８）、弁１５閉弁７開の状態で、ブロワ５により管１０を介して散気装置３より空気を送る。懸濁液ｓは、管９を介して平面池ｐへ押し出される。その後、弁７を閉じ、ブロワ５を停止し、懸濁液ｓを平面池ｐに満たして太陽光照射を受けさせ、光合成微生物を増殖せしめる。夜間（図１２）には、弁７及び弁１５を開け、管９を介して、懸濁液ｓを曝気槽ａへ流下させる。次に、曝気槽ａに満たされた懸濁液ｓに、ブロワ５により、流量調節弁４、管１０、散気装置３を介して、空気を通気し、酸素を供給する。光合成微生物は、この酸素を利用した呼吸により、有機物を分解かつ資化し、増殖する。その後（図１０）ブロワ５を停止し、弁７、流量調節弁４及び弁１５を閉じ、曝気槽ａ内懸濁液ｓを嫌気状態にする。昼間（図８）には、弁７及び弁４を開け、ブロワ５を作動させ、懸濁液を平面池ｐへ送る。以後上記工程を繰返し、培養を行なう。昼間降雨時等他の操作は、前記実施例と同様に行なう。
本実施例では、ポンプは不必要となり、ブロワ５のｏｎ−ｏｆｆにより、簡単に懸濁液ｓを移動することができる。
図１１乃至図１３は、また別の実施例を示す図面であり、図１１は平面図、図１２及び図１３は昼間作動中のＤ−Ｄ縦断面図である。図１乃至図１０に示した実施例と異なる点は、曝気槽ａが、平面池ｐの中央下方に設けられ、導水管２４により平面池ｐ底部と曝気槽ａ底部が連絡されている点である。昼間（図１２、１３）、弁１５閉、弁４開の状態で、ブロワ５により管１０を介して散気装置２５より空気を送る。懸濁液ｓは、導水管２４を介して平面池ｐへ押し出される。その後、曝気槽ａ内の液面ｔが下降し導水管２４の下端に達する。さらに液面は、水の表面張力により、下降し、やがて、空気ｋが一気に導水管２４内に噴出する。そして、導水管２４内の懸濁液ｓは、空気ｋとともに上昇し、平面池ｐ内に噴出する（図１２）。噴出が終わると、平面池ｐ内の懸濁液ｓは、導水管２４内を下降して、曝気槽ａ内に流入する（図１３）。この一連の動作により平面池ｐ内には、波動が生じ、懸濁液ｓは撹拌される。懸濁液ｓは、撹拌を受けながら、太陽光の照射を受け、光合成微生物が増殖する。夜間（図示せず）には、弁１５を開け、導水管２４を介して、懸濁液ｓを曝気槽ａへ流下させる。次に、流量調節弁４を開け、曝気槽ａ内に満たされた懸濁液ｓに、ブロワ５により、流量調節弁４、管１０、散気装置２５を介して、空気を通気し、酸素を供給する。光合成微生物は、この酸素を利用した呼吸により、有機物を分解かつ資化し、増殖する。その後ブロワ５を停止し、流量調節弁４及び弁１５を閉じ、曝気槽ａ内を嫌気状態にする。昼間には、弁４を開け、ブロワ５を作動させ、懸濁液を平面池ｐへ送る。以後上記工程を繰返し培養を行なう。昼間降雨時等他の操作は、前記実施例と同様に行なう。
本実施例では、ブロワ５のｏｎ−ｏｆｆにより、簡単に懸濁液を移動できるとともに、撹拌装置を新たに設置せずに平面池ｐ内懸濁液を簡単に撹拌できる。
図１４乃至図１６は、また別の実施例を示す図面であり、図１４は平面図、図１５は昼間作動中のＥ−Ｅ縦断面図、図１６は昼間作動中のＥ−Ｅ縦断面図である。図１１乃至図１３に示した実施例と異なる点は、平面池ｐ端部と曝気槽ａ底部を連絡する返送管２７が設けられている点である。返送管２７は、曝気槽ａ内の導水管２４の下端よりも下方に開口するよう配備する。本実施例では、空気が導水管２４から平面池ｐへ噴出した場合（図１５）、返送管２７より速やかに懸濁液ｓが曝気槽ａ内に流入するので、懸濁液ｓの混合も行なえる。他の運転操作は、図１１乃至図１３に示した実施例と同様に行なえばよい。
図１７は、図１１乃至図１３に示した実施例の図１１に対応する平面図である。平面池ｐは、長い水路に構成され、その端部下方に曝気槽ａが設けられている。図１８は、図１４乃至図１６に示した実施例の図１４に対応する平面図である。平面池ｐは、長い水路に構成され、その端部下方に曝気槽ａが設けられている。返送管２７は、平面池ｐの端部と曝気槽ａ底部を連絡している。平面池ｐの形状は、上記実施例に限定されるものではなく、敷地の形状、施設予算等いろいろな条件を考慮して決定すればよい。
図１９乃至図２３は、本発明のまた別の実施例を示す図面であり、図１９は平面図、図２０昼間作動中のＦ−Ｆ縦断面図、図２２は昼間作動中のＧ−Ｇ縦断面図、図２１は昼間作動中のＨ−Ｈ横断面図、図２３は夜間曝気中のＩ−Ｉ縦断面図である。本実施例は、図１８に示した装置と同様の機能を有するものである。図１８の装置においては、曝気槽ａ内導水管２４、水路状平面池ｐ、返送管２７、上部密閉曝気槽ｂ内の順に懸濁液ｓが流動するよう構成されている。本実施例の装置においても、平面池ｐを整流壁２８で区画し、上流端と下流端が曝気槽ａ上で隣接する１本の水路に構成し、この上流端に噴出用導水管２９、下流端に吸込み用導水管３０，３１を設け、噴出用導水管２９、平面池ｐ、吸込み用導水管３０，３１、曝気槽ａの順に懸濁液ｓが循環的に流動するよう構成してある。３７は整流壁である。図１８においては、水路状平面池ｐの流積に見合う返送管２７を設けるには、費用が高価となる。本実施例では、平面池ｐを整流壁２８で区画し、上流端と下流端が曝気槽ａ上で隣接する１本の水路に構成し、この上流端に噴出用導水管２９、下流端に吸込み用導水管３０，３１を設けてあるので、費用も安く、平面池ｐ内の流動もよく、混合・撹拌が効率よく行なえる。
図２４乃至図２６は、また別の実施例を示す図面であり、図１乃至図４に示した実施例に対応するものである。図１に対応する図２４は平面図、図２に対応する図２５は昼間作動中のＪ−Ｊ縦断面図，図３に対応する図２６は夜間曝気作動中のＪ−Ｊ縦断面図である。図１乃至図４に示した実施例と異なる点は、曝気槽が液面を覆う浮遊体３８を備えた深い浮蓋付き曝気槽ｂに構成されている点である。昼間には浮遊体３８は支持体３９上に静止する。夜間には浮遊体３８は液面の大部分を覆い液面上に浮遊する。夜間曝気停止時、浮遊体３８と槽壁面等との間隙部分の液面には酸素が供給されるが、その供給量は少なく、有機物存在下では浮蓋付き曝気槽ｂ内の懸濁液ｓは嫌気状態となり、ワムシ等微小動物の増殖は抑制され、光合成微生物の連続培養が可能である。浮遊体３８としては合成樹脂発泡板等を用いればよい。
本実施例の場合、上部が密閉された曝気槽ａと比べて安価となるが、曝気槽ａのような空気の圧入による懸濁液ｓの効率的な移動や撹拌は行なえない。また、曝気時には、衝撃も激しく、浮遊体３８の破損も生じる。本実施例の装置は小規模の培養に適する。
本発明の方法及び装置による運転結果を示せば、下記のようである。
（実施例）
平成１３年２月６日より、図８乃至図１０に示す装置でＣｈｌｏｒｅｌｌａｓｐ．の回分培養を行なった。平面池ｐは、平均水深１５．５ｃｍ、受光面積３．６ｍ２（２．０ｍ＊１．８ｍ）のコンクリートブロック側壁水槽、曝気槽ａは塩ビパイプＶＵφ５００（内径４９０ｍｍ）で作製し、高さ３．０５ｍ、水深２．９５ｍとした。上記装置をＡ，Ｂ２基作製した。豚尿と生ゴミ浸出水を混合し、これに水を加え、１週間放置した上澄液に、さらに水を加え、これに種株液を加えた液を等分し、Ａ、Ｂそれぞれの平面池ｐに投入し、培養を開始した。Ａには、午後４時３０分から８時間、およそ１０Ｌ／分の空気を、曝気槽ａ水深２．８ｍの位置から、通気した。Ｂは、通気を行なわない。Ａ、Ｂともに朝８時３０分から午後４時３０分まで、平面池ｐにて培養し、その後曝気槽ａに戻した。実験期間中、水を添加し水量を調節し、また弁１５は夜間開とした。また、実験は透明ビニールハウス内で行なった。午後４時３０分の水温は、平均でＡ１１．５℃、Ｂ１１．０℃であった。培養の結果を下表に示した。

表より、本発明の夜間曝気の効果が認められる。
その後４月に、ＰＣＶ５の懸濁液に、ワムシが発生し黄色がかった液を添加混合し、Ａ、Ｂそれぞれの平面池ｐに投入し、培養を再開した。Ａの装置に用いる弁は電磁弁を用い、その開閉は自動的に行なった。Ａでの培養は、朝８時３０分から午後４時３０分まで、平面池ｐにて培養し、その後６時間曝気し、その後１０時間曝気を停止し嫌気状態を保った。Ｂでの培養は、平面池ｐで１日中行なった。期間中は、上記と同様に調整した栄養液を適宜添加した。実験開始後、５日目にＢの平面池ｐは、黄色に変化し、ワムシの大量発生が観察された。Ａの装置では、その後２ヶ月間濃い緑色の状態が実験終了まで続いた。
本発明は、上記のクロレラの培養だけでなく、呼吸機能を有する他の光合成微生物（緑藻類、紅色非硫黄細菌、ケイ藻等）の培養にも利用できる。また、これら光合成微生物による有機廃水の浄化にも本発明は利用できることは言うまでもない。
発明の効果
以上のように、本発明の方法は、
第１に、昼間の太陽光エネルギーを利用した増殖を浅い平面池ｐで行なわせ、太陽光のない夜間には懸濁液を外気と水面の接触を避けるよう構成された深い曝気槽に移動し、ここでワムシ等光合成微生物捕食生物を死滅させるために嫌気状態に保つ期間と光合成微生物の呼吸作用による増殖を促すために深い位置から効率的に曝気する期間を設けたことを特徴とするものである。
これによれば、保温、ワムシ抑制に加えて夜間の効果的増殖が可能となる。すなわち、温度が低下する冬期に夜間の曝気量、曝気時間を増加させることにより、光合成微生物の増殖速度を高めることができるとともに、ワムシ等微小動物の大量発生も防止できる。
また、昼間降雨時には、平面池ｐに流入する雨水を排出し、曝気槽にて光合成微生物に酸素呼吸によるエネルギーを利用した増殖を行なわせる特徴がある。このため、日照不足期の増殖低下、降雨による懸濁液の希釈を防止できる。温暖地域においては、透明フィルム上屋が必要ない。また上屋を設けない場合の過度に高い側壁の建設が必要ない。
以上まとめれば、本発明によって、日照不足期や低温期の増殖速度を高めることができ、年間を通して気象条件により左右されないほぼ一定の優れた培養成績をあげることができ、結果的に敷地面積及びそれに伴う施設費の減少につながる。また、ワムシ等微小動物の大量発生も防止でき、年間を通して、効率的な高濃度連続培養が可能となる。 Industrial application fields
The present invention relates to a method for culturing photosynthetic microorganisms such as microalgae and photosynthetic bacteria.
The present invention can be used for purification of organic wastewater in addition to the production of algal cells.
Conventional technology
In general, the cultivation of photosynthetic microorganisms, as seen in the cultivation of microalgae, is representative of large-scale edible chlorella culture ponds using acetic acid and glucose as a carbon source and high-rate oxidation ponds for organic wastewater purification. It is carried out in a shallow and wide flat pond p constructed about 20cm deep. These are all open-type culture devices that receive sunlight directly on the water surface. For this reason,
(1) In cold regions, the heat loss from the vast water surface is large, especially the heat loss at night is large, the photosynthetic microorganism suspension is cooled, and the growth rate is low.
(2) When the water temperature is about 10 ° C. or more, there are many examples in which minute animals such as daphnids and rotifers that prey on photosynthetic microorganisms become active, and photosynthetic microorganisms are actively preyed, and in the case of chlorella, they are annihilated all day and night. Since the minute animals are carried by wind, birds, insects, etc., it is difficult to prevent the invasion and breeding of the culture pond, and a large amount of chemicals must be used to prevent this mass outbreak. .
(3) The photosynthetic microorganism suspension is diluted by rain, and the photosynthetic microorganism concentration is lowered. Furthermore, the photosynthetic microorganism suspension is washed away from the culture pond. In order to prevent this loss, it is necessary to make the side walls of the culture pond higher than necessary, and a transparent film shed is required even in a warm area where a greenhouse is not required.
There were problems such as.
If these are solved, food production, wastewater treatment, carbon dioxide fixation, etc. will be greatly advanced by photosynthetic microorganisms such as photosynthetic bacteria and microalgae. From this point of view, the present inventor proposed Japanese Patent Application No. 4-282146 (cultivation apparatus for photosynthetic microorganisms and its operating method) on September 8, 1992, and Japanese Patent Application No. 8 on December 29, 1996. -359971 (microalgae culture device) was devised and applied.
As a result, the problem (1) was improved, more efficient cultivation of photosynthetic microorganisms was possible, and the disadvantage that the site area was vast was also improved. Also, the problem (2) has been solved, and stable continuous culture of photosynthetic microorganisms has become possible.
However, the problem (1) remains unsolved.
When aiming at the cultivation of photosynthetic microorganisms, especially wastewater treatment, the problem (1) is an obstacle to the installation of facilities. In wastewater treatment, a certain treatment capacity is required every day. When cultivating photosynthetic microorganisms by sunlight, the growth greatly depends on weather conditions such as solar radiation and temperature. Since the growth of photosynthetic microorganisms decreases most in winter, the scale of the culture pond is set based on the growth in winter. For this reason, a large area is still needed.
Further, due to the problem (3), the construction cost of the culture facility is expensive.
Problems to be solved by the invention
Thus, the present invention provides a method and apparatus for culturing photosynthetic microorganisms that can prevent cooling of a suspension in a cold region and can achieve a certain excellent culture result regardless of weather conditions such as sunshine. It is intended.
Means to solve the problem
Photosynthetic microorganisms such as microalgae and red sulfur-free bacteria
(A) Ability to absorb solar energy and use this energy to absorb and grow carbon dioxide, organic matter and other nutrients
(B) Ability to proliferate using energy generated in the process of catabolizing and metabolizing absorbed organic matter (fermentation, respiration)
Have
At night, when sunlight is no longer applied, photosynthetic microorganisms multiply using only the energy generated during the process of catabolizing and metabolizing organic matter (fermentation and respiration).
Japanese Patent Application No. 4-282146 (photosynthetic microorganism culturing apparatus and operation method thereof) and Japanese Patent Application No. 8-359971 (microalgae culture apparatus) are cultivated in the daytime according to the above-mentioned property (A), and at night This suspension was housed in an upper closed container, which enabled the suppression of predatory organisms by keeping the liquid warm and creating anaerobic environmental conditions. After that, while trying to spread the above devices, we faced the above-mentioned site problem and repeated research to further improve this problem. Finally, the technology described in Japanese Patent Application Nos. 4-282146 and 8-359971 was applied. , (B) is devised to add technical contents that demonstrate the properties, and is proposed as a new technology. It also eliminates problems caused by rainfall.
That is, the present invention
First, in a method of growing photosynthetic microorganisms such as microalgae and photosynthetic bacteria, the photosynthetic microorganism is suspended in a solution in which organic matter is dissolved,
In the daytime, in the shallow plane pond p having a large gas-liquid contact area opened to the atmosphere, the suspension s of the photosynthetic microorganisms is irradiated with sunlight,
At night, the suspension s is transferred to a deep aeration tank having a small gas-liquid contact area, and a period in which oxygen-containing gas such as air is aerated in the suspension s in the aeration tank, and the aeration is stopped and the suspension is suspended. Set a period to make s anaerobic,
A method for culturing photosynthetic microorganisms characterized by culturing photosynthetic microorganisms,
Second, in a method for growing photosynthetic microorganisms such as microalgae and photosynthetic bacteria, the photosynthetic microorganisms are suspended in a solution in which organic matter is dissolved.
In the daytime, in the shallow plane pond p having a large gas-liquid contact area opened to the atmosphere, the suspension s of the photosynthetic microorganisms is irradiated with sunlight,
At night, the suspension s is transferred to a deep aeration tank with a small gas-liquid contact area, and there is a period in which air is aerated in the suspension s in the aeration tank, and a period in which aeration is stopped and an anaerobic state is established. And cultivating photosynthetic microorganisms,
During the daytime and raining, the suspension s is transferred to the aeration tank, and oxygen-containing gas such as air is aerated on the suspension s in the aeration tank to culture photosynthetic microorganisms. A method for cultivating photosynthetic microorganisms, characterized in that the photosynthetic microorganisms are cultivated after being discharged out of p.
As described above, in the present invention, the daytime solar energy is propagated in the shallow plane pond p, and the nighttime oxygen breathing without sunlight is propagated in the deep aeration tank a having high oxygen dissolution efficiency. This is a method in which a period for making the suspension s anaerobic in the aeration tank a is also provided to suppress the growth of photosynthetic microorganism predatory organisms such as rotifers, and a field suitable for each metabolism is formed.
[Brief description of the drawings]
FIG. 1 is a plan view showing another embodiment of the present invention.
FIG. 2 is a BB longitudinal sectional view in FIG. 4 and shows a state during daytime operation.
FIG. 3 is a BB longitudinal sectional view in FIG. 4 and shows a state during night aeration operation.
FIG. 4 is a BB longitudinal sectional view in FIG. 1 and shows a state in which aeration is stopped at night.
FIG. 5 is a plan view showing an aspect of the plane pond p.
FIG. 6 is a plan view showing an aspect of the plane pond p.
FIG. 7 is a plan view showing an aspect of the plane pond p.
FIG. 8 is a longitudinal sectional view showing still another embodiment, corresponding to FIG. 2 of the embodiment shown in FIGS. 1 to 4, and showing a state during daytime operation.
FIG. 9 is a longitudinal sectional view of the same device as FIG. 8 and corresponds to FIG. 3, and shows a state during night aeration operation.
FIG. 10 is a longitudinal sectional view of the same apparatus as FIG. 8 and corresponds to FIG. 4 and shows a state in which aeration at night is stopped.
FIG. 11 is a plan view showing another embodiment.
FIG. 12 is a DD longitudinal sectional view in FIG. 11 and shows a state during daytime operation.
FIG. 13 is a DD longitudinal sectional view in FIG. 11 and shows a state during daytime operation.
FIG. 14 is a plan view showing another embodiment.
FIG. 15 is a vertical cross-sectional view taken along line EE in FIG. 14 and shows a state during daytime operation.
FIG. 16 is a vertical cross-sectional view taken along line EE in FIG. 14 and shows a state during daytime operation.
FIG. 17 is a plan view showing another embodiment. This corresponds to FIG.
FIG. 18 is a plan view showing another embodiment. This corresponds to FIG.
FIG. 19 is a plan view showing another embodiment.
FIG. 20 is a FF vertical cross-sectional view in FIG. 19 and shows a state during daytime operation.
FIG. 21 is a cross-sectional view taken along the line HH in FIG. 20 and shows a state during daytime operation.
FIG. 22 is a GG longitudinal sectional view in FIG. 19 and shows a state during daytime operation.
FIG. 23 is a vertical cross-sectional view taken along the line II in FIG. 19, showing a state during night aeration.
FIG. 24 is a plan view showing an embodiment of the present invention.
FIG. 25 is a JJ longitudinal sectional view in FIG. 24 and shows a state during daytime operation.
FIG. 26 is a JJ longitudinal sectional view in FIG. 24 and shows a state during night aeration operation.
Explanation of symbols
a is a deep aeration tank with a sealed top, p is a flat pond, b is an aeration tank with a floating lid, e is a residual liquid discharge pipe, f is a rainwater discharge pipe, g is a bubble, k is an air layer, and s is suspended. Liquid, t is liquid level, 2 is valve, 3 is air diffuser, 4 is flow control valve, 5 is blower, 6 is pump, 7 is valve, 8 is pipe, 9 is pipe, 10 is pipe, 11 is valve , 13 is a valve, 14 is a pipe, 15 is a valve, 16 is a stirring rotor, 17 is a rectifying wall, 18 is a pipe, 19 is a pump, 20 is a stirring device, 21 is a carriage, 22 is a central rotating part, and 24 is a water conduit. , 25 is an air diffuser, 27 is a return pipe, 28 is a rectifying wall, 29 is a jet conduit, 30 is a suction conduit, 31 is a suction conduit, 33 is a rectifier wall, 34 is a valve, 37 is rectifier Wall, 38 floating body, 39 support
Dashed arrows indicate the direction of suspension flow.
Example and operation
1 to 4 are drawings showing another embodiment of the present invention. 1 is a plan view, FIG. 2 is a BB longitudinal sectional view during daytime operation, FIG. 3 is a BB longitudinal sectional view during night aeration operation, and FIG. 4 is a BB longitudinal sectional view during night aeration stop. is there.
The apparatus comprises a shallow flat pond p that receives sunlight and a deep aeration tank a that is sealed at the top. An air diffuser 3 is provided at the bottom of the aeration tank a. A pump 6 and a pipe 8 for sending a solution (hereinafter abbreviated as suspension s) of a photosynthetic microorganism in a nutrient solution containing organic matter from the aeration tank a to the plane pond p, suspended from the plane pond p to the aeration tank a A liquid moving mechanism is configured by the pipe 9 for sending the liquid s. The bottom surface of the plane pond p is provided low toward the tube 9 installation site. A residual liquid discharge pipe e and a rainwater discharge pipe f are provided in the vicinity of the pipe 9. The aeration tank a is provided with a pipe 14 and a valve 15 for taking air in and out.
In the daytime (FIG. 2), the suspension is filled in the flat pond p and irradiated with sunlight. The photosynthetic microorganisms in the liquid absorb light and use this energy to absorb and grow organic matter. At night (FIG. 3), the valve 7 and the valve 15 are opened, and the suspension is allowed to flow down to the aeration tank a through the pipe 9. Suspension s more than filling aeration tank a remains in plane pond p. In the remaining liquid remaining in the plane pond p, the remaining liquid is in contact with air, so that photosynthetic microorganism predatory organisms such as rotifers can survive and multiply. In order to avoid this, the residual liquid is discharged as a harvested product to the storage tank or the like (not shown) through the residual liquid discharge pipe e by opening the valve 2.
Next, air is supplied to the suspension filled in the aeration tank a through the flow control valve 4, the pipe 10, and the air diffuser 3 by the blower 5 to supply oxygen. The photosynthetic microorganisms decompose and assimilate organic matter by the respiration using oxygen and grow. Thereafter (FIG. 4), the blower 5 is stopped, and the

valves

7, 13 and 15 are closed. Oxygen in the sealed aeration tank a suspension s is gradually consumed and becomes anaerobic. Predatory organisms such as rotifers gradually die under anaerobic conditions. The photosynthetic microorganism is alive if it is about 1 to 2 days.
Experimental results have shown that rotifers are half lethal in about 6 hours under anaerobic conditions, all dead in about 12 hours, and return to their original state after aeration for half a lethality for 48 hours. The nighttime aeration stop time is suitably 8 hours or more.
In the daytime (FIG. 2), the blower 5 is stopped, the valve 7 is closed, the valve 13 and the valve 15 are opened, and the suspension 6 is sent to the plane pond p through the pipe 8 by the pump 6 and suspended. The liquid s is filled in the plane pond p and irradiated with sunlight. Thereafter, the above steps are repeated to carry out the culture.
During the daytime rain, the suspension s filled in the aeration tank a is aerated and rainwater flowing into the plane pond p opens the valve 11 and passes through the rainwater discharge pipe f as in the case of the nighttime. To a drain (not shown).
With the exception of pure culture in the laboratory, there is always contamination and growth of non-photosynthetic microorganisms in large-scale outdoor cultivation. The water depth of the plane pond p is suitably 20 cm or less in order to preferentially grow photosynthetic microorganisms. The deeper the water depth is 20 cm or more, the lower the concentration of photosynthetic microorganisms, making it difficult to preferentially proliferate.
It is possible to ventilate the plane pond p at night or during the rain and supply oxygen to grow the photosynthetic microorganisms by respiratory metabolism as described above. However, since the plane pond p is shallow, oxygen supply per unit power The performance is extremely low and is not practically feasible due to cost. In the present invention, since the suspension s is guided to the deep aeration tank a and aerated here, the oxygen supply capacity per unit power is high and can be implemented practically. In an ordinary activated sludge method aeration tank, an oxygen dissolution efficiency of 6-8% is obtained at an aeration depth of 3-4 m. What is necessary is just to set the aeration tank a water depth of this invention to 2.5-4 m.
The bottom surface of the flat pond p is provided low toward the installation site of the pipe 9 so that the nighttime suspension s does not remain in the flat pond p, and a residual liquid discharge pipe e is provided in the vicinity of the pipe 9. This is not an essential condition, and the bottom surface of the planar pond p may be substantially horizontal. If it is almost horizontal, the suspension s will not turn yellow and continuous culture will not be impossible.
As described above, according to the method and apparatus of the present invention, it is possible to increase the amount of proliferation per unit area by efficiently growing photosynthetic microorganisms even during nighttime or daytime rainfall. Since the growth is suppressed, so-called continuous culture in which the suspension s is harvested every day and the same amount of nutrient solution as the harvested amount is added becomes possible. Moreover, when the organic waste water discharged | emitted every day is used as a nutrient solution, it can carry out a purification | cleaning process efficiently continuously every day with the increase in the yield of a photosynthetic microorganism.
In this embodiment, after aeration at night, the aeration is stopped and the anaerobic state is set. However, the same effect can be obtained by a system in which the order is reversed and the aeration is performed after maintaining the anaerobic state.
The flat pond p shown in FIGS. 1 to 4 is not particularly provided with a stirring mechanism, but can hardly prevent the deposition of photosynthetic microorganisms by the flow when the suspension s is moved to the aeration tank a every day. Moreover, since mixing with the added nutrient solution is performed every day in the aeration tank a, the concentration of nutrients in the flat pond p is prevented from becoming uneven. However, an agitation mechanism is necessary to further accelerate the growth.
Examples relating to the plane pond p are shown in FIGS. 5 to 7 in plan view. Both are shallow plane ponds p with a depth of 10-40 cm. In the flat pond p in FIG. 5, a stirring rotor 16 for causing the suspension s to flow in the direction of the arrow is provided in one endless water channel partitioned by the rectifying wall 17, thereby forming a stirring mechanism. The plane pond p in FIG. 6 is sent in the direction of the arrow by sending the suspension s through the pipe 18 by the pump 19 from the downstream end to the upstream end of one water channel partitioned by the rectifying wall 17. The agitation mechanism is configured. FIG. 7 shows that a stirring device 20 with a brush is provided below from a central rotating portion 22 of a circular flat pond p to a carriage 21 on the upper end of the circumferential side wall, and the carriage 21 is moved in the direction of the arrow to stir the pond. To do.
The flat pond p having the stirring mechanism shown in FIGS. 5 to 7 is expensive in the facility cost and the operating cost by the amount of the stirring device, but can also be used in the present invention.
FIGS. 8 to 10 are diagrams showing another embodiment, and correspond to the embodiment shown in FIGS. 1 to 4. 8 corresponding to FIG. 2 is a longitudinal sectional view during daytime operation, FIG. 9 corresponding to FIG. 3 is a longitudinal sectional view during night aeration operation, and FIG. 10 corresponding to FIG. 4 is a longitudinal sectional view during night aeration stopping. is there. The difference from the embodiment shown in FIGS. 1 to 4 is that the tube 9 is open to the bottom of the aeration tank a.
In the daytime (FIG. 8), with the valve 15 closed and the valve 7 open, air is sent from the diffuser 3 via the pipe 10 by the blower 5. The suspension s is pushed out through the pipe 9 into the plane pond p. Thereafter, the valve 7 is closed, the blower 5 is stopped, the suspension s is filled in the flat pond p, irradiated with sunlight, and the photosynthetic microorganisms are grown. At night (FIG. 12), the valve 7 and the valve 15 are opened, and the suspension s is caused to flow down to the aeration tank a through the pipe 9. Next, air is supplied to the suspension s filled in the aeration tank a by the blower 5 through the flow rate control valve 4, the pipe 10, and the air diffuser 3 to supply oxygen. The photosynthetic microorganisms decompose and assimilate organic matter by the respiration using oxygen and grow. Thereafter (FIG. 10), the blower 5 is stopped, the valve 7, the flow rate adjusting valve 4 and the valve 15 are closed, and the suspension s in the aeration tank a is brought into an anaerobic state. In the daytime (FIG. 8), the valve 7 and the valve 4 are opened, the blower 5 is operated, and the suspension is sent to the plane pond p. Thereafter, the above steps are repeated to carry out the culture. Other operations such as during daytime rainfall are performed in the same manner as in the previous embodiment.
In this embodiment, no pump is required, and the suspension s can be easily moved by turning the blower 5 on and off.
11 to 13 are drawings showing still another embodiment, FIG. 11 is a plan view, and FIGS. 12 and 13 are DD longitudinal sectional views during daytime operation. The difference from the embodiment shown in FIGS. 1 to 10 is that the aeration tank a is provided below the center of the plane pond p, and the bottom of the plane pond p and the bottom of the aeration tank a are connected by the water conduit 24. is there. In the daytime (FIGS. 12 and 13), with the valve 15 closed and the valve 4 open, air is sent from the air diffuser 25 through the pipe 10 by the blower 5. The suspension s is pushed out to the flat pond p through the water conduit 24. Thereafter, the liquid level t in the aeration tank a descends and reaches the lower end of the water conduit 24. Furthermore, the liquid level drops due to the surface tension of water, and eventually air k is ejected into the water conduit 24 at once. Then, the suspension s in the water conduit 24 rises with the air k and is ejected into the flat pond p (FIG. 12). When the ejection ends, the suspension s in the plane pond p descends in the water conduit 24 and flows into the aeration tank a (FIG. 13). By this series of operations, a wave is generated in the plane pond p, and the suspension s is stirred. The suspension s is irradiated with sunlight while being stirred, and the photosynthetic microorganisms grow. At night (not shown), the valve 15 is opened, and the suspension s is caused to flow down to the aeration tank a through the water conduit 24. Next, the flow control valve 4 is opened, air is passed through the suspension s filled in the aeration tank a through the blower 5 through the flow control valve 4, the pipe 10 and the air diffuser 25, and oxygen Supply. The photosynthetic microorganisms decompose and assimilate organic matter by the respiration using oxygen and grow. Thereafter, the blower 5 is stopped, the flow rate adjusting valve 4 and the valve 15 are closed, and the inside of the aeration tank a is brought into an anaerobic state. In the daytime, the valve 4 is opened, the blower 5 is operated, and the suspension is sent to the plane pond p. Thereafter, the above steps are repeated for culturing. Other operations such as during daytime rainfall are performed in the same manner as in the previous embodiment.
In the present embodiment, the suspension can be easily moved by on-off of the blower 5, and the suspension in the plane pond p can be easily stirred without newly installing a stirring device.
FIGS. 14 to 16 are views showing still another embodiment, FIG. 14 is a plan view, FIG. 15 is an EE longitudinal sectional view during daytime operation, and FIG. 16 is an EE longitudinal sectional view during daytime operation. FIG. The difference from the embodiment shown in FIGS. 11 to 13 is that a return pipe 27 is provided to connect the end of the flat pond p and the bottom of the aeration tank a. The return pipe 27 is arranged to open below the lower end of the water guide pipe 24 in the aeration tank a. In the present embodiment, when air is ejected from the conduit 24 to the plane pond p (FIG. 15), the suspension s flows into the aeration tank a quickly from the return pipe 27, so that the suspension s is also mixed. Yes. Other driving operations may be performed in the same manner as the embodiment shown in FIGS.
FIG. 17 is a plan view corresponding to FIG. 11 of the embodiment shown in FIGS. The plane pond p is configured as a long water channel, and an aeration tank a is provided below the end portion thereof. FIG. 18 is a plan view corresponding to FIG. 14 of the embodiment shown in FIGS. The plane pond p is configured as a long water channel, and an aeration tank a is provided below the end portion thereof. The return pipe 27 communicates the end of the plane pond p and the bottom of the aeration tank a. The shape of the plane pond p is not limited to the above embodiment, and may be determined in consideration of various conditions such as the site shape and the facility budget.
19 to 23 are views showing still another embodiment of the present invention, in which FIG. 19 is a plan view, FIG. 20 is a longitudinal sectional view of FF during daytime operation, and FIG. 22 is a GG during daytime operation. FIG. 21 is a HH transverse sectional view during daytime operation, and FIG. 23 is a II longitudinal sectional view during night aeration. This embodiment has the same function as the apparatus shown in FIG. The apparatus shown in FIG. 18 is configured such that the suspension s flows in the order of the water guide pipe 24 in the aeration tank a, the water channel planar pond p, the return pipe 27, and the upper sealed aeration tank b. Also in the apparatus of the present embodiment, the plane pond p is partitioned by the rectifying wall 28, and the upstream end and the downstream end are configured as one water channel adjacent on the aeration tank a. The

suction conduits

30 and 31 are provided at the downstream end, and the suspension s is circulated in the order of the ejection conduit 29, the plane pond p, the

suction conduits

30 and 31, and the aeration tank a. is there. Reference numeral 37 denotes a rectifying wall. In FIG. 18, it is expensive to provide the return pipe 27 commensurate with the flow of the water channel planar pond p. In this embodiment, the plane pond p is partitioned by the rectifying wall 28, and the upstream end and the downstream end are configured as one water channel adjacent on the aeration tank a, and the jet guide pipe 29 is connected to the upstream end and the downstream end is connected to the downstream end. Since the

suction conduits

30 and 31 are provided, the cost is low, the flow in the plane pond p is good, and mixing and stirring can be performed efficiently.
FIGS. 24 to 26 are diagrams showing still another embodiment and correspond to the embodiment shown in FIGS. 1 to 4. 24 corresponding to FIG. 1 is a plan view, FIG. 25 corresponding to FIG. 2 is a JJ longitudinal sectional view during daytime operation, and FIG. 26 corresponding to FIG. 3 is a JJ longitudinal sectional view during night aeration operation. is there. The difference from the embodiment shown in FIG. 1 to FIG. 4 is that the aeration tank is configured as an aeration tank b with a deep floating lid provided with a floating body 38 that covers the liquid surface. In the daytime, the floating body 38 rests on the support 39. At night, the floating body 38 covers most of the liquid surface and floats on the liquid surface. When the aeration is stopped at night, oxygen is supplied to the liquid surface in the gap between the floating body 38 and the tank wall surface, but the supply amount is small, and the suspension s in the aeration tank b with a floating lid is present in the presence of organic matter. Is anaerobic, the growth of micro-animals such as rotifers is suppressed, and continuous cultivation of photosynthetic microorganisms is possible. A synthetic resin foam plate or the like may be used as the floating body 38.
In the case of the present embodiment, the cost is lower than that of the aeration tank a whose upper part is sealed, but the suspension s cannot be efficiently moved and stirred by the press-fitting of air as in the aeration tank a. Further, during aeration, the impact is intense and the floating body 38 is damaged. The apparatus of this example is suitable for small-scale culture.
The results of operation by the method and apparatus of the present invention are as follows.
(Example)
From February 6, 2001, Chlorella sp. The batch culture was performed. The plane pond p is made of a concrete block side wall water tank having an average water depth of 15.5 cm and a light receiving area of 3.6 m 2 (2.0 m * 1.8 m), and the aeration tank a is made of a PVC pipe VUφ500 (inner diameter 490 mm). The depth was 05 m and the water depth was 2.95 m. A and B of the above apparatus were produced. Mix the swine urine and raw leachate, add water to this, add water to the supernatant left for 1 week, divide the solution with the seed stock solution into equal parts, It was put into the plane pond p and the culture was started. In A, air of about 10 L / min was ventilated from the position of the aeration tank a water depth of 2.8 m for 8 hours from 4:30 pm. B does not ventilate. Both A and B were cultured in the plane pond p from 8:30 am to 4:30 pm and then returned to the aeration tank a. During the experiment, water was added to adjust the amount of water, and the valve 15 was opened at night. The experiment was conducted in a transparent greenhouse. The water temperature at 4:30 pm was A11.5 ° C. and B11.0 ° C. on average. The results of the culture are shown in the table below.

From the table, the effect of night aeration according to the present invention is recognized.
Thereafter, in April, a liquid in which rotifer was generated and yellowish was added to the suspension of PCV5, and the mixture was added to each of the flat ponds p of A and B, and the culture was resumed. The valve used in the device A was an electromagnetic valve, and the opening and closing was performed automatically. The culture in A was carried out from 8:30 am to 4:30 pm in the plane pond p, then aerated for 6 hours, and then aerated for 10 hours and maintained in an anaerobic state. Culturing with B was performed throughout the day in plane pond p. During the period, the nutrient solution adjusted as described above was added as appropriate. On the fifth day after the start of the experiment, the plane pond p of B turned yellow and a large amount of rotifer was observed. In the apparatus A, the dark green state continued for 2 months until the end of the experiment.
The present invention can be used not only for culturing chlorella as described above but also for culturing other photosynthetic microorganisms having a respiratory function (green algae, red non-sulfur bacteria, diatoms, etc.). Needless to say, the present invention can also be used to purify organic wastewater by these photosynthetic microorganisms.
The invention's effect
As described above, the method of the present invention
First, the daytime solar energy is propagated in a shallow flat pond p and the suspension is moved to a deep aeration tank constructed to avoid contact between the outside air and the water surface at night without sunlight. In this case, a period of keeping anaerobic conditions to kill predators of photosynthetic microorganisms such as rotifers and a period of efficient aeration from a deep position in order to promote the growth of the photosynthetic microorganisms by the respiratory action are provided. is there.
According to this, in addition to heat retention and rotifer suppression, it is possible to effectively proliferate at night. That is, by increasing the night aeration amount and the aeration time during the winter when the temperature decreases, the growth rate of photosynthetic microorganisms can be increased, and a large amount of micro-animals such as rotifers can be prevented.
In addition, when it rains during the day, rainwater flowing into the plane pond p is discharged and the photosynthetic microorganisms are allowed to multiply using the energy of oxygen respiration in the aeration tank. For this reason, it is possible to prevent a decrease in growth in the shortage of sunlight and dilution of the suspension due to rain. In warm regions, a transparent film shed is not required. Moreover, it is not necessary to construct an excessively high side wall when no shed is provided.
In summary, according to the present invention, it is possible to increase the growth rate in the sunshine shortage period and the low temperature period, and to obtain almost constant excellent culture results that are not influenced by weather conditions throughout the year. This leads to a reduction in facility costs. In addition, it is possible to prevent the occurrence of a large amount of minute animals such as rotifers, and efficient high-concentration continuous culture is possible throughout the year.

Claims

In a method of growing photosynthetic microorganisms such as microalgae and photosynthetic bacteria, the photosynthetic microorganisms are suspended in a solution in which organic matter is dissolved.
In the daytime, in the shallow plane pond p having a large gas-liquid contact area opened to the atmosphere, the suspension s of the photosynthetic microorganisms is irradiated with sunlight,
At night, the suspension s is transferred to a deep aeration tank having a small gas-liquid contact area, and a period in which oxygen-containing gas such as air is aerated in the suspension s in the aeration tank, and the aeration is stopped and the suspension s Set a period to make you anaerobic,
A method for culturing photosynthetic microorganisms, comprising culturing photosynthetic microorganisms.

In a method of growing photosynthetic microorganisms such as microalgae and photosynthetic bacteria, the photosynthetic microorganisms are suspended in a solution in which organic matter is dissolved.
In the daytime, in the shallow flat pond p having a large gas-liquid contact area opened to the atmosphere, the suspension s of the photosynthetic microorganisms is irradiated with sunlight,
At night, the suspension s is transferred to a deep aeration tank with a small gas-liquid contact area, the period during which air is aerated in the suspension s in the aeration tank, and the aeration is stopped and the suspension s is in an anaerobic state. While cultivating photosynthetic microorganisms,
During the daytime rainfall, the suspension s is transferred to the aeration tank, and oxygen-containing gas such as air is aerated on the suspension s in the aeration tank to culture photosynthetic microorganisms. A method for culturing photosynthetic microorganisms, characterized in that the photosynthetic microorganisms are cultured after being discharged out of p.

The method for cultivating photosynthetic microorganisms according to claim 1 or 2, wherein the aeration tank is an aeration tank a having a pipe for deaeration and an on-off valve, the upper part of which is sealed with a partition wall.

The method for culturing photosynthetic microorganisms according to claim 1 or 2, wherein the aeration tank is an aeration tank b with a floating lid provided with a floating body that covers a liquid surface.