一般に屋外で太陽光を利用した光合成微生物の培養方式には、微細藻類の培養において見られるように、(1)浅い平面池で攪拌しながら培養するオープンポンド方式、(2)ループ状に設置された直径20cm程度の透明チューブ内を循環させながら培養するチュ−ブラ方式(3)直径およそ1m程度、水深およそ2mの上部開放透明水槽内で攪拌しながら培養する立設透明水槽方式等がある。
立設透明水槽方式は、チュ−ブラ方式と同様にオープンポンド方式に比べて設置面積あたりの受光面積が大きいので、設置面積当たりの収穫量が大きいという利点があるが、受光面に藻類や他の微生物や埃が付着するため、定期的にそれらを除去する必要があるという欠点がある。上部開放の透明水槽方式はチューブラ方式に比べてこの付着物除去が簡単にできる利点がある。また、チューブラ方式では水分の蒸発がほとんどないので、低緯度地域での培養では、過熱による藻類の死滅を防ぐため冷却設備が必要となる欠点があるが、立設透明水槽方式は、上部が開放されているので水分の蒸発があり、かつ受光面積に対する懸濁液量の割合を大きくとれ、冷却設備が必要ないという利点がある。
しかし、径を大きくすると、立設透明水槽方式は受光面積に対する懸濁液量の割合が大きくなるので、高濃度の懸濁液が得にくいという欠点もある。
また、立設透明水槽方式では、他の屋外培養方式と同様に、光合成微生物を捕食するミジンコ,ワムシ等微小動物の侵入とその繁殖を防ぐことが困難であり、これら捕食生物によって藻類が全滅することがあるという問題点もある。そこで、本発明者は、特許第3844365号(微細藻類培養装置)を考案し、オープンポンド方式における捕食生物発生の問題点を解決した。しかし、家畜の尿廃水を微細藻類で浄化処理する場合、前述のように設置面積あたりの増殖量が少ないため、広い敷地が必要となり、これが施設導入の障害となり、更に、掘削等現場施工が主体となり、地盤状態や気象状態により、施工期間や、ひいては施工費が読みきれないという問題点が残されている。
特許第3844365号公報 In general, the photosynthetic microorganism culture method using sunlight outdoors is, as seen in the culture of microalgae, (1) an open pond method in which the culture is performed with stirring in a shallow flat pond, and (2) a loop-like culture. Tubular system for culturing while circulating in a transparent tube having a diameter of about 20 cm (3) There is a standing transparent water tank system for culturing while stirring in an open top transparent water tank having a diameter of about 1 m and a water depth of about 2 m.
The standing transparent aquarium method has the advantage of a large yield per installation area compared to the open pound method, as with the Tubular method. Because of the adhesion of microorganisms and dust, there is a drawback that they need to be removed regularly. The transparent tank system with an open top has the advantage that it is easier to remove the deposits than the tubular system. In addition, since there is almost no water evaporation in the tubular method, there is a disadvantage that a cooling facility is required to prevent algae death due to overheating when culturing in low latitude areas, but the standing transparent water tank method is open at the top Therefore, there is an advantage that moisture is evaporated and the ratio of the suspension amount to the light receiving area can be increased, and no cooling equipment is required.
However, when the diameter is increased, the ratio of the suspension amount to the light receiving area increases in the standing transparent water tank method, so that it is difficult to obtain a highly concentrated suspension.
In addition, in the standing transparent aquarium system, it is difficult to prevent the invasion and breeding of small animals such as daphnia and rotifers that prey on photosynthetic microorganisms, as in other outdoor culture methods, and the algae are annihilated by these predatory organisms. There is also a problem that there are things. Therefore, the present inventor has devised Japanese Patent No. 3844365 (microalgae culture apparatus) and solved the problem of predatory organism generation in the open pound system. However, when purifying urine wastewater from livestock with microalgae, as mentioned above, the amount of growth per installation area is small, so a large site is necessary, which becomes an obstacle to the introduction of facilities and is mainly used for on-site construction such as excavation. Thus, there remains a problem that the construction period and the construction cost cannot be read due to the ground condition and the weather condition.
Japanese Patent No. 3844365
以下、図面を参照しつつ本発明の一実施形態について詳細に説明する。図1及び図2は本発明の装置の一実施例を示す図面であり、図1は平面図、図2はA−A縦断面図である。本装置は、光透過材質で形成された円筒形の透明水槽1内に気体溜り2が設けられている。気体溜り2は上壁面3がほぼ水平で、側面は透明水槽1の側面に並行に下方にのび、側面の下端が透明水槽1の底面のやや上方に位置して設けられている。上壁面3のほぼ中央に上壁面3を貫通して、上壁面3上部と気体溜り2内下方を連絡する管4が設けられている。管4の下端は気体溜り2側面の下端よりもやや上方に位置させてある。
気体溜り2の上部には、気体溜り2内に空気等気体を圧入するための管5、気体溜り2内の気体を排気するための管20を開口させてある。管5は開閉弁6を介してブロワー7に連絡してある。また、管20は開閉弁8を介して大気に連絡してある。これにより通排気機構を構成してある。透明水槽1の側面には、気体溜り2の上壁面3のやや下方の位置に微細藻類懸濁液(以後懸濁液と記す。)を排出させるための排水口として、管9を設けてある。懸濁液は管9及び開閉弁10を介して貯留槽等(図示せず)に排出される。栄養液は開閉弁12を開け管11を介して栄養液槽(図示せず)から送られる。
次に本装置の運転方法について述べる。
夜間、懸濁液を気体溜り2の上壁面3のレベルまで収納する。この場合、開閉弁6、開閉弁8、開閉弁10及び開閉弁12は閉じておく(図3)。
朝には、開閉弁6を開け、ブロワー7を作動させる。空気を気体溜り2内に圧入すると、懸濁液は気体溜り2から押し出され、透明水槽1内水面が上昇する。空気の圧入を続けると気体溜り2内の水面は徐々に下降し、管4の下端に達し、さらに水面は水の表面張力により管4の下端よりやや下方まで下降し、やがて空気は管4の下端から管4内に一気に溢れ、管4内に空気層gを形成する。この空気層gが一気に上昇することにより、透明水槽1内に矢印の方向の旋回流が生じる。空気は透明水槽1内の水面から大気中へ逃げる。図2はこの時の様子を示している。空気の圧入の継続により、前記の噴出が一定の周期で間欠的に繰り返される。前述のように、この噴出により、透明水槽1内には循環流が形成され、懸濁液が撹拌される。このように撹拌された状態で懸濁液は光の照射を受け、液中の微細藻類は光を吸収し増殖する。
日の入りになれば、ブロワー7を止め、開閉弁6を閉め、開閉弁8を開け、気体溜り2内の空気を排出する。これに伴い透明水槽1内の懸濁液は気体溜り2内に移行する。この移行が終了したら、水または培養液を上壁面3のレベルまで投入し、開閉弁8を閉めておく(図3)。この様にして、気体溜り2内に格納された懸濁液は外気からの空気の供給がほとんどなく各微生物の呼吸による酸素消費により次第に嫌気状態となり、ワムシやミジンコなど光合成微生物を捕食する微小動物の生存や増殖が制限される。
懸濁液を収穫する場合は、開閉弁8および開閉弁10を開け、管9により上方の懸濁液を排出する。その後開閉弁10を閉め水または培養液を上壁面3のレベルまで投入し、開閉弁8を閉めておく。上記の操作を毎日繰り返しながら培養を続けると、ワムシやミジンコなど微小動物による微細藻類の捕食が制限され、微細藻類の培養を安定的かつ効率的に行なえる。また、昼間懸濁液は大気と接触するので、水蒸発が生じ、懸濁液は冷却されるので、高温期の過熱による微細藻類の死滅を防ぎ、微細藻類を健全に増殖させる事が出来る。
次に本発明の実施形態を更に詳しく示す。本発明の図1乃至図3に示した装置において、透明水槽1の直径0.87m、高さ1.8m、気体溜り2の直径0.79m、高さ0.95m、とすると、図3の状態で水深およそ0.95m、捜査容量がおよそ0.56m3となる。図2の状態で、水深およそ1.7mとなる。設置面積は0.87m×0.87m=0.76m2、受光面積は側面と水面合わせて5.2m2となる。これらから、設置面積に対する受光面積の割合は6.84、操作容量に対する受光面積の割合は9.29となる。
表1に本発明の立設透明水槽と及び平面池との比較を示した。
設置面積に対する受光面積の割合は、単位設置面積当たりの増殖量に相当し、操作容量に対する受光面積の割合は、懸濁液の濃度に相当する。本発明の設置面積に対する受光面積の割合は、平面池のおよそ7倍である。本発明の操作容量に対する受光面積の割合は、平面池及び従来の立設透明水槽のおよそ1.8倍である。この様に、本発明によれば、単位面積当たりの収穫量が多く、得られる懸濁液の濃度がより高くなる。これは敷地面積の節約と懸濁液濃縮等の費用節約につながる。
管4を介した噴出に関して、噴出は気体圧入速度に関係なく、1回の噴出規模はほぼ一定であり、1回の噴出よる攪拌効果は一定である。このため気体圧入速度を小さく設定しても効果的な攪拌をすることが可能で、電力費の低下につながる。 さらに、管4の口径を一定とすると、気体溜り2の横断面積が大きいほど、また管4下端から水面までの距離が大きいほど、管4内に流入する空気の量が多く、その結果管4内に形成される空気層gの容積が大きくなり、噴出が激しくなる。また、管4と気体溜り2の横断面積の比は、
1:30から1:50 程度が適当である。
図4及び図5に示した装置は、本発明の別の実施形態を示す縦断面図である。
図4が図2に、図5が図3に相当する。本態様では、管4の上端に有孔管14を設け、その内部に球状の浮遊体15を備え、透明水槽1側面と気体溜り2の側面の間にドーナツ状の浮遊体13が設けられ、浮遊体13の浮上を阻止する突起物16を備えている点が、図1乃至図3に示した実施形態と異なる。管4で噴出が起こっている状態(昼間)では、浮遊体15は、有孔管14内上部に位置し、浮遊体13は突起物16の下方に位置し、矢印の様な旋回流が生じる。気体溜り2の気体を排出した状態(夜間)では、浮遊体15は、管4水面に位置し、浮遊体13も水面に位置し、気液接触面積がより小さくなり、ワムシやミジンコなど微小動物による生存や増殖がより制限され微細藻類の培養をより安定的かつより効率的に行なえる。
図6に示した装置は、本発明の別の実施形態を示す縦断面図であり、図2に相当する。本態様では、管4内下方に散気管17を設け、管18、ブロワー19によって、気体を散気管17を介して微細気泡として通気する点が、図1乃至図3に示した実施形態と異なる。この微細気泡の通気によって、旋回流が生じ、懸濁液は攪拌される。
培養液としては、家畜尿廃水、無機合成培養液、を用い、炭酸ガスを通気する場合は、通気管5を介して炭酸ガス強化空気を通気すればよい。
微細藻類の商業的生産では、この装置を多数連結して用いる。前述の大きさの装置であれば、2人で移動することも可能である。工場でこの装置を大量生産して、現場で短期間で設置する事が出来る。
また、本発明は、微細藻類以外の光合成微生物、例えば、光合成細菌の培養にも用いる事が出来る事は言うまでもない。Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 and 2 are drawings showing an embodiment of the apparatus of the present invention. FIG. 1 is a plan view, and FIG. In this apparatus, a gas reservoir 2 is provided in a cylindrical transparent water tank 1 made of a light transmitting material. The gas reservoir 2 is provided such that the upper wall surface 3 is substantially horizontal, the side surface extends downward in parallel with the side surface of the transparent water tank 1, and the lower end of the side surface is positioned slightly above the bottom surface of the transparent water tank 1. A pipe 4 is provided in the middle of the upper wall surface 3 so as to pass through the upper wall surface 3 and communicate with the upper portion of the upper wall surface 3 and the lower part in the gas reservoir 2. The lower end of the tube 4 is positioned slightly above the lower end of the side surface of the gas reservoir 2.
In the upper part of the gas reservoir 2, a tube 5 for press-fitting a gas such as air into the gas reservoir 2 and a tube 20 for exhausting the gas in the gas reservoir 2 are opened. The pipe 5 communicates with the blower 7 via the on-off valve 6. Further, the pipe 20 communicates with the atmosphere via the on-off valve 8. In this way, a ventilation mechanism is configured. On the side surface of the transparent water tank 1, a pipe 9 is provided as a drain outlet for discharging a microalgae suspension (hereinafter referred to as suspension) at a position slightly below the upper wall surface 3 of the gas reservoir 2. . The suspension is discharged to a storage tank or the like (not shown) through the pipe 9 and the on-off valve 10. The nutrient solution is sent from a nutrient solution tank (not shown) through the open / close valve 12 and the tube 11.
Next, the operation method of this apparatus is described.
At night, the suspension is stored up to the level of the upper wall surface 3 of the gas reservoir 2. In this case, the on-off valve 6, on-off valve 8, on-off valve 10 and on-off valve 12 are closed (FIG. 3).
In the morning, the on-off valve 6 is opened and the blower 7 is operated. When air is press-fitted into the gas reservoir 2, the suspension is pushed out of the gas reservoir 2 and the water level in the transparent water tank 1 rises. If the pressure of the air continues, the water level in the gas reservoir 2 gradually descends and reaches the lower end of the pipe 4. The water level further falls below the lower end of the pipe 4 due to the surface tension of the water. The pipe 4 overflows from the lower end at once, and an air layer g is formed in the pipe 4. As the air layer g rises at once, a swirling flow in the direction of the arrow is generated in the transparent water tank 1. Air escapes from the water surface in the transparent water tank 1 to the atmosphere. FIG. 2 shows the situation at this time. Due to the continuation of the press-fitting of air, the ejection is intermittently repeated at a constant cycle. As described above, by this ejection, a circulating flow is formed in the transparent water tank 1, and the suspension is stirred. In this state of stirring, the suspension is irradiated with light, and the microalgae in the liquid absorb light and grow.
When the sunset comes, the blower 7 is stopped, the on-off valve 6 is closed, the on-off valve 8 is opened, and the air in the gas reservoir 2 is discharged. Along with this, the suspension in the transparent water tank 1 moves into the gas reservoir 2. When this transition is completed, water or culture solution is added to the level of the upper wall surface 3 and the on-off valve 8 is closed (FIG. 3). In this way, the suspension stored in the gas reservoir 2 is hardly supplied with air from the outside air, and gradually becomes anaerobic due to oxygen consumption by the respiration of each microorganism, and is a micro animal that prey on photosynthetic microorganisms such as rotifers and daphnia Survival and proliferation are limited.
When harvesting the suspension, the on-off valve 8 and the on-off valve 10 are opened, and the upper suspension is discharged by the pipe 9. Thereafter, the on-off valve 10 is closed, and water or a culture solution is added to the level of the upper wall surface 3, and the on-off valve 8 is closed. If the culture is continued while repeating the above operation every day, predation of microalgae by tiny animals such as rotifers and daphnia is restricted, and microalgae can be cultured stably and efficiently. In addition, since the daytime suspension comes into contact with the atmosphere, water evaporation occurs, and the suspension is cooled. Therefore, the microalgae can be prevented from being killed by overheating in the high temperature period, and the microalgae can be grown healthy.
Next, embodiments of the present invention will be described in more detail. In the apparatus shown in FIGS. 1 to 3 of the present invention, the diameter of the transparent water tank 1 is 0.87 m, the height is 1.8 m, the diameter of the gas reservoir 2 is 0.79 m, and the height is 0.95 m. In the state, the water depth is about 0.95 m, and the investigation capacity is about 0.56 m 3. In the state of FIG. 2, the water depth is about 1.7 m. The installation area is 0.87 m × 0.87 m = 0.76 m 2, and the light receiving area is 5.2 m 2 including the side surface and the water surface. From these, the ratio of the light receiving area to the installation area is 6.84, and the ratio of the light receiving area to the operation capacity is 9.29.
Table 1 shows a comparison between the standing transparent water tank of the present invention and the flat pond.
The ratio of the light receiving area to the installation area corresponds to the amount of growth per unit installation area, and the ratio of the light receiving area to the operation volume corresponds to the concentration of the suspension. The ratio of the light receiving area to the installation area of the present invention is approximately 7 times that of the plane pond. The ratio of the light receiving area to the operating capacity of the present invention is approximately 1.8 times that of the flat pond and the conventional standing transparent water tank. Thus, according to the present invention, the yield per unit area is large, and the concentration of the resulting suspension is higher. This leads to cost savings such as site area saving and suspension concentration.
Regarding the ejection through the tube 4, the ejection size is almost constant regardless of the gas injection speed, and the stirring effect by one ejection is constant. For this reason, even if the gas injection speed is set to a small value, effective stirring can be performed, which leads to a reduction in power cost. Furthermore, if the diameter of the tube 4 is constant, the greater the cross-sectional area of the gas reservoir 2 and the greater the distance from the lower end of the tube 4 to the water surface, the greater the amount of air that flows into the tube 4, resulting in the tube 4 The volume of the air layer g formed inside becomes large, and the ejection becomes intense. The ratio of the cross-sectional area of the tube 4 and the gas reservoir 2 is
About 1:30 to 1:50 is appropriate.
The apparatus shown in FIGS. 4 and 5 is a longitudinal sectional view showing another embodiment of the present invention.
4 corresponds to FIG. 2, and FIG. 5 corresponds to FIG. In this embodiment, a perforated tube 14 is provided at the upper end of the tube 4, a spherical floating body 15 is provided therein, and a donut-shaped floating body 13 is provided between the side surface of the transparent water tank 1 and the side surface of the gas reservoir 2, The point which is provided with the protrusion 16 which prevents the floating body 13 from rising is different from the embodiment shown in FIGS. In a state where the pipe 4 is ejected (daytime), the floating body 15 is located in the upper part of the perforated pipe 14, and the floating body 13 is located below the protrusion 16, and a swirling flow as indicated by an arrow is generated. . In a state where the gas in the gas reservoir 2 is discharged (nighttime), the floating body 15 is located on the water surface of the tube 4 and the floating body 13 is also located on the water surface, the gas-liquid contact area becomes smaller, and tiny animals such as rotifers and daphnids Survival and growth by this are more restricted, and microalgae can be cultured more stably and efficiently.
The apparatus shown in FIG. 6 is a longitudinal sectional view showing another embodiment of the present invention, and corresponds to FIG. In this embodiment, a diffuser pipe 17 is provided in the lower part of the pipe 4, and the point where air is passed as fine bubbles through the diffuser pipe 17 by the pipe 18 and the blower 19 is different from the embodiment shown in FIGS. 1 to 3. . A swirling flow is generated by the ventilation of the fine bubbles, and the suspension is stirred.
As the culture solution, livestock urine wastewater or inorganic synthetic culture solution is used. When carbon dioxide gas is ventilated, carbon dioxide-enriched air may be ventilated through the vent pipe 5.
In commercial production of microalgae, a large number of these devices are connected and used. If it is the apparatus of the above-mentioned size, it is also possible for two people to move. This device can be mass-produced at the factory and installed in the field in a short time.
Moreover, it cannot be overemphasized that this invention can be used also for culture | cultivation of photosynthetic microorganisms other than a micro algae, for example, photosynthetic bacteria.
1は透明水槽、2は気体溜り、3は上壁面、4は管、5は管、6は開閉弁、7はブロワー、8は開閉弁、9は管、10は開閉弁、11は管、12は開閉弁、13は浮遊体、14は有孔管、15は浮遊体、16は突起物、17は散気管、18は管、19はブロワー、20は管、gは空気層、実線矢印は微細藻類懸濁液の流れの方向を示す。1 is a transparent water tank, 2 is a gas reservoir, 3 is an upper wall surface, 4 is a pipe, 5 is a pipe, 6 is an open / close valve, 7 is a blower, 8 is an open / close valve, 9 is a pipe, 10 is an open / close valve, 11 is a pipe, 12 is an on-off valve, 13 is a floating body, 14 is a perforated tube, 15 is a floating body, 16 is a projection, 17 is a diffuser tube, 18 is a tube, 19 is a blower, 20 is a tube, g is an air layer, solid arrows Indicates the direction of flow of the microalgae suspension.