Hiroyo Matsumoto

CO2 removal by hollow-fiber gas-liquid contactor

We have conducted a series of basic experiments for CO2 removal from the flue gas of thermal power plants by use of hollow-fiber gas-liquid contactors. It was confirmed that the stability of PTFE membrane having a high degree of hydrohobicity is more than 6,600 hours and that by improving the degree of hydrophobicity on the surface of the membrane, the durability and performance of the membrane can be improved. Furthermore, we have confirmed that flow characteristics of fluid in hollow-fiber can be estimated based on Hagen-Poiseuille law. The overall volumetric mass transfer coefficient Ka(=K×a) of the hollow-fiber gas-liquid contactor is more than 5 times larger than that of a conventional packed bed, which suggests that adoption of the present method has the advantage of making the absorber more compact.

Stably sustained hydrogen production by biophotolysis in natural day/night cycle

Our photobiological hydrogen production system was successfully scaled up to a pilot plant scale in the photosynthetic starch accumulation and the fermentative production of organic compounds from starch by Chlamydomonas MGA 161 and the hydrogen photoproduction by Rhodovulum sulfidophilum W-1S from organic compounds produced by Chlamydomonas MGA 161 in the natural day/night cycle. The conversion yield of organic compounds from starch of Chlamydomonas MGA 161 was 80 to 100 % of the theoretical yield, but the molar yield of hydrogen photoproduction of Rv. sulfidophilum W-1S was approximately 40 %. One main cause for the low hydrogen yield of Rv. sulfidophilum W-1S was a competition between the accumulation of intracellular Poly (3-hydroxybutyric acid), PHB, and the hydrogen production under light anaerobic conditions. The PHB accumulation was repressed and the hydrogen photoproduction was promoted by enhancing the nitrogenase activity of Rv. sulfidophilum W-1S.

Excretion of glycerol by the marine Chlamydomonas sp. strain W-80 in high CO2 cultures☆

Abstract A Chlamydomonas sp. strain, which excretes glycerol as the major carbon compound, was isolated and designated as strain W-80. The glycerol production was much enhanced by a high concentration of CO2, and the final concentration of the product was measured at levels up to 24.9 mM (2.29 g/l).

Fundamental Study on CO 2 Removal from the Flue Gas of Thermal Power Plant by Hollow-fiber Gas-Liquid Contactor

ABSTRACT Microporous membranes are suitable for the CO2-MEA (monoethanolamine) system because the overall mass transfer coefficient K of the membrane is approximately 10 times larger than that of composite membranes consisting of microporous membranes and homogeneous membranes. The overall volumetric mass transfer coefficient K• a of the hollow-fiber contactor is more than 5 times larger than that of a conventional packed bed, which suggests that adorption using the present method has the advantage of making the absorber more compact.

Enhancement of starch degradation by CO2 in a marine green alga, Chlamydomonas sp. MGA161

Abstract Algal starch photosynthetically accumulated in Chlamydomonas sp. MGA161 was metabolized to low-molecular-weight compounds—H 2 , ethanol, glycerol, and acetate—under an O 2 -free CO 2 atmosphere. When cells in the logarithmic growth phase was fermented under CO 2 -anaerobic conditions, starch degradation in the alga was enhanced to 1.4-fold that in N 2 -anaerobic fermentation. Due to the inhibition of hydrogenase under CO 2 , H 2 and acetate decreased, while ethanol and glycerol increased, when the atmosphere was changed from N 2 to CO 2 . Addition of CO, an inhibitor of hydrogenase, also stimulated starch degradation and changed the excretion pattern of the fermentation products.

Fundamental Study of Small Closed Life Support System Utilizing an Artifical Gill.

宇宙開発において重要な技術である閉鎖系生命維持システム (CELSS) の基礎実験として, 鯉-人工えら-クロレラ系よりなる小CELSS実験を行った.その結果, 魚類飼育槽の水処理法として不織布-活性炭-ゼオライトよりなる3層の濾過・吸着法が有効であることを確認した.人工えらの総活物質移動係数の算出は純水系で得られた前報の方法が実液でも使用でき, また疎水性多孔質膜よりなる人工えらは長期間の耐久性を有することを確認した.鯉-クロレラ系よりなる閉鎖系では, 鯉の呼吸商RQとクロレラの同化商の比RQ/AQが1より大きいため, 系内のO2濃度は連続的に上昇した.これ等の溶存ガスの挙動は、魚類飼育槽-人工えら-藻類培養槽よりなる定量化モデルにより表されることがわかった.