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Yoshikazu Noguchi, Yoshiyuki Tazaki, Masaki Iijima, Kazuitsu Ito, Yuji ...
1993 Volume 19 Issue 5 Pages
705-713
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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As huge volumes of CO
2 exist underground in the form of various substances, the underground storage of CO
2 probably involves fewer environmantal effects on surrounding areas than those remaining as a serious challenge for ocean storage.
This report summarizes a study of technology for the underground storage of CO
2 that can be dissolved in water so as to be treated in large volumes. The report gives findings on how much CO
2 can be stored and how much it will cost when dissolved in the water of aquifers that are not in use now. As a result, the calculation of possible quantities of CO to be stored world wide worked out at 320 billion tons. In addition, the treatment cost to be worked out at 3, 000 yen/ton-CO
2 and an energy loss to be taken as 73kWh/ton-CO
2 of electricity. These are all considerd to be technically and economically feasible costs. More investigations are necessary for assesment of the effect of CO
2 injection on groundwater environment.
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Kenji Haraya, Masaru Nakaiwa, Naotsugu Itoh, Chiyoshi Kamisawa
1993 Volume 19 Issue 5 Pages
714-721
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The application of membrane separation in CO
2 removal from flue gases was investigated by computation with three types of operation modes, i.e., conventional single-stage permeator (SSP), continuous membrane columun (CMC) and simple twostage cascade (TSC).
To recover 60% of CO
2 with 90% in purity, membrane selectivity of 210 was necessary for SSP, 70 for CMC with a recycle ratio (
RR) of 2, 44 for CMC (
RR=3) and 24 for TSC, respectively. TSC mode consumed the largest power, equivalent to 15.6% of the power generated from petroleum, whereas SSP mode consumed 36%, that of TSC. Total energy consumption combined with liquefaction was estimated as 28.0 for TSC, 26.9for CMC (
RR=3), 22.9 for CMC (
RR=2), and 14.9 kWh·kmol
-1-CO
2 recovered forSSP, respectively. The three types of membrane separation modes combined with liquefaction have an economical advantage in operation energy compared to the combined process of chemical absorption and liquefaction.
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Izumi Tsuboi, Takuji Hashimoto, Eiichi Kunugita, Isao Komasawa
1993 Volume 19 Issue 5 Pages
722-728
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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A process was developed for recovery and purification of nickel, vanadium and molybdenum from spent desulfurizing catalyst. Nickel was could not be recovered by the conventional process. Nickel as well as molybdenum and vanadium weredissolved by roasting at a relatively low temperature, 360°C, and then by leaching with ammonium carbonate solution at 80°C. Solutions containing nickel, molybdenumand vanadium as main components were obtained, leaving iron and aluminium in the solid residue. The degree of dissolution of nickel, molybdenum and vanadium were 54, 77 and 65%, respectively. By cooling and storing the leach liquor at room temperature, 75% of the vanadium in the liquor was precipitated as ammonium vanadate and was recovered by filtration. The purity of the precipitate was 96%. Solvent extraction using a single extractant, an alkylmonothiophosphoric acid, was used for the successive isolation of the three metals from the filtrate liquor, by employing a suitable pH value for each metal. 74% of nickel, 58% of molybdenum and 91% of vanadium in the filtrate were recovered by single extraction, with respective purities of 99, 91 and 91%.
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Daisuke Taneda, Isamu Yasutomi, Setsuo Shibata, Tsutomu Toida
1993 Volume 19 Issue 5 Pages
729-735
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Computer simulation results obtained for the 2-propanol/acetone/hydrogen chemical heat punp system proved the relationship between operating conditions and performance.
Actual experiments were subsequently conducted to investigate the performance of the basic technologies under consideration. The results of the computer simulation were compared with the results obtained experimentally, with the aim of resolving any problems anticipated to occur in the practical application of the heat pump.
It was found that enthalpy efficiency was affected by the activity of the dehydrogenation catalyst and that the coefficient of performance was affected by the pressure drop of the hydrogenation reactor.
In the case of increasing the temperature from 353K to 423K, an estimate based on the activity of the catalyst employed, shows that the enthalpy efficiency is 5-10%, the exergy efficiency is 9-18 %, and the coefficient of performance reaches 50 if the pressure drop of the hydrogenation reactor is below 0.01MPa.
For practical use of the heat pump system, the development of a catalyst, improvement of the system, require further study.
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Experimental studies of pyrolytic performance and operating conditions using a conical distributor
Osamu Tomita, Sung-Keun Bae, Toshio Kajiuchi, Takashi Akehata
1993 Volume 19 Issue 5 Pages
736-744
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Pyrolytic gasification of high-density polyethylene pellets (HDPE) was carried out by a partial-combustion method in a high-temperature fluidized bed for a waste plastice recycling system. A conical distributor was installed in a fluidized bed of 57.5mm i.d and 600mm height, and operating conditions for efficient gasificasion were studied experimentally.
Better gasification performance was obtained than that in a fluidized bed with a multiorifice plate distributor. In the case of a conical distributor, a leanphase fluidized zone was developed between the dense phase fluidized zone and the freeboard in the bed, in spite of a low fluidizing gas velocity. This fluidization realized a long residense gas time and an effective bed temperature for pyrolytic gasification. In this operation, the optimum condition was
U0 /
Umf (600°C) = 1.4 and
m = 0.23, the product gas heat value and the combustible gas conversion ratio of HDPE pelletsreached 13.1MJ/Nm
3 and 82wt % at 730°C (
Tbr), respectively. Furthermore, the valuesof partial combustion ratio and thermal efficiency under these conditions were calculated to be 6. 5 wt % and 42 %.
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Akira Saji, Matsushige Sakai, Hidetomo Noda, Tadaaki Tanii, Yutaka Kaw ...
1993 Volume 19 Issue 5 Pages
745-752
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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As a step in investigating the possibility of CO
2 clathrate for the fixation of carbon dioxide in deep seas, experiments were performed at temperatures from 277 to 281K, stirring rate range from 300 to 1600 min
-1, salt concentration range from 0 to 5.7% as NaCl and pressure range from 3.5 to 9.1MPa. Furthermore, simulations for CO
2 clathrate sedimentation in deep sea were performed. The following results were obtained.
(1) The rate of CO
2 clathrate formation is proportional to the difference between the fugacity of CO
2 and the equilibrium fugacity at the experimental temperature and to the interfacial area.
(2) Large particles of CO
2 clathrates must be formed so that they should sediment to the settled deep sea bottom.
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Kunio Horiuchi, Toshinori Kojima, Atsushi Inaba, Korekazu Ueyama
1993 Volume 19 Issue 5 Pages
753-761
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Fertilization technique is one of the countermeasures using the ocean, that can be used against the global warming. Fertilazation of the oceans with nutrients, such as nitrogen and phosphate, can promote the propagation of plant biota, leading to a decrease in the surface-ocean partial pressure of CO
2, drawing down CO
2 from the atmosphere.
In the present study, we evaluate the validity of this countermeasure from the view-points of mass balance, energy balance and dynamics. First, we determined the desired amount of nutrients based on the PNC ratio in the plant biota in the ocean, and assumed several ways of fertilization. Second, we evaluated its response by a numerical box model taking the unsteady-state recirculation of the inorganic/organic carbon and nutrients, and carbon fixation by plant biota into account. The results indicated that this technique possibly can have the expected effect on the restraint of increse in atmospheric CO
2 within a few years, while its effect on the oceanic organic carbon in the surface is only doubling the present thin concenration for a hundred years' fertilization. The energy evaluation also indicated that the amount of CO
2 produced from the manufacture and transportation of both N and P fertilizers is no more than 9% of the amount that is expected to be taken up into the ocean from the atmosphere.
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Motoyuki Suzuki, Akiyoshi Sakoda, Takeshi Fujiwara, Hideo Watanabe, Ya ...
1993 Volume 19 Issue 5 Pages
762-770
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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To establish a methodology for elucidating the proper approaches to a new industrial system with less CO
2 emission based on the harmony between activities of human beings and the global system should be understood on the basis of a quantitative analysis of specific industrial technologies and their linkage in the whole industrial system. In this work, the CO
2 emission by the fossil fuel combustion was evaluated for 10 industrial categories in 8 regions in Japan. The annual production of each industry in each region given by Input-Ouput Tables was then linked with CO
2 emission, resulting in the establishment of CO
2 emission constants per unit amount of production. A model developed in this work can systematically estimate the local and overall CO
2 emission by taking into account not only the above-mentioned fossil fuel conbustion but also the limestone consumption and waste treatments. This model will be quite useful for the simulations of the new industrial system.
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Naohiro Goto, Akiyoshi Sakoda, Motoyuki Suzuki
1993 Volume 19 Issue 5 Pages
771-780
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The effect of climate change by the increase of atmospheric carbon dioxide on terrestrial ecosystems has attracted much attention. For estimating these effects quantitatively, model that expresses the global carbon cycle is needed. We constructed models a express vegetation growth and carbon cycle in soil. In this report, by using these two models, we estimated the carbon cycle between terrestrial ecosystems and the atmosphere and predicted the effects on the global carbon cycle. By this model we can predict that terrestrial ecosystems emit carbon dioxide to the atmosphere with increase of temperature.
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Unsteady-State box diffusion model
Masahiro Hosokawa, Hidetoshi Nagamoto
1993 Volume 19 Issue 5 Pages
781-788
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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A six-box diffusion model has been developed in which the transport of inorganic carbon, the carbon fixation by plant biota, and the transport of the fixed carbons are taken into consideration and the ocean is horizontally divided into an oceanic region where sea water flows upward and a polar region where water flows downward. By use of this model, the concentrations of carbons in the ocean have been calculated from the industrial revolution to the present. It has been shown that the effect of carbon fixation by plant biota on the increase in carbon dioxide uptake by the ocean is negligibly small. The increase in carbon concentration is larger in the polar region than that in the oceanic region, and the airborne fraction obtained with this model is smaller than that with a model in which only the oceanic region is taken into account. The airborne fraction decrease with increasing circulation velocity of sea water. The importance of the existence of a downflow region and the estimation of circulation velocity has been clarified.
The yearly amount of emitted carbons estimated by this model where the dissolution equilibrium of carbon dioxide is employed as a boundary condition at the surface odean has agreed well with the observed value. This boundary condition has been examined by comparing another boundary condition employed in previous models.
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Prediction of nitrogen flow from terrestrial ecosystems to the ocean by a numerical model
Hiroyuki Kawashima, M. J. Bazin, J. M. Lynch
1993 Volume 19 Issue 5 Pages
789-794
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Industrial fixation of nitrogen for fertilizer has become one half of the nitrogen fixed in the terrestrial ecosystem naturally and it will be increasing into the next century. Nitrogen supply into the oceanic ecosystem consists of fixation in the ocean and flux from the terrestrial ecosystem. The nitrogen concentration in the ocean will increase due to the increase in flux from the terrestrial ecosystem.
The nitrogen flow rate from the terrestrial ecosystem to the ocean due to the increasing use of fertilizer was investigated. The use of fertilizer changes the nitrogen flow in the terrestrial ecosystem. The nitrogen flow rate from the terrestrial ecosystem to the ocean into the next century was predicted by using a numerical model.
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Tetsuji Chohji, Chie Nakagawa, Eiji Hirai
1993 Volume 19 Issue 5 Pages
795-802
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The phenomena of environmental acidification by acidic precipitation is a global environmental problem. In this study, in order to assess the effect of acidic precipitation on water quality in rivers and lakes, a new method for estimating the neutralization mechanisms of acidic precipitation with soil is proposed. The method was based on the chemical equilibrium analysis of the relationship between the metal ions released from soil and the pH value in the aqueous phase. The mechanisms of neutralization by soil are generally listed as ; calcium carbonate buffer, cation exchange buffer, aluminum buffer, and anion exchange buffer. However, it is recognized that cation exchange reaction and dissolution of aluminum from the soil are the principal contributors to neutralization of acid precipitation with soil. Many cations take part in neutralization reaction. To represent the multiple components in a lump, a new function is proposed. It is estimated from the pH value of an acid solution before and after equilibration with soils. To estimate the neutralization reaction, a relationship between pH and concentrations of metal ions released from soil and of metal ions derived from neutral soils was proposed. Four samples of soil were used for equilibration experiments between the acid solutions and the soil materials. The results of the analyses revealed that the carbon dioxide in gaseous phase and cations derived from neutral soils contribute strongly to the neutralization of the acidified precipitation during contact with the soil materials.
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Yoshitaka Sudo, Takuji Yamamoto, Motoyuki Suzuki
1993 Volume 19 Issue 5 Pages
803-808
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Recently, it often happens that some of the public waterways are contaminated by agiricultural chemicals eluted from golf links, etc. Removal of these agricultural chemicals is needed. Activated carbon adsorption is considered as one of the solutions to this problem.
The present work is aimed at determining adsorption isotherms and rates of four agriculture chemicals on activated carbon at various temperatures.
The isotherms were correlated with a Freundich-type equation in the investigated concentration ranges. Surface diffusion was considered to be dominant, and the coefficients varied with amount adsorbed.
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Atsushi Inaba, Tetsu Shimatani, Soichi Tabata, Shin-ich Kawamura, Hisa ...
1993 Volume 19 Issue 5 Pages
809-817
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The energy balance of large-scale photovoltaic power systems was evaluated for both polycrystal silicon cells and amorphous silicon cells. The evaluated scale of their production were 10MW/y, 1 GW/y. The energy payback time of 10 MW/y was 5.7 years for the polycrystal silicon cells and 6.3 years for the amorphous sillicon cells, which included construction energy for the power plant but excluded energy for storage. This estimation includes the introduction of current developing technologies and efficency improvement of PV cell production processes. Further reduction in energy payback time due to the progress of technology development and the effect of scale-up was expected for the production scale of 100 GW/y. These payback times were 3.2 years for the polycrystal silicon cells and 3.0 years for the amorphous silicon cells.
Energy input for construction of the power station was relatively large in comparison with that for the production of PV cells. This suggested that the establishment of a more moderate system is essential for large-scale production of PV cells.
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Hiroshi Komiyama, Tadashi Fujitani
1993 Volume 19 Issue 5 Pages
818-828
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Separation of CO
2 from the stack gas of plants that burn fossil fuels, followed by sequesterring it in ocean deeps or depleted oil fields is an important means for mitigating CO
2 emission into the atmosphere. This paper presents 1) a discussion of the minimum energy requirement of CO
2 separation integrated with power plants, and 2) a comparison of separation processes based on various principles, including absorption, adsorption, distillation, and crystallization, from the viewpoint of energy consumption. As the first step of the comparison, conventional processes were designed to examiae the substantial energy consumption structure and to determined energysaving policies via these processes.
Next, attempts to compare the different separation processes were made by designing optimum processes which adopted all the energy-saving policies that were considered to be practical in the near future. The most energy-saving type of process consumes energy as little as 2.6 times the thermodynamic minimum energy requirement. Ideally, none-energy consuming separation of CO
2 from power plant stack gas is possible.
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Hideo Kameyama, David L. Block, James E. Funk
1993 Volume 19 Issue 5 Pages
829-834
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The decomposition of sulfur trioxide is an important endothermic reaction in many thermochemical processes for the production of hydrogen from water. A solar central-cavity receiver enclosing a tubular catalytic reactor is a potential heat source for this reaction. This paper presents an analysis of the thermal performance of the reactor in the steady state and in response to changes in energy input to the receiver and flow of sulfur trioxide. The mathematical model includes heat transfer from the cavity and the packed-bed tubular reactor coupled to heat transfer and reaction kinetics in the axial and radial directions in the packed bed. The results of the mathematical analysis are compared with experimental data obtained by GA Technologies from a simulated solar central receiver. The transient data are cast in the form of the time constants for the response to radiation temperature (receiver energy input) and sulfur trioxide flow rate. A comparison of the predicted and measured time constants is presented and implications for the control of the thermochemical solar reactor are discussed.
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Katsuyuki Nakano, Tetsunori Ogawa
1993 Volume 19 Issue 5 Pages
835-839
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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To develop an ethanol emission converter, Pt-TiO
2/SiO
2 was examined for the catalytic activity of ethanol combustion where TiO
2/SiO
2 was prepared by so-called sol-gel method using titanium tetraisopropoxide. The experimental results show that the reaction rate of ethanol combustion over the catalysts was proportional to the ethanol concentration in the range between 3000 and 5000 ppm at temperatures of 443 to 523K. From the Arrhenius plots of the rate constants, the apparent activation energy of this reaction was found to be about 70 kJ/mol in the reaction control region. On bead catalysts of 3mm dia. the reaction process was controlled by pore diffusion, and the apparent activation energy was about 33 to 35 kJ/mol. A SMSI state affected the reaction rate, increasing the activity of the catalysts reduced at the temperature of about 873K compared with the catalysts reduced at lower temperatures. The TiO
2/ SiO
2 supports were superior to silica or alumina supports because of their ease of eutering the SMSI state.
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Yoshio Kobayashi
1993 Volume 19 Issue 5 Pages
840-848
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Reaction-rate equations and acid gas concentration exponent
m1 were derived theoretically by applying the shell mode to the lime aerosol-SOx/HC
l reaction system. The following results were found by applying experimental data to the theoretical equation.
(1) For the changes of stoichiometric ratio, acid gas concentration and reaction time, the theoretical rate equation of product layer diffusion control is in good agreement with experimental data.
(2) Judging from theoretical analysis of acid gas concentration, the controlling step of both SOx and HC
l removal reactions by lime aerosol is the diffusion process in the product layer.
This mechanism of product-layer diffusion control has been empirically allumed up to now. The validity of the theoretical equations was verified by agreement with above 2 points.
Furthermore, according to theoretical analysis of the particle radius exponent
m2, the
m2 value should be 0.850.97 under the normal SOx removal condition, but an
m2 value of about 0.35 or less is observed in many experiments. And it has been suggested that the dependence of particle size for lime conversion is small. This gap between theory and experiment is due to aggregation of fine particles in the lime aerosol, it is thought.
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Kyu Murata, Kyoko Yamamoto, Hideo Kameyama
1993 Volume 19 Issue 5 Pages
849-855
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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A chemical heat pump with a reaction couple of cyclohexane dehydrogenation and benzene hydrogenation was proposed to utilize waste thermal energy. In this system, a wall-type reactor with high thermal conductivity is needed to transform thermal energy efficiently into chemical energy. A thin-layer catalyst supported on a metal has high thermal conductivity and well suits the wall-type reactor.
In this study, we determined a rate equation of dehydrogenation of cyclohexane. The reaction rate was found to be controlled by the adsorption rate of cyclohexane molecules on the catalyst surface. Then, conversion and temperature distributions of a tube-wall reactor and of a fixed-bed reactor were calculated.
The calculated results showed that the temperature and conversion differences between those at the center and at the wall of the reactor, and the pressure drop of the tube-wall reactor were less than those in the fixed-bed reactor. It was shown that a compact endothermic reactor can be designed by reducing the diameter of the reactor from 10 mm to 20 mm and by increasing the thickness of the catalytic layer from 300 μm in the tube-wall reactor.
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Hiroyasu Nagase, Tetsuo Hirono, Yasuaki Okamoto, Toshinobu Imanaka
1993 Volume 19 Issue 5 Pages
856-862
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Tin oxide thin films were deposited by a microwave plasma CVD method using tetramethyltin mixed in oxygen and argon. Gas responses of the film were examined by measuring the change in film resistance. The resistance increased when the film was exposed to air containing NO
2. A reversible response was observed above 250°C.The optimal response was obtained at around 300 °C. The resistance at 20 ppm NO
2 was about 10 times as large as that in air at 300 °C and the response time was about 60s. The sensitivity to NO was one-fifth of that to NO
2. The film shows very low sensitivities to hydrogen, carbon monoxide and hydrocarbons. It was demonstrated that the tin oxide film shows a high sensitivity and selectivity to NO
2 which suggests possible use as a NO
2 sensor in exhaust gases.
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Yasuaki Okamoto, Yoshiharu Ohto, Toshinobu Imanaka
1993 Volume 19 Issue 5 Pages
863-869
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Novel supported metal oxide catalysts were used for NO-CO reaction and their catalytic properties were studied. It was found that 3-5 wt% Fe/ZrO
2 shows a higher activity for the reaction, no decay in activity at 250-350 °C, and high resistance against thermal treatment. The turnover frequency of iron atom for the reaction showed a maximum at a 1 wt% Fe loading. 1 wt% Cu/ZrO
2 catalyst showed a high activitiy for the NO reduction at 150-200°C and a high selectivity to N
2 production. Deactivation of active copper species, however, was observed during the reaction. Compared with the catalytic behavior of CO oxidation over these catalysts, it is estimated that the NO-CO reaction over the Fe and Cu/ZrO
2 catalysts proceeds via redox mechanisms. It was found that at a low temperature 2wt%Fe-0.5wt% Cu/ZrO
2 composite catalyst shows a considerably higher activity for the reduction of NO to N
2 than the sum of the activities of the corresponding Fe/ZrO
2 and Cu/ZrO
2 catalysts. The composite catalyst was also found to show a high selectivity to N
2 and high stability toward activity decay.
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Hidehiro Iizuka, Shinichi Ichikawa, Eiji Ando, Ryoetsu Hase
1993 Volume 19 Issue 5 Pages
870-877
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Catalytic hydrogenation of carbon dioxide was studied as one of the possible ways to convert CO
2 to useful chemicals. Rhodium supported on alumina showed high conversion (over 80% at 300°C) and selectivity (over 90% to methane) in a wide range of space velocity and other conditions. Field-emission transmission electron microscopy analysis indicated that the Rh particles are very small with preferential exposure of contracted (111) crystal plane. The high activity of Rh particles are also due to characteristic bond states of H and CO as indicated by thermal desorption measurements. Methanation of CO
2 on Rh seems to proceed through CO produced by the reverse water-gas shift reaction. Usefulness of methane and energy efficiency are also discussed.
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Yasushi Inomata, Takayuki Nakatsukasa, Kenji Umeda, Sumitoshi Ogata
1993 Volume 19 Issue 5 Pages
878-884
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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A new classification technique for satellite remote-sensing data which consist of multispectral images has been developed from the viewpoint of memory saving and intensive reduction of image processing time. In the new method, adjacent pixels from some tens to some hundreds are merged to make a cell, and classification is made on the basis of the cell. All the cells are classified simply at a time by comparing the degree of the histograms of two cells. The present method was applied to the investigation of turbidity distributions in the Kanmon area and the Bungo Sea. It is shown that the present method is quite efficient for practical use on personal computer, and that the turbidity of the water of the Suo Sea is higher than that of the Hibiki Sea. The strong effect of the surface waves on the sea features of the Bungo Sea was also demonstrated by the present method.
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Miki Fukuma, Kentaro Takesada, Akira Yasunishi
1993 Volume 19 Issue 5 Pages
885-892
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The continuous two-phase anaerobic treatment of highly concentrated waste-water containing insoluble cellulose powder together with easily digestible substances such as starch and glucose was studied. Three kinds of acidogenic-phase reactors, i.e. packed bed, empty tube and stirred tank types, and four kinds of methanogenicphase fermenters, i.e. tank and three kinds of packed beds, were used.
In all acidogenic-phase reactors, even though the easily digestible substrates were contained in wastewater at high concentration, the digestibility of cellulose was promoted by symbiosis of methanogens. The methanogenic activity was enhanced in the presence of cell-growth substances such as polypeptone. The highest gas yield was obtained at about a 10 C/N ratio.
The gas yield in every methanogenic-phase fermenter was a minority of the two-phase (total system) COD balance. That is the performance of the two-phase anaerobic treatment of waste cellulose was largely determined by that of the acidogenic phase.
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Minoru Seki, Kunihiko Shigematsu, Kentaro Shigeta, Shintaro Furusaki
1993 Volume 19 Issue 5 Pages
893-900
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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Growth and carbon fixation rates of a typical calcareous alga
Cricosphaera carterae, which plays an important role in the global carbon cycle, were investigated. Nutrient uptake rates of the cells. in light were higher than those in the dark. Dependence of nitrate concentration on specific growth rate was determined and formulated using a semi-continuous culture system. The specific growth rate was 0.53d
-1 at 15mg/m
3 of nitrogen concentration in the medium. This nitrogen concentration is the average value at the ocean surface. The maxmum growth rate was 0.9d
-1. The ratio of inorganic carbon fixed to organic carbon fixed was about 0.1. CO
2 enriched air (715 ppm) was used for the microalgae cultivation. The growth rate and the amount of inorganic carbon fixed by a cell were little affected by CO
2 enrichment. A similar result was obtained for the cells after the acclimation culture where the CO
2 concentration was gradually increased during six weeks. Using these results, the amount of total carbon fixation by the calcareous algae in the ocean was estimated for the global carbon balance.
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Motohiko Hikuma, Hiroshi Matsuoka, Minoru Takeda, Yasuhiko Tonooka
1993 Volume 19 Issue 5 Pages
901-907
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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A microbial electrode for measuring ammonia concentration was assembled with immobilized nitrifying bacteria and an oxygen probe. A microbial electrode for estimating BOD (Biochemical oxygen demand) was similarly constructed, except that it used the yeast
Trichosporon cutaneum. A flow system was employed for the automatic measurement of samples every 30 min. Wastewater used for the experiment was obtained from a fermentation factory. It was diluted to 0.42-0.48 kg·m
-3 of ammonia nitrogen and 1.7-3.0 kg·m
-3 of BOD to adjust the ammonia and BOD loadings by using the microbial electrodes. On-line measurement of ammonia concentrations in the denitrification and the nitrification vessels (liquid volume 0.07 and 0.17 m
3, respectively) was carried out to observe the performance of the process. The average removals of ammonia nitrogen and total Kjeldahl nitrogen were 96 % and 89 %, respectively during experimental runs for a period of two weeks.
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Eiichi Kojima
1993 Volume 19 Issue 5 Pages
908-913
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The effects of inorganic salts used in addition to an oxygen absorber, sodium hydrosulfite, were studied during the photoevolution of hydrogen by
Chlorella.
When sodium sulfite was applied in addition to Na
2S
2O
4, the amount of H
2 doubled as compared to the case without Na
2SO
3 because Na
2S
2O
4 is more stable in higher pH and lasts longer. In the case of sodium pyrophosphate, the duration of hydrogen photoevolution and the amount of hydrogen increased, six to eight times and approximately 5 times, respectively. The pyrophosphate raised the pH of the algal suspension and served to prevent the decomposition of Na
2S
2O
4. The pyrophosphate could also serve to preserve the photosystems and electron transfer components, and/ or increase the flow of electrons to the hydrogen passway by inhibiting ferredoxin-NADP
+ reductase, which were tested by measurement of fluorescence induction curves of the algal suspension.
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Characteristics of carbon dioxide solubility in water
Masaki Iijima, Kazuitsu Ito, Hirotoshi Horizoe, Yoshikazu Noguchi, Yos ...
1993 Volume 19 Issue 5 Pages
914-918
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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For the purpose of stabilizing CO
2 in aquifers, CO
2 solubility tests in water were carried out by changing the conditions of various parameters. The test results are summarized as follows :
(1) The results of the CO
2-H
2O equilibrium tests are in good conformity with other literature. Therefore, these test results are considered reliable.
(2) CO
2-H
2O equilibrium tests were carried out under the following conditions :
-Temperature 3070 °C
-Pressure 25200 ata.
-Salt Content 02.7 wt. %
-Methane Concentration in Gas Phase 075 mol. %
Test Results·CO
2 solubility in water decreases as salt content increases.
·In the CO
2-CH
4-H
2O equibrium tests, CO
2 solubility in water changes in proportion to the gas phase CO
2 partial pressure.
Detailed tests under a wide range of parameter conditions are currently continuing.
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Hiroyuki Harada, Shigeki Nakajima, Kazuhiko Tanaka, Masaharu Sakai
1993 Volume 19 Issue 5 Pages
919-923
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
JOURNAL
FREE ACCESS
Sulfate leaching was studied in the laboratory in undistributed Ando soil cores comprising I A, I B, and II A horizons that were taken in a Japanese cedar forest. The soil cores were watered with 0.4 me.
l-1 sulfuric acid solution having pH 3.0. The sulfate concentration of the leachate remained at about 0.05 me.
l-1 at pH 4.1 to 4.2, but after 15
l sulfuric acid solution was applied, SO
42- leaching was accelerated at pH 3.9 to 4.0. The stability diagram showed a better fit with gibbsite. In the I A horizon, which did not accumulate SO
42, the soil pH was 3.1. SO
42- accumulation had occurred in both the I B and II A horizons. The adsorption maximum was about 4.0 me · 0.1 kg
-1.
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Hideyuki Tagaya, Shigemitsu Sato, Koji Chiba, Koji Takahashi, Takao Yo ...
1993 Volume 19 Issue 5 Pages
923-925
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
JOURNAL
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Hydrotalcite-like compounds are layer compounds known to intercalate carbon dioxide. They were tested to recover carbon dioxide. The appropriate ratio of aluminium/ (aluminium+magnesium) was about 0.3. It was indicated that the deintercalation temperature should be lowered to 653K to use a hydrotalcite-like compound repeatedly as carbon dioxide adsorber.
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Utilization of water as an additive reactant
Hidetoshi Sekiguchi, Atsushi Kanzawa
1993 Volume 19 Issue 5 Pages
925-928
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
JOURNAL
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The decomposition of dichlorodifluoromethane was carried out using the thermal argon plasma generated by DC arc discharge, where water was added to react with CCl
2F
2. Complete decompositions of CCl
2F
2 were observed in all experimental conditions and the product gases consisted of CO
2 and CO in regard to carbon, which agreed with the results obtained by numerical calculations. The numerical analyses indicated the following results. Only hydrogen fluoride was formed from fluorine, while HCl and Cl were produced from chlorine. The formation of Cl
2 was suppressed by the addition of H
2, the amount of which was reduced when the ratio of H
2O to CCl
2F
2 was increased. The suppression of Cl formation was also observed in the experiments.
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Yoshihito Shirai, Motoaki Kawase, Kenji Hashimoto
1993 Volume 19 Issue 5 Pages
928-931
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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The plant factory system is an environmentally friendly food production system. However, it requires much electric power, resulting in indirect exhaustion of greenhouse gases. Here, it was calculated how large an area is needed for providing electric power to a plant factory by solar batteries. Simulations indicated that an area for solar batteries approximately ten times as large as the cultivated area in the plant factory is required for its operation in many parts of the world.
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Toyotaro Kawabe
1993 Volume 19 Issue 5 Pages
932-936
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
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This paper describes the potential use of CO
2 at its triple point as a thermal energy storage medium. Because CO
2 has both a nominal triple point and a relatively high latent heat of fusion, it can be used as an attractive thermal energy-storage medium. Solid phase is formed with a conventional cascade chiller and accumulated in a storage vessel which initially contains CO
2 as liquid. On demand, CO
2 liquid from the vessel is circulated through a process heat exchanger. The vaporized CO
2 returns to the vessel and condenses directly against the solid/ liquid slush, thereby melting the solid.
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Miki Fukuma, Kentaro Takesada, Akira Yasunishi
1993 Volume 19 Issue 5 Pages
936-939
Published: September 10, 1993
Released on J-STAGE: November 12, 2009
JOURNAL
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Performances of two-phase anaerobic treatments of wastewater containing cellulose using acidogenic-phase reactors combined with various membrane separation units was compared with those without membrane.
By using a ceramic membrane module (pore size = 0.1 μm) submerged in a stirredtank reactor, almost all the cellulose and microbial cells could be retained in the reactor. The gas yield in this system was considerably greater than that in a stirred tank without membrane unit, even when treating a high C/N-ratio cellulose-waste-water.
On the contrary, by using the membrane module immersed in a empty tube the accumulation of cellulose occured in the case of treating a high C/N-ratio wastewater. This low digestibility of cellulose was, however, improved by using a packed bedcolumn.
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