We attempted a dewatering operation using the osmotic pressure of activated sludge with high moisture content, which is discharged in large quantities from a sewage treatment facility, and elucidated its dewatering effect. A filter cake with a moisture content of approximately 80 wt% prepared by filtration of activated sludge was immersed in a high-concentration salt solution. The intracellular water was discharged owing to the osmotic pressure difference between the inside and outside of the microbial cells constituting the activated sludge, whereby a low moisture-content dewatered cake was obtained. The higher the osmotic pressure, the greater was the dewatering effect. With an osmotic pressure of approximately 22 MPa, the moisture content of the cake decreased to approximately 60 wt% within a few minutes. This value of moisture content could not be reached even if the cake was consolidated by filtration at a pressure of 500 kPa, and it took approximately 370 min to reduce the moisture content from 80 wt% to 70 wt%. Therefore, it was observed that high-speed and high-level dewatering of activated sludge could be realized using osmotic pressure. The effect of osmotic dewatering was also confirmed for sludge flocculated with an organic polymer flocculant, which was applied to shorten the filtration time. Compared to non-flocculated sludge, although the moisture content tended to hardly decrease, a dewatered cake with a moisture content of approximately 66 wt% was obtained. The sludge cake dehydrated by osmotic pressure had an extremely low moisture content, suggesting the possibility of use as a solid fuel.

The size and morphology of particles generated by a spray dryer strongly depend on the atomization process because it is the initial stage of the process. In a practical apparatus, a rotating disk atomizer is exposed to the hot dry air, while liquid raw material is usually kept at room temperature. In this study, the effect of the temperature condition on the droplet size distributions is, therefore, investigated using ion-exchanged water and castor oil. Not only the temperature of liquid raw material, but also the temperature of the rotating disk are individually controlled in the experiment. As a result, the droplet size distribution was strongly influenced by the difference between liquid and disk temperatures. When the temperature difference was large, bimodal droplet size distributions were observed. On the contrary, monomodal size distributions were obtained for the smaller temperature differences. Furthermore, when temperature of disk was much higher than that of the liquid raw material, film flow locally fluctuated on the rotating disk was observed. According to these results, droplet size distributions could be affected by the stability of liquid film flow on the rotating disk. When the temperature difference between liquid and disk is large, the physical properties of the liquid raw material near the disk surface would be changed. In particular, when the temperature of the disk is higher than that of liquid, local density and viscosity near the disk surface are always smaller than those of the upper bulk liquid, respectively. Such two-layer flow could lead to unstable film flow. Thus, the distributions of droplet size could be characterized by the temperature dependence of physical properties of the liquid raw material.

By adding drop-wise a phospholipid bicelle solution, which shows different phase states, onto a glass substrate, a supported lipid bilayer (SLB) that can be used as a biomembrane model was prepared. Bicelles were prepared at different molar ratios, x_DHPC=[DHPC]/([DPPC or DMPC]+[DHPC]), from long-chain phospholipids (DMPC or DPPC) as build bilayer membranes and short-chain phospholipid (DHPC) as a detergent: x_DHPC=0.40, and 0.67. Fluorescent lipids (Rhod PE, DiI, or NBD PE) were mixed as probes in each bicelle. The fluorescent probes in the bicelles were observed under a fluorescence microscope for bicelle-derived SLB on a glass substrate at room temperature (ca. 298 K). The formation of the SLBs was confirmed irrespective of the types of long-chain phospholipids and molar ratios; however, more aggregates were formed on the SLB when adding drop-wise onto the glass substrate the DMPC/DHPC bicelle of x_DHPC=0.40 than of x_DHPC=0.67. An SLB consisting of a DPPC bilayer membrane was prepared in 5 min by a DPPC/DHPC bicelle. In addition, after mixing a DMPC/DHPC bicelle and a DPPC/DHPC bicelle, they were added drop-wise onto a glass substrate to form an apparently uniform SLB membrane. However, fluorescence spectrum measurements suggested that DMPC and DPPC-derived SLB membranes have phase separation.

The power produced from renewable energy sources should ideally be converted into H₂ for the purpose of long-term storage and long-distance transportation. In this study, an energy supply chain was considered by assuming that wind turbines whose total output of 3 GW were installed in Yokkaichi city, the electricity generated was calculated based on meteorological data, the obtained electricity was converted into H₂ by electrolysis of water and transported to consumers in Yokkaichi city, Nagoya city or Kyoto city after (1) compression, (2) liquefaction, (3) conversion into compressed CH₄ or liquefied CH₄, (4) conversion into organic hydride, or (5) conversion into NH₃. Upon delivery to the consumer, the energy efficiency, CO₂ emission reduction effect and number of households and days for which the energy demand of general households could be satisfied were evaluated. In addition, a case of utilizing the cold heat generated from phase change of liquefied natural gas on a liquefaction of H₂ as an auxiliary heat source was also evaluated. As a result, the H₂ carrier having the smallest energy consumption and CO₂ emission in the course of transport was (3) liquefied CH₄ after methanation. When the H₂ transported to the consumer is used for H₂ gas turbine power generation, the CO₂ emission for H₂ carrier excluding compressed CH₄ and liquefied CH₄ was 4.29×10⁸ kg/year. In addition, it became evident that the annual energy demand for two-person households could be satisfied for 30.2 households. When the H₂ transported to the consumer is used as a fuel for a mobility, the CO₂ emission reduction effect became larger in the order of diesel buses, hybrid cars, diesel cars and gasoline cars. Moreover, the energy loss ratio was the smallest in the case of liquefied H₂ utilizing the cold heat generated from the phase change of liquefied natural gas irrespective of the transport distance. This is because the energy assist ratio of the cold heat upon phase change of liquefied natural gas to the total energy needed for liquefaction process of H₂ was high at 64.3%.

A novel livestock waste composting process, which directly supplies the relatively high-temperature and high humidity exhaust gas generated from a composter to another composter, was investigated in order to reduce the heating of raw material and treatment of ammonia in exhaust gas in a vertical composter. In the experiments, high humidity air, carbon dioxide, and ammonia gas generated during composting were supplied to simulated compost, and the effects of the supplied gas components on the composting behavior such as compost mass, exhaust gas composition, and composting temperature were studied. The mass change during the composting differed greatly depending on the composition of the supplied gas, and the gas composition generated during composting varied. It was found that the initial fermentation of the compost was promoted by supplying high-humidity air, while the supply of carbon dioxide reduces the mass loss of compost during composting and the supply of ammonia inhibited the fermentation in the early stage. When two composting fermenters were connected and the exhaust gas from the first one was directly supplied to the second one, earlier fermentation start-up, longer high-temperature fermentation time and homogeneous bed temperature in the second one were observed without significant inhibition of the fermentation.