We developed vibration mill with ring media as a highly efficient pretreatment technique to obtain monomeric sugar from biomass. The enzymatic digestibility of Japanese cedar powder was improved to 60% by vibration mill with ring media dry pulverization. However, improvement of enzymatic digestibility mechanism was not clarified because of pulverized powder agglomeration. This study investigated the structural change and domain size of a vibration milling with ring media pulverized Japanese cedar powder using solid state NMR. Results show that the between domain size of Japanese cedar powder decreased to 8 nm during 60 min pulverization. A relation was confirmed between domain size and enzymatic digestibility. The enzymatic digestibility was expected to improve by increase surface area through contact by cellulose enzymes. Furthermore, cellulose crystallinity remained almost natural. These results suggest that Japanese cedar powder from vibration milling with ring media can be used as a cellulose nanomaterial. Investigation using ICP-MS was applied to assess the noise of the NMR spectrum from the remnant carbon steel. Results showed no influence of any remnant carbon steel powder. This study clarified the improved enzymatic digestibility mechanism and demonstrated the possibility of cellulose nanomaterial production by dry pulverization.

An inverse diffusion flame is formed during the partial combustion of the reformed gas for tar reduction in the producer gas generated by the gasification of woody biomass. The polymerization and decomposition of tar occur simultaneously in the vicinity of this inverse diffusion flame. The combustion reaction of producer gas proceeds in the diluted phase. In order to decompose tar without it polymerizing into soot, it is necessary to understand the flame structure. Therefore, this study is aimed at understanding the flame structure of an inverse diffusion flame. In particular, in order to analyze the influence of the diluent, the effect of the concentration of carbon dioxide as an oxidizer on the flame structure and tar decomposition was investigated by observing the CH* chemiluminescence, the planar laser-induced fluorescence (LIF) of polycyclic aromatic hydrocarbons (PAHs), and the laser-induced incandescence (LII) of soot. The results showed that the peak intensities of CH* chemiluminescence, LIF signals from PAHs, and LII signals from soot are distributed in the stated order in a radial direction from the central axis. While PAHs are formed in the upstream of the flame and decrease gradually along the mainstream direction, the relative volume fraction of primary soot particles continued to increase along the mainstream direction. Further, a high carbon dioxide concentration resulted in a longer flame. At the same time, it led to a large volume fraction of soot downstream of the flame. As the concentration of carbon dioxide in the oxidizer increased, carbon yield decreased, suggesting an increase in soot formation.

The purpose of this research was to provide an accurate estimate of greenhouse gas (GHG) emissions during the storage of liquid digested slurry after separation (LDSS) produced by a dairy-manure-fed biogas plant in Hokkaido, Japan, in order to create a reliable gas inventory for life-cycle assessment (LCA) of the system. To the best of our knowledge, there have been no case studies measuring GHG generation by anaerobic digesters in such snowy cold regions. Therefore, a GHG measurement method adapted to snowfall and freeze-thaw conditions was newly developed; we measured the amounts of GHGs produced before and after the melting of frozen LDSS at the surface layer of the storage tank during the snowmelt period. The concentrations of CO₂, CH₄, N₂O and NH₃ in the LDSS storage tank (above ground, open-type, diameter: 44 m, capacity (effective volume): 6,839 m³ (5,471 m³)) were measured with a multi-gas monitor (infrared photoacoustic detector manufactured by INNOVA) using an openchamber technique. The measurements were conducted at the LDSS storage tank for a biogas plant in Ebetsu City, central Hokkaido, Japan from February 20 to April 3, 2018. This plant processes 29 m³/day, has a fermentation temperature of 40 °C, and hydraulic retention time (HRT) of 40 days. The results revealed that almost no GHG emissions were observed from the frozen storage tank. In addition, when the frozen LDSS began to melt, the GHG emission pattern showed diurnal fluctuations that generally moved in tandem with the ambient temperature. The GHG emissions greatly changed during the period immediately after the frozen LDSS began melting until it melted completely. After the frozen LDSS was melted, CH₄, CO₂, and N₂O emissions were 113.0 mg CH₄/m²/day, 88.8 mg CO₂/m²/day, and 0.021 mg N₂O/m²/day.

This study aims to prepare nanocelluloses from chemically purified celluloses of oil palm empty fruit bunch (CPC-OPEFB) by using acid hydrolysis. The nanocelluloses from CPC-OPEFB was prepared with sulfuric acid treatment at the concentration of 67 wt% and temperature of 40 ± 1 °C, for 10, 20, 30, and 40 min. As a comparison, nanocelluloses from commercial microcrystalline cellulose (C-MCC) were also prepared with the same condition. The effects of hydrolysis time on the morphology and physical properties of the obtained nanocelluloses were investigated. Observation with TEM showed that nanocelluloses from CPC-OPEFB were long and fibril, whereas the ones from C-MCC showed a rod-like structure and crystalline. This observation was in agreement with the DSC analysis, i.e. the endothermic peaks were not present on the DSC curve of nanocelluloses from CPCOPEFB, whereas it was clearly observed on the DSC curve of nanocelluloses from C-MCC, indicating that the nanocelluloses from CPC-OPEFB were amorph, and the ones from C-MCC were crystalline. The particle size analysis revealed that the diameter of the obtained nanocelluloses was affected by hydrolysis time. The best hydrolysis time to obtain the smallest diameter of NFCs from CPC-OPEFB and NCCs from C-MCC was 30 and 40 min, respectively.