Biomass combustion is one of the major sources of particulate matter (PM) emission, which forms a crucial part of air pollution. This study investigated the effects of particle size of rice husk and bran impurities on the emission trend of PM_2.5. Rice husk from the Koshihikari variety, Oryza sativa was prepared into 3.00 g as rice husk samples from Japan (JPN). JPN had no bran impurities and consisted of normal sized Japonica husk particles (4.00 – 5.50 mm). Rice husk from the Nerica rice variety (a hybrid of O. sativa and O. glaberima) was imported and was prepared into 3.00 g as Nerica rice husk samples from Nigeria (NGR). The samples were smooth rice husk particles (0.10 – 2.00 mm) and had bran impurities. Rice husk briquette was made from JPN samples without a binding material, was prepared into 3.00 g as rice husk briquette (RB) sample. Three samples were combusted in temperatures between 600 °C and 1000 °C for a 3 minutes duration. The experimental set up comprised a Yamato F100 fixed bed electric furnace, Dust Track II aerosol analyzer and Testo 350 flue gas analyzer. Higher PM_2.5 emission (32.4 mg/g) was recorded for the combustion of RB at 700 °C compared to that of NGR husk (23.7 mg/g) at 800 °C, and JPN (13.6 mg/g) at 900 °C. That is because, RB had a lower surface area and pore volume, which affected its air-fuel mixing during the combustion phases. JPN emitted higher carbon monoxide (1592.4 ppmv) due to higher Sulphur content (0.2wt%db). That caused additional competition for oxygen in the oxidation process of Sulphur from SO₂ emission.

In recent years, bicycle sharing systems have been increasingly promoted in our society as an environmentally friendly mode of transportation. In this study, we discuss the bike sharing system in terms of the mitigation of eco-burden and/or biomass energy use (e.g., sewage sludge). Here, biomass energy use indicates that the bicycle’s fuel cell (FC) system is powered by H₂ from the biomass. In other words, the bicycle is assisted with an FC and H₂ storage as an alternative to the conventional Li-ion battery. Note that the H₂ fuel is purified through the fermentation process and metal hydrides (MHs) are used for storing H₂. In our study, we selected Sendai city as the model area. Our objective was to estimate the eco-burdens of our proposed bicycle using life cycle assessment methodology. We estimated the environmental impacts of the bicycles in the target area, considering their FC performance over a period of 10 years. Consequently, bicycle sharing using FC bicycles can reduce abiotic depletion potential by 15% and global warming potential by 10% compared to conventional bicycle sharing systems.