The rice husk is one of the most typical agricultural waste which is low bulk density and high ash content. Since rice consists of 20% of rice husk in weight, about 1 million tons of rice hull were generated during rice milling process in KOREA. The development of integral utilization method of the rice husk has been increasing interest in terms of recycling agricultural waste.

The properties of rice husk and rice husk fibers were evaluated. There were big differences in Morphological characteristics and chemical composition of rice husk between the outer surface and the inner surface. Especially, the outer surface showed the regular patterns in which most of silica of rice hull were existed. The average fiber length of rice hull fiber was shorter than wood fiber.

In this study, bio-refinery process for the high value-added of rice husks was investigated. Rice husk fiber and silica were separated from the bio-refinery process based on the alkaline treatment conditions with anthraquinone for activation of reaction. These experiments provided the optimal process conditions such as 15.5% effective alkali, 170℃ for 2 hours with anthraquinone. The higher effective alkali and higher pulping temperature resulted in the higher efficiency in removal of lignin and ash, which leaded to the higher strength properties of handsheets made of rice husk fiber.

The properties of rice hull fibers as an alternative to wood fibers were investigated. The addition of rice husk fibers in the wood pulp resulted in the increase in bulk and opacity properties of handsheet paper.

In order to improve the application properties of rice husk fiber, the physical and chemical treatment were applied with various condition. The physical and chemical treatment of rice husk fiber leaded to the recover in the strength properties of handsheet paper.

The liquor solution obtained by the biorefinery process of the rice husk included large amounts of silica. The process conditions were optimized to obtain natural silica from the liquor solution.