During the production of rice, rice husk is generated on site as
a byproduct in the milling factory [1]. Annual production of rice
husk is about 140 million tons worldwide. However, rice husk does
not provide important use or commercial interest due to its high
ash and lignin contents [2]. Traditional methods such as composting
and incineration are not suitable to process these organic solid
wastes. The reason is that they contain small concentrations of
nitrogen for composting and a considerable amount of solid grains
and smoke would be released to pollute the environment during
incineration [3]. From a different perspective, rice husk may be a
species of potential renewable energy resource. Utilization of rice
husk in this way, instead of as waste, will mean less pollution [4].
Therefore, more efficient treatment methods satisfying both energy
conversion and wastes disposal are required [5].