The effects of biomass binders and moisture content on the mechanical durability of rice husk pellets

Paddy straw and rice husk (RH) are considered agricultural waste. About 22 wt% of paddy is RH, which is normally disposed of by open burning. Pelletizing RH increases the bulk density of the waste and is capable of providing benefits such as ease of transport and potentially a more efficient fuel for combustion. This will allow for RH to be utilized for more meaningful applications instead of just being burnt. However, one of the main challenges of producing RH pellets is their low durability, causing pellets to be broken into fines and dust during transportation and thus making them unattractive to potential buyers. This work aims to investigate suitable locally-sourced biomass waste as binder compounds that could improve the mechanical durability of RH pellets. Here, the effects of binder types, binder contents and moisture contents on RH pellet durability were evaluated. Palm kernel shell (PKS), palm oil mill effluent (POME) and sawdust were selected due to their abundance in Malaysia. In general, it was observed that the mean durability improved as moisture contents increased. More specifically, pellets with PKS and POME binders improved mean durability whereas sawdust deteriorated the durability. The results presented would be beneficial for the improvement of RH pellet production for domestic and export consumptions.