Conclusion
This work demonstrates that physical properties of the composting
feedstock significantly affect the composting process. The
water absorption capacity of the composting mixture was the
dominant physical property that affected the composting rate.
More sawdust in the composting mixture resulted in the increases
of the water absorption capacity and the composting rate, shorter
composting and acidification times, and lower final pH value. As
the free air space of the composting feedstock increased, composting
rate accelerated and higher temperature reached due to more
air flow through the particles.
Among the 12 mixtures studied, only the products of a mixture
prepared using 100% rice husk and another one using an equalweighted
mixture of rice husk and sawdust as bulking agents
passed the germination test. Therefore, rice husk was considered
as a safe agent that could be used alone. Sawdust should be mixed
with rice husk, but the content should be less than 50%. Rice bran
was not recommended as a bulking agent