Evaluating Availability as a Filter Material in Subsurface Drainage Systems of Rice Husk-Derived Biochar Produced at Different Pyrolysis Temperatures

Abstract

We made biochar samples from rice husk at four different pyrolysis temperatures and investigated effects of pyrolysis temperatures on elemental compositions, carbon degradation resistance, creation of cristobalite, which is carcinogen, and dissolution characteristics of organic and inorganic compositions to evaluate an applicability as a filter material in subsurface drainage systems. Estimated unmineralized carbon in soil after 100 years was about 40% for rice husk biochar at 400℃ to less than 10% for rice husk biochar at 700℃. Creation of cristobalite was not confirmed for pyrolysis by 700℃. With increasing pyrolysis temperature, dissolution of organic carbon was suppressed. On the other hand, with increasing pyrolysis temperature, potassium, which shows alkali metal, was accumulated, and it should be took careful for high pH in subsurface drainage water from rice husk derived biochar produced at high temperatures.