Effects of feedstock and carbonization types on potential applications of biochar

This thesis explored the effects of production method and feedstock type on the fuel and agronomic properties of chars. For this purpose, different type of agricultural, animal and agro industrial wastes, and algal biomass were carbonized by two methods, namely dry carbonization (pyrolysis) and wet carbonization. Dry carbonization experiments were carried out under nitrogen atmosphere at different temperatures between 250 and 600 °C. The pyrolysis temperature of 350 °C was found as critical upper temperature in the production of biochar used as fuel. It was found that agricultural and agro industrial wastes were more suitable than animal waste and algal biomass for solid fuel production via pyrolysis. On the other hand, high pyrolysis temperatures (500 °C and 600 °C) produced the biochars having high stable carbon contents, indicating persist in soil resulting in an effective means of carbon sequestration. Wet carbonization experiments were performed at the temperature range of 150 – 275 °C under autogenic pressure. The effect of three process variables (temperature, biomass:water ratio and reaction time) on hydrochar properties were investigated. Response surface methodology was used to study the influence of each factors as well as their combined interactive effect on the hydrochar properties. Findings from this work showed that char properties related to fuel and soil amendment are essentially determined by the type of carbonization. It was found that wet carbonization was more suitable for the production of solid fuel. The hydrochar had higher calorific value and lower ash content than biochars. But, from the point of agronomic value of chars, dry carbonization produced more stable char than wet carbonization.