(583b) Analysis on the Production of Bio-Oil and Biochar from Switchgrass Grown for Phytoremediation of Lead-Containing Soil

A combination of biochemical and thermochemical process to produce sugars and bio-oil by using switchgrass which was grown in lead-contaminated soil was studied. Four different process routes which involve fast pyrolysis, enzymatic hydrolysis, acid hydrolysis, and their combinations were investigated. The main goal of this study is to identify the effects of process combinations on the yields of bio-oil and biochar along with the amounts of lead contained in the products. The first route only involved fast pyrolysis process only. The second route involved an acid hydrolysis pretreatment followed by the fast pyrolysis. In the third route biomass was hydrolyzed enzymatically to produce sugars. The solid remaining then was pyrolyzed to produce bio-oil. In the fourth route, biomass was pretreated with acid hydrolysis prior to the enzymatic hydrolysis to produce sugar followed by pyrolysis of the remaining solid to produce bio-oil. The impact of lead content in the switchgrass feedstock used to produce sugars and bio-oil along with the recovery of lead through the above-mentioned routes were evaluated by using switchgrass grown in regular soil for comparison. Overall, the distribution of product yields did not seem to be affected by the presence of lead in the biomass feedstock. The highest overall yields of the liquid products were obtained from the fourth route which utilized all the three process steps, resulting to the lowest bio-char byproduct. On lead recovery, it was found the hydrolysis step is important for extracting lead from biomass in order to produce bio-oil and bio-char products almost free of lead. Pyrolysis of the solid remaining from the combined both hydrolysis steps resulted in the bio-char which had the lowest content lead (2ppm) which is not believed to be dangerous by EPA standards which enable biochar to be used as soil amendment agent. In addition to technical aspects of the processes, to be presented are Life Cycle Assessment (LCA) of the production of fuels and chemicals from switchgrass grown for phytoremediation of lead contaminated soil. Results of the environmental impact analysis obtained were compared with the production of the same products obtained from fossil fuels refinery system and the lead removal by ex-situ extraction from a same size land as the one used by the bio-refinery process.