Investigation On the Utilization of Grassy Biomass Grown in Heavy Metal Contaminated Soils for the Production of Sugars and Fast Pyrolytic Oil Via a Hybrid Biochemical and Thermochemical Approach
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Our society is still highly reliant on fossil fuels which are not renewable and causing environmental issues , primarily due to greenhouse gas emissions. To reduce this dependency , it is necessary to find resources that are renewable. Biomass is the only renewable source of carbon that , when utilized efficiently and optimally , can significantly help to reduce our reliance on fossil fuels. Lignocellulosic biomass is abundant , inexpensive and does not compete with the production of food crops. Nevertheless , the complex nature of biomass and many ill-defined issues related to biomass utilization pose a substantial challenge to large-scale biomass utilization. Growing biomass for energy crops , such as switchgrass , means that more land needs to be utilized. It is desired that biomass for energy crops would be grown in land areas that are considered marginal and not currently being utilized for anything productive. At Villanova University , we are working on the development of a sustainable processing system for producing biofuels from grassy plants that can be grown on heavy-metal contaminated soils in underutilized areas such as superfund sites. Certain types of perennial grasses , such as switchgrass , have great potential to be used as bio-renewable feedstock for the production of bioenergy and biofuels due to their relatively high yields of biomass per acreage of land. Also , they have the capability of extracting heavy metals from the contaminated soil , which in turn can improve the quality of the soil. Our preliminary studies reveal great potentials of both switchgrass and timothy grass grown as soil remediating agents. The purpose of this study was to find the optimal conditions for biofuel production from switchgrass that has been grown in soil contaminated with lead through a hybrid biochemical (i.e. enzymatic hydrolysis) and thermochemical (i.e.fast pyrolysis) approach. For the biochemical approach we are investigating the performance of enzymatic hydrolysis by using various combinations of three different enzymes , Trichoderma Reesei , Aspergillus Niger and Humicola Grisea for producing sugars from switchgrass that was grown in lead contaminated soils. With the thermochemical approach , we are evaluating the production of fast pyrolytic oil from the fast pyrolysis of switchgrass and the solid remaining from enzymatic hydrolysis of switchgrass. Also , the study evaluates the effects that acid hydrolysis pretreatment has on the performance of enzymatic hydrolysis and the fast pyrolysis of the biomass in producing sugars and fast pyrolytic oil , respectively. To be reported are results of the performances of several different process configurations of combined mild-acid hydrolysis pretreatment , enzymatic hydrolysis , and fast pyrolysis for producing sugars and fast pyrolytic oil from switchgrass materials that were grown in lead-contaminated soils and un-contaminated soils. Process variables reported in this study include variation of acid concentration levels in the acid hydrolysis steps , variation of the enzymes used in enzymatic hydrolysis for the production of sugars and the variation of process temperatures of the fast pyrolysis step for the production of fast pyrolytic oil. Important results to be reported include the yields and properties of products produced from each step of the process. Properties of the solid products evaluated include results from proximate analysis (volatiles , fixed carbon and ash composition) , fiber analysis (cellulose , hemicellulose , and lignin content) , heating values , and elemental analysis (CHONS). On fast pyrolysis step , analysis includes the chemical product distribution of the fast pyrolytic oil. Finally , understanding the distributions of the inorganic minerals , including the heavy metal , based on various combinations of the process system configurations is another important part of the study to be reported.