Extent Of Biomass Research Articles

Fluidized Bed Pyrolysis of Biomass: A Model-Based Assessment of the Relevance of Heterogeneous Secondary Reactions and Char Loading

A model of non-catalytic fast fluidized bed pyrolysis of biomass has been developed with the aim of investigating the relevance of secondary heterogeneous reactions between primary products of biomass decomposition and the char accumulated in the bed. The fate of biomass and the extent of biomass and char holdup in the pyrolyzer have been modeled by considering entrainment and elutriation of biomass and char particles, char attrition, as well as bed drain/regeneration. The kinetics of primary and secondary pyrolitic reactions is modeled according to a semi-lumped reaction network using kinetic parameters selected among published correlations. The rate of heterogeneous volatile–char secondary reactions has been modeled borrowing a kinetic expression from the neighboring area of tar adsorption/decomposition over char during biomass gasification. Model computations are helpful to assess the role of heterogeneous vapor–char secondary reactions. The sensitivity of the pyrolyzer performance on char loading in the bed as a result of combined char entrainment, elutriation, attrition, and bed drain/regeneration, the extent of gas-phase backmixing, the process temperature, the gas superficial velocity and residence time, and the particle size is demonstrated and discussed. Model results provide useful guidelines and pinpoint future research priorities for optimal design and control of fluidized bed pyrolyzers.

Translocation Induced Outgrowth of Fungi in Nutrient-free Environments

The study of alternatives to chemical methods of nematode control in agriculture has received significant recent interest. One such method is biological control using nematode trapping fungi such as Arthrobotrys superba. To understand how these fungi can be implemented as effective nematicides, it is essential to study their outgrowth into soil from localized nutrient resources. In this paper, we use a mathematical model to investigate the outgrowth of fungi into an environment essentially without available nutrients capable of supporting net growth. By comparing model solutions with experimental results, we show that in such circumstances, continual mycelial expansion can only be obtained if internal metabolites are actively translocated through the mycelium. Predictions are made concerning the maximal extension possible from a given quantity of nutrients and a testable functional relationship between the two is derived. Using this modelling technique we are able to map not only biomass extent but also biomass distribution at each stage. The type of environmental heterogeneity investigated here is encountered by many species of fungi in nature and is of relevance for the introduction of specific fungi into soil for biological control or bioremediation purposes.