Fluidized-bed gasification (FBG) of Phyto-assisted Bioremediation (PABR) biomass is analyzed focusing on the contaminants' dispersion. Poplar pruning coming from an area contaminated by polychlorinated biphenyls (PCBs) and heavy metals (HM) are considered. The biomass analysis showed relevant contents in HMs, especially Cd and Cr, and no significant PCB content. FBG process was analyzed to: a) track pollutants, b) detect con taminants in the FBG and c) investigate the HMs concentration in the produced streams. The results showed that most of the metals are concentrated in the ashes collected in the bottom of the reactor (Pb, Cd, Cu, Cr), or in the cyclone (B, Na, Mg, Al, K and Fe). Interestingly, metals are also released by the olivine bed (Mg, Fe, Ni and Al) and transported downstream. Consistent fractions of Zn and Fe (also Cu) were detected in the fugitive ashes. As for the Volatile Organic Compounds (VOC) concentration, we noted similarities between PABR and virgin biomass syngas streams. A reduced-scale process was carried out in TGA-DTA to investigate the potential of such technique in reproducing the main features of the FBG process. Comparable results were obtained, thus sug gesting its possible application for small-scale preliminary assessment of FBG process.

This work reports on a study, carried out in a lab-scale fluidized bed apparatus, on fragmentation and attrition of two biomass fuels, namely wood chips and wood pellets, under both combustion and gasification conditions. The aim was to highlight the effect of their different mechanical strength on the fuel particle size distribution and overall carbon conversion. Primary fragmentation tests showed that for wood pellets limited fragmentation occurred during devolatilization, with a fragmentation probability around 30% and particle multiplication factor of 1.4. On the contrary, wood chips were subject to extensive fragmentation as witnessed by large values of the particle multiplication factor and of the fragmentation probability. Results of char attrition experiments carried out under inert, combustion and gasification conditions showed that the carbon loss by elutriation is critical only during gasification, especially for the wood chips char. A gasification-assisted attrition mechanism was proposed to explain the experimental results, similar to the well known combustion-assisted attrition patterns already documented for coal under oxidizing conditions. The higher mechanical strength of the wood pellets appears to be beneficial for reducing carbon elutriation and for obtaining a higher carbon conversion.