Fate of trace elements during the combustion of phytoremediation wood.

We investigated the fate of trace elements (TE) in poplar wood on the conversion of biomass to heat in a 0.2 MW combustion unit equipped with a fabric filter. The phytoremediation wood was harvested from a TE-contaminated agricultural site planted with a high-density poplar stand. The combustion technology used in the present experiment allows for an efficient separation of the various ash fractions. The combustion process concentrates Cu, Cr, and Ni in the bottom ash, heat exchanger ash, and cyclone ash fractions. Therefore, the impact of the fabric filter is negligible for these elements. Conversely, Cd, Pb, and Zn are significantly recovered in the emission fraction in the absence of the fabric filter above the emission limits. The use of a fabric filter will allow the concentration of these three TEs in the ashes collected below the filter, thus complying with all regulatory thresholds, i.e., those from the large combustion plant EU directive. Because the TE concentrations in the different fractions differed significantly, it is recommended that these fractions be treated separately, especially when recycling of ashes from phytoremediation wood through application in agriculture is envisaged.

[1]  M. Öhman,et al.  Trace element enrichment and behavior in wood pellet production and combustion processes. , 2006 .

[2]  F. van Oort,et al.  Use of major‐ and trace‐element correlations to assess metal migration in sandy Luvisols irrigated with wastewater , 2006 .

[3]  Filip Tack,et al.  Fate of heavy metals during fixed bed downdraft gasification of willow wood harvested from contaminated sites , 2006 .

[4]  R. Ottesen,et al.  Element levels in birch and spruce wood ashes: green energy? , 2008, The Science of the total environment.

[5]  S. Castiglione,et al.  Poplar clones of different sizes, grown on a heavy metal polluted site, are associated with microbial populations of varying composition. , 2012, The Science of the total environment.

[6]  Yvonne Andersson-Sköld,et al.  Biofuel or excavation? - Life cycle assessment (LCA) of soil remediation options. , 2011 .

[7]  Larry L. Baxter,et al.  Ash deposition during biomass and coal combustion: A mechanistic approach , 1993 .

[8]  R. Pitman,et al.  Wood ash use in forestry – a review of the environmental impacts , 2006 .

[9]  J. Domingo,et al.  Levels of metals in soils of Alcalá de Henares, Spain: human health risks. , 2002, Environment international.

[10]  R. Ceulemans,et al.  Clonal variation in heavy metal accumulation and biomass production in a poplar coppice culture. II. Vertical distribution and phytoextraction potential. , 2005, Environmental pollution.

[11]  Anne Juul Pedersen,et al.  Characterization and electrodialytic treatment of wood combustion fly ash for the removal of cadmium , 2003 .

[12]  C. Pruvot,et al.  Heavy Metals in Soil, Crops and Grass as a Source of Human Exposure in the Former Mining Areas (6 pp) , 2006 .

[13]  P. Tlustoš,et al.  Heavy metal accumulation in trees growing on contaminated sites in Central Europe. , 2007, Environmental pollution.

[14]  D. Lelie,et al.  Phytoremediation of contaminated soils and groundwater: lessons from the field , 2009, Environmental science and pollution research international.

[15]  B. Clothier,et al.  Poplar for the phytomanagement of boron contaminated sites. , 2007, Environmental pollution.

[16]  Catherine N. Mulligan,et al.  Remediation technologies for metal-contaminated soils and groundwater: an evaluation , 2001 .

[17]  M. Modigell,et al.  Multizonal thermochemical modelling of heavy metal transfer in incineration plants , 2012 .

[18]  G. Watkins,et al.  Heavy metal concentrations in bottom ash and fly ash fractions from a large-sized (246 MW) fluidized bed boiler with respect to their Finnish forest fertilizer limit values , 2010 .

[19]  Joakim Krook,et al.  Metal contamination in recovered waste wood used as energy source in Sweden , 2004 .

[20]  A. Nordin,et al.  Theoretical feasibility for ecological biomass ash recirculation : Chemical equilibrium behavior of nutrient elements and heavy metals during combustion , 1997 .

[21]  R. Backman,et al.  A simple two-reactor method for predicting distribution of trace elements in combustion systems , 1999 .

[22]  H. Insam,et al.  Recycling of Biomass Ashes: Current Technologies and Future Research Needs , 2011 .

[23]  Jaco Vangronsveld,et al.  Phytoremediation, a sustainable remediation technology? Conclusions from a case study. I: Energy production and carbon dioxide abatement , 2012 .

[24]  D. Blaudez,et al.  Metal Accumulation by Woody Species on Contaminated Sites in the North of France , 2009 .

[25]  Ingwald Obernberger,et al.  From waste to raw material—the route from biomass to wood ash for cadmium and other heavy metals , 1996 .

[26]  Yong-Guan Zhu,et al.  Exposure to metal mixtures and human health impacts in a contaminated area in Nanning, China. , 2005, Environment international.

[27]  Arne Villumsen,et al.  Electrodialytic removal of heavy metals from different fly ashes. Influence of heavy metal speciation in the ashes. , 2003, Journal of hazardous materials.

[28]  Ioannis Dimitriou,et al.  Wastewater and sewage sludge application to willows and poplars grown in lysimeters–Plant response and treatment efficiency , 2011 .