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Energy production potential of phytoremediation plant biomass: Helianthus annuus and Silybum marianum

Hunce, Selda Yiğit, Clemente, Rafael, Bernal, Maria Pilar
Industrial crops and products 2019 v.135 pp. 206-216
Helianthus annuus, Silybum marianum, anaerobic digestion, biodegradability, bioenergy, combustion, energy recovery, feedstocks, gas production (biological), laboratory experimentation, methane, phytomass, phytoremediation, polluted soils, potential energy, seeds, trace elements
The use of the biomass of two plant species (Helianthus annuus and Silybum marianum) generated during the phytoremediation of a trace element contaminated soil was studied for the production of clean and renewable energy in laboratory experiments. Biogas production potential, aerobic biodegradability and calorific values of the plants were determined and compared with the results of the plants grown in non-contaminated soil to evaluate the effect of trace elements contamination on their potential use as feedstock for bioenergy production. The biogas production potential of the aerial vegetative biomass of S. marianum (194 - 223 ml g−1) was found to be higher than that from H. annuus (134 - 154 ml g−1), with no significant differences between non-contaminated and contaminated soils (average CH4 concentration: 63.1% for S. marianum and 65.7% H. annuus, respectively). The greatest biogas production was obtained from the seeds of H. annuus (356 - 473 ml g−1; 70.7% of CH4) after 9 days of anaerobic digestion. Also, the aerial vegetative biomass of H. annuus had higher calorific values than that of S. marianum (17.1 and 14.3 MJ kg−1, respectively). Combustion was the most efficient method for energy production compared to anaerobic digestion, while the presence of low concentrations of trace elements in plant biomass did not limit the potential energy recovery. These findings show the suitability of bioenergy production as an added value alternative for the management of plant biomass coming from phytoremediation processes.