The potential of phytoremediation derived maize biomass for the production of biomethane via anaerobic digestion

Maize is an energetic plant with ability for heavy metals removal from contaminated soil. The growth and ability for heavy metals removal by this energetic culture was tested using an industrialised soil contaminated with zinc (Zn) and cadmium (Cd) vs. an agricultural soil. Plants biomass production and metal accumulation was monitored and resulting biomass (roots, stems and cobs) was used for biogas production in several biomethane assays (BMP) in a factorial design with different inoculum to substrate ratios being tested. The biogas produced during the anaerobic digestion was monitored until stable production and its composition was analysed through gas-chromatography. It was possible to observe that maximum methane production seems to be proportional to the amount of anaerobically degradable substrate and is quickly obtained (ca. 8 days after incubation). It was also noticeable that the metals present in the industrial soil were not damaging to the anaerobic biodegradation of the biomass. The production of biomethane from metal contaminated soils’ phytoremediation derived maize biomass appears thus as a possibility to counterpart biogas production in an increasingly demanding status of renewable energy requirements