Abstract

The approaches to integral utilisation of biomass for sustainable development are becoming more comprehensive. Sequential beneficial implementations for crops such as Miscanthus sinensis x giganteus contribute the sustainability of the natural resources. All parts of the plant such as leaves, bark, fruits, and seeds can be turned into useful products. In this study, successive utilisation of Miscanthus sinensis x giganteus for two consecutive treatment applications was investigated. First, the effectiveness of constructed wetland, planted with Miscanthus sinensis x giganteus, in domestic wastewater treatment was investigated in a two-stage vertical-flow wetland (VFCW). Then the crops were harvested from two successive VFCW, stems and leaves were separated, ground down and adsorbents were obtained (Stem-1/Stem-2, and Leaf-1/Leaf-2). Fe(II), Cu(II) and Zn(II) adsorption by these four adsorbents were investigated. In the first step, average COD, Turbidity, NH3-N and Phosphorus removal efficiencies were 91, 98, 98 and 83% respectively. NH3-N degradation by nitrification caused NO3-N to increase, but mass balance indicated that denitrification also occurred simultaneously. In the second step, the crops could adsorb Fe(II), Cu(II) and Zn(II) with different capacities changed between 6-56 mg metal/g of the adsorbent. Equilibrium data followed both Langmuir and Freundlich isotherms, with a better fit to Langmuir. Adsorption followed second-order rate kinetics. The data from this study, and the high energy yield and variety of utilisation areas of the crop indicated that it can be used in three sequential beneficial implementations, thereby sustainable utilisation of the plant resource was achieved.