Agricultural and Industrial Valorization of Arundo donax L.

Abstract

Some agricultural and industrial characteristics of different parts of the giant reed (Arundo donax L.) were studied in this work to evaluate their capacity as growing media and for the manufacturing of the insulating board employed in the building sector. Three different particle sizes (>0.25, 1–2, and 2–4 mm) of the stem and rhizome of Arundo donax L. (SAD and RAD, respectively) were evaluated on bulk density (BD), total pore space (TPS), air capacity, easily available water (EAW), water buffering capacity (WBC), total water-holding capacity (TWHC), shrinkage, total organic carbon (TOC), total nitrogen (TN), and macro- and microelements. Moreover, density, bending strength, internal bond strength, screw-holding strength, and thermal conductivity were determined in boards manufactured with three different particle sizes (>0.25, 1–2, and 2–4 mm) of the stem of Arundo donax. The manufacturing conditions of these boards were three different press pressures (15.7, 21.0, and 26.0 kg cm−2) and two press temperatures (120 and 140 °C). With respect to the agricultural value of this vegetative species, most of physical properties were not inside the interval of values for an ideal substrate. Bulk density, TPS, air capacity, and EAW values were greater in SAD substrates than those of RAD-based media. In general, the particle size of different parts of the giant reed had a significant effect on the physical parameters studied. The macro- and microelement contents were low in comparison to peat, except in the cases of K in both substrates types (SAD and RAD) and TN in RAD substrates. In general, no great differences were observed in the chemical properties related to the particle size of media used. On the other hand, the physical and mechanical properties of the fiberboards from giant reed were comparable to those of the wood-based composites, and the thermal conductivity of these boards was similar to that of other environmentally friendly fiberboards. Mechanical and physical properties of the boards were more significantly affected by the particle size and press pressure than by the press temperature.