Use of giant reed to treat wastewater for resource recycling in South Australia

Abstract

Certain agricultural crops can produce very large biomass and at the same time act as biofiltering systems to treat wastewaters, thus recycling nutrients and water, and producing value added products. Overseas research has shown the high annual growth and cellulose content make giant reed a potential crop for converting solar energy to industrial fibre or biofuels. There is no information on the agronomy and yield potential of giant reed grown in Australia. In order to obtain preliminary data on the maximum yield potential of giant reed (Arundo donax L.) as a biomass and biofilter crop, field studies were conducted at Roseworthy, South Australia. Crop yield, nutrient content and uptake responses to drip irrigation with wastewaters and harvest time were evaluated. The irrigated treatment of an established planting of giant reed produced 40.7 and 37.7 t/ha of oven dry stems and 51.0 and 45.7 t/ha of total dry matter yield of tops when harvested at 10 and 12 months after the planting was clear felled. A comparable non-irrigated treatment produced a total dry matter yield of 15.4 and 12.7 t/ha at 10 and 12 months after clear felling. Nutrient uptake of N, P and K in the above ground biomass from the irrigated treatment was 773.2, 39.7 and 831.6 kg/ha, respectively, at the 10 month harvest. Stems and leaves contained 41.8 to 44.0% organic carbon on a dry matter basis, confirming that giant reed is a useful carbon sequestration and biofuel crop. Preliminary estimates indicate that giant reed, irrigated with the wastewaters used, has potential to produce up to 5 times the air dry pulp yield per ha per year (15.2 t) compared to Eucalyptus hardwoods (3.11) when grown in southern Australia. Initial results indicate that giant reed is a promising alternative to conventional non wood fibre options and is a useful biofilter and biomass crop. Show more