ENVIRONMENTAL AND SOCIO-ECONOMIC IMPACT ASSESSMENT OF THE PRODUCTION OF PERENNIAL CROPS WHEN IRRIGATED WITH TREATED WASTEWATERS

The production of energy crops has been presented as a promising alternative to partially replace fossil fuels. Perennial crops are promising because of their high productivity, resistance to low water regimes, and pests. Yet, the need to irrigate biomass during cultivation can cause the depletion of water resources, an environmental constraint in the Mediterranean region, due to water scarcity. In this context, the aim of this work was to evaluate the environmental and socio-economic impact of the production of perennial crops, when irrigated with wastewaters, in order to integrate them into a sustainable agriculture development. Studies conducted at FCT-Universidade Nova de Lisboa indicate that perennials show potential to simultaneously deliver high yields, restore soil properties and promote water quality improvement under wastewater irrigation. To determinate the environmental and socio-economic sustainability, different categories were studied: energy savings, reduction of greenhouse gases, carbon sequestration, emissions to soil, air and water, impact on water and mineral resources, costs savings, employment potential creation and consumers/producers acceptance. Overall results suggest that reuse of wastewater on the production of perennial crops have an advantage over traditional irrigation, namely regarding use of water and mineral resources and costs savings. No effects were observed in terms of energy savings, reduction of greenhouse gases, or carbon sequestration. But the reuse of wastewater still involves much controversy, and not always have social acceptance. In the study, several technical and economic barriers were also addressed, namely those related with the quantity and quality of biomass produced.