Environmental assessment of pig slurry management after local characterization and normalization

Due to its environmental impact, pig slurry management is of great importance in the Region of Murcia, Spain, where pig production is considerable. The current slurry management system consists in its direct use in agricultural land, yet this entails an important associated problem, i.e., the limits of nitrogen imposed by legislation (<170 kg N ha−1 yr−1). The use of constructed wetlands affords another possibility, achieving a reduction of physicochemical parameters of up to 80%. This paper presents the comparison of both the alternatives by means of life cycle assessment, and reports a major impact in the categories of acidification and eutrophication potential. However, the abiotic depletion potential could be minimized by avoiding the application of fertilizers and irrigation water. For the category of global warming potential, the wetland building displayed a negative role as compared to direct use. After normalization of the data, the main environmental problem for both management alternatives proved to be eutrophication, followed by acidification and global warming potential. The use of the great amounts of pig slurry produced in the Region of Murcia generates a problem of eutrophication in the Valle del Guadalentín, the Campo de Cartagena and the Mar Menor lagoon. For the purposes of normalizing, a database is needed to take all the inputs and outputs into account, in order to establish more realistic scenarios for the use and management of pig slurries in different geographical areas.