sustainability Review Environmental and Economic Sustainability of Swine Wastewater Treatments Using Ammonia Stripping and Anaerobic Digestion: A Short Review Adele Folino 1, Demetrio Antonio Zema 1,* and Paolo S. Calabrò 2 1 Department Agraria, Mediterranea University of Reggio Calabria, Località Feo di Vito, I-89122 Reggio Calabria, Italy;
[email protected] 2 Department Diceam, Mediterranea University of Reggio Calabria, Via Graziella, Località Feo di Vito, I-89124 Reggio Calabria, Italy;
[email protected] * Correspondence:
[email protected] Received: 30 April 2020; Accepted: 16 June 2020; Published: 18 June 2020 Abstract: One of the most promising systems to treat swine wastewater is air stripping. This system simultaneously recovers nitrogen salts, to be used as fertiliser, and reduces the organic pollutant load in the effluents of swine breeding farms. Several reviews have discussed the air stripping as a treatment for many types of industrial wastewater or nitrogen-rich digestate (the liquid effluent derived from the anaerobic digestion plants) for the stripping/recovery of nutrients. However, reviews about the use of air stripping as treatment for raw or anaerobically digested swine wastewater are not available in literature. To fill this gap, this study: (i) Summarises the experiences of air stripping for recovery of ammonium salts from both raw and digested swine wastewater; and (ii) compares air stripping efficiency under different operational conditions. Moreover, combined systems including air stripping (such as struvite crystallisation, chemical precipitation, microwave radiation) have been compared. These comparisons have shown that air stripping of raw and digested swine wastewater fits well the concept of bio-refinery, because this system allows the sustainable management of the piggery effluent by extracting value-added compounds, by-products, and/or energy from wastewater.