title: Assessing the agricultural reuse of the digestate from microalgae anaerobic digestion and co-digestion with sewage sludge.
abstract: Microalgae anaerobic digestion produces biogas along with a digestate that may be reused in agriculture. However, the properties of this digestate for agricultural reuse have yet to be determined. The aim of this study was to characterise digestates from different microalgae anaerobic digestion processes (i.e. digestion of untreated microalgae, thermally pretreated microalgae and thermally pretreated microalgae in co-digestion with primary sludge). The main parameters evaluated were organic matter, macronutrients and heavy metals content, hygenisation, potential phytotoxicity and organic matter stabilisation. According to the results, all microalgae digestates presented suitable organic matter and macronutrients, especially organic and ammonium nitrogen, for agricultural soils amendment. However, the thermally pretreated microalgae digestate was the least stabilised digestate in comparison with untreated microalgae and co-digestion digestates. In vivo bioassays demonstrated that the digestates did not show residual phytotoxicity when properly diluted, being the co-digestion digestate the one which presented less phytotoxicity. Heavy metals contents resulted far below the threshold established by the European legislation on sludge spreading. Moreover, low presence of E. coli was observed in all digestates. Therefore, agricultural reuse of thermally pretreated microalgae and primary sludge co-digestate through irrigation emerges a suitable strategy to recycle nutrients from wastewater.
authors.affiliation: GEMMA - Environmental Engineering and Microbiology Research Group, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, c/ Jordi Girona 1-3, Building D1, E-08034 Barcelona, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Solé-Bundó
authors.affiliation: GEMMA - Environmental Engineering and Microbiology Research Group, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, c/ Jordi Girona 1-3, Building D1, E-08034 Barcelona, Spain; Department of Civil and Environmental Engineering, University of Perugia, Borgo XX Giugno 74, 06124 Perugia, Italy.
authors.forename: Mirko
authors.initials: M
authors.lastname: Cucina
authors.affiliation: Department of Natural Products, Plant Biology and Soil Science, School of Pharmacy, University of Barcelona, Avda. Joan XXIII s/n, E-08028 Barcelona, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Folch
authors.affiliation: Department of Natural Products, Plant Biology and Soil Science, School of Pharmacy, University of Barcelona, Avda. Joan XXIII s/n, E-08028 Barcelona, Spain.
authors.forename: Josefina
authors.initials: J
authors.lastname: Tàpias
authors.affiliation: Department of Civil and Environmental Engineering, University of Perugia, Borgo XX Giugno 74, 06124 Perugia, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gigliotti
authors.affiliation: GEMMA - Environmental Engineering and Microbiology Research Group, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, c/ Jordi Girona 1-3, Building D1, E-08034 Barcelona, Spain.
authors.forename: Marianna
authors.initials: M
authors.lastname: Garfí
authors.affiliation: GEMMA - Environmental Engineering and Microbiology Research Group, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, c/ Jordi Girona 1-3, Building D1, E-08034 Barcelona, Spain. Electronic address: ivet.ferrer@upc.edu.
authors.forename: Ivet
authors.initials: I
authors.lastname: Ferrer
mesh_terms: D057914:Agricultural Irrigation; D000383:Agriculture; D000693:Anaerobiosis; D058086:Microalgae; D059027:Recycling; D012722:Sewage / Q000382:microbiology*; D062065:Wastewater
chemical_list: D012722:Sewage; D062065:Wastewater
keywords: Anaerobic co-digestion; Biofertiliser; Biogas; Land spreading; Phytotoxicity; Thermal pretreatment