title: Agronomic characteristics of five different urban waste digestates.
abstract: The use of digestate in agriculture is an efficient way to recycle materials and to decrease the use of mineral fertilizers. The agronomic characteristics of the digestates can promote plant growth and soil properties after digestate fertilization but also harmful effects can arise due to digestate quality, e.g. pH, organic matter and heavy metal content. The objective of this study was to evaluate the differences and similarities in agronomic characteristics and the value of five urban waste digestates from different biogas plants treating either food waste, organic fraction of organic solid waste or a mixture of waste-activated sludge and vegetable waste. The digestate agronomic characteristics were studied with chemical analyses and the availability of nutrients was also assessed with growth experiments and soil mineralization tests. All studied urban digestates produced 5-30% higher ryegrass yields compared to a control mineral fertilizer with a similar inorganic nitrogen concentration, while the feedstock source affected the agronomic value. Food waste and organic fraction of municipal solid waste digestates were characterized by high agronomic value due to the availability of nutrients and low heavy metal load. Waste-activated sludge as part of the feedstock mixture, however, increased the heavy metal content and reduced nitrogen availability to the plant, thus reducing the fertilizer value of the digestate.
authors.affiliation: Natural Resources Institute Finland (Luke), Bio-based Business and Industry, Tietotie 2 C, FI-31600, Jokioinen, Finland; Tampere University of Technology, Department of Chemistry and Bioengineering, P.O. Box 541, FI-33101, Tampere, Finland. Electronic address: elina.tampio@luke.fi.
authors.forename: Elina
authors.initials: E
authors.lastname: Tampio
authors.affiliation: Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Tietotie 4, FI-31600, Jokioinen, Finland.
authors.forename: Tapio
authors.initials: T
authors.lastname: Salo
authors.affiliation: Tampere University of Technology, Department of Chemistry and Bioengineering, P.O. Box 541, FI-33101, Tampere, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Rintala
mesh_terms: D000383:Agriculture / Q000379:methods*; D056804:Biofuels; D019149:Bioreactors; D018556:Crops, Agricultural / Q000254:growth & development; D005308:Fertilizers / Q000032:analysis; D019216:Metals, Heavy / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D012722:Sewage / Q000737:chemistry; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis; D062611:Solid Waste / Q000032:analysis; D018505:Waste Management / Q000379:methods*
chemical_list: D056804:Biofuels; D005308:Fertilizers; D019216:Metals, Heavy; D012722:Sewage; D012987:Soil; D012989:Soil Pollutants; D062611:Solid Waste; D009584:Nitrogen
keywords: Anaerobic digestion; Digestate; Fertilizer value; Heavy metals; Nutrients; Plant growth