Mechanical pretreatments of different agri-based feedstock in full-scale biogas plants under real operational conditions. (March 2022)

• Record Type: Journal Article
• Authors: Garuti, Mirco; Sinisgalli, Erika; Soldano, Mariangela; Fermoso, Fernando G.; Rodriguez, Antonia Jimenez; Carnevale, Monica; Gallucci, Francesco
• Is Part Of: Biomass and bioenergy. Volume 158(2022)
• Publication Date: 2022-03
• Subjects: Agricultural feedstock -- Mechanical pretreatments -- Anaerobic digestion -- Biomethane -- Particle size distribution; Biomass energy -- Periodicals; Biomass -- Periodicals; Energy-Generating Resources -- Periodicals; Bioénergie -- Périodiques; 333.9539
• DOI: 10.1016/j.biombioe.2022.106352
• Languages: English
• ISSNs: 0961-9534

Abstract

Abstract: Mechanical pretreatments are commonly used devices at full-scale to reduce the size of feedstock and to increase methane production, improving mixing, heat, and mass transfer into the anaerobic digesters of biogas plants. Nevertheless, physical pretreatments require considerable energy. This work aimed to investigate how the energy consumption in different mechanical pretreatments that effectively run under real operational conditions at full-scale level affects physical modifications and anaerobic degradability of agri-based feedstock. Four mechanical pretreatment were investigated: knife milling, hammer milling, extrusion, shredding + hydrodynamic cavitation. After pretreatments, the specific methane yield increased in the range from 1% to 13% and the maximum methane production rate increased in the range from 4% to 48%. Each pretreatment leads to a positive energy balance (0.14–27 kJ kJ −1 used). The increasing of energy consumption indicates a more intense pretreatment with an incremental reduction of particles with diameter bigger than 5 mm. On the basis of the calculated regression analysis, a specific combination of additional specific surface area and additional energy in the day of maximum methane production should be expected with mechanical pretreatment that run effectively at full-scale level. Graphical abstract: Image 1 Highlights: Four mechanical pretreatments in real operational conditions were investigated. Benefits in methane yield (+1–13%) and methane production rate (+4–48%) were achieved. 10–40 kJ kg −1 leads to incremental reduction of particles ≥ 5 mm. Methane production rate is related to the increasing of specific surface area.