title: Anaerobic digestion of microalgal biomass after ultrasound pretreatment.
abstract: High rate algal ponds are an economic and sustainable alternative for wastewater treatment, where microalgae and bacteria grow in symbiosis removing organic matter and nutrients. Microalgal biomass produced in these systems can be valorised through anaerobic digestion. However, microalgae anaerobic biodegradability is limited by the complex cell wall structure and therefore a pretreatment step may be required to improve the methane yield. In this study, ultrasound pretreatment at a range of applied specific energy (16-67 MJ/kg TS) was investigated prior to microalgae anaerobic digestion. Experiments showed how organic matter solubilisation (16-100%), hydrolysis rate (25-56%) and methane yield (6-33%) were improved as the pretreatment intensity increased. Mathematical modelling revealed that ultrasonication had a higher effect on the methane yield than on the hydrolysis rate. A preliminary energy assessment indicated that the methane yield increase was not high enough as to compensate the electricity requirement of ultrasonication without biomass dewatering (8% VS).
authors.affiliation: GEMMA - Group of Environmental Engineering and Microbiology, Department of Hydraulic, Maritime and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, c/Jordi Girona 1-3, Building D1, E-08034 Barcelona, Spain.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Passos
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: Sergi
authors.initials: S
authors.lastname: Astals
authors.affiliation: GEMMA - Group of Environmental Engineering and Microbiology, Department of Hydraulic, Maritime 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: D000693:Anaerobiosis; D018533:Biomass; D019149:Bioreactors; D006868:Hydrolysis; D007700:Kinetics; D008697:Methane / Q000378:metabolism*; D058086:Microalgae / Q000737:chemistry*; D008962:Models, Theoretical; D009930:Organic Chemicals / Q000737:chemistry*; D014463:Ultrasonography; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis
chemical_list: D008697:Methane; D009930:Organic Chemicals; D062065:Wastewater
keywords: Algae; Anaerobic biodegradability; Biogas; High rate algal pond; Microalgae; Wastewater