title: Effect of thermal hydrolysis and ultrasounds pretreatments on foaming in anaerobic digesters.
abstract: Foam appears regularly in anaerobic digesters producing operational and safety problems. In this research, based on the operational observation at semi-industrial pilot scale where sludge pretreatment mitigated foaming in anaerobic digesters, this study aimed at evaluating any potential relationship between foaming tools applied to activated sludge at lab-scale (foam potential, foam stability and Microthrix parvicella abundance) and the experimental behavior observed in pilot scale and full-scale anaerobic digesters. The potential of thermal hydrolysis and ultrasounds for reducing foaming capacity was also evaluated. Filamentous bacteria abundance was directly linked to foaming capacity in anaerobic processes. A maximum reduction of M.parvicella abundance (from 5 to 2) was reached using thermal hydrolysis with steam explosion at 170°C and ultrasounds at 66.7kWh/m(3), showing both good anti-foaming properties. On the other hand, foam potential and stability determinations showed a lack of consistency with the bacteria abundance results and experimental evidences.
authors.affiliation: University of Valladolid, Chemical Engineering and Environmental Technology Department, EII (sede Mergelina), 47011 Valladolid, Spain. Electronic address: natalia.alfaro@iq.uva.es.
authors.forename: N
authors.initials: N
authors.lastname: Alfaro
authors.affiliation: University of Valladolid, Chemical Engineering and Environmental Technology Department, EII (sede Mergelina), 47011 Valladolid, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Cano
authors.affiliation: University of Valladolid, Chemical Engineering and Environmental Technology Department, EII (sede Mergelina), 47011 Valladolid, Spain. Electronic address: ffp@iq.uva.es.
authors.forename: F
authors.initials: F
authors.lastname: Fdz-Polanco
mesh_terms: D039903:Actinobacteria / Q000254:growth & development / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D019149:Bioreactors; D004063:Digestion / Q000502:physiology*; D006358:Hot Temperature; D006868:Hydrolysis; D013016:Sound
keywords: Anaerobic digestion; Foaming; Pretreatment; Thermal hydrolysis; Ultrasound