title: A full-scale study of mixing and foaming in egg-shaped anaerobic digesters.
abstract: Seasonal foaming in full-scale egg-shaped digesters (ESD) at the Oceanside Water Pollution Control Plant was investigated over a two-year period. The causes and contributors of anaerobic digestion (AD) foaming, namely, Gordonia amarae filaments and mixing effects were evaluated in these ESDs. The seasonal presence of high levels of G. amarae as a primary cause and excessive induced mixing as an important contributor of AD foaming has been established. The induced mixing frequency in the ESDs was gradually reduced and eventually shut off in a series of controlled experimental phases. Total solids and temperature profiles indicated that reducing mixing frequency did not significantly impact digester performance or disrupt the homogeneity of digester contents, although it did reduce the occurrence of foam in the digesters. Excessive induced mixing, a contributor to foaming, increased foam events at G. amarae thresholds above 10(6)intersections/mg VSS in the mixed liquor.
authors.affiliation: Department of Civil, Architectural, and Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA.
authors.forename: Bhargavi
authors.initials: B
authors.lastname: Subramanian
authors.affiliation: San Francisco Public Utilities Commission, San Francisco, CA 94132, USA.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Miot
authors.affiliation: San Francisco Public Utilities Commission, San Francisco, CA 94132, USA.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Jones
authors.affiliation: San Francisco Public Utilities Commission, San Francisco, CA 94132, USA.
authors.forename: Corey
authors.initials: C
authors.lastname: Klibert
authors.affiliation: Department of Civil, Architectural, and Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA. Electronic address: pagilla@iit.edu.
authors.forename: Krishna R
authors.initials: KR
authors.lastname: Pagilla
mesh_terms: D000693:Anaerobiosis; D019149:Bioreactors / Q000382:microbiology; D004867:Equipment Design; D033601:Gordonia Bacterium / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D012722:Sewage; D013499:Surface Properties; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods
chemical_list: D012722:Sewage
keywords: Anaerobic digestion foaming; Egg-shaped digesters; Gordonia amarae; Mixing