title: The effect of organic loading rate on foam initiation during mesophilic anaerobic digestion of municipal wastewater sludge.
abstract: The impact of increasing organic load on anaerobic digestion foaming was studied at both full and bench scale. Organic loadings of 1.25, 2.5 and 5 kg VS m(-3) were applied to bench-scale digesters. Foaming was monitored at a full scale digester operated in a comparable organic loading range over 15 months. The bench scale batch studies identified 2.5 kg VS m(-3) as a critical threshold for foam initiation while 5 kg VS m(-3) resulted in persistent foaming. Investigation of a full scale foaming event corroborated the laboratory observation that foaming may be initiated at a loading rate of ≥ 2.5 kg VS m(-3). Experimental findings on foam composition and differences in the quality characteristics between foaming and non-foaming sludges indicated that foam initiation derived from the combined effect of the liquid and gas phases inside a digester and that the solids/biomass ultimately stabilized foaming.
authors.affiliation: Cranfield Water Science Institute, School of Applied Sciences, Cranfield University, Cranfield, Beds MK43 0AL, UK.
authors.forename: Nafsika
authors.initials: N
authors.lastname: Ganidi
authors.forename: Sean
authors.initials: S
authors.lastname: Tyrrel
authors.forename: Elise
authors.initials: E
authors.lastname: Cartmell
mesh_terms: D000704:Analysis of Variance; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D012722:Sewage / Q000032:analysis* / Q000382:microbiology; D013053:Spectrophotometry; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D012722:Sewage