@article {Narayanan:2003:1938-6478:724,
	author = "Narayanan, B. and de Leon, C. and Radke, C.J. and Jenkins, David",
	title = "THE ROLE OF DISPERSED NOCARDIOFORM FILAMENTS IN ACTIVATED SLUDGE FOAMING",
	journal = "Proceedings of the Water Environment Federation",
	volume = "2003",
	number = "11",
	year = "2003",
	abstract = "Activated sludge foaming caused by filamentous microorganisms is a major wastewater treatment plant operating problem. This paper presents the results of an investigation of the role of dispersed nocardioforms in activated sludge foaming. Dispersed nocardioforms had a greater propensity for foaming than floc-bound nocardioforms. The mode of effluent withdrawal from an aeration basin plays a major role in determining the relative proportion of dispersed and floc-bound nocardioforms in the activated sludge. Reactors with “trapping” features (sub-surface effluent withdrawal) had significantly higher dispersed nocardioform populations than reactors with “non-trapping” features (surface effluent withdrawal). High dispersed nocardioform filament concentrations were correlated with a high propensity for foaming. Cationic polymer and poly-aluminum chloride reduced foaming by flocculating dispersed nocardioforms, thereby converting them to floc-bound nocardioforms. Low non-ionic surfactant concentrations changed the relative proportions of dispersed and floc-bound nocardioforms by deflocculating floc-bound filaments and converting them to the dispersed growth form. This could act as a trigger for initiating the rapid-onset nocardioform foaming events observed at activated sludge plants.",
	pages = "724-739",
	url = "http://www.ingentaconnect.com/content/wef/wefproc/2003/00002003/00000011/art00057",
	doi = "doi:10.2175/193864703784756020"
}