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Long-Term Study of an Activated Sludge System Exhibiting a Seasonal Biological Foaming Problem

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Biological foaming is a widespread problem in the USA and in the world. Although great progress has been made with respect to identifying the microorganisms and the physical principals – causing foaming, the fundamental ecological mechanisms leading to foam formation remain ambiguous and illusive. Thus, general design and operation guidelines to avoid foaming have not found widespread use. In this study, we investigate the seasonal biological foaming problem at the Urbana-Champaign Sanitary District Northeast plant. We show that variation in temperature is the main factor contributing to the observed phenomenon. Further statistical analyses support the proposal that foam-causing organisms are specialists of the degradation of slowly degradable substrates (presumably lipids). According to this proposal, temperature selects for these organisms during the summer by increasing the degradation kinetics of their substrates. As a secondary mechanism, high concentrations of mixed liquor suspended solids (MLSS) are found to render the plant more prone to biological foaming. This suggests that the successful reports of control of biological foaming by means of increase sludge wastage can be due to both the washout of the foam-causing population and the reduction in MLSS.

Document Type: Research Article


Publication date: January 1, 2002

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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