Effect of chemical and biological surfactants on activated sludge of MBR system: microscopic analysis and foam test
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Updated: Apr 19, 2026

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Marco Capodici1, Gaetano Di Bella2, Salvatore Nicosia1
1Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali - Università degli Studi di Palermo, Viale delle Scienze, 90128 Palermo, Italy.
Abstract:
A bench-scale MBR unit was operated, under stressing condition, with the aim of stimulating the onset of foaming in the activated sludge. Possible synergies between synthetic surfactants in the wastewater and biological surfactants (Extra-Cellular Polymeric Substances, EPSs) were investigated by changing C/N ratio. The growth of filamentous bacteria was also discussed. The MBR unit provided satisfactory overall carbon removal overall efficiencies: in particular, synthetic surfactants were removed with efficiency higher than 90% and 95% for non-ionic and ionic surfactants, respectively. Lab investigation suggested also the importance to reduce synthetic surfactants presence entering into mixed liquor: otherwise, their presence can significantly worsen the natural foaming caused by biological surfactants (EPSs) produced by bacteria. Finally, a new analytic method based on "ink test" has been proposed as a useful tool to achieve a valuation of EPSs bound fraction.
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