A method for visualising polyelectrolyte distribution after polyelectrolyte conditioning of a biotic sludge

摘要

Charge neutralisation is an important mechanism in (polyelectrolyte) conditioning of biotic sludgesnand required for efficient sludge dewatering. Based on results from streaming potential and zetanpotential measurements, it has been suggested that charge neutralisation is more complete on thenoutside of the sludge flocs than on the inside. This paper discusses the development of a techniquenfor assessing the spatial distribution of polyelectrolyte (PE) within sludge flocs. After flocculation withna fluorescently labelled PE, fluorescence microscopy can be used to visualise the distribution of thenPE in the sludge flocs. Preliminary results indicate that the PE can penetrate relatively deep into thensludge flocs (and flocculi). Inhomogeneity in the PE distribution arises from differences in exposure tonPE in different regions, and from differences in the affinity of the PE for different substances.