AWWA WQTC69372

This powerpoint presentation begins by presenting the study focus on floc size that includes the following: granular filtration performance is a function of the influent particle size distribution; potential to be used on-line - Dynamic Particle Analyzer (PDA) from Brightwell Technologies, and - Photometric Dispersion Analyzer (PDA) from Rank Brothers; and, Drewes et al. have recently suggested that the average floc size (dn) was a useful parameter when charge neutralization coagulation conditions prevailed. The Photometric Dispersion Analyzer and the Dynamic Particle Analyzer 2100 are presented as analytical tools. Study objective was to evaluate to what extent direct filtration performance could be linked to the floc size or the flocculation index. Experimental desgin and set-up, and water characteristics are provided. Presentation conclusions indicated the following: the parameter, d_v, was the best indicator found to describe flocculation from the particle counter PSD; this indicator was more sensitive and less variable than the Flocculation Index provided by the PDA; establishing a direct link between d_v and filtered water turbidity was not a simple task, although it was observed that increasing d_v to values higher than 25 um generally led to lower filtered water turbidities; the addition of polymer significantly reduced the importance of flocculation, although its impact was minor on d_v; another characteristic than size was most likely impacted by the polymer; PASS100 in combination with polyDADMAC was selected as the best coagulation strategy; this strategy was confirmed to be optimal using an industrial pilot plant (50 m³/d); and, combining pre-ozonation and flocculation into a single process is currently under investigation. Includes tables, figures.