Settling regimen transitions quantify solid separation limitations through correlation with floc size and shape

This study monitored three different activated sludge systems from the Blue Plains Advanced Wastewater Plant for a 1 year period to explore the relationship between effluent quality and activated sludge settling and flocculation behavior. Hindered settling rates (ISV) and sludge volume index (SVI) measurements were collected weekly. Novel metrics based on the solids concentration at which the transition between settling regimens occurred were also collected weekly. The transitional metrics were Threshold of Flocculation (TOF), and Limit of Stokesian Settling (LOSS). They marked the transition from discreet to flocculant settling, and from flocculant to hindered settling, respectively. A pilot clarifier and settling column were run and filmed to determine floc morphological properties. SVI was found to lose sensitivity (r