“…Although sludge settling is a multiphase problem, a single‐phase flow model has become the most widely applied approach in the academic (e.g. De Clercq, ; Lakehal, Krebs, Krijgsman, & Rodi, ; Patziger et al, ; Ramin et al, ; Saffarian, Hamedi, & Shams, ; Vitasovic et al, ; Weiss et al, ) and non‐academic SST projects (e.g., Morse et al, ; Shaw, McGuffie, Wallis‐Lage, & Barnard, ; Wicklein & Samstag, ) because of its economy and accuracy for the prediction of sludge distribution. Additionally, Wicklein and Samstag () quantitatively compared the performance of this single‐phase modeling approach with the mixture multiphase model in both full‐scale circular and rectangular SSTs.…”