“…This has led to an urgent need to manage large volumes of biosolids under the increasingly strict environmental regulations and license operation conditions imposed upon water utilities and other wastewater operators. The hydraulic inefficiency of WSPs is a problem that increases in severity over time, as long-term hydraulic performance of ponds is increasingly compromised as sludge accumulates, which results in reduced effective treatment volume and changes in bottom bathymetry (Nelson, Cisneros, Tchobanoglous, & Darby, 2004;Olukanni & Ducoste, 2011;Peña, Mara, & Sanchez, 2000;Persson, 2000;Persson, Somes, & Wong, 1999;Persson & Wittgren, 2003;Sah, Rousseau, & Hooijmans, 2012). In turn, the build-up of sludge in these systems contributes to the complexity of pond hydrodynamics (Faleschini, Esteves, & Valero, 2012); for example, pond features such as channels can result in short-circuiting of flow and reduced mean hydraulic residence time (Figure 3).…”