Hindered and compression solid settling functions – sensor data collection, practical model identification and validation

Benedek Plosz, Javier Climent, Christopher Griffin, Sergio Chiva, Rani Mukherjee, Eleni Penkarski-Rodon, Matt Clarke, BOrja Valverde-Perez

Research output: Contribution to journalArticle


Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in activated sludge water resource recovery facilities (WRRF). Mathematical models for predicting activated sludge solids settling velocity include parameters that show irreducible epistemic uncertainty. Therefore, reliable and periodic calibration of the settling velocity model is key for predicting activated sludge process capacity, thus averting possible failures under wet-weather flow- and filamentous bulking conditions. The two main knowledge gaps addressed here are: (1) Do constitutive functions for hindered and compression settling exist, for which all velocity parameters can be uniquely estimated? (2) What is the optimum sensor data requirement of developing reliable settling velocity functions? Innovative settling column sensor and full-scale data were used to identify and validate amended Vesilind function for hindered settling and a new exponential function for compression settling velocity using one-dimensional and computational fluid dynamics simulations. Results indicate practical model identifiability under well-settling and filamentous bulking conditions.
Original languageEnglish
Article number116129
JournalWater Research
Early online date7 Jul 2020
Publication statusE-pub ahead of print - 7 Jul 2020

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