- qsdsan.utils.get_SRT(system, biomass_IDs, wastage=None, active_unit_IDs=None)#
Estimate sludge residence time (SRT) of an activated sludge system.
system (obj) – The system whose SRT will be calculated for.
biomass_IDs (tuple[str]) – Component IDs of active biomass.
WasteStream]) – Streams with wasted biomass.
active_unit_IDs (tuple[str], optional) – IDs of activated sludge units. The default is None, meaning to include all units in the system.
[float] Estimated sludge residence time in days.
.. note:: –  This function uses component flowrates of the system’s product WasteStream for calculation, which does not carry time-dependent information. So, it should not be used for a system with dynamic influents.  The units included in calculation must all have
get_retained_mass()to calculate the retained biomass.