WAS Rate to Hold Target SRT (Sludge Age)
The daily wasting decision: how much sludge to waste today to hold a target SRT. Q_WAS = (system_solids/SRT - effluent_solids) / (WAS x 8.34), in MGD and gpm. The inverse of a sludge-age readout; effluent solids over the weir count as wasted and cut the pump rate. SRT lags ~one SRT, so change gradually.
Formula and source
system_solids = V x MLSS x 8.34; solids_to_waste = system_solids / SRT; effluent_solids = Qeff x TSSeff x 8.34; Q_WAS = (solids_to_waste - effluent_solids) / (WAS x 8.34); Q_WAS_gpm = Q_WAS x 1e6 / 1440.
WAS rate for a target SRT (MCRT/SRT control; WEF operator training), by name.
Audience
This tile is built for trades and the adjacent professions in the Water and Wastewater Operations group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.