Operator math, plug-and-go.
Every formula operators run on shift, worked with real plant numbers — 13 calculators across activated sludge, clarifiers, chemical dosing, disinfection, hydraulics, and pumping, all on one page.
Open the full calculator page
All 13 calculators grouped by category, mobile-friendly, plug in your own numbers for an accurate result.
Pounds per day of chemical and the metering pump rate for liquid feed dosing.
Detention time and unit conversion between MGD, gpm, and cfs.
Chlorine CT values and contact-time verification for disinfection compliance.
Water and brake horsepower for a given pump duty point.
F/M, MCRT, and RAS rate — the math behind keeping the biology in balance.
F/M Ratio
Compare the organic load entering the aeration basin to the biomass available to treat it.
MCRT (Sludge Age)
Calculate mean cell residence time from MLSS, wasting, and effluent solids data.
Required RAS Rate
Estimate the return activated sludge rate needed to maintain a target MLSS.
Settling performance checks: surface overflow rate, weir overflow, solids loading, and removal efficiency.
Surface Overflow Rate (SOR)
Check clarifier settling performance by dividing flow by surface area.
Weir Overflow Rate
Check the flow rate per foot of weir length in a clarifier.
Solids Loading Rate
Check how many pounds of solids per day are applied per square foot of clarifier area.
BOD/TSS Removal Efficiency
Calculate the percent reduction between an influent and effluent concentration.
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