SBR Cycle Time Calculator

Work out sbr cycle time instantly with clear inputs, formula shown and shareable results.

About SBR Cycle Time Calculator

A sequencing batch reactor cycles through fill, react, settle, decant and idle in one tank. Total cycle time determines how many batches a day each tank handles and therefore the volume it can treat. Typical cycles are 4-8 hours, with the react phase split into anoxic and aerobic sub-phases for nutrient removal.

Formulas

Cycle time

Cycle = fill + react + settle + decant and idle

Throughput

Cycles per day = 1440 / cycle time in minutes

Worked example

With the default values below, SBR Cycle Time Calculator returns Total Cycle Time of 270.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Fill Timeminimum 0 minutes: 60 minutes
React Timeminimum 0 minutes: 120 minutes
Settle Timeminimum 0 minutes: 45 minutes
Decant And Idle Timeminimum 0 minutes: 45 minutes

Results

Total Cycle Time: 270.0
Cycles Per Day: 5.333
React Phase Share: 44.444%
Aerated Share Of Cycle: 55.556%

Step by step

1Values used
2Cycle time
3Throughput
4Total Cycle Time= 270.0
5Cycles Per Day= 5.333
6React Phase Share= 44.444
7Aerated Share Of Cycle= 55.556

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How many tanks are needed?

At least two so one can accept flow while the other settles and decants, unless upstream balancing storage is provided. Three or more gives smoother operation and redundancy.

Why is settle time critical?

Decanting must draw clarified supernatant without disturbing the blanket. Insufficient settle time carries solids over; excessive settle time wastes cycle capacity and can trigger denitrification and rising sludge.