Interactive Calculator · 2026
BOD Load Calculator
Work out the organic (BOD) load on a sewage treatment plant. Enter the daily flow and the inlet and target outlet BOD to get the load in kg/day and the removal efficiency your STP must achieve to meet discharge norms.
Inlet BOD must fall by 96.7% to reach the target outlet BOD
Flow & BOD
Average daily sewage flow into the STP.
Raw sewage is typically ≈250–350 mg/L.
CPCB discharge norms usually cap treated-sewage BOD at 10 mg/L (reuse) to 30 mg/L (disposal).
Inlet vs outlet BOD
Your STP must strip 96.7% of the incoming BOD — 29 kg of organic load every day.
The gap between inlet and target outlet BOD is the work the biology must do. A higher removal % means a bigger aeration/treatment stage and more careful operation.
How this is calculated
- Inlet BOD load = flow × inlet BOD ÷ 1000 = 100 × 300 ÷ 1000 = 30 kg/day.
- Outlet BOD load = flow × target outlet BOD ÷ 1000 = 100 × 10 ÷ 1000 = 1 kg/day.
- BOD removal required = (1 − target outlet BOD ÷ inlet BOD) × 100 = 96.7%.
Indicative organic-load figures for concept planning. A detailed design also fixes peak factor, F/M ratio, MLSS and aeration demand — confirm with a qualified consultant before procurement.
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