Interactive Calculator · 2026
Air Requirement Calculator
Estimate the process air an aeration tank needs. Enter the flow, inlet BOD and how efficiently your diffusers transfer oxygen — get the blower air requirement in m3 per minute, the number every aeration design starts from.
Your aeration load
Average daily sewage volume to the aeration tank.
Organic load reaching the tank — domestic ≈250–350.
Oxygen consumed per unit of BOD removed — typically 1.0–2.0 including endogenous respiration.
Share of supplied oxygen the diffusers actually dissolve — fine-bubble ≈8–12%.
From oxygen demand to air supplied
Air must far exceed the O2 demand — it is only ≈21% oxygen and diffusers dissolve just a fraction of it.
45 kg O2/day requires ≈2,008.9 m3/day of air at 8% transfer
How this is calculated
- BOD load = flow × BOD ÷ 1000 = 100 × 300 ÷ 1000 = 30 kg/day.
- O2 demand = BOD load × O2 factor = 30 × 1.50 = 45 kg/day.
- Air (m3/day) = O2 demand ÷ (0.28 × 8%) = 2,008.9 m3/day.
- Air (m3/min) = air per day ÷ 1440 = 1.4 m3/min.
Indicative aeration sizing for concept planning. A detailed design must also fix alpha/beta factors, temperature, altitude and diffuser layout — confirm with a qualified consultant before procurement.
Related Guides — Deep-dive reading
Aeration Design Principles for STPs: Oxygen Demand, Diffusers & Blower Sizing
How engineers actually size the aeration system at the heart of a sewage treatment plant — from oxygen demand and alpha/beta factors to SOTE, fine versus coarse bubble diffusers, blower selection and the energy bill that follows for decades.
Sewage Treatment PlantsHow to Size an STP: A Step-by-Step Method (With Worked Example)
The complete sizing methodology for a domestic sewage treatment plant — from headcount and LPCD to sewage generation, peak flow and tank-by-tank volumes — worked end to end with an Indian apartment example.
Sewage Treatment PlantsThe Sewage Treatment Process Flow, Explained: Every Stage From Inlet to Reuse
Follow a drop of sewage through a typical STP — inlet, screening, aeration, clarifier, filtration, disinfection and reuse — as one connected flow, with a block diagram and a unit-by-unit table, in plain language.
Sewage Treatment PlantsRelated Tools — You may also find these useful
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