Set the flow, detention, channel geometry and air rate — get the chamber volume, channel length,
diffused-air demand and blower capacity, and the daily grit production. Air — not just velocity — drives
organics away from the grit in this tropical headworks workhorse.
1Duty & chamber
Rectangular channels with diffused air along one wall create a roll that keeps organics in
suspension while 0.2 mm sand settles. Size by peak-flow detention (1–3 min) and air rate (0.3–0.6 m³ air/m³ water).
Results — chamber & air
Chamber volume V
—m³
Channel length L
—m
Grit / day
—kg/d
Item
Value
Basis
2Air & blower
Diffused air demand and the blower duty it implies — the instrument that actually runs this unit.
Item
Value
Basis
Operation envelope
Item
Value
Basis
Quote the grit instruments at factory price
An aerated chamber needs an inlet magnetic flowmeter, a level transmitter, a blower and its air-flow
signal — all mappable to our catalogue and supplied at the manufacturer's ex-works price (margin from the export rebate only).
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Sources & parameter basis
[1]
METCALF & EDDY 5th ed. / WEF MOP-8 — aerated grit detention 1–3 min, air 0.3–0.6 m³ air per m³ water, channel depth 2.5–4.5 m, design grain 0.2 mm, grit 5–10 L per 1000 m³.
[2]
Volume V = Qp·t; cross-section n·b·H; length L = V/(n·b·H); horizontal velocity = Qp/(n·b·H).
[3]
Air demand = AirRate·Qp; blower capacity = AirRate·Qp·60 (standard m³/min). Grit bulk density ≈ 1600 kg/m³ (wet).
Full derivation and worked example: Aerated-Grit-Calculation-Sheet.md. The aerated chamber is the organics-friendly alternative to the vortex — run it, then carry Q into the primary clarifier.
