Equalization Basin

Set the flow, peaking factor and peak duration — get the basin volume that smooths the diurnal surge, the hydraulic retention time, the surface area and the mixing power. The unit that turns a spiky SEA influent into a steady feed for the biology and the dosing skids.

1Duty & basin

Size the basin to absorb the peak surge while discharging at the average: V = (Peak−1)·Q·τ/24. Then mix to stop septicity and keep solids in suspension.

Avg flow Q^[1] (1k–500k)m³/d

Peak factor^[1] (1.5–3)×

Peak τ^[1] (2–10)h

Depth H^[1] (3–6)m

Mix power^[2] (4–10)W/m³

Mix type^[2]

Results — basin & mixing

EQ volume V

—m³

Retention

—h

Mixing power

—kW

Item	Value	Basis

2Mass balancing

What the basin actually does to the flow and load profile hitting the plant.

Item	Value	Basis

Operation envelope

Item	Value	Basis

Quote the EQ instruments at factory price

An equalization basin needs in/out flowmeters, a level transmitter, pH and the mixer/VFD 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]	WEF / METCALF & EDDY — equalization volume V = (Peak−1)·Q·τ/24; peak factor 1.5–3×, peak duration 2–10 h, depth 3–6 m.
[2]	Mixing 4–10 W/m³ (mechanical) or 0.006–0.012 m³ air/m³·min (diffused); power = V·w_mix (mechanical) — prevents settling & septicity.

Full derivation and worked example: Equalization-Basin-Calculation-Sheet.md. The EQ basin is the buffer that makes every downstream unit predictable — run it, then carry Q into the primary clarifier.

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