Process Control · Hydraulic & Organic Loading
Weir Loading Rate
Flow per linear foot of effluent weir, a check against solids being pulled over the weir by excess velocity.
Weir Loading Rate = Flow (gpd) ÷ Weir Length (ft), typically kept under roughly 10,000–20,000 gpd/ft for secondary clarifiers depending on design standard.
Excessive weir loading concentrates flow velocity right at the weir edge, which can pull settled solids upward before they've fully compacted.
V-notch weirs distribute flow more evenly than straight weirs and can tolerate a somewhat higher loading rate for the same solids carryover risk.
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