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Clarifier & Solids

BOD/TSS Removal Efficiency

Calculates percent removal efficiency — the percent reduction between an influent and effluent concentration. Operators use it for performance tracking on BOD, TSS, total phosphorus, ammonia, and other parameters with NPDES limits.

BOD/TSS Removal Efficiency

Calculate the percent reduction between an influent and effluent concentration.

Enter all values above to calculate.

When you'd use this

Calculates percent removal efficiency — the percent reduction between an influent and effluent concentration. Operators use it for performance tracking on BOD, TSS, total phosphorus, ammonia, and other parameters with NPDES limits.

Category

Clarifier & Solids
Formula
Removal Efficiency (%) = ((Influent − Effluent) ÷ Influent) × 100
Variables & Units
Influent Concentration(mg/L)

Influent (incoming) concentration — typically primary effluent for secondary removal, or raw influent for total plant removal.

Effluent Concentration(mg/L)

Effluent (outgoing) concentration after the treatment step.

Worked Example
BOD influent 200 mg/L; effluent 10 mg/L: Removal Efficiency = ((200 − 10) ÷ 200) × 100 = 95% removal. Federal Secondary Treatment Regulation (40 CFR 133.102) requires ≥ 85% BOD and TSS removal as a 30-day average. Removal efficiency above 95% usually indicates good biological performance and effective final clarification.
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Reference

EPA Secondary Treatment Regulation — 40 CFR 133.102 (85% BOD/TSS removal).

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