Work out bod removal efficiency instantly with clear inputs, formula shown and shareable results.
BOD removal efficiency is the fractional reduction in concentration. Conventional activated sludge achieves 90-96%, trickling filters 80-90% and primary settlement alone 25-40%. Because consent limits are absolute, a strong influent requires a higher percentage removal to reach the same effluent quality.
Removal efficiency
Efficiency % = (influent BOD - effluent BOD) x 100 / influent BOD
Consent requirement
Required efficiency = (influent - consent limit) x 100 / influent
Effluent quality limits are legally binding consent conditions with sampling and reporting requirements. Verify against the specific consent.
The consent is a fixed concentration. Doubling influent BOD from 250 to 500 mg/L means removal must rise from 92% to 96% to hit 20 mg/L, which needs longer sludge age and more aeration.
Yes. Many consents impose both a maximum concentration and a minimum percentage removal, so a plant cannot comply simply by dilution.