Use this engineering calculation for a transparent preliminary estimate or independent arithmetic check when geometry, materials, loads, operating conditions, and units are defined consistently.

Flow Cubic Meters Per Day (m³/day)

Required number input.

Influent Bod Milligrams Per Liter (mg/L)

Required number input.

Aeration Volume Cubic Meters (m³)

Required number input.

Biomass Milligrams Per Liter (mg/L)

Required number input.

Activated-sludge food-to-microorganism ratio Q·S0/(V·X) using matching influent substrate and biomass concentration units. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Food To Microorganism Per Day (1/day)

The resulting food to microorganism per day returned as a number.

• Activated-sludge ratios and removal estimates depend on sampling basis, biodegradable versus total load, solids inventory, sludge age, temperature, oxygen, settling, recycle streams, and steady-state assumptions. Plant control and discharge compliance require validated process measurements.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check assumptions against drawings, measurements, current material data, and the applicable design code. Apply required load combinations and safety factors, then obtain qualified review and testing for consequential designs.

• Chiller Cop

  Chiller coefficient of performance as cooling output divided by electrical input power, in matching power units.

• Factor Of Safety

  Nominal strength-to-applied-demand ratio for quantities expressed in the same units; does not select an acceptable design margin.

• Belt Drive Speed Ratio

  Ideal no-slip driven-to-driver pulley speed ratio from pitch diameters.