How to use this tool

Enter the required measurements in the stated units.
Choose Calculate.
Review the result, formula, source, and scope caveat.

Formula and units

Secondary clarifier solids loading = MLSS × (Q + RAS) ÷ area, with flow units made consistent. Keep all flow values on the same time basis and use the displayed units.

Scope and limitations

This is a screening calculation from your inputs. It does not select design criteria, account for hydraulics, settling behavior, short-circuiting, peak factors, safety factors, or regulatory compliance. Confirm design decisions with applicable permits, standards, and a qualified wastewater professional.

Source

Reference: U.S. EPA, Wastewater Technology Fact Sheet and design guidance: https://19january2021snapshot.epa.gov/sites/static/files/2019-12/documents/activated_sludge_process_control_and_troubleshooting_manual.pdf

Local processing

Inputs stay in your browser; no values are uploaded.

GOOD TO KNOW

Common questions

Does this choose a design value?

No. It applies the stated formula to your inputs only.

Are inputs uploaded?

No. Calculation runs locally in your browser.