Membrane Flux Calculator

Example data table

Saved runs

Operational context on job sites

Membrane flux is a practical KPI for filtration skids used on construction projects. It connects permeate production to installed membrane area, helping crews size temporary treatment for dewatering, tunnel drainage, and concrete wash‑water recovery. By recording flux per run, you can compare performance across pumps, hoses, and module counts, even when flow meters or tank volumes differ between locations.

Typical performance bands

Field flux depends on membrane type and solids loading. For many microfiltration or ultrafiltration modules treating site runoff, operators commonly track stabilized ranges around 30–120 LMH. Higher values may be achievable with strong pretreatment, while slurry or high‑silt streams can sit lower. Use the example table to benchmark early runs, then set your own baseline after commissioning and initial conditioning.

Temperature and normalization

Temperature swings can change measured flux without any real fouling. Water viscosity drops as temperature rises, so the same pump setting often produces a higher observed flux. Normalizing to a reference temperature makes morning and afternoon readings comparable, and supports consistent reporting across seasons. If you run multiple shifts, use one reference temperature for the entire project to avoid mixed comparisons.

TMP and permeability interpretation

Flux alone shows output; TMP explains resistance. When TMP rises while flux falls, membrane resistance is increasing due to fouling or cake formation. Many systems trigger cleaning or backwash review when normalized flux drops 10–15% from baseline or when TMP approaches the supplier’s operating window. Permeability (LMH/bar) is useful for comparing modules because it combines flux and TMP in one indicator.

Data capture for reporting and audits

Reliable decisions come from repeatable logging. Capture area, flow or volume/time, temperature, and—when available—feed, retentate, and permeate pressures. Add simple water‑quality notes such as turbidity, pH, conductivity, and any coagulant or polymer dose. The saved‑run history and exports support daily reports, subcontractor handovers, and evidence for discharge compliance checks. Include timestamp, operator name, backwash interval, and any chemical cleaning performed so trends can be explained later. When possible.

FAQs

What does LMH mean in the results?

LMH means liters per square meter per hour. It is permeate flow divided by active membrane area, so different module sizes can be compared consistently.

When should I use Volume/Time mode instead of Flow/Area?

Use Volume/Time when you measured permeate in a tank over a known filtration period. Use Flow/Area when you already have a reliable flow meter reading at steady operation.

Why is my normalized flux higher or lower than the measured flux?

Normalization adjusts flux for viscosity differences between the operating temperature and the reference temperature. Cooler water is more viscous, so normalized values often increase when correcting cold runs.

How do I interpret a rising TMP with steady flux?

Rising TMP at steady flux usually means increasing resistance in the membrane or cake layer. Review pretreatment, backwash frequency, and solids loading, and consider a cleaning step if the trend continues.

What membrane area should I enter for multi-module skids?

Enter the total active area of all installed modules that are online during the run. If one module is isolated or offline, exclude its area for that calculation.

How many runs are included in the exports?

The calculator stores up to 50 recent runs in your browser session. The CSV and PDF exports include the saved history, and you can clear it at any time.