Measure net production
Express J in L/m²·h and calculate it as permeate flow divided by active area. Distinguish instantaneous flux, the average while filtering, and net daily flux after backwashes, CIP and downtime. The initial area equation A = Qp/J works only when J represents the real design duty.
TMP combines feed/return-side and permeate pressure according to module geometry. Record it alongside simultaneous flow, temperature and concentration; TMP alone is not productivity.
- Record flux, TMP, recirculation flow, temperature and solids concentration in the same interval.
- Separate clean-membrane start-up from end-of-cycle operation.
- Compare at equivalent temperature when viscosity changes.
Why more pressure can make the result worse
Initially, higher TMP may raise flux. Once deposit resistance or polarisation dominates, gains diminish while cake compaction and energy can rise. Measure a flux–TMP curve at several concentrations, not only with clean water.
Higher crossflow may limit some deposit, but needs pumping. Less fouling does not automatically repay its electricity. UltraFlux™ states a reference velocity range of 0.5–2.0 m/s for V8/V10; the viable point depends on the wastewater and the whole circuit.
| Variable | Intended effect | Cost or limit |
|---|---|---|
| TMP | Drive permeate | Fouling/energy at higher pressure |
| Velocity | Surface scouring | Pumping and pressure drop |
| Target flux | Reduce installed area | Shorter cycles if too high |
Design a test matrix
Change one variable at a time, keep feed comparable, and measure stable flux, permeate quality, specific energy and cleaning recovery. Repeat at target final concentration. The best operating point yields repeatable useful water over the intended duty, not a laboratory peak.
Plot flux against TMP at each tested concentration and note the time spent at every point. A single short reading after a pressure change can reflect transient deposition rather than a sustainable state. Keep a separate record of permeability after standardised cleaning to detect cumulative loss.
Common questions
Can clean-water flux size the plant?
No for a loaded effluent. It provides an integrity or reference test, not sustainable feed flux or cleaning performance.