CIP interval2× (from 4–6 to 8–12 weeks)
Normalized permeate flow≥ 98% @ 8 weeks
ΔP trendStable (±0.2 bar)
Recovery+3–5% at same feed
Customer
Industrial RO user treating high-TDS well water; frequent CIP from carbonate/sulfate scaling.
Challenge
- Premature scaling on lead elements; rising ΔP.
- Short CIP cycle; production downtime.
- Maintain membrane warranty and food-grade compliance where required.
Approach
Screened phosphonate actives with polymer dispersant for carbonate/sulfate/silica control. Selected a PBTC/HEDP blend + AA/SA terpolymer, dosed ahead of cartridge filters with 60–90 s contact time.
Formulation window
| Component | Function | Use level (mg/L) | Notes |
|---|---|---|---|
| PBTC / HEDP blend | Threshold inhibitor | 2–6 | Tune vs. CaSO₄/SiO₂ load & recovery. |
| AA/SA terpolymer | Dispersant | 1–3 | Holds precipitates/iron fines in suspension. |
| pH adjust (acid) | LSI control | as needed | Typical RO pH 6.5–7.5. |
| Biocide (optional) | Biofouling control | per SDS | Use non-oxidizing; check membrane guide. |
Processing & testing
- Dose before 5 µm cartridges; ensure steady feed and mixing.
- Avoid oxidants on polyamide membranes; verify compatibility.
- Track normalized flow, ΔP, conductivity, and scaling indices weekly.
Results
CIP interval doubled; ΔP stabilized; recovery increased within pump limits. Visual inspection showed cleaner lead elements and less scale in housings.