A falling permeate flow is a symptom, not a cleaning instruction. Feed temperature, salinity, recovery, pressure and pretreatment condition can change the observed result without a new deposit on the membrane. Before an industrial RO plant is accepted, the supplier and operator should agree on a comparable baseline, a decision route and the exact cleaning-in-place interfaces. The installed membrane instructions control chemicals and operating limits.
1. Establish a comparable operating baseline
Record each train and stage separately at stable operation: feed, concentrate and permeate flows; feed, interstage and concentrate pressures; temperature; feed and permeate conductivity; recovery; pH; and pretreatment condition. Preserve instrument calibration, membrane model, element arrangement and the acceptance water analysis with the same record. A single daily permeate volume cannot separate hydraulic fouling from colder feed water or changing salinity.
Normalize permeate flow, salt passage and pressure drop using the method approved for the actual membrane and plant. Compare the result with a valid post-commissioning or post-cleaning baseline, at a documented operating point. Investigate filter differential pressure, dosing, oxidant exposure, feed chemistry, valve position and recovery before ordering a chemical clean. DuPont publishes example trigger percentages for its FilmTec elements; these are manufacturer examples, not automatic thresholds for a BOKAWATER package.
2. Specify the cleaning skid and safe operating boundary
Ask the supplier to identify which membranes are installed and provide the current element manual. The cleaning procedure must list compatible chemicals, permitted pH and temperature together, exposure time, circulation direction, flow and pressure, and the required quality of dilution and rinse water. Do not transfer limits from another brand, membrane family or operating temperature. Confirm who approves any exceptional procedure.
On the piping diagram mark cleaning supply and return, isolation valves, permeate route, tank usable volume, pump and filter duties, heater or cooling control, pH and temperature measurement, sample points, vents and drains. Check chemical storage, operator protection, spill containment and the legally accepted destination for spent solution. Define how normal production is isolated and how a second train remains protected while one train is cleaned.
3. Make acceptance depend on evidence after cleaning
Before cleaning save the trend and the suspected foulant evidence. During the work log chemical identity and batch, prepared concentration, pH, temperature, circulation periods, flow, pressure, tank condition, changes in solution appearance and any abnormal event. Rinse and restart only under the installed element and plant instructions; never infer that an arbitrary cleaning recipe will restore rated production.
After stabilization record the same flows, pressures, temperature and conductivities as the baseline, then normalize by the same method. Compare stage pressure drop, permeate flow and salt passage and note what recovered, what did not, and the next investigation. Confirm final permeate quality against the project specification and keep a signed service record. BK-3000RO is an existing BOKAWATER catalog model, but its catalog name alone does not identify the membrane chemistry or a verified cleaning interval.
Data to collect before comparing proposals
| Parameter / interface | Unit / format | Why it matters |
|---|---|---|
| Decision | Minimum record | Acceptance question |
| Baseline | Stable flows, pressures, temperature and conductivity | Comparable point available? |
| Normalization | Approved method and reference conditions | Trend corrected consistently? |
| Pretreatment | Filter, dosing and feed-water history | Alternative cause checked? |
| Elements | Installed model and current manual | Chemical limits confirmed? |
| CIP interface | Valves, tank, pump, filter and drains | Connections demonstrated? |
| Chemistry | Identity, concentration, pH and temperature | Within actual element limits? |
| Waste route | Spent solution and rinse destination | Legal route documented? |
| Post-cleaning | Same measurements and normalization | Recovery quantified? |
| Release | Permeate quality and signed operator record | Project specification met? |
Technical references
- DuPont — Cleaning Procedures for FilmTec Elements ↗Source checked:
Evidence scope — original English record
Manufacturer guidance distinguishes normalized flow, salt passage and stage differential pressure from temperature or pretreatment changes; published example cleaning triggers belong to FilmTec elements, not BOKAWATER guarantees.
- DuPont — FilmTec RO and NF Technical Manual ↗Source checked:
Evidence scope — original English record
Manufacturer manual documents membrane-specific cleaning limits and warns that late cleaning can limit recovery; chemistry and limits must be checked against the actual installed elements.
- Hydranautics — RO and NF membrane cleaning and flushing procedures ↗Source checked:
Evidence scope — original English record
Manufacturer bulletin supports logging cleaning solution conditions, safe flushing and normalized performance after cleaning; its operating limits are not transferable to other membrane models.
- BOKAWATER — BK-3000RO industrial system ↗Source checked:
Evidence scope — original English record
Current BOKAWATER product page confirms the BK-3000RO industrial RO equipment family; it does not identify every installed membrane or establish a universal CIP recipe.