Industrial Reverse Osmosis (RO) Systems and RO + EDI Pure Water Lines
In Turkey, Mikron Proses (Üsküdar, Istanbul) designs, installs, commissions and services industrial and pharmaceutical reverse osmosis (RO) systems: single-pass, double-pass and RO plus EDI, selected from the raw-water analysis, the target permeate flow and the target water class. Pharmaceutical lines are carried out with DQ, IQ, OQ and PQ validation. Reverse osmosis passes water under pressure through a semi-permeable membrane that separates dissolved salts, organic molecules, colloids and microorganisms; it is the main stage of process water and ultrapure water lines in pharmaceutical (PW and WFI pre-treatment), biotechnology, power plant boiler feed, food and beverage and chemical plants.
Five Core Decisions in RO System Design
- Configuration: single-pass RO (or RO plus EDI) is typical for process water and boiler feed water; double-pass RO plus CEDI is selected for high feed conductivity and for pharmaceutical PW and membrane-based WFI lines.
- Pre-treatment chain: turbidity/SDI removal, activated carbon or SMBS dechlorination, softening and/or antiscalant dosing, and a 5 µm security cartridge filter at the RO inlet protect polyamide TFC membranes.
- Dissolved gas (CO₂ / O₂) management: because dissolved CO₂ passes through the RO membrane, a membrane contactor or pH adjustment lowers the CO₂ load ahead of EDI.
- CEDI integration: for continuous production without acid/caustic regeneration, RO permeate feeds Ionpure CEDI modules; Mikron Proses is an OEM partner and system integrator for Ionpure.
- Instrumentation and CIP follow-up: inlet/outlet conductivity, pH, ORP, flow and stage differential pressure (ΔP) are monitored continuously so that membrane fouling is caught early from normalized data.
Source note: membrane operating and CIP criteria come from the DuPont FilmTec RO membrane technical manual (Form No. 609-00071-1009), CEDI feed limits from the Ionpure LX manual (Table 2-3), membrane values from the manufacturer datasheets, and pharmaceutical water requirements from USP <1231> / <645> / <643>, Ph. Eur. and ISO 22519.
What an RO System Includes and the Design Inputs
An RO system is not a single machine but a chain of equipment sized relative to each other, from pre-treatment to the permeate line.
System components
- Pre-treatment group: multimedia/sand filter or UF, activated carbon or SMBS, softening and/or antiscalant dosing.
- Security cartridge filter: fine particle retention (5 µm) ahead of the RO high-pressure pump.
- High-pressure pump: delivers the feed water to the membrane array at the required pressure.
- Membrane elements and pressure vessels: spiral-wound RO elements are arranged in serial pressure vessels; concentrate recovery is raised by the number of stages.
- Instrumentation and control: inlet/outlet conductivity, pH, ORP/free chlorine, flow and stage ΔP, with normalized data tracking.
- Chemical cleaning (CIP) connections for periodic membrane cleaning; see CIP and SIP explained.
- For double-pass and RO plus EDI lines, additionally: a second-pass pump and membrane array, membrane gas removal, and the CEDI module with its DC power supply.
Design inputs
- Raw-water analysis: conductivity, hardness, silica, free chlorine, turbidity and SDI, temperature, TOC.
- Target permeate flow and operating pattern.
- Target water class: process water, boiler feed water, PW or WFI; the class decides the number of passes and the need for EDI.
- Recovery rate and concentrate discharge conditions.
- Existing system configuration: a new line or an extension of an existing line.
- Validation need: URS, DQ, IQ, OQ and PQ scope for pharmaceutical lines.
System Architectures
A "pass" is the number of times water passes through the membrane; a "stage" is serial pressure vessels that recover concentrate.
| Architecture | Flow Summary | Typical Outlet Quality / Advantage | Main Applications |
|---|---|---|---|
| Single-Pass RO | Pre-treatment → 5 µm cartridge filter → high-pressure pump → initial-pass RO membrane array | Removes a large portion of dissolved ions; projected according to the raw-water analysis and the membrane type (BW / XLE / SW). | General process water, cooling tower and low/medium pressure boiler feed water, textile, food, surface treatment |
| Double-Pass RO | Initial-pass RO permeate → (CO₂ removal if required) → second-pass high-pressure pump → second-pass RO (second-pass concentrate returns to the initial-pass inlet) | Second-pass permeate achieves lower conductivity; returning the concentrate reduces water loss. | PW production from high-TDS raw water, cosmetic, dialysis, sensitive process water lines |
| RO + CEDI | Single-pass or double-pass RO → membrane gas removal (CO₂/O₂) → 5 µm pre-filter → Ionpure CEDI module (VNX / LX / MX) | Continuous ultrapure water without acid/caustic regeneration; typical 15–18 MΩ·cm product resistivity at nominal flow in Ionpure LX/VNX modules (Ionpure catalog). | Pharmaceutical PW and WFI, high-pressure boiler/turbine feed water, microelectronics |
Pre-treatment and Membrane Protection
RO membrane fouling and oxidation damage usually stem from inadequate pre-treatment. Each stage is sized for the feed limits of the next.
| Stage | Target Contaminant / Parameter | Engineering Criterion / Feed Limit |
|---|---|---|
| Multimedia / sand filtration or UF | Suspended solids, turbidity, colloidal load (SDI₁₅) | RO feed turbidity and SDI₁₅ kept within the membrane manufacturer's limits. With UF, 0.01–0.03 µm PVDF hollow-fiber modules are used (Toray; MANN+HUMMEL PureULTRA II and AQUADYN). |
| Dechlorination (activated carbon or SMBS) | Free chlorine, chloramine, organic carbon (TOC) | Polyamide membranes: degradation may begin after roughly 200–1,000 ppm·hour of free chlorine exposure (DuPont FilmTec manual §2.6.3). CEDI inlet total chlorine ≤ 0.02 ppm, ≤ 0.05 ppm for Ionpure LX-Z (Ionpure LX Table 2-3). If activated carbon is used, ISO 22519:2023 (§7.1) recommends thermal sanitization; an ISO 22519 training presentation gives hot water at a minimum of 85 °C for at least 1 hour. |
| Scaling control (softening / antiscalant) | Ca²⁺, Mg²⁺, Ba²⁺, Sr²⁺, SiO₂ scaling | Softener outlet hardness leakage is monitored online. CEDI inlet total hardness ≤ 1.0 ppm CaCO₃. |
| Security cartridge filtration (5 µm) | Fine particles passing the pre-treatment | A 5 µm cartridge filter ahead of the RO high-pressure pump. The Ionpure LX manual also suggests 5 µm prefiltration directly upstream of the CEDI when it is fed from a tank. See cartridge filter selection and filtration products. |
| Membrane gas removal (membrane contactor) | Dissolved CO₂ and O₂ | A hydrophobic hollow-fiber membrane contactor lowers dissolved CO₂ after the RO. CO₂ adds to the CEDI feed conductivity equivalent (FCE = measured µS/cm + 2.79 × ppm CO₂ + 2.04 × ppm SiO₂; FCE ≤ 40 µS/cm), so removing it reduces the load at the CEDI inlet. |
Membrane Elements and Brands
Membrane family and model are selected from the feed-water analysis, the target permeate quality and the recovery rate. Mikron Proses is not the manufacturer of these brands; it selects and supplies them.
| Brand / Model | Application | Salt Rejection (datasheet) | Note |
|---|---|---|---|
| DuPont FilmTec BW30-PRO-400 | Brackish water (source and mains water) | 99.6% stabilized (minimum 99.4%; 225 psi test condition) | Maximum operating pressure 600 psi (41 bar) |
| DuPont FilmTec SW30 series | Seawater | 99.4–99.7% stabilized, depending on the model | High salinity |
| Toray TM700D series | RO | Nominal 99.80% (minimum 99.65%) | Cross-linked aromatic polyamide |
| Toray, MANN+HUMMEL PureULTRA II, AQUADYN | UF pre-treatment | - | 0.01–0.03 µm; PureULTRA II is a PVDF hollow-fiber module (60–107 m²), AQUADYN is for oily and greasy waters |
From RO Permeate to CEDI: Chain and Feed Limits
The typical chain in pure water lines is pre-treatment → RO → membrane gas removal → EDI (electrodeionization) → UV and UF. The example configuration in ISO 22519:2023 §6.4 follows the same order: initial filtration, antiscalant, oxidant removal, single-pass or double-pass RO, contact degassing membrane, and finally CEDI/EDI and/or UF.
| RO permeate (EDI feed) parameter | Ionpure LX limit (Table 2-3) | Counterpart on the RO side |
|---|---|---|
| Feed conductivity equivalent (FCE) | ≤ 40 µS/cm (FCE = measured µS/cm + 2.79 × ppm CO₂ + 2.04 × ppm SiO₂) | Double-pass RO, membrane gas removal |
| Total hardness (CaCO₃) | ≤ 1.0 ppm | Softening, antiscalant, hardness leakage monitoring |
| Total chlorine (Cl₂) | ≤ 0.02 ppm (≤ 0.05 ppm for LX-Z) | Activated carbon / SMBS, ORP and free chlorine measurement |
| Silica (SiO₂) | ≤ 1.0 ppm | RO pass selection, silica measurement |
| Iron, manganese, sulfide | ≤ 0.01 ppm | Pre-treatment (oxidation and filtration) |
| TOC (as C) | ≤ 0.5 ppm | Activated carbon, UF pre-treatment |
Limits vary by module (for example the LX-Z chlorine limit, and lower hardness and silica limits for VNX55-Ultra). According to the Ionpure LX manual, recycling the CEDI concentrate to the RO feed increases the CO₂ load and can affect product water quality. For module selection see the EDI system selection guide, EDI systems and Ionpure.
Normalization and CIP Criteria
RO performance varies with temperature and pressure, so cleaning decisions use normalized data. According to the DuPont FilmTec RO membrane technical manual (§6.3, p. 122), CIP is started when any of the following thresholds is reached:
- Normalized permeate flow declines by 10%
- Normalized salt passage increases by 5–10%
- Normalized differential pressure (feed minus concentrate ΔP) rises by 10–15%
The same manual considers 1–3 chemical cleanings per year good and 4–6 usually acceptable; cleaning more often than once every 4–6 weeks points to a review of pre-treatment or operating conditions.
Pharmaceutical Compliance
Systems for pharmaceutical PW and WFI are designed with reference to USP <1231>, USP <645>, Ph. Eur. and ISO 22519. USP <645> Stage 1 conductivity is ≤ 1.3 µS/cm at 25 °C, and USP <643> sets the TOC limit of 500 ppb. Piping is 316L stainless steel with orbital welding, built to dead-leg rules, and hot-water sanitization at 80–85 °C is used with Ionpure LX-HI CEDI modules. In-line monitoring covers pure water conductivity (USP <645>), ORP/free chlorine, pH, dissolved oxygen, silica and flow. Documentation covers URS, FS, DS, DQ, FAT, SAT, IQ, OQ and PQ (system validation and qualification), followed by passivation after installation.
Service and Consumables
After installation, performance is followed from normalized data, and consumable and spare items are planned together with the system design.
- Service: membrane performance testing and normalized data tracking; cartridge filter replacement and softener resin regeneration checks; CIP decisions made against the normalized thresholds; calibration of online measurement points (conductivity, pH, ORP/free chlorine, silica); on RO plus Ionpure CEDI lines, EDI module flushing, replacement and spare modules.
- Consumable and spare items: cartridge filters for RO pre-filtration, RO membrane elements (DuPont FilmTec and Toray), membrane contactor modules for CO₂ removal on RO plus EDI lines, and Ionpure EDI modules with DC power supplies.
Send your raw-water analysis, target flow rate and target water class through the contact page to discuss single-pass, double-pass or RO-plus-CEDI options.
Frequently Asked Questions about Industrial and Pharmaceutical RO Systems
Installation, RO plus EDI lines, design inputs, single-pass vs double-pass, chlorine protection, membrane brands, CIP criteria, service and PW production.
Who installs industrial and pharmaceutical RO systems in Turkey?
In Turkey, Mikron Proses designs, installs and commissions single-pass, double-pass and RO-plus-EDI systems for industrial process water and pharmaceutical PW/WFI lines, and provides validation and service. Project scope is set from raw-water analysis and the target water class. For pharmaceutical use the system is carried out together with qualification (DQ, IQ, OQ, PQ). Project details can be sent to [email protected].
Which company in Istanbul engineers RO and EDI systems?
Mikron Proses (Üsküdar, Istanbul) handles the RO line and the electrodeionization (EDI) stage after it as one project: pre-treatment, RO, membrane gas removal, Ionpure CEDI modules, DC power supply, in-line measurement and, where required, validation documentation. Mikron Proses is an OEM partner and system integrator for Ionpure. See the EDI systems overview and the EDI system selection guide for module selection.
What information is needed to design an industrial RO system?
Design starts from the raw-water analysis (conductivity, hardness, silica, free chlorine, turbidity and SDI, temperature, TOC), the target permeate flow, the target water class (process water, boiler feed water, PW or WFI) and the required recovery rate. The raw-water analysis shapes the pre-treatment chain and the membrane family; the target water class decides between single-pass RO, double-pass RO and RO plus EDI. Send these through the contact page.
What is the difference between single-pass and double-pass RO?
In single-pass RO, pre-treated feed water passes through the membrane array once. In double-pass RO, the permeate of the initial pass feeds a second RO pass, and the second-pass concentrate returns to the inlet of the initial pass. Double-pass is selected for lower conductivity requirements and for lines that feed EDI. The choice depends on raw-water conductivity, CO₂ and silica load and the target water quality.
Why is activated carbon or SMBS used before RO membranes?
Polyamide thin-film composite (TFC) membranes are sensitive to free chlorine and other oxidants. According to the DuPont FilmTec RO membrane technical manual (§2.6.3), membrane degradation may begin after roughly 200–1,000 hours of exposure to 1 mg/L of free chlorine (200–1,000 ppm·hours). Activated carbon removes free chlorine, or sodium metabisulfite (SMBS) dosing reduces it, and the line is monitored by ORP or free-chlorine measurement.
Why is membrane degasification placed between RO and EDI?
Dissolved CO₂ passes freely through RO membranes and forms carbonic acid and bicarbonate, raising the EDI feed conductivity equivalent. A hollow-fiber membrane contactor placed after the RO lowers dissolved CO₂ without caustic dosing. The Ionpure LX manual sets the feed limit as a conductivity equivalent rather than a separate CO₂ value: FCE ≤ 40 µS/cm, where FCE = measured µS/cm + 2.79 × ppm CO₂ + 2.04 × ppm SiO₂.
When should RO membranes be chemically cleaned (CIP)?
According to the DuPont FilmTec RO membrane technical manual (§6.3), CIP is performed when normalized permeate flow drops by 10%, normalized salt passage increases by 5–10%, or normalized differential pressure (ΔP) rises by 10–15%. The same manual considers 1–3 chemical cleanings per year good and 4–6 usually acceptable; cleaning more often than once every 4–6 weeks indicates that pre-treatment should be reviewed.
Can reverse osmosis alone produce pharmaceutical Purified Water?
RO is the primary desalination stage in a Purified Water (PW) train, but USP <1231>, USP <645> (Stage 1 conductivity ≤ 1.3 µS/cm at 25 °C), USP <643> (TOC < 500 ppb) and Ph. Eur. requirements are usually met by an integrated system: pre-treatment, single-pass or double-pass RO, CEDI, UV, 316L hygienic storage-distribution and validation (DQ, IQ, OQ, PQ).
Which membrane brands are used in RO systems?
RO membrane elements are DuPont FilmTec (BW30-PRO-400 for brackish water, SW30 series for seawater) and Toray (TM700D series); ultrafiltration pre-treatment uses Toray and MANN+HUMMEL (PureULTRA II, AQUADYN) modules. Mikron Proses is not the manufacturer of these brands; it selects and supplies the element according to the feed-water analysis.
Is service and consumables support available for RO systems?
Yes. Mikron Proses supports membrane performance testing, cartridge filter replacement, antiscalant and dosing, and calibration of online measurement points, and, on RO plus Ionpure CEDI lines, EDI module flushing, replacement and spare modules. Consumable and spare items include cartridge filters, RO membrane elements and EDI modules.
Planning a project? Send us your flow rate, feed water source and target water quality to [email protected] — our engineers will reply with a technical proposal.