What Is an RO + EDI System in Pharmaceutical Water Treatment?

In the pharmaceutical industry, high-purity water is essential not just for product quality but also for regulatory compliance. One of the most effective and widely accepted methods for producing Purified Water is through a Reverse Osmosis (RO) + Electrodeionization (EDI) system. This combination ensures consistent, chemical-free water purification that meets global pharmacopeial standards.

This article explains how an RO + EDI system works, its components, benefits, and importance in pharmaceutical applications.

What Is an RO + EDI System?

An RO + EDI system is a two-stage water purification solution. Reverse Osmosis removes a majority of dissolved solids, organics, and microorganisms, while Electrodeionization polishes the water further by removing residual ions and ensuring ultra-low conductivity without the use of chemicals.

Together, the system delivers Pharma-grade Purified Water suitable for use in:

• Drug formulation (non-parenteral)

• Equipment washing and rinsing

• Laboratory processes

• Feed water to WFI and Pure Steam systems

RO + EDI System in Pharmaceutical Water Treatment

How the RO + EDI System Works

1. Pre-Treatment Stage

   • Raw water is passed through filters (sand, carbon, softener)

   • Chlorine, particulates, and hardness are removed to protect RO membranes

2. Reverse Osmosis Stage

   • RO membranes eliminate up to 98–99% of dissolved salts, organics, bacteria, and endotoxins

   • The permeate from RO becomes the feed water for the EDI

3. Electrodeionization (EDI) Stage

   • EDI uses ion exchange resins and membranes combined with direct current

   • It continuously removes residual ions without chemical regeneration

   • Polished water with conductivity as low as 0.1 µS/cm is achieved

4. Post-Treatment (Optional)

   • UV disinfection and ultrafiltration may be added for enhanced microbial control

   • Water is stored in sanitary SS316L tanks and distributed through loop systems

Why Use RO + EDI in Pharma?

✅ Chemical-Free Operation
EDI eliminates the need for acid or caustic regeneration used in traditional ion exchange.

✅ Consistent Water Quality
Delivers stable output with low conductivity and TOC, critical for pharma-grade water.

✅ Fully Automated
PLC/SCADA systems enable real-time monitoring and control of quality parameters.

✅ Compliance Ready
Meets Purified Water standards set by USP, EP, IP, and WHO.

✅ Eco-Friendly
Reduced chemical usage and lower wastewater generation improve sustainability.

Pharmaceutical Water Quality Parameters Achieved

The RO + EDI system ensures compliance with:

• Conductivity: ≤ 1.3 µS/cm (USP)

• Total Organic Carbon (TOC): ≤ 500 ppb

• Microbial Count: <100 CFU/mL

• Hardness & Chlorides: < defined limits

• Endotoxins: Controlled by upstream filtration and optional UF

Validation and Qualification

All systems in pharma must be validated under GMP guidelines:

• DQ/IQ/OQ/PQ documentation is mandatory

• Online analyzers monitor conductivity, TOC, and temperature

• Periodic microbiological tests and sanitization (hot water or ozone) are conducted

• Systems include audit trails and 21 CFR Part 11 compliant software, where required

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Applications of RO + EDI in Pharma

• Purified Water generation

• Feed water to WFI and Clean Steam Generators

• Equipment cleaning (CIP/SIP)

• Utility and non-parenteral production

• Ophthalmic and topical preparations

Conclusion

The RO + EDI system represents a robust, efficient, and compliant solution for generating high-purity water in pharmaceutical manufacturing. Its ability to deliver consistent quality without chemicals makes it an ideal choice for companies seeking sustainable and GMP-compliant operations.

Swjal Process Pvt. Ltd. designs and manufactures advanced RO + EDI systems customized for the pharmaceutical industry, offering turnkey solutions with validation, automation, and post-installation support.