Treatment Process and Quality Control of Pharmaceutical Purified Water System
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Update time : 2025-09-10 16:53:03
The source water for pharmaceutical purified water is mostly tap water or deep well water. Due to the presence of impurities, it cannot be directly used for pharmaceutical preparation and must undergo pretreatment, core treatment, post-treatment, and auxiliary measures, combined with a sound quality control system to ensure that the water quality meets the required standards.
1. Pretreatment: Laying the Foundation for Purification
The purpose of pretreatment is to purify the source water and lay a solid foundation for subsequent high-standard purification. It mainly includes three steps:
Multimedia Filtration: A quartz sand filter is used, and layered filter media are employed to remove large-particle impurities, suspended solids, etc., reducing the turbidity of the water. This ensures that the Silt Density Index (SDI) of the effluent is less than 5, meeting the water inlet requirements of the reverse osmosis system.
Activated Carbon Filtration: Utilizing the porous structure of granular activated carbon, it adsorbs residual chlorine, pigments, organic substances, and some heavy metals, further reducing the SDI and improving the taste and color of the water.
Softening Treatment: Whether to install a softener depends on the quality of the raw water. If used, the softener removes Ca²⁺ and Mg²⁺ through ion exchange with Na⁺-based softening resins, preventing scaling on the surface of reverse osmosis membranes and ensuring the smooth progress of subsequent treatment.
2. Core Treatment: Reverse Osmosis Purification
Reverse osmosis is the core of the system, consisting of a security filter, heat exchanger, high-pressure pump, and reverse osmosis membrane:
The security filter traps particles larger than 5μm to protect the reverse osmosis membrane.
The heat exchanger adjusts the raw water temperature to 25±2℃ to improve the separation efficiency of the reverse osmosis membrane.
The high-pressure pump provides sufficient pressure to drive water through the semipermeable membrane.
The reverse osmosis membrane can retain dissolved salts, macromolecular organic substances, etc. Under ideal conditions, the desalination rate of a single reverse osmosis membrane can be as high as 99.5%, and it also reduces the levels of Total Organic Carbon (TOC) and endotoxins.
3. Post-treatment: Upgrading Water Quality to Meet Standards
Water treated by reverse osmosis needs further post-treatment to meet the high requirements of the pharmaceutical industry:
Ion Exchange: A resin bed is used to remove trace ions not completely eliminated by reverse osmosis, improving water purity.
Ultraviolet (UV) Disinfection: It efficiently kills residual bacteria without chemical residues, ensuring water quality safety.
EDI System (Electrodeionization): Driven by an electric field, it combines a mixed resin bed and a selective permeable membrane to remove anions and cations from water. It can continuously produce high-quality ultrapure water without chemical regeneration, conforming to the concept of environmental protection.
4. Storage and Distribution: Preventing Secondary Contamination
Purified water must undergo strict testing before storage. Only when it meets the standards can it be stored in a sterile water tank that complies with GMP standards. The distribution system should be reasonably designed and equipped with emergency facilities such as backup pumps to ensure that the water quality is not contaminated during transportation and the supply is uninterrupted.
5. Auxiliary Measures: Enhancing Water Quality Stability
Add acid-base regulators to adjust the pH of the water to an appropriate range, optimizing the efficiency of the reverse osmosis membrane.
Install additional filtration devices to remove bacteria killed by UV and other particles.
Add scale inhibitors to prevent insoluble salts in the reverse osmosis concentrate from precipitating and clogging the reverse osmosis membrane.
Use a heat exchanger to perform pasteurization on activated carbon, killing microorganisms and decomposing adsorbed organic substances and bacterial endotoxins; equip disinfection devices for the final disinfection of purified water.
6. Quality Control: Ensuring System Stability
Enterprises must establish a full-process quality control system to monitor the quality of raw water, pretreatment effects, reverse osmosis processes, post-treatment effects, and final effluent. Regularly test key water quality indicators such as conductivity, TOC, and microbial limits, and promptly identify and resolve potential problems to ensure the long-term stable operation of the pharmaceutical purified water system and the continuous production of purified water that meets standards.
