Design and Purification Process for a Centralized Laboratory Pure Water Supply System

Research institutions and testing centers require large volumes of pure water at various grades. A centralized production and loop distribution approach can improve efficiency and reduce maintenance costs. A centralized laboratory pure water system typically consists of three parts: pretreatment, purification, and the pipe network circulation loop.

Municipal tap water enters the raw water tank and then is pressurized by a booster pump and delivered to the pretreatment unit. The pretreatment unit includes a multi-media filter, an activated carbon filter, and a softener or antiscalant dosing system. The multi-media filter is used to remove suspended solids, the activated carbon filter adsorbs residual chlorine and organic matter, while the softener or antiscalant system prevents scaling on the reverse osmosis membranes. A security filter serves as the final barrier for the RO feed water.

The primary purification stage employs a reverse osmosis unit. This unit can remove over 97% of ions, bacteria, and pyrogens from the water. Its permeate typically has a conductivity of less than 20 μS/cm and is stored in an intermediate water tank.

Based on the needs of different laboratories, the system can branch out to supply different grades of pure water. A portion of the RO permeate can be delivered directly to points of use with lower purity requirements, such as autoclaves and washing machines. The other portion enters the deep purification subsystem. Within this subsystem, an electrodeionization (EDI) module polishes the water to a resistivity greater than 10 MΩ·cm and significantly reduces TOC, thereby meeting the needs of most chemical analyses and buffer solution preparation. If ultrapure water is required, the water further passes through a UV oxidation unit, a polishing mixed bed, and a 0.2-micron terminal filter, yielding Type 1 ultrapure water with a resistivity of 18.2 MΩ·cm at the point of use.

The entire piping network is designed as a circulation loop, with no dead legs, ensuring that the pure water remains in constant flow without stagnation. The system undergoes regular ozone disinfection or heat sanitization. The fully automatic centralized pure water equipment we build for laboratories can monitor water quality in real time, support remote distribution, and ensure that analytical results are not affected by fluctuations in water quality.