Laboratory Ultra-Pure Water System Equipment

I. Working Principle

Pre-treatment phase




Removing Impurities: Laboratory ultra-pure water systems typically start by mechanically filtering out large particle suspended matter from the water, such as mud and rust.石英砂filters or PP cotton filter cores are commonly used; as water passes through these filtering mediums, large particle impurities are trapped on the surface of the filter cores, providing an initial level of purification. For instance, the pore size of PP cotton filter cores can reach 1-5 micrometers, effectively blocking visible impurities in the water.

Water Softening: Next comes the softening process, which primarily involves removing calcium and magnesium ions from the water to reduce its hardness. This process typically employs ion exchange resins. As water containing calcium and magnesium ions passes through the cation exchange resin, the sodium ions on the resin exchange with the calcium and magnesium ions in the water, thereby reducing the hardness ions and preventing scale buildup in subsequent equipment.

To adsorb organic matter and residual chlorine: Active carbon filters are also used to absorb organic matter and residual chlorine in the water. Activated carbon has a rich microporous structure, which can absorb odors, colors, and some organic compounds in the water. The residual chlorine in tap water can damage subsequent reverse osmosis membranes, and activated carbon can effectively remove it, improving the taste and chemical properties of the water.







Reverse Osmosis (RO) Stage




This is a critical step in the preparation of ultra-pure water in the laboratory. The pore size of the reverse osmosis membrane is extremely small, typically ranging from 0.0001 to 0.001 micrometers, effectively removing most ions (such as sodium, chloride, calcium, magnesium, etc.), organic matter, bacteria, and viruses from the water. Under pressure, the water passes through the reverse osmosis membrane, while impurities are retained on one side of the membrane. For instance, when water containing dissolved salts passes through the reverse osmosis membrane, the salt ions cannot pass through, only water molecules can, resulting in water of higher purity.







Ultra-Purification Stage (Optional Refining)




Ion Exchange Resin Deep Desalination: To further remove residual ions from water, some ultra-pure water systems utilize ion exchange resins for deep desalination. These resins can exchange with a smaller amount of ions in the water, resulting in higher purity. For instance, water that has undergone reverse osmosis may still contain trace amounts of sodium and chloride ions. By using strong acidic cation exchange resins and strong alkaline anion exchange resins, these ions can be almost completely removed.

Ultrafiltration or Microfiltration for Particle Removal: Ultrafiltration or microfiltration techniques can also be used to remove tiny particles and colloidal substances from water. The pore size of ultrafiltration membranes ranges from 0.001 to 0.1 micrometers, while microfiltration membranes have slightly larger pores, between 0.1 and 10 micrometers. They can intercept particles in water, large organic molecules, etc., making the water clearer and more transparent.

Ultraviolet Sterilization: UV sterilization is a crucial method to ensure the microbiological safety of ultra-pure water, rendering microorganisms unable to reproduce and survive.

Two: Main Components

Original Water Tank




Raw water storage is typically used for tap water or other water sources. The raw water tank serves as a buffer, ensuring that the ultra-pure water system still has a water supply even when the raw water supply is unstable. It also facilitates preliminary sedimentation, allowing larger particles to settle at the bottom of the tank, thereby reducing the workload on subsequent filters.







Pre-treatment System




Mechanical Filters: As previously mentioned, quartz sand filters or PP cotton core filters are used to remove large particle impurities.

Softener: Contains ion exchange resin for reducing water hardness.

Activated Carbon Filters: Adsorb organic matter and residual chlorine. These pretreatment devices can be combined and adjusted according to the quality of the raw water and the specific requirements for ultra-pure water.







Reverse Osmosis System




The system is primarily composed of high-pressure pumps and reverse osmosis membranes. The high-pressure pump supplies the necessary pressure for water to pass through the reverse osmosis membrane, typically ranging from 1 to 10 MPa. The reverse osmosis membrane is the core component of the system, offering various materials and specifications for selection. Its performance directly determines the desalination efficiency and water production during the reverse osmosis stage.







Ultra-Pure System (Refined Processing System)




Ion Exchange Columns: Resin columns used for deep desalination, which can be mixed beds (a combination of cationic and anionic exchange resins) or series-connected columns of cationic and anionic exchange resins, as required.

Ultrafiltration or Microfiltration Units: Including ultrafiltration or microfiltration membrane modules for particle and colloidal removal.

Ultraviolet Sterilizer: Equipped with UV lamps that emit specific wavelengths of ultraviolet light (typically 254nm), capable of sterilizing and disinfecting water.







Pure Water Tank




Storage tanks for ultra-pure water are generally made of non-toxic, corrosion-resistant materials such as polyethylene or polypropylene. These tanks are typically equipped with level sensors for real-time water level monitoring, as well as measures to prevent water quality contamination, such as sealed designs and ventilation filters, ensuring the stored ultra-pure water quality remains unaffected by external factors.







Control System




This is the brain of the laboratory ultra-pure water system, responsible for monitoring and adjusting various operational parameters of the equipment. It controls the start and stop of the pump, the opening and closing of valves, and water quality monitoring, etc. Users can conveniently set the water output and water quality parameters through a touch screen or other operational interfaces, while also being able to view the equipment's operational status and fault alarm information.

III. Advantages

High-purity Water Supply




Our ultra-pure water systems can produce water that meets the stringent requirements of various laboratories. The resistivity can reach above 18.2 MΩ·cm, containing almost no ions, organic matter, or microorganisms. This high purity water is crucial for the accuracy and reproducibility of experimental results. For instance, in analytical chemistry experiments like trace element analysis and high-precision acid-base titrations, ultra-pure water can prevent interference from impurities in the water.




Meets Various Experimental Needs




Our laboratory water purification systems are suitable for various lab types, including chemical, biological, and materials labs. In biological labs, for experiments like cell culture and genetic engineering, sterile and pyrogen-free ultra-pure water is required, which our systems can provide, creating an ideal environment for cell growth and experimental procedures. In materials labs, ultra-pure water serves as a pure reaction medium or cleaning agent for material synthesis and characterization, ensuring that material properties and quality are unaffected by water quality.







Convenient and flexible




The water production capacity and quality parameters can be flexibly adjusted according to the actual needs of the laboratory. Some ultra-pure water systems offer various operating modes, such as producing slightly lower resistivity pure water for general experiments, or high-purity ultra-pure water for high-precision experiments. Additionally, the installation and operation of the equipment are relatively convenient, typically requiring only the connection of water and power sources, followed by a simple adjustment before it can be put into use.







Enhance laboratory efficiency and quality




By providing stable high-purity water, the risk of experimental failures or results deviation due to water quality issues is reduced, thereby enhancing the success rate and efficiency of experiments. For instance, in High-Performance Liquid Chromatography (HPLC) experiments, using ultra-pure water as the mobile phase can improve the separation efficiency and lifespan of the chromatographic column, resulting in more accurate analytical results.

IV. Drawbacks

High equipment costs




The price of our laboratory ultra-pure water systems is relatively high, primarily due to the cost of advanced filtration and purification technologies, such as reverse osmosis membranes, ion exchange resins, and ultraviolet sterilizers. Moreover, the precision of the equipment also drives up production costs. For labs with limited budgets, purchasing the equipment may pose significant financial strain.







High maintenance costs and technical requirements




Equipment requires regular maintenance, such as replacing filters, reverse osmosis membranes, and ion exchange resins, among other components. The replacement costs for these parts are high, and they necessitate the operation by professional technicians. For instance, the lifespan of reverse osmosis membranes typically ranges from 1 to 3 years, and they must be handled with care during replacement to avoid damaging the membrane assembly. Additionally, the daily operation of the equipment also requires water quality monitoring and parameter adjustments, which have certain technical requirements for the operators.







Our company has certain requirements for raw water.




Although the equipment itself has pretreatment capabilities, if the raw water quality is extremely poor, such as containing excessive heavy metals, organic matter, or microorganisms, it can increase the equipment's burden, shorten the lifespan of the components, and even affect the quality of ultra-pure water. Therefore, in areas with poor water quality, additional pretreatment of the raw water may be necessary, such as adding a pre-filter or conducting chemical treatment, etc.







High operating energy consumption




During operation, especially during the reverse osmosis stage, the ultra-pure water generator requires high pressure to drive water through the reverse osmosis membrane, which consumes a significant amount of electrical energy. Furthermore, the operation of components such as the UV sterilizer and water pumps also consumes a certain amount of electricity. Over time, energy costs are also a factor to consider.