Analysis of the Root Causes of Performance Decline in EDI Ultrapure Water Equipment

EDI ultrapure water equipment, also known as Continuous Electrodeionization (EDI) systems, combines three technologies: ion exchange, ion exchange membranes, and ion electromigration. It is a highly efficient and environmentally friendly technology for producing ultrapure water. The operation of EDI systems is extremely simple, making them increasingly popular and widely recognized. However, what are the root causes that lead to the decline in performance of EDI ultrapure water equipment?

Feed Water Temperature Requirements :
EDI ultrapure water equipment has specific requirements for feed water temperature. If the temperature does not meet or exceeds the design standards, it will affect the normal operation of the equipment. Experiments have shown that the optimal operating temperature range is between 1°C and 45°C. Users must ensure that the water temperature remains within this controllable range.
Raw Water Impurities and Content :
Due to variations in water quality across different regions, if the raw water quality changes, the pretreatment process of the ultrapure water equipment should be adjusted accordingly. Otherwise, sudden changes in the type or concentration of impurities can result in inadequate pretreatment, which will negatively impact the performance of subsequent systems.
Consumables and Spare Parts :
The service life of consumables and spare parts is closely related to the efficiency of the ultrapure water equipment. During the use of the equipment, users must strictly adhere to the maintenance and replacement cycles of these components. Regular cleaning or replacement is necessary to ensure their proper functioning and maintain the overall performance of the system.
Pressure Levels :
The reverse osmosis (RO) membrane in ultrapure water equipment operates under pressure. Only when the pressure is within an appropriate range can the system achieve optimal purification results. Insufficient pressure will reduce the water production rate, while excessive pressure will accelerate the wear of the RO membrane, increasing operational costs. The normal working pressure for most ultrapure water equipment is between 1 and 5 kg/cm². Both too high or too low pressure will affect its normal operation.
Storage Tanks :
Since ultrapure water contains very low or no dissolved ions, it is highly susceptible to absorbing ionic contaminants from the external environment. Storage tanks made of low-quality plastics or glass may leach ions and organic substances, increasing the water's conductivity and degrading its quality. Therefore, it is recommended to use low-leaching polyethylene storage tanks.
Ventilation Ports :
Most storage tanks are equipped with ventilation ports to allow air circulation during water withdrawal. However, these ports can also introduce CO₂, bacteria, particles, and volatile organic compounds (VOCs) from the surrounding laboratory air, contaminating the stored pure water. To prevent this, ventilation ports should be fitted with air filters to block organic substances, bacteria, and CO₂ from entering the tank.
In conclusion, maintaining the performance of EDI ultrapure water equipment requires careful attention to factors such as feed water temperature, raw water quality, consumables, pressure levels, storage materials, and ventilation. Proper management of these aspects will help ensure the long-term efficiency and reliability of the system.