Mixed-bed ion exchange technology has been the standard process for ultrapure water production for decades. However, it requires periodic regeneration, which consumes large quantities of chemicals (acids and alkalis) and pure water, and causes certain environmental problems. Therefore, there is a demand for environmentally friendly, acid- and alkali-free ultrapure water systems.
Traditional ion exchange has become increasingly unable to meet the requirements of modern industry and environmental protection. Against this background, EDI (Electrodeionization) technology, which combines membrane, resin and electrochemical principles, has revolutionized water treatment.
The regeneration of its ion exchange resin uses electricity instead of acids and alkalis, making it more consistent with current global environmental requirements.
Since the industrialization of EDI stack technology in 1986, thousands of EDI systems have been installed worldwide. They have developed rapidly especially in industries such as electroplating and coating, electric power, pharmaceuticals, semiconductors and surface cleaning. EDI is also widely used in environmental fields including wastewater treatment, beverages and microbiological applications.
This is the development history of ultrapure water equipment for electroplating and coating.
In the electroplating and coating industry, to improve the smoothness, brightness and adhesion of plated surfaces, pure water with conductivity below 15 μS/cm is required for electroplating bath preparation. In addition, rinsing of plated parts requires pure water with conductivity below 10 μS/cm.
Water treatment systems for the electroplating industry include:
Pure water systems for electroplating bath preparation
Rare metal recovery systems from electroplating rinse wastewater
Rinse water recycling and zero-discharge systems
Generally, ultrapure water systems for electroplating and coating consist of ultrafiltration (UF), reverse osmosis (RO), ion exchange (IX) and EDI to meet the industry’s strict water quality requirements.
EDI is an advanced water treatment method that combines electrodialysis and ion exchange. It uses the polarization phenomenon in electrodialysis to achieve continuous electrochemical regeneration of ion exchange resin without acids or alkalis, making it highly suitable for modern environmental requirements. EDI can replace mixed-bed ion exchange to produce ultrapure water.
