How to Clean the Edi System of an Ultrapure Water System?

The EDI system of an ultrapure water system scientifically integrates electrodialysis and ion exchange technologies. Through the selective permeation of cation and anion membranes and the exchange of ions in water by ion exchange resins, ions migrate directionally under the influence of an electric field, achieving deep purification and desalination. However, after a period of use, cleaning is necessary for optimal operation. So, how is the EDI system of an ultrapure water system cleaned?

Depending on the operating status of the EDI system, cleaning uses an acid wash—disinfection—alkaline wash method to clean the EDI module.

1. During cleaning, the desalination chamber, concentrate chamber, and electrode chamber of the EDI system all need to be cleaned. The cleaning solution enters the EDI from the raw water inlet and concentrate inlet, and returns to the cleaning water tank from the "product water," "concentrate outlet," and "electrode outlet" outlets. (Forward wash)

2. First step: Acid wash: Prepare a 2.0% hydrochloric acid solution in the cleaning water tank and circulate it for 30 minutes.

Rinsing: After draining the acid wash solution from the cleaning tank, rinse the water in the tank until neutral. Then rinse the inlet and return pipes until the return water is neutral.

Second Step: Disinfection: Prepare a 0.2% H2O2 solution (approximately 10 kg of concentrated 25% H2O2) in the cleaning tank and circulate it for 50 minutes.

Rinsing: After draining the disinfectant solution from the cleaning tank, rinse the EDI until the conductivity of the return water in the tank drops below 100 μS/cm.

Third Step: Alkaline Wash: Prepare a 1.2% NaOH + 5.0% NaCl solution in the tank and circulate it for 50 minutes.

This concludes the introduction to cleaning the EDI system of ultrapure water equipment. Using EDI in ultrapure water equipment has many advantages over mixed bed systems. The EDI water production process can continuously produce high-quality ultrapure water without the need for acid or alkali chemical regeneration. It has the advantages of advanced technology, compact structure, and simple operation, making it applicable to a wider range of applications and representing a green revolution in water treatment technology.