Electrochemical water softening using air-scoured washing for scale detachment

- Air-scoured washing has been proposed and tested for scale detachment in the electrochemical water softening process.
- Effective scale detachment was achieved.
- High softening efficiency and low energy consumption could be obtained stably.

Treatment of recirculate cooling water using electrochemical method has obtained great attentions in recent years due to its environmental friendliness and easy operation. In order to ensure persistent hardness removal efficiency, periodical cleaning of cathode surface is essential. However, currently available electrode cleaning techniques are either inefficient or laborious. In this work, air-scoured washing was proposed to replace conventional scale detachment methods in the electrochemical water softening process. Mirror stainless steel was found to be the most suitable cathode material because it could enhance scale detachment significantly. Effective water softening and scale detachment were achieved. The precipitation rate was as high as 25.5-34.3 g/h/m2. After the air-scoured washing scale detachment, the cathode could resume their ability to soften. The energy consumption and the total removal efficiency were 17.6-22.3 kWh/kg CaCO3 and 12.2-15.2%, respectively. Repetitive experimental results indicated the electrochemical water softening process using air-scoured washing could run steadily without any performance decay detected after repetitive operation.