Chinese term (edited): ��������

浸发 literally means to soak and to let swell. However, since the main objective of this process includes cleaning (in addition to plumping up the sea cucumbers), I would think that something like "(to undergo) an extended period of soaking and cleaning" or “an extensive process of soaking and purging” would be appropriate.

http://www.asiafood.org/glossary_1.cfm?alpha=S&wordid=2923&s...
"They still have to be soaked to soften them and make them swell before they are finally ready to be made into soup or otherwise cooked."

Chinese term (edited): ��������

Hydrating process!