Most common form of disinfection of alginate impression material is
The  current  protocol  for  disinfecting  hydrocolloid impressions recommended by the Centers for Disease Control and Prevention is to use household bleach (1-to-10 dilution), iodophors, or synthetic phenols as disinfectants. 
Guide for selection of Appropriate Disinfection Method for Impressions Transported to a Dental Laboratory
Spraying 1% sodium hypochlorite
Spraying 5% sodium hypochlorite
Immersing in 1% sodium hypochlorite
Immersing in 5% sodium hypochlorite