Disclosed is a method for removing a neutral or an ionic guanidine
compound from aqueous media optionally comprising an alkali metal halide,
wherein the method is selected from the group consisting of (a)
adsorption onto a carbonaceous adsorbent, (b) adsorption onto a clay
adsorbent, (c) filtration through a nanofiltration membrane, and (d)
removal of water and calcination.