Prussian Blue (PB, iron hexacyanoferrate) is an efficient micron-sized sorbent that can be encapsulated in a biopolymer matrix (chitin) for the treatment of Cs (I)-bearing solutions. Different conditionings have been designed for the treatment of Cs-contaminated effluents (with natural Cs (I) solutions, and with 137Cs spiked solutions). The sorbents conditioned under the form of beads or discs can be used in columns while sponges can be used for the treatment of accidental discharge of effluents (contaminated water absorption by the sponge, metal ions sorption on the ion-exchanger, treated water removal by centrifugation, metal concentration in the composite material).