A treatment device and method for treatment of a bio-fluid are disclosed. The device includes a treatment chamber configured to receive bio-fluid to be treated, a light treatment element disposed around at least a portion of the treatment chamber, and a piston mechanism disposed inside the treatment chamber for advancing the bio-fluid inside the treatment chamber toward a constricted location corresponding to the at least the portion of the treatment chamber around which the treatment element is being disposed. Upon passing bio-fluid through the location, the treatment element applies a treatment to the passing bio-fluid.
