Abstract: A tube has a plurality of sections, several with a transparent wall and a static mixer in each section, which mixers may also be transparent. The initial section mixes a photo inactivation agent with a body fluid such as blood and so on. The static mixers each have adjacent static mixing elements including a pair of axially aligned static mixing sections each formed of a 180° helix, adjacent sections being relatively rotated 90°, all of the elements being aligned in a corresponding tube section and having the same orientation. The apparatus is disposable and includes fluid supply containers, tubing, valves, sensors, and mixing devices coupled to pumps, all under control of a CPU. A static mixer filter filters the processed fluid and may contain porous resin particles coated on the inner surfaces of or packed into a mixing device, and/or coated on a porous membrane in a mixing device.