Abstract: A UV reactor comprises a reactor body shaped to define longitudinally extending inner and outer reactor chambers. One or more passages located at a first longitudinal end of the inner reactor chamber provide fluid communication between the inner and outer reactor chambers. The outer reactor chamber surrounds a portion of the inner reactor chamber that includes the first longitudinal end. The UV reactor also comprises: an inlet/outlet in fluid communication with the outer reactor chamber; and an outlet/inlet in fluid communication with the inner reactor chamber. The outlet/inlet is located at a second longitudinal end of the inner reactor chamber. A cap connected to the reactor body houses one or more UV radiation emitters optically oriented to direct UV radiation into the inner reactor chamber. An inner fluid-flow cross-section of the inner reactor chamber may be greater than an outer fluid flow cross-section of the outer reactor chamber.

Abstract: An ultraviolet disinfectant head attachable to a fluid container having a central axis for disinfecting a fluid housed in a cavity of the fluid container. The system comprises an ultraviolet light emitting diode (UV-LED) having a principal emission axis and a lens (e.g. a diverging lens) having a primary optical axis. The lens is located and/or oriented to receive radiation from the UV-LED and direct refracted radiation toward the cavity of the fluid container. The refracted radiation may be diverging when it reaches a fill plane of the fluid container.