A system for disinfecting a fluid, including: a flow cell including one or more inlet ports and one or more outlet ports, wherein the flow cell is configured to communicate a fluid containing a biological contaminant from the one or more inlet ports to the one or more outlet portions through an interior portion thereof; and one or more point radiation sources disposed about the flow cell, wherein the one or more point radiation sources are operable for delivering radiation to the biological contaminant; wherein an interior surface of the flow cell is operable for reflecting the radiation delivered to the biological contaminant by the one or more point radiation sources; and wherein the interior surface of the flow cell is operable for reflecting the radiation delivered to the biological contaminant by the one or more point radiation sources such that a radiation intensity is uniform throughout the interior portion of the flow cell. In one exemplary embodiment, the flow cell is an integrating sphere. Optionally, the system also includes a photocatalyzing material disposed on at least a portion of the interior surface of the flow cell.