Large-scale uv-led fluid treatment device

A fluid treatment apparatus for processing a treatment flow, comprising:

• a) a cylindrical irradiation chamber comprising an annular wall of a UV light-transmissive material, having an outer surface, an inner surface, first and second open ends forming a treatment flow path, and a centerline;
• b) a planar array of UV-light emitting diodes (LEDs) configured to emit UV light, having a length with a centerline parallel to the centerline of the irradiation chamber, and a width, and wherein the emitted UV light impinges and passes through an arc segment of the outer surface of the length of the irradiation chamber, through the annular wall, and into the treatment flow path;
• c) a light-reflecting material covering a non-irradiated portion of the outer surface of the irradiation chamber not within the arc segment, to reflect UV light that passes from the treatment flow path through the annular wall back into and through the annular wall;
• and
• d) a heat exchanger apparatus configured to removed heat generated by the planar array of UV-LEDs.