An ultraviolet (UV) liquid treatment apparatus is disclosed. The apparatus may include a conduit having an inlet to receive liquid to be treated and an outlet to discharge treated fluid, the conduit defining a plurality of liquid flow paths between the inlet and the outlet. The apparatus may further include an UV light emitting diode (LED) module array to illuminate the liquid, wherein the UV LED module array comprises a plurality of UV LED modules arranged on a curved surface of an array holder, such the UV LED module array is configured to generate a customized spatial light flux distribution within the conduit that matches the liquid flow paths so as to obtain a desired UV dose distribution.
