There is provided a treatment device for disinfecting a fluid being configured as a conduit for conveying a flow of fluid to be treated, said device being toroidal-shaped with an inner concave parabolic surface, wherein the device is provided with apertures extending from the outer to the inner surface of the toroidal-shaped device； one or more UV LED(s) provided in the apertures thereby enabling emitted light to be transmitted through the apertures into the interior part of the device for disinfecting said fluid； a power source for powering the UV LEDs, wherein the inner surface is made from a light reflecting material, and the apertures are sealed in the ends extending into the interior part of the device by a UV-transparent material.
