A UV Disinfection System is provided comprising a wastewater treatment device in combination with a UV treatment device. Multiple embodiments provide that the UV treatment device is contained substantially within the wastewater treatment device. Embodiments include those wherein the UV treatment device is substantially vertically oriented and extends downward from an outlet shared by the wastewater treatment device and the UV treatment device, thereby requiring all flow exiting the wastewater treatment device to pass through the UV treatment device.