There is described a radiation source module for use in a fluid treatment system. The radiation source module comprises: a housing having an inlet, an outlet and a fluid treatment zone disposed between. The fluid treatment zone comprises a first wall surface and a second wall surface interconnected by a floor surface. The first wall surface, the second wall surface and the floor surface are configured to receive a flow of fluid through the fluid treatment zone. The radiation source module further comprises at least one radiation source assembly secured with respect to the first wall surface and the second wall surface and a module motive coupling element connected to the housing and configured to be coupled to a module motive element to permit the radiation source module to be installed in and extracted from the fluid treatment system. A fluid treatment system comprising the radiation source module is also described.

A disinfection device including a pipe with a taper, inlet, and outlet; an ultraviolet laser; a beam steering device and a transparent layer. The laser, located at a smaller diameter end of the pipe, projects a laser beam towards a larger diameter end of the pipe. The laser beam projects through and/or off the beam steering device and through the transparent layer at a plurality of angles in a cycle. The beam steering device reflects, refracts and/or deflects the laser beam at angles such that a laser beam profile projects through part or all of an inner profile of any point along the taper in the cycle. The pipe receives a fluid that passes through the pipe. One of the inlet or the outlet is located at the smaller diameter pipe end and the other of the inlet or the outlet is located at the larger diameter pipe end.

An embodiment provides a device for cleaning a sleeve of an ultraviolet light source, including: the ultraviolet light source for the disinfection of a fluid, wherein the sleeve surrounds the ultraviolet light source; a cleaning composition encapsulated in a polymer material to form a compound; a canister around and in contact with the sleeve and encapsulating the compound against the sleeve thereby placing the compound in a location adjacent to the sleeve, wherein the polymer material dissolves at a pH above a target value above the polymer material dissolution point releases the cleaning composition. Other aspects are described and claimed.