Abstract: An ultraviolet processing chamber for treating contaminated waste water and the like. The processing chamber includes a chamber body defining a passageway through which the water under treatment flows. An enclosed volume is defined which contains an array of linear UV lamps and which includes a protective wall formed of a material substantially transparent to UV radiation. The protective wall is disposed with respect to the flow passageway so as to permit UV radiation to pass in substantial amounts into the flow passageway to irradiate the water or other substance under treatment. For ease of maintenance the array of UV lamps is contained in a module which is removable from the remainder of the processing chamber. More specifically, the lamps are mounted on a base portion, which may be secured in position on the chamber, and the plurality of lamps forming the array extend into the enclosed volume separated from the substance under treatment by the protective wall.