Aq. soln. of Na dodecylbenzenesulfonate and biolog. pretreated laundry wastewater were purified by advanced oxidn. (photolysis, photocatalysis, ozonation) under UV irradn. with 2 types of light source (medium and high pressure UV lamps). The use of medium pressure UV lamp was more effective than the monochromatic low pressure one. The highest redn. level of total org. was 86% after 6 h of UV irradn.