Effluent of a municipal wastewater treatment plant was treated with UV/chlorine (UVIHOCI) advanced oxidation process (AOP) in technical scale on-site using a medium pressure UV lamp with an adjustable power of up to 1 kW (Siemens AG, Germany). Results, obtained from parallel experiments, where state of the art UV/H202 AOP was applied, were compared especially regarding the elimination of emerging contaminants (e.g. carbamazepine, diclofenac) and hygienic aspects (bacterial count). The total estrogenic activity was measured in samples, where UV/chlorine AOP was applied. By variation of oxidant dosage at constant UV radiation as well as constant oxidant dosage at variation of UV radiation several process settings were tested. Additional experiments examined the influence of the organic load (measured as COD) on the UV/chlorinc AOP performance. It could be shown that the UV/chlorine AOP is more effective concerning the elimination of emerging contaminants and hygienic aspects compared to the UVIH202 AOP. The total estrogenic activity of wastewater treatment effluent could be reduced by the UV/chlorine AOP significantly.