Complementary treatments can allow a reduction of concentrations of micropollutants to reach values compatible with a good state of the environment. Processes that seem more efficient to eliminate refractory substances from treated wastewater are advanced technologies similar to the ones used for drinking water production : ozonation, UV light, adsorption on activated carbon, membranes and advanced oxidation processes. Advanced oxidation processes (AOP) rely on the formation of HO° radical witch is less selective than ozone and has higher reaction constants. An advanced oxidation processes pilot was tested in two plants. The AOP pilot is a container with two reactors in parallel (O3/H2O2 and O3/H2O2/UV). Mass balances were performed based on wastewater flow and micropollutants concentration data at the inlet and at the outlet of the studied processes. All advanced oxidation processes tested were efficient on beta blockers and other drugs (>90%). The removal of alkylphenols was not complete with UV and hydrogen peroxide.