**4. Conclusions**

AOPs undergo through different reacting systems such as homogeneous or heterogeneous phases and in light or dark. It causes consecutive unselective degradation of organic materials. Complete mineralization occurs even at very low concentration and the byproducts formed may be environmentally non-hazardous. Biological treatment is recognized as the cheapest available technology to remove and degrade organic contaminants. However, advanced separation technology gives very inefficient degradation of PhACs because they are usually resistant to biodegradation and characterized by low BOD/COD ratio. Partial Fenton oxidation yields more biodegradable products together with the destruction of inhibitory effect towards microorganisms in the downstream biological treatment. It also increases the overall treatment efficiencies compared to the efficiency of individual process. AOPs can be employed for the detoxification of PhACs until the biodegradability is improved to a level amicable for subsequent biological treatment.
