The EU Water Framework Directive defines a water pollution strategy in the EU. It contains a list of priority pollutants (POs), chemicals that represent significant risk to the water environment. Due to the very nature of the POs, advanced oxidation processes (AOPs) are proposed for their removal from the water. AOPs are based on creation of highly reactive radicals and one of the simplest ways to do it is by photooxidation. In that purpose, UVC/ H2O2 or UV-C/S2O8 2- processes were applied in this thesis. For determination of optimal conditions of the POs degradation processes and for explanation of the degradation mechanism but also to envision the environmental aspects inside or outside the field of study (without new experiments), modeling approach is considered. The modeling was based on statistical and empirical approaches, such as response surfaces modeling (RSM), but phenomenological approaches based on mathematicalmechanistic modeling were applied as well. RSM is used as a tool for analyzing the influence of key process-parameters on process efficiency and determination of optimal conditions in the investigated area. These key parameters are in this dissertation are pH-value of the solution and the initial concentration ratio pollutant/oxidant. RSM is applied for assessment of the impacts of process parameters, but does not include information on specific chemistry within the system, nor on degradation mechanism of targeted POs. Mathematical-mechanistic models are developed in order to describe the processes chemistry and phenomena occurring during POs degradation and to allow the prediction of system behavior beyond the range of examined process parameters. In order to increase the scope of the cases that involves modeling, quantitative structure-activity relationship modeling was applied. In this case, the second-order kinetics reaction rate constants and the empirical parameters of mathematical-mechanistic models were predicted; with the aim of obtaining more information on the chemistry of the degradation process but also the environmental risk assessment. The aim of this dissertation was to develop models for simulating behavior of POs degradation by AOPs on the basis of experimental results, combining responsive surfaces modeling, mathematical-mechanical modeling and quantitative structure-activities relationship modeling. Accordingly, a methodology for predicting, evaluating and controlling the environmental aspects of AOP-treated water solutions containing POs were proposed by integrated methodology that combines experimental data with different modeling approaches that provides an expanding insight into the environmental aspects of the water treatment system.