Chlorophenols (CPs) are toxic rumbiodegradable pollutants. In recent decades, several alternative processes for the treatment of these compounds have been investigated. Advanced Oxidation Processes (AOPs) are some of the most promising technologies. Among them, the UV-based AOPs [O-3+Fe(II)+UV, photo-Fenton, UV+Fe(III), UV+H2O2, photocatalysis and photolysis] have previously been studied for the degradation of 2,4dichlorophenol (DCP) in air aqueous solution at laboratory scale. In this paper, these techniques are compared and kinetic constants and pseudoquantum yields are estimated. O-3 + Fe(II) + UV and photo-Fenton seem to be the most effective. To study scale-up of these processes from the laborcitory to a pilot plant operating with sunlight, equivalent photocatalytic experiments were carried out in such installations. The results are promising and show trends similar to those obtained in the laboratoly, with lamps. The data obtained have been used to calculate some scale-up factors, which have been employed to make a tough estimation of the amount of waste water that call be treated by the solar A OPs studied. The results obtained are encouraging and prove the feasibility of this type of technology.