Pulp and paper industry is well known for employing a massive amount of fresh water as well as producing large quantities of wastewater. The wastewater from paper and pulp industry contains high strength organic and inorganic pollution which has the potential to deteriorate the environment and have adverse effects on human health and water receiving bodies. The conventional treatment processes are less efficient to remove persistent organic compounds like colour, COD, lignin and other organic pollutants from paper and pulp wastewater. This research presents the advanced treatment of real wastewater by optimizing operational parameters like initial pH of wastewater, ozone dose, catalyst dose, catalyst stability, the initial concentration of COD in wastewater and reaction time. Three types of catalysts including natural zeolite (NZ), activated carbon (AC) and alumina (Al) were used. The advanced oxidation processes (O3/UV, O3/NZ, O3/AC, O3/Al) were used to treat real wastewater (black liquor) from the paper industry. Three main parameters (COD, colour, and TOC) were selected to investigate the performance of said processes. The reason behind this selection was that if we control these parameters in wastewater then other parameters (in the form of pollution) automatically decreases and this will result in cost and time-saving in the process. Catalysts were prepared under optimal conditions and their characterization was performed by considering adsorption properties, morphology, and chemical structure. Scanning Electron Microscopy (SEM) showed the physical and chemical aspects of the catalyst structure. FTIR analysis presents catalysts typical profile and presence of different functional groups. BET analysis showed surface properties (pore size, pore volume, etc) of catalysts. The EDX studies showed the presence of different elemental composition in the selected catalyst. The results reveal that the O3/UV process showed 43.64% COD, 64.42% colour and 45.64% TOC removal. The COD and colour removal efficiency during the O3/NZ process was 71.75% and 88.79% respectively. The TOC removal during O3/NZ process was 56.43%. The O3/AC process showed the maximum COD and colour removal efficiency of 91.75% and 97.51% respectively. The TOC removal during O3/AC was 64.1% The O3/Al process showed 82% COD, 93.78% colour and 53.09% TOC removal. Among the studied AOPs, the catalytic ozonation by using AC showed the maximum COD, TOC and color removal efficiencies at the natural pH of the wastewater. The parameters (pH 6.8, ozone dose 0.3mg/ml, CODo 400 mg/l, catalyst dose 10 g/L, time 120 min) proved to be optimum for the studied processes.