Adsorption onto activated carbon is a simple way to remove many ECs from aqueous solutions. The appropriateness of utilizing activated carbon (charcoal) in an adsorption application, on the other hand, is determined not only by its uptake capacity but also by its ability to be reused multiple times. Thermal reactivation is the most widely used technology for regenerating spent activated carbons, but it has some disadvantages, such as high energy demand and regeneration costs and carbon loss caused by attrition and oxidation (San Miguel et al. 2001). Thus, it is desirable to conduct R&D on alternative methods of regeneration that can be carried out in situ to save money on shipping. In this case, ozone-assisted regeneration of the spent activated carbon (SAC) could be a viable option. The method entails the long-term adsorption of wastewater pollutants onto the activated carbon surface until reaching the saturation point. The next step involves the in situ regeneration of the SAC via a short-term reaction with gaseous ozone. This method has already been tested on activated carbons that have been exposed to phenol and benzothiazole (Álvarez et al. 2004). In this study, to achieve an affordable method which prepares GAC particles to be used several times two strategies were used. GAC was placed in a glass jar before being used. Through ozone oxidization and NaOH treatment of the GAC surface, the functional group comprising oxygen was improved. Approximately 0.5 l of 0.1 N NaOH were poured into the glass, and the suspension was stirred for 2 h at 150 revolutions per minute. The specimens were then removed from the solution and dried for 24 h at 115 °C in the oven. GAC samples were placed in a glass column with various heights and diameters, resulting in various GAC densities. After that, gaseous ozone was used to treat the adsorbent. After that, the samples were rinsed with DIW and then dried in a 115 °C furnace for 24 h before being stored in a dryer. Secondly, pumping ozone from the bottom of the GAC tank, besides increasing system efficiency which greatly reduces the consumption of GAC particles, makes catalytic ozonation using GAC as a catalyst which greatly increases the useful life of GAC particles. The physical properties of the adsorbent are shown in Table 1.