The Design-Expert software was utilized to perform the optimization procedure and determine the optimum values of TDS, TOC, and COD removal performance. The optimum conditions were predicted using the numerical optimization section (Nehra et al. 2008). The optimal values of input parameters were acquired by solving the quadratic model based on experimental results and analysis of response surface plots. The desired objective was chosen ‘within’ the range for each practical state (GAC density and ozone concentration) in the software optimization stage. Responses (TOC, TDS, and COD) were determined as the maximum removal for obtaining the highest efficiency. The software combined the individual desirability into a singular number. Then, the optimization is searched in terms of the response, after achieving the optimum removal efficiencies and working conditions (Table 6). As shown in Table 6, the removal percentages of 62.34, 61.63, and 55.13% are forecasted for COD, TDS, and TOC, respectively. The model's improved practical circumstances in this regard are the ozone dosage of 151.49 mg/l, and the GAC density of 1.39 g/cm³. The desirability function value was 1.0 for these optimum circumstances. Then, a further experiment was performed to confirm the desired results. There is a consistency between the experimental results and the estimated response values.