The sequencing batch reactor (SBR) process was used for the treatment of raw landfill leachate. Optimum preliminary parameters of leachate/activated sludge ratio, powdered activated carbon (PAC) dosage, and settling time were studied. Optimum obtained parameters (mixing ratio of 10%, PAC dosage of 10 g/L, and settling time of 1.5 h) were applied on two types of SBRs, namely, non-powdered and powdered activated carbon (NPAC and PAC, respectively). Consequently, the effect of factors, the aeration rate and contact time, on both NPAC and PAC reactors were studied. Response surface methodology was used for the design, analysis, and optimization of the experiments. Removal efficiencies of ammonia (NH3-N), color, chemical oxygen demand (COD), total dissolved salts (TDS), and sludge volume index (SVI) were measured for 13 experiments. Based on the obtained results, the optimum aeration rate and contact time for both NPAC and PAC reactors were 2 and 1 L/min and 5.56 and 5.5 h, respectively. Better performance (in terms of NH3-N, color, COD, and TDS removal efficiencies and SVI values) was exhibited by PAC reactors rather than NPAC.