A bstract Today, the growth of population, industrial development and rising of demand have caused excessive utilization of natural resources. One problem that living creatures are facing is the limitation of water resources. Paying attention to sustainable development, comprehensive management and long-term planning can be an influential step to solve the problems, therefore today, management of the utilization of water resources and the treatment of the wastewater has grown significantly. In wastewater treatment, it is necessary to meet the existing conditions and the desired purposes and choose the best method for treatment. The method of absorbing and using different adsorbents is widely thought as a simple method with low cost. Zeolites are not expensive and highly used adsorbents that are used to absorb different pollutants. Sludge of stub materials is a waste which is rich in amount of silicon and aluminum that can be used to synthesize zeolite. In this study, two types of natural zeolite and synthetic zeolite of sedimentary slime were used to reduce the organic load of urban wastewater. The prepared zeolites were first characterized by XRD, XRF, BET, SEM and CEC analyzes. The results of XRD showed that the synthesized zeolite was sodium sulfate and zeolite Y with 31% of purity. In addition, according to BET results, the specific level of synthetic zeolite was 2.5 times that of normal zeolite. To investigate the effect of adsorbent on organic matter decline, RSM test design method was used. 20 tests were designed according to 3 factors including adsorbent amount, contact time and concentration of organic load in 4 levels. According to the results of the software, the proposed model was the reduction of organic load of wastewater with a second-order adsorbent. Also, among the selected factors, the concentration of organic loading of the effluent was the most effective. According to the optimum point, at 30 min, the concentration of effluent was 318 mg / l and the adsorbent content of 1 g / l had the highest percentage reduction of organic matter of 21% for natural zeolite and 17% for synthetic zeolite. The adsorption companion studies by Langmuir and Freundlich showed that Langmuir companion with 0.9% R ^ 2 was more suitable model for reducing organic load. This showed that absorption of the single-layer and absorbent surfaces was uniform. Also, the kinetics of the pseudo-first-order and second-order kinetics were shown above the pseudo-second-order model with R2 = 0.98. Column method studies and increasing organic matter removal, confirmed the greater efficiency of this method than the discontinuous method. The examination of various zeolite efficiencies in reducing the organic load of urban wastewater showed that the most appropriate zeolite, synthetic peroxide zeolite and zeolite Y with a purity of 81%. Keywords: Wastewater, Adsorption, Zeolite, Test Design, RSM, Isotherm, Kinetics