Surface and groundwater resources, as the two main resources of drinking water, should possess certain characteristics in terms of quality. This makes water treatment as one of the most environmental concerns. Nitrate is the most stable form of nitrogen and high concentrations of nitrate in water resources is considered as a water pollution source. Nitrate is present in water resources as a result of biochemical decomposition of organic and inorganic compounds, which is discharged directly or indirectly into surface and ground waters. High concentrations of nitrate can cause a disease called methemoglobinemia. Available treatment methods for nitrate removal are 7) and 8 g/L of dolomite and red travertine were added to each sample. Samples were mixed on the shaker with a mixing rate of 200 rpm and 150 rpm for dolomite and red travertine, respectively. For kinetics studies, samples at 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300 minutes were collected and analyzed. Equilibrium time was determined to be about 120 minutes for travertine and 180 minutes for dolomite. In adsorption kinetic models, quasi first order model didn't match the data, but quasi second order model (with a correlation coefficient of 0.99) described the results well. Analysis of variance showed that three mentioned factors had considerable effect on nitrate removal. Dosage had the biggest impact on adsorption, 40.59% of response for travertine and 51.6% for dolomite. The maximum nitrate removal achieved were 82.7% and 84.7% for travertine and dolomite respectively, for an initial concentration of 50 mg/L, adsorbent dosage of 8 g/L, and initial pH = 3. Isotherm adsorption tests were carried out in batch reactor in concentrations of 10, 20, 50 mg/l and different dosages of absorbent, and in identical pH level to reach the equilibrium time determined in kinetics. As a result, amount of nitrate absorption per unit mass of absorbent (q) obtained, which concludes that Langmuir model was not able to describe the adsorption data but Freundlich model successfully described the adsorption data.
