Population growth, coupled with the expansion of agricultural and industrial activities, has led to increased demand for water and, as a result, peak utilization of high-quality water and excessive pressure on the country's water resources. Increasing contamination of surface and groundwater with nitrate ions also necessitates finding environmentally acceptable solutions to remove these substances from water sources. Surface adsorption is the most common method for adsorption of water pollutants using porous adsorbents such as biochar, activated carbon, silicon dioxide, activated aluminum and clay minerals. In this study, biochar adsorbents produced from waterborne and acid-modified biomass were used to adsorb compounds such as anions. Biochar due to its high surface area, porous structure, high cation exchange capacity and low cost, are good adsorbents for the removal of water pollutants. In this study, natural biochemical biochar from Vetiver plant (NVB) and hydrochloric acid-modified biochar (MVB) were used to remove nitrate ions from aqueous solutions. SEM, FTIR and BET methods and pH and CEC parameters were used to characterize biochemical adsorbents and their potential as adsorbents were evaluated by changes in initial nitrate concentration, adsorbent amount, contact time and pH of the nitrate solution. In the modular experiment, the pH of the nitrate solution was 7.5, the equilibrium time was 270 minutes, and the optimum adsorbent mass was 0.5 g. Increasing the initial nitrate concentration from 20 to 160 mg /l reduced the nitrate uptake efficiency from 87.6 to 58.5%. Langmuir adsorption isotherm models were fitted to the nitrate adsorption data. Among these models, the Langmuir model showed the best fit for the nitrate adsorption data and the maximum predicted adsorption from the Langmuir model was 10.31 mg/g. Pseudo-first-order, pseudo-second-order kinetics models, intraparticle diffusion, power function, and Elovich were used to describe the nitrate adsorption kinetics data. The Elovich model fitted best to the biochar modified nitrate adsorption data indicating that chemical adsorption is the rate-controlling mechanism. To complete the investigations on the introduced adsorbent, column experiments were carried out by the continuous introduction of nitrate solution into the adsorbent column until the adsorbent reached saturation. Column experiments with continuous inlet nitrate solution showed that the maximum adsorption capacity of the column for removal of nitrate ions was in the adsorbent column with 2 cm diameter, 5 cm natural and modified biochar, 4 cm sand above the biochar and 4 cm below the column. When input concentrations were 500 and 100 mg/l as constant discharge, in the natural biochar column, the output concentration did not change significantly, whereas in the modified biochar column, the output concentration was significantly reduced and it was obtained that it is optimally equal to 0.4 mg / l for the concentration of 50 mg / l and 0.16 mg / l for the concentration of 100 mg/l. The results of column experiments showed that the adsorption capacity increased with increasing concentration of nitrate solution but the adsorbent saturation time decreased. The results of this study showed that hydrochloric acid (HCl) modified biochar has a high potential for the removal of nitrate from aqueous solutions. Keywords : nitrate, biochar, modified biochar, hydrochloric acid, adsorption, modular test, column test