Abstract: As a type of the microbial community, indigenous microorganisms play an important role in degrading nitrate in groundwater, which has the advantages of low cost and basically no secondary pollution. In this paper, a numerical simulation model of groundwater was established based on the experimental data and model structure of the rectangular tank remediation, and the maximum ammonia nitrogen load, nitrate load and hydraulic load corresponding to the different distances of the cascade remediation were determined by combining the flow and solute transport models. The results show that the maximum loads of ammonia nitrogen and nitrate pollutants in the simulated area are $ 18.05 \, \text{g}/(\text{m}^2 \cdot \text{d}) $ and $ 54.14 \, \text{g}/(\text{m}^2 \cdot \text{d}) $ when the recharge intensity is 0.68 m/d with the Class III standard value for groundwater as the constraint condition. The maximum hydraulic load in the 15 mg/L ammonia nitrogen and 20 cm nitrification zone is $ 1.62 \, \text{m}^3/(\text{m}^2 \cdot \text{d}) $, and the corresponding maximum hydraulic load is $ 1.14 \, \text{m}^3/(\text{m}^2 \cdot \text{d}) $ when nitrate concentration is 40 mg/L. These findings are expected to provide technical reference for remediation and treatment of in situ nitrate pollution in groundwater.
Keywords: nitrate pollution; microorganism; numerical model; in situ cascade remediation