Experimental study of wastewater artificial recharge and its effect on nitrate concentrations

Abstract

In this study, the effect of wastewater artificial recharge on the nitrate pollution was experimentally investigated. For this purpose, Gavkhaneh district located in Arak city (Iran) was selected as the case study. In order to simulate the water movement until the groundwater level, the soil layers were simulated in PVC cylindrical columns. To simulate three soil layers with thicknesses of 20 m, 20 m and 10 m, three columns with the heights of 2 m, 2 m, and 1 m were respectively considered. In addition, in order to evaluate the effect of natural zeolite filter, the first soil column, in two types (with and without zeolite) was considered. To simulate the wastewater movement, two management strategies were adopted. One strategy is the permanent submersion in water for twenty days, and the other one is dryness-submersion for forty days (submersion in water for 24 h and in dryness 24 h). The results indicated that the reduction of nitrate content is more efficiently obtained up to 54.5% in the second layer having a heavier soil. Furthermore, the use of zeolite had no effect on the reduction in the nitrate concentration. Finally, the results showed that the dryness-submersion strategy was a more effective method to reduce nitrate content than the permanent submersion in the water. Therefore, the absorption in the permanent submersion increases up to 57%, 84%, and 122%, respectively in the first, second, and third layers as compared with the permanent submersion strategy and in the final absorption stage.