The Effect of Wetting-Drying Cycles of Treated Wastewater on Hydraulic Conductivity in Stabilized Sewage Sludge and Gypsum Treated Saline-Sodic Soils

Abstract

This study was carried out to determine changes in hydraulic conductivity of a saline sodic soil subjected to different wetting-drying cycles and treated wastewater after stabilized sludge sewage and gypsum application. In a factorial experimental design, the study was conducted with three replication by using 3 treatment sewage sludge doses (50, 100 and 150 t ha-1), 3 wetting-drying cycles (0, 7 and 14 days) and 2 different water types (fresh water and treated wastewater). The hydraulic conductivity values of the saturated saline-sodic soils were measured at 2, 12 and 24 hour intervals by using a constant level ICW laboratory permemeter. The increase in the applied treatment sludge dose significantly affected the hydraulic conductivity value of the soils and significantly depending on the measurement range. It was determined that irrigation waters have different properties caused a significant change in the hydraulic conductivity value of the soils, with measurements made at intervals of 2 and 24 hours. Depending on the measurement interval, it was determined that the increase in sewage sludge doses caused significant effect and very important on the soil hydraulic conductivity. The study results indicated that the application of gypsum and stabilized waste sludge to the soil cause an increase in hydraulic conductivity values. The study results indicated that the application of gypsum and sewage sludge to the soil cause an increase in hydraulic conductivity values of saline sodic soils. The study results also showed that treated wastewater containing low amount of suspended solids can be used safely for irrigation on the land have saline-sodic soils. The study result also indicated that by applying solid and liquid wastes obtained from treatment units to the saline-sodic soils can be significant contribution in terms of waste management and environmental protection.