Determination of quality changes in treated wastewater during percolation through the soil media

A laboratory-scale soil aquifer system (SAT) was investigated in this thesis to determine the quality changes that occur in secondary treated wastewaters during percolation through soil media. The experimental setup consisted of soil-packed vertical columns, which were equipped with multiple ports at different depths for effluent sample collection. The system was operated with two different operational cycles that consisted of three-wetting/four-drying days and seven-wetting/seven-drying days. All experimental studies were carried out in columns that contained an effective soil depth of seventy-five centimeters using silt loam soil collected from an agricultural field in Menemen (Izmir). The experiments were conducted with synthetically prepared wastewater and with the secondary treated effluents of Cigli (Izmir) municipal wastewater treatment plant. In the first part of the thesis, the removal of dissolved solids, organic matter and nutrients were investigated from synthetic secondary treated wastewater (SSTWW) and real secondary treated wastewater (RSTWW). Temperature, pH, salinity, electrical conductivity, total dissolved solids, oxidation-reduction potential, dissolved oxygen, total organic carbon, chemical oxygen demand, ammonium-nitrogen, nitrate-nitrogen, nitrite-nitrogen, total nitrogen and phosphate-phosphorus were measured during the first part of the thesis and their changes during percolation through soil columns were assessed based on fundamental removal mechanisms. First stage experimental studies were carried out for fifty-five and twenty-five week periods using SSTWW and RSTWW, respectively. In the second part of the thesis, fate of heavy metals was investigated through the columns operated with synthetic single metal solutions. Copper, lead and zinc were selected for experimental studies carried out for twenty-one weeks. Overall, it could be concluded that laboratory-scale SAT system was effective in the removal of dissolved solids, organic matter, nitrogen, phosphate and heavy metals. Biodegradation, adsorption, ion exchange, precipitation and filtration were found to be the most effective mechanisms for polishing of secondary treated wastewater using SAT system. Keywords: Soil aquifer treatment (SAT), soil columns, organic matter, nutrients, heavy metals, wastewater reuse, wastewater polishing, secondary treated wastewater.