Fate of Nutrients in Secondary Treated Municipal Wastewater during Percolation through the Soil Media

摘要

The fate of nutrients (phosphorous and nitrogen species) was investigated in secondary treated municipal wastewater (STMWW) during percolation through soil media by using an experimental set-up that consists of multiple soil columns. The columns were packed with silt loam soil samples and were operated under two different wetting and drying cycles to represent the typical operational conditions in a soil aquifer treatment (SAT) system. Dissolved oxygen, oxidation–reduction potential, ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, total nitrogen, and phosphate phosphorus concentrations were measured in samples collected from different sampling ports along the columns. Average removal values of 62.8, 67.1, and 97.1% were achieved over 75 cm of effective soil depth over 25 weeks of operation for ammonium nitrogen, total nitrogen and phosphate phosphorus, respectively. The removal performance of nutrients typically increased by soil depth and no decrease in removal performance was observed up to end of the study. Consequently, SAT system can be considered to be an effective and low cost advanced treatment method for polishing residual nutrients in a STMWW.