The Performance of Pyrite-based Autotrophic Denitrification Column for Permeable Reactive Barrier under Natural Environment

Abstract The effect of temperature on pyrite-based autotrophic denitrification performance and conversion between N species under natural conditions was investigated by using dynamic-flow column experiment. Phosphate and bicarbonate were added trying to enhance denitrification performance when the temperature decreased to 20 °C. However, the temperature had a much more sensitive influence on the denitrification process than substances addition. NO3−-N removal efficiency decreased with the decrease of temperature. When the temperature was higher than 20 °C, the NO2−-N reduction process was more sensitive to the temperature drop, while the process of NO3−-N to NO2−-N was more sensitive to temperature drop when the temperature was lower than 20 °C. The different influence of temperature drop on the two processes led to changes of the distribution of NO3−-N, NO2−-N, and SO42−-S along the column. However, the electron contribution of pyrite among the electron donors only changed slightly.