The performance of pyrite-based autotrophic denitrification column for permeable reactive barrier under natural environment

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 degrees 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 degrees 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 degrees 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.