Using a compact unit for nitrification and denitrification processes followed by activated carbon filtration to remove total nitrogen from ammonium-contaminated groundwater

Abstract

Abstract The current study aims to evaluate the removal of ammonium-nitrogen (NH4+-N), generated nitrite (NH2−-N), and nitrate (NH3−-N) from groundwater using a compact unit for nitrification and denitrification processes that consist of a dripping nitrification reactor followed by a denitrification biofilter filled with treated cotton. Moreover, activated carbon filtration was applied as a post-treatment technique to remove the released total organic carbon (TOC) after the denitrification biofilter. The raw groundwater had an average NH4+-N concentration of 29.8 mg/L. To complete the analytical measurements, samples were taken from the compact unit's inlet, outlet, and sampling points for nitrification and denitrification, as well as the activated carbon filter. The obtained results indicated that the nitrification efficiency reached 98.81%, while the denitrification efficiency reached 95.98%. Moreover, the removal rate of total nitrogen ranged between 122.5 and 147 mg/d. On the other hand, the denitrification process utilizing cotton media resulted in a considerable increase in the outlet TOC concentrations, which ranged from 52.1 to 74.2 mg/L. The activated carbon filtration was applied to vanish the released TOC from the denitrification process after 10 days of operation.