Shortcut nitrification-denitrification achieved by hydroxylamine addition in constructed rapid infiltration system

Shortcut nitrification-denitrification process is a promising method for nitrogen removal from domestic wastewater. In this study, hydroxylamine (NH2OH) was adopted for the promotion of shortcut nitrification-denitrification in constructed rapid infiltration (CRI) system. Two CRI systems (C1, C2) were operated, C1 was the contrast no adding NH2OH center dot HCl, and C2 was added NH2OH center dot HCl at gradient-increased concentration (3, 5, 10, 15, 20, 25, 30, 35 mg/L). Finally, shortcut nitrification-denitrification was successful achieved when the added concentration of NH2OH increased to 20 mg/L. Under this condition, the chemical oxygen demand and ammonia nitrogen (NH4+-N) removal efficiencies reached 85.9% and 84.37%, respectively. The total nitrogen removal reached 75.4% and the nitrite accumulation rate increased to 87.2%. The main genus of nitrite-oxidizing bacteria (NOB), Nitrospira, was eliminated from the system, while the main genura of ammonium-oxidizing bacteria (AOB), Nitrosomonas, norank_f_Nitrosomonadaceae and Phycisphaera, and the main genura of denitrifying bacteria (DNB), Thauera, Ottowia, Pseudomonas and Paracoccus, was enhanced. Overall, NH2OH addition is an excellent strategy to achieve Shortcut nitrification-denitrification in CRI system for domestic wastewater.