Abstract: Aiming at the carbon source limitation of denitrification in oligotrophic habitat, this paper studied the effects of intermittent aeration on the nitrogen-removal capability of biological contact oxidation remediation system for micro-polluted source water, and approached the feasibility and process mechanism of shortcut nitrification and denitrification in the system. Under the condition of 8 h-1 6 h anoxic-aerobic phase (Ⅰ), the remediation system performed stably, and its average removal efficiency of ammonium (NH₄⁺-N), permanganate index (COD_Mn), and total nitrogen (TN) was 93.0%, 78.1%, and 19.4%, respectively. Under the condition of 16 h-8 h anoxic-aerobic phase (Ⅱ), the NH₄⁺-N and COD_Mn removal efficiency still maintained at 81.2% and 76.4%, respectively, the accumulation of nitrite (NO₂^--N) was significant, and the removal efficiency of TN reached more than 50%. The nitrogen transformation characteristics in the system during a cycle under condition Ⅱ demonstrated that at the prerequisite of effluent NH₄⁺-N and DO concentrations reaching the standards, shortening aerobic phase length could maintain the DO concentration at 0.5-1.5 mg·L^-1 in a long term, inhibit the growth and activity of nitrite-oxidizing bacteria, and thereby, NO₂^--N had an obvious accumulation, and the nitrogen removal via shortcut nitrification-denitrification in the biological contact oxidation remediation system for micro-polluted source water was finally achieved.

Key words: micro-polluted source water, biofilm, intermittent aeration, shortcut nitrification-denitrification