With the purpose of enhancing the removal of nitrogen pollutants from wastewater by the constructed rapid infiltration(CRI)system,a bench-scale experimental appratus,including a single-stage nitrosation CRI reactor(N-CRI)and an anaerobic ammonia oxidation CRI reactor(A-CRI),was erected to explore the effective start-up regulatory strategies and coupled nitrogen removal performance.The findings of the experiment with the reactors suggested that increasing the mass concentration of NaCl in the feed water up to 4 g/L,after starvation for 14 days an efficient start-up of nitrosation in the N-CRI reactor was realized with an average NO2--N accumulation rate of 98.1％;and by gradually increasing the hydraulic load to 1.0 m/d,after 45-day operation anaerobic ammonia oxidation successfully start in the A-CRI reactor.When the N-CRI was coupled with A-CRI in series the wastewater treatment operation demonstrated the removal efficiency of NH4+-N could reach 98.5％,and TN 93.1％in average respectively.As to the structure of the bacterial community in the treatment system,the analysis revealed that the main species of ammonia-oxidizing bacteria(AOB)in the N-CRI reactor were Nitro-somonas and Nitrosospira,and the main NOB species was Nitrospira,and the starvation synergistic NaCl modulation could lead to the restriction of NOB activity and prevented it from further oxidizing NO2--N;the main anaerobic ammonia-oxidiz-ing bacteria(AAOB)species in the A-CRI reactor mainly consisted of Candidatus Brocadia and Candidatus Kuenenia,whose enormous proliferation in relative abundance created conditions for the simultaneously high-efficient removal of NH4+-N and NO2-N,providing a new pathway to enhance the nitrogen removal performance of the CRI system.
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