Insights into two stable mainstream deammonification process and different microbial community dynamics at ambient temperature.

How to achieve stable mainstream deammonification is still a huge challenge. In this work, satisfactory nitrogen removal were achieved in a deammonification granular sludge reactor (R1, 0.42 ± 0.03 kg N / (m·d)) and a mixed flocculent with granular sludge reactor (R2, 0.39 ± 0.04 kg N / (m·d)) at ambient temperature (21-28 ℃) . The good adaptability of anammox bacteria (Candidatus Jettenia) to ambient temperature ensured its efficient activity (0.84-1.54 mg N/(g VSS·h)). The overexpression ammonia monooxygenase gene abundances in ammonia oxidizing bacteria (Nitrosomonas) was also predicted. The inhibition of hydrazine and the competition of denitrifying bacteria (Denitratisoma) to nitrite nitrogen, leading to a low Nitrospira relative abundances (0.2%-2.1%) . It was also found that R1 was more resistant to the unfavorable condition. For R2, higher Denitratisoma abundances (9.2%-18.5%) and predicted metabolic pathway abundances related to carbon metabolism were observed.