[Adaptability of Completely Autotrophic Nitrogen Removal over Granular Sludge to Low-Strength at Low Temperature].

A single-stage PN-ANAMMOX (PN/A) granular sludge cultured at room temperature was used to investigate the completely autotrophic nitrogen removal efficiency and microbial community structure of low-strength wastewater based on the completely autotrophic nitrogen removal over nitrite in granular sludge at a low temperature. The results showed that at the low temperature (15±1)℃, the ammonia nitrogen load was maintained at 1.29 kg ·(m ·d), and the ammonia nitrogen concentration in the injection was gradually reduced from 70 mg ·L to 40 mg ·L. DO/TAN was controlled at 0.22-0.25. The total nitrogen removal rate was maintained at (85±4)%, and the average TN concentration in the effluent was 8.9 mg ·L. There was no significant proliferation of nitrite-oxidizing bacteria (NOB) during the operation period, and the abundance was less than 1%. Elutriation of the floc sludge and the control of low DO/TAN values can be used as effective control strategies to inhibit NOB proliferation. Through completely autotrophic nitrogen removal over nitrite in granular sludge operated under low-temperature and low-substrate conditions, the particle size became smaller, and the color changed from brown red to brown yellow. The total amount of PS decreased slightly, and the ratio of PN/PS stabilized at 2.5-3.0. Planctomycetes and Proteobacteria dominated the community, and and were two AMX bacteria in the sludge.