Isolation of aluminum-tolerant bacteria capable of nitrogen removal in activated sludge

•Four strains of Al-resistant bacteria were isolated from activated sludge.•These bacteria could withstand 20 mM concentration of aluminum.•Brevundimonas diminuta B3 and Hydrogenophaga sp. B4 could remove NO3− and NH4+.

Four strains of bacteria capable of withstanding 20 mM concentration of aluminum were isolated from activated sludge in a bioreactor. 16S rRNA identification and morphological characteristics indicated that these strains were Chryseobacterium sp. B1, Brevundimonas diminuta B3, Hydrogenophaga sp. B4, and Bacillus cereus B5. Phylogenetic analysis revealed the position and interrelationships of these bacteria. B. diminuta B3 and Hydrogenophaga sp. B4 could achieve nitrate nitrogen removal of 94.0% and 76.8% within 36 h of its initial concentration of 148.8 and 151.7 mg/L, respectively. Meanwhile, B3 and B4 could degrade ammonia with little nitrite accumulation. Results of this study provide more information about aluminum-resistant bacteria and laid the foundation for aluminum salt when it is simultaneously used for chemical precipitation.