Keywords: 
• SBBR /
• livestock wastewater /
• bacterial diversity /
• PCR-DGGE /
• phylogenetic tree

Abstract: A sequencing batch biofilm reactor (SBBR) was used to treat livestock and poultry breeding wastewaters (LPBWs). An operational mode of alternant aeration and non-aeration and 8 h every period was adopted with room temperatures ranging from 9 to 18℃ and DO during aeration phase controlled around 2 mg/L. Nitrite accumulation occurred and the removal efficiencies were as high as (95.1±0.8)% and (87.2±0.6)% for NH3-N and TN， respectively. To reveal the bacterial community structure and its dynamic change trend in the SBBR， bacterial diversity was analyzed using PCR-DGGE technique and phylogenetic trees were constructed. The results indicated that no obvious change of bacterial community richness happened， taking the biofilm samples of the start-up phase and the seeding sludge into comparison. Alternation between aeration and non-aeration during the running phase helped to improve the diversity index of bacteria in the biofilm， however， suffered the change of operational modes and ammonia load rates， the diversity indexes of ammonia-oxidizing bacteria during the running phase were slightly lower than that during the start-up phase. Except for anaerobic ammonia oxidation bacteria， some kinds of proteobacterium with denitrification function and special ammonia-oxidizing bacteria were convinced to exist in the biofilm under the experimental conditions， demonstrating that simultaneous shortcut nitrification and denitrification were the main mechanisms for the nitrogen removal.