Comparison of denitrifier communities in the biofilms of bioaugmented and non-augmented zeolite–biological aerated filters

Abstract

The denitrifier communities of a bioaugmented and non-augmented zeolite–biological aerated filter (Z-BAFs) were investigated and compared because the bioaugmented Z-BAF provided better and more stable treatment efficiency for nitrate and nitrite removal. Terminal restriction fragment length polymorphism (T-RFLP) and reverse transcription T-RFLP (RT-T-RFLP) were applied to analyse the denitrifier community diversity in the biofilm collected from each Z-BAF. The results showed that the bioaugmentation technology favourably changed the indigenous denitrifier community and enhanced denitrification under nitrogen loading shocks. The cDNA clone libraries were developed to explore the active denitrifier community structures of both filters. The results showed that the active denitrifiers in both the bioaugmented and non-bioaugmented Z-BAF belonged to α-, β- and γ-proteobacteria. However, the sequence of the introduced denitrifier (Paracoccus sp. BW001) was not found in the clone library of the bioaugmented filter, which implied that the removal of nitrate and nitrite was attributed mainly to the indigenous denitrifiers in the adjusted bacterial community in the bioaugmented Z-BAF.

Keywords:

• bioaugmentation
• zeolite
• biological aerated filter
• denitrifier community
• coking wastewater

Acknowledgements

This study was supported by an ‘863’ Follow-up Exploration Project (2009AA06Z309) granted by the Chinese Ministry of Science and Technology. We sincerely thank Mr. Anping Lü who kindly provided the natural zeolite and helped to prepare the modified zeolite at Jinyun, Zhejiang Province, China.