Identification of nitrifiers in a full-scale biological treatment system using fluorescent in situ hybridization

Abstract

Diversity of nitrifying bacterial population was investigated in sludge samples taken from a full-scale biological wastewater treatment plant (WWTP) treating domestic wastewater by fluorescent in situ hybridization (FISH) during seasonal operation. Duplicate grab samples were collected in March 2003, June 2003, December 2003 and May 2004 from the aerobic tank of the treatment plant. FISH results were interpreted with system performance in terms of BOD₅, TKN and NO₃-N removals and also with operational parameters such as wastewater temperature and sludge age. BOD₅ removal efficiencies were always greater than 90% whilst TKN removal in a range of 69–95% were achieved during the monitoring period. Although there were variations in operational conditions of the biological treatment system both Nitrosomonas and Nitrosospira genera from AOB and Nitrobacter genus from NOB were found to be present in all samples examined.

Keywords:

• Biological wastewater treatment
• fluorescent in situ hybridization
• nitrification
• ammonia-oxidizing bacteria
• nitrite-oxidizing bacteria.

Acknowledgments

Orhan Ince and Bahar Kasapgil Ince would like to acknowledge the Scientific Research Projects of Istanbul Technical University (Project no: 30333) and the Scientific Research Projects of Bogazici University (Project no: 02S104), respectively. The authors also acknowledge the Scientific and Technical Research Council of Turkey (TUBITAK) (Project no: ICTAG C-054) and ISKI Pasakoy Advanced Biological Wastewater Treatment Plant administration and personnel for their cooperation.

Notes

*Sampling times.