STATISTICAL ASSESSMENT OF BACTERIAL COMMUNITIES IN ACTIVATED SLUDGE.

LOZADA, MARIANA; ERIJMAN, LEONARDO

Queensland, Australia

Congreso; 4th IWA Activated Sludge Population Dynamics Specialist Conference. Microbial Population Dynamics in Biological Wastewater Treatment; 2004

International Water Association

The variability of bacterial communities in replicate lab-scale activated sludge reactors over a period of almost two years was evaluated by statistical analysis of denaturing gel gradiente1ectrophoresis (DGGE) fingerprints. Four sequential batch reactors were red with synthetic sewage, two of which received additionally 0.1 % of nonylphenol ethoxylate (NPE), a nonionic surfactant. The highly dynamical character of bacterial communities was confirmed by the differences in populations among replicate reactors. Addition ofNPE exerted a strong influence in the development of distinct bacterial groups. Statistical measurement of similarities between reactors was obtained by pairwise similarity analysis using the Dice coefficient. The group of NPE-amended reactors exhibited the highest similarities values indicating that bacterial community structure ofNPE-amended reactors was better replicated than control reactors. Simpson index of dominance was algo significantly higher in NPE-amended reactors. Reactors red with NPE and control reactors were grouped into distinct clusters. Bootstrapping was used to assess the validity ofthe observed clusters. Replicate NPE-amended reactors taken at 12´months clustered together with a high bootstrap support, whereas analogous relations within the control reactor cluster were not supported, suggesting that changes in microbial community structure upon addition ofNPE in the wastewater were not random, but mar have occurred as a result of biological succession.