Valentín-Vargas, Alexis

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    Dinámica y distribución de comunidades bacterianas en dos biorreactores de lodos activados en plantas de tratamiento de aguas residuales domésticas
    (2009) Valentín-Vargas, Alexis; Massol-Deyá, Arturo A.; College of Arts and Sciences - Sciences; Montalvo-Rodríguez, Rafael; Rodríguez-Minguela, Carlos; Department of Biology; Saliceti Piazza, Lorenzo
    Biological wastewater treatment systems are recognized today as the most common biotechnological application in the World. But despite of their widely distributed use, there is a very limited knowledge of their distinctive microbial diversity, the dynamics between populations, and biogeographical pattern in the community structure, especially in tropical environments. In order to comprehend the highly complex microbial dynamics of these ecosystems, two activated sludge bioreactors in Puerto Rico were studied. Temporal and spatial variations of dominant populations, as well as patterns between community variations and operational parameters were assessed during a 13 months period through molecular techniques, consisting of t-RFLP and clone libraries analyses. Both biological and environmental data were analyzed using a combination of multivariate statistical tools, including: Canonical Correspondence Analysis, Non- Metric Multidimensional Scaling and Analysis of Similarity. Although an apparent overlapping between populations was observed, the results revealed significant differences between the two treatment plants and shows that the microbial community in the smaller bioreactor (Adjuntas, 0.6 millions of gallons per day, MGD) is more unstable and inefficient than the community in the bigger one (Mayagüez, 28 MGD). We identified operational parameters such as pH, solid and hydraulic retention times, and flow showing strong correlations with shifts in the community structure. The bacterial community in Adjuntas bioreactor appeared to be more susceptible to chemical variations in the influent wastewater. Furthermore, the shorter solid retention time of the system (≈ 5 days) promotes a codominance of microbial populations, which results in system inestability. In both plants, bacteria from the Proteobacteria, Cyanobacteria and the Bacteroidetes were the most abundant groups, which differed from some diversity studies previously published. In general, our findings demonstrate that each treatment plant has a distinctive microbial community structure while the microbial community at the smaller bioreactor was more inconsistent in the water cleaning process than the community in the Mayagüez bioreactor. These findings can contribute to the development and implementation of more stable, efficient and less expensive biological treatment systems.