Pilar Gargallo Valero

Bioaccumulation of pathogenic bacteria and amoeba by zebra mussels and their presence in watercourses.

Dreissena polymorpha (the zebra mussel) has been invading freshwater bodies in Europe since the beginning of the nineteenth century. Filter-feeding organisms can accumulate and concentrate both chemical and biological contaminants in their tissues. Therefore, zebra mussels are recognized as indicators of freshwater quality. In this work, the capacity of the zebra mussel to accumulate human pathogenic bacteria and protozoa has been evaluated and the sanitary risk associated with their presence in surface water has also been assessed. The results show a good correlation between the pathogenic bacteria concentration in zebra mussels and in watercourses. Zebra mussels could therefore be used as an indicator of biological contamination. The bacteria (Escherichia coli, Enterococcus spp., Pseudomonas spp., and Salmonella spp.) and parasites (Cryptosporidium oocysts and free-living amoebae) detected in these mussels reflect a potential sanitary risk in water.

Inactivation of Enterococcus sp. by Conventional and Advanced Oxidation Processes in Synthetic Treated Urban Wastewater

The aim of this research work was to evaluate the disinfection efficiency of several techniques on the inactivation of the bacteria Enterococcus sp. inoculated in synthetic treated urban wastewater. Different types and doses of reagents and times of exposure were studied. The compared treatments include chlorination, ozone-based treatments in the absence and presence of H2O2 and UVA-visible irradiation-based processes with TiO2 and H2O2. Different combinations of chlorine doses and times of contact inactivated all the bacteria (-7.5 log units). Ozone and O3/H2O2 also achieved high disinfection levels (-6 log units), showing similar inactivation curves. However, the studied phototreatments were less efficient.

Enterococcus sp. Inactivation by Ozonation in Natural Water: Influence of H2O2 and TiO2 and Inactivation Kinetics Modeling

ABSTRACT This article presents the results about the disinfectant power of treatments based on the application of ozone (578 mg O3 h−1) and ozone combined with TiO2 (1 g L−1) and H2O2 (0.04 mM) on Enterococcus sp., a bacteria indicator used in the control of water quality. The results show that all the ozone-based treatments under study achieve the inactivation of Enterococcus sp. solution in natural water. Moreover, the combination of ozone with H2O2 or TiO2 lightly improves the inactivation of Enterococcus sp. compared to the ozonation. However, the treatment with O3, H2O2 and TiO2 is less effective than the use of O3, O3/H2O2 or O3/TiO2. Finally, the primary mathematical models are applied (Hom, biphasic and Mafart) and they adequately describe the disinfection kinetics of the ozonation treatments studied for Enterococcus sp.