Tecnologías para tratamiento de aguas de lastre mediante procesos fotoquímicosdiseño, evaluación y optimización

Abstract

The present Ph. D. Thesis studies the effects of UV based disinfection treatments and the enhancement by the application of photocatalysis with titanium dioxide on bacteria and microalgae, focused to the application as ballast water treatment. The treatments was applied by through flow reactors, previously characterized with salt tracer for checking their operation as a plug-flow system, then validating the mechanisms for evaluating the applied UV dose as the product of the intensity and the exposure time. The assessment of treatment effects was performed by obtaining the survival profiles of treated organisms. The UV and photocatalytic treatments were applied to bacteria Escherichia coli and Enterococcus faecalis, both organisms controlled by the Ballast Water Convention, using distilled and salt water matrix. The survival response of bacteria was determined by selective chromogenic agar after membrane filtration of samples treated with different UV doses. Additionally, results were matched with disinfection experiments with a standard collimated beam reactor for validation of the experimental procedures. The disinfection profiles determined the increased inactivation of bacteria by the application of photocatalytic treatment in distilled and salt water. The disinfection of microalgae required the development of a mechanism to study the concentration of viable organisms after treatment. The irradiated samples were incubated and subjected to periodical determinations of cellular density. The concentration of initial viable organisms was estimated by the modeling of growth curves of samples treated to different UV doses. The disinfection profiles depicted an enhancement by the application of photocatalytic treatment in relation to UV light only. Additionally, results demonstrated the relevance of the UV treatment prior to dark storage as occurring when the treatment is applied during the ballasting operation. A semi-automatic device based on microscopy ad flow cytometry (FlowCAM¿) was tested for assessing its feasibility as systematic ballast water monitor. The analytic capacities to determine the accurately the size, concentration and viability of organisms were examined by analysis of artificial beads, monoculture and real seawater. Additionally, logistic features were studied, such as physical characteristics, staff required and files management.