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Rimozione di nutrienti e microinquinanti attraverso un processo a fanghi attivi assistito da membrana e carboni attivi

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Nutrients and micropollutants removal by a membrane bioreactor (MBR) and activated carbons 12 OBJECT AND STRUCTURE OF THE THESIS Nutrients biological removal from wastewater is a well established process and it is generally agreed that the availability of organic biodegradable matter, process configuration and activated sludge characteristics determine predominantly the efficiency and reliability of the process. Nevertheless, regarding the production of excess sludge and the removal of particular types of pollutants conventional activated sludge systems still need to be improved. The aim of the experimental work carried out during the three-years PhD was to verify the reliability of and advanced biotechnological process for wastewater treatment: the membrane biological reactor (MBR). Besides typical aspects of wastewater treatment such as suspended solids, nutrients and pathogens removal, one of the main goals of this thesis was to study and validate a process to reduce excess sludge production and to uncouple the hydraulic characteristics of the system (i.e. hydraulic retention time) from the biological ones (i.e. mean cell residence time) in order to attain a better control of the process, avoiding the typical problems of conventional activated sludge systems linked to the sludge final sedimentation. Furthermore, the removal of peculiar micropollutants outfits (organics and metals) was faced with particular concern to the process modelling. According to these general themes, every chapter of this thesis is a self-sustaining section. In Chapter I membranes and membrane bioreactors are described. A first part is dedicated to the membrane itself and to the description of the theoretical aspects linked to its configuration, fabrics and use. A second part is then dedicated to the state of the art in the field of membrane bioreactors applied to wastewater treatment. Chapter II is about the materials used and the methods applied for the experimentation. The pilot plant is described, together with the explanation of the research structure. In Chapter III the theme of nutrients biological removal from wastewater is faced with single chapters dedicated to carbon, nitrogen and phosphorus. In each section the fundamentals of the process are reported and then discussed on the basis of experimental data. A provisional simplified model for carbon and nitrogen removal has been outlined. Conclusions are then drawn for each component analysed. Chapter IV is about organic micropollutants removal from wastewater. The experimental data are discussed and compared with literature and with a conventional wastewater treatment process with particular concern for the influence of sludge age on removal efficiencies. Chapter V regards metals removal from wastewater. Particular attention has been given to the mechanism of biosorption and to the effect of sludge age on metals uptake by activated sludge, both from the MBR and from a conventional activated sludge system. In Chapter VI pathogens removal is described. Removal efficiencies are discussed for total coliforms and Escherichia coli. Chapter VII is dedicated to sludge production. In this section the relationship existing between excess biomass production and SRT has been investigated together with the determination of sludge growth and typical kinetic parameters. Chapter VIII describes the ultrafiltration module performances with particular concern for flux and suction pressure. The effect of biomass concentration on the filtration module has been investigated and the resistance-in-series model has been applied to determine the relative

Anteprima della Tesi di Laura Innocenti

Anteprima della tesi: Rimozione di nutrienti e microinquinanti attraverso un processo a fanghi attivi assistito da membrana e carboni attivi, Pagina 7

Tesi di Dottorato

Dipartimento: Dipartimento di Scienze Ambientali

Autore: Laura Innocenti Contatta »

Composta da 183 pagine.

 

Questa tesi ha raggiunto 4319 click dal 01/04/2005.

 

Consultata integralmente 4 volte.

Disponibile in PDF, la consultazione è esclusivamente in formato digitale.