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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 18 the treatment of some hazardous wastes through concentration of hazardous chemical constituents, where pure water can be recovered on the other side of the membrane. There high- pressure devices require pre-treatment for effective operation. Other important membrane technologies include dialysis, electrodialysis and pervaporation. The largest market for membranes is still haemodialysis where a co-current or counter-current membrane system is used to clean the blood. Electrodialysis (ED) involves setting up an electric cell across membranes so that cations and anions are attracted to the anode and cathode and travel through the membranes to the waste stream. The difference in electrical potential is the driving force. ED is used primarily in desalination of seawater or deionization (including softening) of water, as well as the removal of heavy metals form water and wastewater. Electrodialysis reversal (EDR) is an ED process in which the polarity of the electric cell is reversed during the process to reduce fouling and maintain flux through the system. Pervaporation (PV) is a process that essentially evaporates solvents through a membrane. PV is used to separate water from solvents, either to remove a small amount of solvents from a clean water stream or to remove a small amount of water to purify a solvent stream and to separate one organic solvent from another. 1.2.3 Membrane configurations Figure 1 presents schematic of the various types of ideal continuous-flow membrane separation process. Figure 1. Types of ideal continuous flows used in membrane separation processes. Co-current flow (Fig.1a) is the flow pattern in a membrane module in which the fluids on the upstream and downstream sides of the membrane move parallel to the membrane surface and in the same direction. Co-current flow is used in certain dialysis units. Counter-current flow (Fig.1b) is the flow pattern in a membrane module in which the fluids on the upstream and downstream sides of the membrane move parallel to the membrane surface but in opposite directions. Counter-current flow is also used in certain dialysis units. Cross-flow or tangential flow (Fig.1c) is the flow pattern in a membrane module in which the fluid on the upstream side of the membrane moves parallel to the membrane surface and the Concentrate Permeate Feed Sweep (a) Co-current flow Concentrate Permeate Feed Sweep (b) Counter-current flow Concentrate Permeate Feed (c) Cross flow (d) Dead-end flow Permeate Feed

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 13

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.