Distribution des temps de sejour en infiltration-percolation. Performances de deux types de materiaux

摘要

The aim of this work is a physical and hydrodynamic characterization of granules used in certain treatment systems for wastewater. Beds of infiltration percolation are simulated by engines provided with different garnishings. The performances of those engines are evaluated in a virgin medium, that is a medium non corrupted by the biomass. After a granulometric study allowing the determining of the mechanical parameters of sands used, an experimental pilot consisting in an automaton of order, of columns of sand, and of a data acquisition post allow using tracage, the determination of the resident time distribution of the effluent within the engines. We highlight the fact that the hydrodynamic behaviour of the columns varies appreciably not only according to the permanent or pulsated-periodic character of the mode; but also and mainly according to the type of garnishing. Thus, it is advantageous to have a resident time large enough in order to increase the time of contact between the biomass and the percolating effluent; which is the case with crushed sand. However, the process could be hazardous, because very large resident time can quicken the clogging of beds of infiltration.