Scheda di dettaglio – i prodotti della ricerca
| Dato | Valore |
|---|---|
| Title | HYDRAULIC SHEAR STRESS CALCULATION IN A SEQUENCING BATCH BIOFILM REACTOR WITH GRANULAR BIOMASS |
| Abstract | This paper reports the results of an experimental study specifically aimed at developing a simple methodology for calculating hydrodynamic shear forces in a sequencing batch biofilm reactor (SBBR) system with granular biomass. Using such a methodology, the hydrodynamic shear forces are simply calculated by measuring bed porosity and pressure losses. In addition, by applying this methodology an explanation for the biomass evolution from biofilm to granules under aerobic conditions has been provided and the following mechanism has been proposed: (i) formation of a thin biofilm that fully covers the carrier; (ii) increase of biofilm thickness; (iii) break-up of the attached biofilm with release of biofilm particles; (iv) rearrangement of biofilm particles in smooth granules. The hydrodynamic shear forces trend during the start-up period provides an explanatory key for the generation process of granular biomass. In fact, during the first two steps, the SBBR is characterized by rather weak shear forces values (lower than 1 dyn/ cm(2)). Under these weak shear forces, the biofilm grows by increasing its thickness through a porous structure and weak adhesion strengths. Such a continuous increase of biofilm thickness produces an increase of the shear forces with negative effect on biomass stability, causing the detachment of biofilm particles. In turn, such detachment causes a further sharp increase of shear forces (more than 10 times) that promotes the rearrangement of the detached biofilm particles in smooth granules, A correlation between biomass density and hydrodynamic shear forces was observed. In particular, the biomass density linearly increases with the increase of shear stress. |
| Source | Environmental science & technology 39(3), pp. 889–894 |
| Keywords | Aerobic granulationhydrodynamic shear forcesbiomass density |
| Journal | Environmental science & technology |
| Editor | American Chemical Society,, Easton, Pa., Stati Uniti d'America |
| Year | 2005 |
| Type | Articolo in rivista |
| DOI | 10.1021/es0400483 |
| Authors | DI IACONI C., RAMADORI R., LOPEZ A., PASSINO R. |
| Text | 42170 2005 10.1021/es0400483 ISI Web of Science WOS 000226712600040 Aerobic granulation hydrodynamic shear forces biomass density HYDRAULIC SHEAR STRESS CALCULATION IN A SEQUENCING BATCH BIOFILM REACTOR WITH GRANULAR BIOMASS DI IACONI C., RAMADORI R., LOPEZ A., PASSINO R. Istituto di ricerca sulle acque This paper reports the results of an experimental study specifically aimed at developing a simple methodology for calculating hydrodynamic shear forces in a sequencing batch biofilm reactor SBBR system with granular biomass. Using such a methodology, the hydrodynamic shear forces are simply calculated by measuring bed porosity and pressure losses. In addition, by applying this methodology an explanation for the biomass evolution from biofilm to granules under aerobic conditions has been provided and the following mechanism has been proposed i formation of a thin biofilm that fully covers the carrier; ii increase of biofilm thickness; iii break up of the attached biofilm with release of biofilm particles; iv rearrangement of biofilm particles in smooth granules. The hydrodynamic shear forces trend during the start up period provides an explanatory key for the generation process of granular biomass. In fact, during the first two steps, the SBBR is characterized by rather weak shear forces values lower than 1 dyn/ cm 2 . Under these weak shear forces, the biofilm grows by increasing its thickness through a porous structure and weak adhesion strengths. Such a continuous increase of biofilm thickness produces an increase of the shear forces with negative effect on biomass stability, causing the detachment of biofilm particles. In turn, such detachment causes a further sharp increase of shear forces more than 10 times that promotes the rearrangement of the detached biofilm particles in smooth granules, A correlation between biomass density and hydrodynamic shear forces was observed. In particular, the biomass density linearly increases with the increase of shear stress. 39 3 Articolo pubblicato Allegati_EST_pubblicazione.pdf Articolo in rivista American Chemical Society, 0013 936X Environmental science technology Environmental science technology Environ. sci. technol. Environmental science technology. ES T Environmental science and technology PASSINO ROBERTO claudio.diiaconi DI IACONI CLAUDIO antonio.lopez LOPEZ ANTONIO roberto.ramadori RAMADORI ROBERTO TA.P07.001.001 Sviluppo di tecnologie depurative a regime non stazionario |