The analysis of the rheological properties of the sludge produced in biological purification plants is paramount for the design of equipment (pumping, mixing, conditioning, aeration, filtration, etc.) and the management of these plants. In particular, solid content in the sludge plays a significant role in the rheological quantities. In this study, an investigation of the sludge rheology produced in different sectors of an activated sludge plant (aerated sludge, recirculation sludge, and thickened sludge) has been performed. Specifically, for each sludge sample, various physical-chemical parameters have been analyzed, and rheological tests have been performed at different temperatures (10°C, 20°C, 30°C, and 40°C ± 0.1). The sludge was considered as a non-Newtonian Bingham fluid. Viscosity and critical stress were determined, and their dependence at different temperatures, on some physical parameters, such as solid content and settling solids, has been studied. Results evidenced that viscosity and critical stress increase with increasing solid concentration. Moreover, at the same concentration, as the temperature increases, the viscosity decreases, whereas the critical stress decreases until temperature values of about 30°C and then increases again. PRACTITIONER POINTS: An investigation of the sludge rheology produced in different sectors of an activated sludge plant has been performed. For each sludge sample, various physical-chemical parameters have been analyzed, and rheological tests have been performed at different temperatures. Viscosity and critical stress were determined, and their dependence at different temperatures, on some physical parameters, has been studied. Results evidenced that viscosity and critical stress increase with increasing solid concentration.

Municipal wastewater sludge rheology: Impact of temperature, solid content, and settling solids

Infusino, Ernesto;Caloiero, Tommaso
2021-01-01

Abstract

The analysis of the rheological properties of the sludge produced in biological purification plants is paramount for the design of equipment (pumping, mixing, conditioning, aeration, filtration, etc.) and the management of these plants. In particular, solid content in the sludge plays a significant role in the rheological quantities. In this study, an investigation of the sludge rheology produced in different sectors of an activated sludge plant (aerated sludge, recirculation sludge, and thickened sludge) has been performed. Specifically, for each sludge sample, various physical-chemical parameters have been analyzed, and rheological tests have been performed at different temperatures (10°C, 20°C, 30°C, and 40°C ± 0.1). The sludge was considered as a non-Newtonian Bingham fluid. Viscosity and critical stress were determined, and their dependence at different temperatures, on some physical parameters, such as solid content and settling solids, has been studied. Results evidenced that viscosity and critical stress increase with increasing solid concentration. Moreover, at the same concentration, as the temperature increases, the viscosity decreases, whereas the critical stress decreases until temperature values of about 30°C and then increases again. PRACTITIONER POINTS: An investigation of the sludge rheology produced in different sectors of an activated sludge plant has been performed. For each sludge sample, various physical-chemical parameters have been analyzed, and rheological tests have been performed at different temperatures. Viscosity and critical stress were determined, and their dependence at different temperatures, on some physical parameters, has been studied. Results evidenced that viscosity and critical stress increase with increasing solid concentration.
2021
municipal sludge
rheology
settling solids
solids content
temperature
viscosity
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/324770
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 1
  • ???jsp.display-item.citation.isi??? 1
social impact