The rheology of sewage sludge at different steps of treatment

Lotito, V.; Spinosa, L.; Mininni, Giuseppe; Antonacci, R.

doi:10.2166/wst.1997.0396

Cited by 89 publications

(74 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…September, 2010 (13) where µ p is the plastic viscosity that should be replaced with molecular viscosity in all equations, τ xy is the shear stress of flow with individual definition in each model, and is the shear rate. According to Vradis and Protopapas [9], the shear rate may be defined as:…”

Section: Present Simulationmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of various settling velocity functions and non-Newtonian fluid models in circular secondary clarifiers

Saffarian

Hamedi

Shams

2010

Korean J. Chem. Eng.

View full text Add to dashboard Cite

An axisymmetric single-phase model that predicts the sedimentation of activated sludge in a circular secondaryclarifier is developed. The k-ε turbulence model is used on a two-dimensional, orthogonal and stepwise grid. The concentration equation, which is extended to incorporate the sedimentation of activated sludge in the field of gravity, governs the mass transfer in the clarifier. The computational domain includes the sludge blanket where the viscosity is affected by the rheological behavior of the sludge. Results in case of non-Newtonian fluid model are compared with another numerical approach provided by Lakehal et al. Non-Newtonian fluid models--Bingham, Casson, and HerschelBulkley--are used. The influence of settling velocity functions and non-Newtonian models on the flow behavior isinvestigated. Finally, the best models are introduced and the ways that the non-Newtonian model introduces the plastic viscosity are discussed.

show abstract

Section: Present Simulationmentioning

confidence: 99%

“…Bingham Plastic, Herschel-Bulkley (pseudoplastic with yield stress), pseudoplastic and dilatant models may be defined for behavior of non-Newtonian fluids [1,[12][13][14].…”

Section: Present Simulationmentioning

confidence: 99%

Comparison of various settling velocity functions and non-Newtonian fluid models in circular secondary clarifiers

Saffarian

Hamedi

Shams

2010

Korean J. Chem. Eng.

View full text Add to dashboard Cite

show abstract

“…Sozanski et al (1997) also applied this type of model for thickened sludge. Others employed both Bingham and pseudo plastic models [12,13], while Manoliadis and Bishop (1984) only applied the pseudo plastic model. Different models have been compared by Sanin [14] and for this type of sludge the pseudo plastic model appeared to fit the best [1,[12][13][14].…”

Section: Rheology Of Activated Sludgementioning

confidence: 99%

Numerical simulation of secondary clarifier with activated sludge and suction lift removal system: Modified Casson model and sludge withdrawing sensitivity analysis

Saffarian

Hamedi

Shams

2010

Korean J. Chem. Eng.

View full text Add to dashboard Cite

A computational fluid dynamics model that predicts the sedimentation of activated sludge in a circular secondary clarifier with activated sludge is developed. The axisymmetric single-phase flow is simulated by using a CFD code that has been written with Intel Visual Fortran. First, sludge withdrawing by suction-lift in the near-bottom region of the clarifier is simulated using suction at the bottom of clarifier. The flow and settling processes are simulated using k-ε turbulence model on a two-dimensional and orthogonal grid. A convection-dispersion equation that is extended to incorporate the sedimentation of activated sludge in the field of gravity is used. The computational domain includes the sludge blanket where the viscosity is affected by the rheological behavior of the sludge. Experimental data provided by Weiss et al. show that the relationship between shear stress and shear rate follows the Casson law for the shear rates lower than 50 s −1 . Plastic viscosity of activated sludge is not removed from the concentration diffusion, so using regular non-Newtonian models leads to overestimation of blanket height. Modified Casson model is introduced to overcome the blanket height overestimation problem. Results show that the local sludge distribution in the clarifier has excellent agreement with concentration profile measurements of Weiss et al., for different treatment plant loadings. Alternative sludge withdrawing methods include withdrawing from pipes position at the bottom of clarifier and withdrawing by using sink terms in governing equations are used. Results show that the first withdrawing method gives less error comparing to these withdrawing methods.

show abstract

“…Researchers have studied the rheological properties of sludge, knowing that the sludge is non-Newtonian fluid with the property of shear thinning, and proposed a series of model [9][10][11][12][13][14]. In addition, the rheological parameters of sludge have something to do with the extent of sludge dewatering [15], and at the same time it points out that the relationship between the sludge viscosity and suspended matter concentration is in line with the exponential model [9,10,16]. But the previous research on the quantitative relationship between the apparent viscosity of the sludge and the types, moisture content as well as temperature of the sludge is still lacking.…”

Section: Introductionmentioning

confidence: 99%

The research of model on the apparent viscosity of sludge

Xue¹,

Lou²,

Wei³

2016

Proceedings of the International Symposium on Mechanical Engineering and Material Science

View full text Add to dashboard Cite

Abstract. The viscosity of sludge not only affects its transport properties, but also the drying efficiency. In the paper, the sludge property of apparent viscosity was studied with the different types of sludge、moisture content of sludge and temperature with the help of NDJ series digital viscometer. The results show that the different content of organic matter between municipal sludge and dyeing sludge makes the viscosity of municipal sludge much larger than dyeing sludge's, and the difference increases with the decrease of respective moisture content of the two kinds of sludge. The apparent viscosity of sludge shows exponential growth in the form of )with the decrease of the moisture content, and coefficient of g is approximately the constant value under different temperatures and different moisture content .In addition, the values of municipal sludge and dyeing sludge are -49.64 and -25.10 respectively. In the meanwhile, indicating that the models of coefficient f of municipal sludge and dyeing sludge are accordance with ExpDec1 model and Log3P1 model respectively, and finally model equations are obtained between apparent viscosity of sludge and moisture content and temperature.

show abstract

The rheology of sewage sludge at different steps of treatment

Cited by 89 publications

References 3 publications

Comparison of various settling velocity functions and non-Newtonian fluid models in circular secondary clarifiers

Comparison of various settling velocity functions and non-Newtonian fluid models in circular secondary clarifiers

Numerical simulation of secondary clarifier with activated sludge and suction lift removal system: Modified Casson model and sludge withdrawing sensitivity analysis

The research of model on the apparent viscosity of sludge

Contact Info

Product

Resources

About