Rheological behavior of sewage sludge and strain-induced dewatering

Chaari, Fahmi; Racineux, Guillaume; Poitou, Arnaud; Chaouche, Mohend

doi:10.1007/s00397-002-0276-5

Cited by 53 publications

(17 citation statements)

References 10 publications

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“…Dentel (1997) has underlined the fact that in many cases it is quite difficult to correlate the theoretically described physical properties of the sludge (the viscosity that derives from rheological studies is one of these parameters) with the operational physical properties that are important in plant processes such as pumping characteristics and dewatering; despite of this, many studies furnish important correlations between these two aspects. In particular, the dewatering efficiency can be correlated with different squeezing velocities applied to the sludge (Chaari et al, 2003); the obtained results show that the dewatering increases with the decreasing of the squeezing velocity. The aim of this study is that of defining a method to perform rheological tests with sewage sludge keeping into account the sludge pretreatment phase, comparing two different protocols taken from literature in order to achieve the best conditions for rheological tests.…”

Section: Introductionmentioning

confidence: 96%

Rheological Characterization of Sludge Coming from a Wastewater Treatment Plant

Novarino¹,

Santagata²,

Dalmazzo³

et al. 2010

American J. of Environmental Sciences

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Problem statement: The aim of this study was that of studying the rheology of sewage sludge using two different rheological test protocols taken from literature and comparing them in order to evaluate which useful information are given from every protocol. Approach: Two different protocols have been used taking particularly into account the problems connected to sludge heterogeneous composition and to the interaction between solid-solid and solid-water particles in order to completely understand the rheological behavior of this suspension; moreover, the consequences of particular effects connected to test geometry and conditions have been considered. Two fundamental parameters have been modified in the samples: The total solids content and the polyelectrolyte addition. Sludge with 3 and 5% of total solids have been investigated, with or without polyelectrolyte using also microscope analysis to understand the effect of polyelectrolyte on the sludge. Results: As expected, it was noticed that sludge viscosity grows up increasing the total solids content and with the presence of polyelectrolyte. The effect of polyelectrolyte is that of separating the liquid-phase from the solid-phase of the sludge giving a more space-heterogeneous suspension with higher viscosity and higher non-Newtonian behavior. Conclusion: This study proved that combining two different protocols of analysis can be useful to furnish important and complementary information on sludge rheology especially when some parameters change from sample to sample. Moreover, in order to have good and consistent results, it is necessary to use particular attention on samples pretreatments

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Section: Introductionmentioning

confidence: 96%

Rheological Characterization of Sludge Coming from a Wastewater Treatment Plant

Novarino¹,

Santagata²,

Dalmazzo³

et al. 2010

American J. of Environmental Sciences

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“…However, this unique control of microstructure and property for polymer-based composites has less been achieved in practice due to the technical difficulties in controlling the fillers positions. Squeezing [18][19][20] is a process which can make fillers entrapped and compacted in matrix. The heterogeneity of composites occurs when the rate of matrix flow through the fillers is greater than that of composites deformation [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…Squeezing [18][19][20] is a process which can make fillers entrapped and compacted in matrix. The heterogeneity of composites occurs when the rate of matrix flow through the fillers is greater than that of composites deformation [19,20]. However, this method is limited to the thin films and demands highly accurate control of the squeeze rate [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…The heterogeneity of composites occurs when the rate of matrix flow through the fillers is greater than that of composites deformation [19,20]. However, this method is limited to the thin films and demands highly accurate control of the squeeze rate [19,20]. Electric field [21] is another approach to achieve the unique microstructure, in which the localization of fillers is induced by electric field concentration.…”

Section: Introductionmentioning

confidence: 99%

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Locally reinforced polymer-based composites for efficient heat dissipation of local heat source

Yuan

Bin

et al. 2016

International Journal of Thermal Sciences

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Local heat source in electronic device is likely to produce hot spot which can degrade the reliability and performance of the device. Various materials have been attempted to enhance the heat dissipation of local heat source. Many theoretical studies have demonstrated that the heterogeneous composite materials with fillers concentrated at the preferential paths of heat flux are effective in cooling the local heat source. However, this unique control of microstructure and property for polymer-based composites has less been achieved in practice due to the technical difficulties in controlling the fillers positions. In this paper, a locally reinforced heterogeneous composite with conductive particles concentrated at the preferential path of heat flux was fabricated to cool the local heat source. The local reinforcement was achieved by using magnetically responsive particles as reinforcing elements and a specific magnetic field to organize the elements into the predefined structure. To evaluate the thermal performance of the proposed material, we performed the comparative thermal tests. The results show that compared to the homogeneous composites, the present composites with local reinforcement can significantly enhance the heat dissipation of local heat source. When heat flux is 5840 W m-2 , the locally reinforced composites with a fillers volume fraction of 5% reduced the average and maximum temperature of heater 7.7 °C and 8.7 °C, respectively.

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“…POITOU; CHAOUCHE, 2000;RACINEUX, 2001;CHAARI et al, 2003;KOLENDA et al, 2003;MASCIA et al, 2006; GADALA-MARIA, 2014) ou parte da fase líquida forçada para a borda da amostra (CHAARI et al, 2003;CHALENCON et al, 2016). Essas evidências visuais são qualitativas e só ocorrem em casos mais extremos, sendo que é possível que haja separação de fases sem um indício visualmente perceptível.…”

Section: Configurações De Ensaiounclassified

Mapeamento dinâmico da distribuição de pressão interfacial de argamassas em squeeze flow.

Grandes¹

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RESUMOArgamassas no estado fresco são suspensões heterogêneas multifásicas com grande extensão granulométrica, tendo um comportamento relativamente complexo. Para a sua caracterização reológica já é empregado o ensaio de squeeze flow, método normalizado (ABNT NBR 15839/2010) que fornece informações importantes sobre o fluxo das argamassas em condições similares às de aplicação prática. No entanto, alguns fenômenos relevantes relacionados ao squeeze flow de suspensões não podem ser diretamente avaliados somente através da resposta padrão do ensaio (curva carga ou tensão vs. deslocamento), como o tipo de fluxo e a ocorrência de separação de fases, não havendo ainda um método consolidado para investigação destes efeitos. Neste contexto, uma técnica de mapeamento dinâmico da distribuição de pressão interfacial é apresentada como ferramenta para a complementação do método, visando permitir uma análise mais aprofundada durante o ensaio de squeeze flow em argamassas, nas configurações de área e de volume constante, que podem fornecer informações diferentes. Um método de quantificação gravimétrica da separação de fases foi empregado ainda para verificação do fenômeno. Essa metodologia inovadora requer desenvolvimento, e dessa forma são analisados, além da influência de variáveis do material, aspectos do ensaio e diferentes procedimentos de tratamento e calibração dos dados desenvolvidos para análise dos resultados. Modelos teóricos são utilizados para a comparação das distribuições de pressão experimentais com previsões para fluidos de comportamento conhecido, o que ajuda a indicar o tipo de fluxo predominante. O método desenvolvido mostrou grande potencial para a análise de fluxos complexos, sobretudo suspensões concentradas, e contribui com a ampliação do conhecimento sobre o comportamento reológico de argamassas e os fatores que o influenciam. Palavras-chave: Squeeze flow. Distribuição de pressão. Argamassas. Reologia. Separação de fases. ABSTRACT Mortars while in fresh state are multiphasic heterogeneous suspensions with wide granular extension, presenting a relatively complex behavior. For rheological evaluation the squeeze flow test is already employed, being a standard test (ABNT NBR 15839/2010) and providing relevant information about the flow behavior of mortars under conditions which are similar to those in practical situations. Nevertheless, important phenomena related to the squeeze flow of suspensions cannot be directly assessed by the usual results from the test (load or stress vs. displacement curves), like type of flow and the occurrence of phase separation. Thereis not yet a stablished method for the investigation of these effects. In this context, a dynamic pressure mapping technique is presented as a tool in addition to the method, aiming to achieve a more thorough analysis during the squeeze flow of mortars, both in constant area and constant volume configuration, which can provide different information. A phase separation quantification method was employed to validate the phenomenon. This original me...

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Rheological behavior of sewage sludge and strain-induced dewatering

Cited by 53 publications

References 10 publications

Rheological Characterization of Sludge Coming from a Wastewater Treatment Plant

Rheological Characterization of Sludge Coming from a Wastewater Treatment Plant

Locally reinforced polymer-based composites for efficient heat dissipation of local heat source

Mapeamento dinâmico da distribuição de pressão interfacial de argamassas em squeeze flow.

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