Rheological measurements as a tool for monitoring the performance of high pressure and high temperature treatment of sewage sludge

Hii, K, Parthasarathy, R, Baroutian, S, Gapes, D and Eshtiaghi, N 2017, 'Rheological measurements as a tool for monitoring the performance of high pressure and high temperature treatment of sewage sludge', Water Research, vol. 114, pp. 254-263.


Document type: Journal Article
Collection: Journal Articles

Title Rheological measurements as a tool for monitoring the performance of high pressure and high temperature treatment of sewage sludge
Author(s) Hii, K
Parthasarathy, R
Baroutian, S
Gapes, D
Eshtiaghi, N
Year 2017
Journal name Water Research
Volume number 114
Start page 254
End page 263
Total pages 10
Publisher Elsevier
Abstract Hydrothermal processing plays a significant role in sewage sludge treatment. However, the rheological behaviour of sludge during these processes is not fully understood. A better understanding of the sludge rheology under hydrothermal processing conditions can help improve process efficiency. Moreover, sludge rheology is easier to measure than chemical analyses. If a relationship could be established, it provides a possibility of using rheological measurement as a basis for monitoring the performance of hydrothermal processing. The rheological changes in thickened waste activated sludge (7 wt%) was investigated using a pressure cell-equipped rheometer during 60-min thermal hydrolysis (TH) at various temperatures (80-145 °C) and constant pressure (5 bar). Changes in the soluble chemical oxygen demand (COD) were measured using a separate reactor with a similar operating condition. The sludge behaved as a shear-thinning fluid and could be described by the Herschel-Bulkley model. At constant temperature, the yield stress and high-shear (600 s-1) viscosity of sludge decreased logarithmically over 60 min. At constant time, the yield stress and the high-shear viscosity decreased linearly with increasing TH temperature and these values was much less than corresponding properties after treatment and cooling down to 25 °C. The soluble COD of sludge also increased logarithmically over 60 min at constant temperature, and increased linearly with increasing temperature at constant time. Furthermore, the yield stress and high-shear viscosity reduction showed a linear correlation with the increase in soluble COD.
Subject Rheology
Wastewater Treatment Processes
Keyword(s) Thermal hydrolysis
Sewage sludge rheology
Yield stress
Apparent viscosity
Waste activated sludge
DOI - identifier 10.1016/j.watres.2017.02.031
Copyright notice © 2017 Elsevier Ltd. All rights reserved.
ISSN 0043-1354
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