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Sludge disinfection using electrical thermal treatment: The role of ohmic heating

Yin, Ziqiang and Hoffmann, Michael and Jiang, Sunny (2018) Sludge disinfection using electrical thermal treatment: The role of ohmic heating. Science of the Total Environment, 615 . pp. 262-271. ISSN 0048-9697. PMCID PMC5711000.

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Electrical heating has been proposed as a potential method for pathogen inactivation in human waste sludge, especially in decentralized wastewater treatment systems. In this study, we investigated the heat production and E. coli inactivation in wastewater sludge using electrical thermal treatment. Various concentrations of NaCl and NH_4Cl were tested as electrolyte to enhance conductivity in sludge mixtures. At same voltage input (18 V), sludge treated with direct current (DC) exhibited slower ascent of temperature and lower energy efficiencies for heat production comparing to that using alternate current (AC). However, DC power showed better performance in E. coli inactivation due to electrochemical inactivation in addition to thermal inactivation. Greater than 6log_(10) removal of E. coli was demonstrated within 2 h using 0.15 M of NaCl as electrolyte by AC or DC power. The heat production in sludge was modeled using Maxwell–Eucken and effective medium theory based on the effective electrical conductivity in the two-phase (liquid and solid) sludge mixtures. The results showed that the water and heat loss is a critical consideration in modeling of sludge temperature using ohmic heating. The experimental data also suggested that the models are less applicable to DC power because the electrochemical reactions triggered by DC reduce the concentration of NH_4+ and other ions that serve as electrolyte. The results of this study contribute to the development of engineering strategies for human waste sludge management.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Hoffmann, Michael0000-0001-6495-1946
Jiang, Sunny0000-0002-4993-8038
Additional Information:© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license ( Received 18 July 2017, Revised 17 September 2017, Accepted 17 September 2017, Available online 30 September 2017. This work was supported by the Bill and Melinda Gates Foundation OPP 1111252.
Funding AgencyGrant Number
Bill and Melinda Gates FoundationOPP 1111252
PubMed Central ID:PMC5711000
Record Number:CaltechAUTHORS:20171002-124309898
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Official Citation:Ziqiang Yin, Michael Hoffmann, Sunny Jiang, Sludge disinfection using electrical thermal treatment: The role of ohmic heating, Science of The Total Environment, Volume 615, 15 February 2018, Pages 262-271, ISSN 0048-9697, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81952
Deposited By: Tony Diaz
Deposited On:02 Oct 2017 19:50
Last Modified:09 Mar 2020 13:18

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