Effect of ultrasound, low-temperature thermal and alkali pre-treatments on waste activated sludge rheology, hygienization and methane potential

Ruiz-Hernando, M., Martin-Diaz, J., Labanda, J., Mata-Alvarez, J., Llorens, J., Lucena, F. and Astals, S. (2014) Effect of ultrasound, low-temperature thermal and alkali pre-treatments on waste activated sludge rheology, hygienization and methane potential. Water Research, 61 119-129. doi:10.1016/j.watres.2014.05.012

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Author Ruiz-Hernando, M.
Martin-Diaz, J.
Labanda, J.
Mata-Alvarez, J.
Llorens, J.
Lucena, F.
Astals, S.
Title Effect of ultrasound, low-temperature thermal and alkali pre-treatments on waste activated sludge rheology, hygienization and methane potential
Journal name Water Research   Check publisher's open access policy
ISSN 1879-2448
0043-1354
Publication date 2014-09-15
Year available 2014
Sub-type Article (original research)
DOI 10.1016/j.watres.2014.05.012
Volume 61
Start page 119
End page 129
Total pages 11
Place of publication London, United Kingdom
Publisher I W A Publishing
Collection year 2015
Language eng
Formatted abstract
Waste activated sludge is slower to biodegrade under anaerobic conditions than is primary sludge due to the glycan strands present in microbial cell walls. The use of pre-treatments may help to disrupt cell membranes and improve waste activated sludge biodegradability. In the present study, the effect of ultrasound, low-temperature thermal and alkali pre-treatments on the rheology, hygienization and biodegradability of waste activated sludge was evaluated. The optimum condition of each pre-treatment was selected based on rheological criteria (reduction of steady state viscosity) and hygienization levels (reduction of Escherichia coli, somatic coliphages and spores of sulfite-reducing clostridia). The three pre-treatments were able to reduce the viscosity of the sludge, and this reduction was greater with increasing treatment intensity. However, only the alkali and thermal conditioning allowed the hygienization of the sludge, whereas the ultrasonication did not exhibit any notorious effect on microbial indicators populations. The selected optimum conditions were as follows: 27,000 kJ/kg TS for the ultrasound, 80 °C during 15 min for the thermal and 157 g NaOH/kg TS for the alkali. Afterward, the specific methane production was evaluated through biomethane potential tests at the specified optimum conditions. The alkali pre-treatment exhibited the greatest methane production increase (34%) followed by the ultrasonication (13%), whereas the thermal pre-treatment presented a methane potential similar to the untreated sludge. Finally, an assessment of the different treatment scenarios was conducted considering the results together with an energy balance, which revealed that the ultrasound and alkali treatments entailed higher costs.
Keyword Waste activated sludge
Anaerobic digestion
Pre-treatment
Rheology
Hygienization
Post-treatment
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
Advanced Water Management Centre Publications
 
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