The use of hydrodynamic cavitation for waste-to-energy approach to enhance methane production from waste activated sludge

Zupanc, Mojca (author), Brajer Humar, Barbara (author), Dular, Matevž (author), Gostiša, Jurij (author), Hočevar, Marko (author), Kolbl Repinc, Sabina (author), Krzyk, Mario (author), Novak, Lovrenc (author), Ortar, Jernej (author), Pandur, Žiga (author), Stres, Blaž (author), Petkovšek, Martin (author)

Anaerobic digestion in wastewater treatment plants converts its unwanted end product – waste activated sludge into biogas. Even if the process is well established, pre-treatment of the sludge can further improve its efficiency. In this study, four treatment regimes for increasing methane production through prior sludge disintegration were investigated using lab-scale cavitation generator and real sludge samples. Three different cavitating (attached cavitation regime, developed cloud shedding cavitation regime and cavitation in a wake regime) and one non-cavitating regime at elevated static pressure were studied in detail for their effectiveness on physical and chemical properties of sludge samples. Volume-weighted mean diameter D[4,3] of sludge's particles decreased by up to 92%, specific surface area increased by up to 611%, while viscosity (at a shear rate of 3.0 s$^{−1}$) increased by up to 39% in the non-cavitating and decreased by up to 24% in all three cavitating regimes. Chemical changes were more pronounced in cavitating regimes, where released soluble chemical oxygen demand (sCOD) and increase of dissolved organic matter (DOM) compounds by up to 175% and 122% were achieved, respectively. Methane production increased in all four cases, with the highest increase of 70% corresponding to 312 mL CH$_4$ g$^{−1}$ COD. However, this treatment was not particularly efficient in terms of energy consumption. The best energy balance was found for the regime with a biochemical methane potential increase of 43%.

• Language: English
• Keywords: hydrodynamic cavitation, waste activated sludge, disintegration, viscosity, methane production, energy balance
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering; FGG - Faculty of Civil and Geodetic Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 11 str.
• Numbering: Vol. 347, art. 119074
• PID: 20.500.12556/RUL-151587
• UDC: 532.528
• ISSN on article: 0301-4797
• DOI: 10.1016/j.jenvman.2023.119074
• COBISS.SI-ID: 167876867
• Publication date in RUL: 11.10.2023

Record is a part of a journal

• Title: Journal of environmental management
• Shortened title: J. environ. manag.
• Publisher: Elsevier
• ISSN: 0301-4797
• COBISS.SI-ID: 720405

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: hidrodinamska kavitacija, aktivno odpadno blato, dezintegracija, viskoznost, proizvodnja metana, energijska bilanca