Integral analysis of hydrodynamic cavitation effects on waste activated sludge characteristics, potentially toxic metals, microorganisms and identification of microplastics

Kolbl Repinc, Sabina (author), Bizjan, Benjamin (author), Budhiraja, Vaibhav (author), Dular, Matevž (author), Gostiša, Jurij (author), Brajer Humar, Barbara (author), Kaurin, Anela (author), Kržan, Andrej (author), Levstek, Meta (author), Morales Arteaga, Juan Francisco (author), Petkovšek, Martin (author), Rak, Gašper (author), Stres, Blaž (author), Širok, Brane (author), Žagar, Ema (author), Zupanc, Mojca (author)

Wastewater treatment plants, the last barrier between ever-increasing human activities and the environment, produce huge amounts, of unwanted semi-solid by-product - waste activated sludge. Anaerobic digestion can be used to reduce the amount of sludge. However, the process needs extensive modernisation and refinement to realize its full potential. This can be achieved by using efficient pre-treatment processes that result in high sludge disintegration and solubilization. To this end, we investigated the efficiency of a novel pinned disc rotational generator of hydrodynamic cavitation. The results of physical and chemical evaluation showed a reduction in mean particle size up to 88%, an increase in specific surface area up to 300% and an increase in soluble COD, NH$_4$-N, NO$_3$-N, PO$_4$-P up to 155.8, 126.3, 250 and 29.7%, respectively. Microscopic images confirmed flocs disruption and damage to yeast cells and Epistilys species due to mechanical effects of cavitation such as microjets and shear forces. The observed cell ruptures and cracks were sufficient for the release of small soluble biologically relevant dissolved organic molecules into the bulk liquid, but not for the release of microbial DNA. Cavitation treatment also decreased total Pb concentrations by 70%, which was attributed to the reactions triggered by the chemical effects of cavitation. Additionally, the study confirmed the presence of microplastic particles and fibers of polyethylene, polyethylene terephthalate, polypropylene, and nylon 6 in the waste activated sludge.

• Language: English
• Keywords: hydrodynamic cavitation, waste activated sludge, sludge characteristics, microbial damage, potentially toxic metals, microplastics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FGG - Faculty of Civil and Geodetic Engineering; FS - Faculty of Mechanical Engineering; BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2022
• Number of pages: 14 str.
• Numbering: Vol. 806, pt. 4, art. 151414
• PID: 20.500.12556/RUL-133321
• UDC: 532.528:628.355
• ISSN on article: 0048-9697
• DOI: 10.1016/j.scitotenv.2021.151414
• COBISS.SI-ID: 83741955
• Publication date in RUL: 22.11.2021

Record is a part of a journal

• Title: Science of the total environment
• Shortened title: Sci. total environ.
• Publisher: Elsevier
• ISSN: 0048-9697
• COBISS.SI-ID: 26369024

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: hidrodinamska kavitacija, odpadno blato, lastnosti blata, poškodbe mikroorganizmov, potencialno nevarne kovine, mikroplastika