INTEGRAL ANALYSIS OF HYDRODYNAMIC CAVITATION EFFECTS ON WASTE SLUDGE CHARACTERISTICS

date: 08.12.2021

category: Sporočila za javnost

 

Researchers from the Laboratory for Water and Turbine Machines (LVTS) have published an article in the internationally renowned environmental journal Science of the Total Environment (IF: 7,963), in which they explained in detail the effects of cavitation on the WAS from one of the WWTPs in Slovenia. They have performed the analysis together with colleagues from the UL, Faculty of Civil and Geodetic Engineering, National Institute of Chemistry, Domžale-Kamnik WWTP and UL, Biotechnical faculty.

Wastewater treatment plants (WWTPs), the last barrier between human activities and the environment, produce huge amounts (up to 13 million tonnes per year within the EU alone) of an unwanted by-product – waste activated sludge (WAS). Currently, one of the biggest costs for WWTPs is its removal and destruction/incineration. In the future, it will be necessary to introduce innovative circular economy approaches to achieve the objectives of the EU Green Agreement, which include the production of smaller quantities of final waste products. For example, looking at WAS as a source and not as an unwanted end product is the first step towards sustainable wastewater treatment. One of the very attractive options for using WAS is anaerobic digestion, the end product of which is methane - a renewable energy source. In the Laboratory for Water and Turbine Machines (LVTS) we try to use hydrodynamic cavitation for the pre-treatment of WAS to improve its disintegration and solubilization. In this way, we can reduce the amount of WAS that needs to be destroyed, and at the same time produce larger amounts of methane and in this way contribute to greater self-sufficiency of WWTPs. Analyses, given in the article, have shown that hydrodynamic cavitation damages both flocs and individual cells of microorganisms present in WAS, thus effectively disintegrating it. This results in improved solubilization of the substances trapped in the flocs, which results in more efficient subsequent anaerobic process. We also showed the positive effects of cavitation on one of the most important WAS contaminants – potentially toxic metals, as we managed to decrease total Pb concentrations by 70 %. Due to their presence in concentrations above the permitted levels, WAS cannot not be disposed of on agricultural land. At the same time, we also confirmed the presence of microplastic particles and fibers of polyethylene, polyethylene terephthalate, polypropylene and nylon 6 in the WAS.

Web link to the article: https://doi.org/10.1016/j.scitotenv.2021.151414.

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The authors would like to acknowledge that this project has been co-financed by the Slovenian Research Agency (core funding nos. P2-0401 and P2-0180 and grant nos. J7-2601 and J7-1814), Horizon 2020: MSC 860720, COST Action: CA16215 and ERC: 771567 — CABUM.

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