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J. Kosel, et al.
showed that supercavitation was more e ffi cient for the destruction of B. subtilis, Gram positive bacteria problematic in paper mill production plants. The results were evaluated in terms of chemical, physical and microbiological characterisation. Using the supercavitation set-up we were able to destroy 2.3 logs of B. subtilis , 4.2 logs of anaerobic sulphate reducing bacteria, 4 logs of yeast, 3 logs of aerobic bacteria and 1.3 logs of bacterial spores. In terms of chemical characterisation of samples, we achieved 22% COD reduction, a 77% increase in redox potential and a 27% increase in dissolved oxygen levels. Evaluation of physical char- acterisation of treated samples showed that sediment portion was re- duced by 50% and the insoluble portion by 67%. When the achieved results are compared to di ff erent cavitation set-ups, it can be deduced that rotation cavitation generator of supercavitation is economically more feasible than for example a Venturi device. Based on the achieved results we plan to investigate the e ffi ciencyof the rotation generator of hydrodynamic cavitation on a pilot scale in- tegrated into the enclosed water recycle system of a paper plant.
Declaration of Competing Interest
The authors declare that they have no known competing fi nancial interests or personal relationships that could have appeared to in fl u- ence the work reported in this paper.
Acknowledgments
The authors would like to thank the Slovenia ’ s Smart Specialisation Strategy for funding the Research, development and innovation project (RDI) Cel.Cycle: »Potential of biomass for development of advanced materials and bio-based products« (contract number: OP20.00365), which is co fi nanced by the Ministry of Education, Science and Sport of the Republic of Slovenia and the European Union as part of the European Regional Development Fund 2016 – 2020; and the Slovenian Research Agency for funding the core research No. P2-0401. We thank the paper company Vipap Videm Kr š ko for their cooperation and sup- port. Mathematical and grammatical help was provided by Professors Franc Kosel and Bernarda Kosel.
References
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