20.500.12556/RUL-126442 Application of (super)cavitation for the recycling of process waters in paper producing industry In paper production industry, microbial contaminations of process waters are common and can cause damage to paper products and equipment as well as the occurrence of pathogens in the end products. Chlorine omission has led to the usage of costly reagents and products of lower mechanical quality. In this study, we have tested a rotation generator equipped with two sets of rotor and stator assemblies to generate developed cavitation (unsteady cloud shedding with pressure pulsations) or supercavitation (a steady cavity in chocked cavitation conditions) for the destruction of a persistent bacteria Bacillus subtilis. Our results showed that only supercavitation was effective and was further employed for the treatment of waters isolated from an enclosed water recycle system in a paper producing plant. The water quality was monitored and assessed according to the chemical (COD, redox potential and dissolved oxygen), physical (settleable solids, insolubles and colour intensity) and biological methods (yeasts, aerobic and anaerobic bacteria, bacterial spores and moulds). After one hour of treatment, a strong 4 logs reduction was achieved for the anaerobic sulphate reducing bacteria and for the yeasts; a 3 logs reduction for the aerobic bacteria; and a 1.3 logs reduction for the heat resistant bacterial spores. A 22% reduction in COD and an increase in the redox potential (37%) were observed. Sediments were reduced by 50% and the insoluble particles by 67%. For bacterial destruction in real industrial process waters, the rotation generator of supercavitation spent 4 times less electrical energy in comparison to the previously published cavitation treatments inside the Venturi constriction design. In paper production industry, microbial contaminations of process waters are common and can cause damage to paper products and equipment as well as the occurrence of pathogens in the end products. Chlorine omission has led to the usage of costly reagents and products of lower mechanical quality. In this study, we have tested a rotation generator equipped with two sets of rotor and stator assemblies to generate developed cavitation (unsteady cloud shedding with pressure pulsations) or supercavitation (a steady cavity in chocked cavitation conditions) for the destruction of a persistent bacteria Bacillus subtilis. Our results showed that only supercavitation was effective and was further employed for the treatment of waters isolated from an enclosed water recycle system in a paper producing plant. The water quality was monitored and assessed according to the chemical (COD, redox potential and dissolved oxygen), physical (settleable solids, insolubles and colour intensity) and biological methods (yeasts, aerobic and anaerobic bacteria, bacterial spores and moulds). After one hour of treatment, a strong 4 logs reduction was achieved for the anaerobic sulphate reducing bacteria and for the yeasts; a 3 logs reduction for the aerobic bacteria; and a 1.3 logs reduction for the heat resistant bacterial spores. A 22% reduction in COD and an increase in the redox potential (37%) were observed. Sediments were reduced by 50% and the insoluble particles by 67%. For bacterial destruction in real industrial process waters, the rotation generator of supercavitation spent 4 times less electrical energy in comparison to the previously published cavitation treatments inside the Venturi constriction design. anaerobic sulphate reducing bacteria Bacillus subtilis COD hydrodynamic cavitation paper mill industry Redox potential rotational cavitation generator rotacijski generator hidrodinamska kavitacija stopnja drenaže Bacillus subtilis COD papirna inustrija true false true Angleški jezik Slovenski jezik Članek v reviji 2021-04-22 12:10:57 2021-04-22 12:11:02 2025-03-18 11:18:36 0000-00-00 00:00:00 2020 0 0 Str. 1-11 art. 105002 Vol. 64 Jun. 2020 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 2020-02-03 2020-06-01 532.528:676.026(045) 1350-4177 10.1016/j.ultsonch.2020.105002 514117931 RAZ_Kosel_Janez_2020.pdf RAZ_Kosel_Janez_2020.pdf 1 92D22ED9C555543671E1657C90E8013D 068d257283280922bed8002cb5cd7d4cf36a62c36c576e6aa606e4c0c8042af7 54342771-a359-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=142412 https://www.sciencedirect.com/science/article/abs/pii/S1350417719313410 1 0b6e316d-a353-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=142410 Fakulteta za strojništvo 0 0 0