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Application of (super)cavitation for the recycling of process waters in paper producing industry
ID Kosel, Janez (Author), ID Šuštaršič, Matej (Author), ID Petkovšek, Martin (Author), ID Zupanc, Mojca (Author), ID Sežun, Mija (Author), ID Dular, Matevž (Author)

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Abstract
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.

Language:English
Keywords:anaerobic sulphate reducing bacteria, Bacillus subtilis, COD, hydrodynamic cavitation, paper mill industry, Redox potential, rotational cavitation generator
Work type:Article (dk_c)
Typology:1.01 - Original Scientific Article
Organization:FS - Faculty of Mechanical Engineering
Year:2020
Publication status in journal:Published
Article version:Publisher's version of article
Article acceptance date:03.02.2020
Publication date:01.06.2020
Number of pages:Str. 1-11
Numbering:Vol. 64, art. 105002
UDC:532.528:676.026(045)
ISSN on article:1350-4177
DOI:10.1016/j.ultsonch.2020.105002 This link opens in a new window
COBISS.SI-ID:514117931 This link opens in a new window
Publication date in RUL:22.04.2021
Views:223
Downloads:108
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Record is a part of a journal

Title:Ultrasonics Sonochemistry
Shortened title:Ultrason. sonochem.
Publisher:Elsevier
ISSN:1350-4177
COBISS.SI-ID:707668 This link opens in a new window

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.
Licensing start date:01.06.2020

Secondary language

Language:Slovenian
Keywords:rotacijski generator, hidrodinamska kavitacija, stopnja drenaže, Bacillus subtilis, COD, papirna inustrija

Document is financed by a project

Funder:Drugi - Drug financer ali več financerjev
Funding programme:Republic of Slovenia, Ministry of Education, Science and Sport
Project number:OP20.00365
Name:Potential of biomass for development of advanced materials and bio-based products
Acronym:(RDI) Cel.Cycle

Funder:EC - European Commission
Funding programme:European Regional Development Fund 2016 – 2020
Project number:OP20.00365
Name:Potential of biomass for development of advanced materials and bio-based products
Acronym:(RDI) Cel.Cycle

Funder:ARRS - Agencija za raziskovalno dejavnost Republike Slovenije (ARRS)
Project number:P2-0401
Name:Energetsko strojništvo

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