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Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I
Dissertation (MSc (Applied Science: Environmental Technology))--University of Pretoria, 2020.
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University of Pretoria
2020
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| _version_ | 1867613644387254272 |
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| access_status_str | Open Access |
| author2 | Brink, Hendrik Gideon |
| author_browse | Brink, Hendrik Gideon |
| author_facet | Brink, Hendrik Gideon |
| collection | Thesis |
| dc_rights_str_mv | © 2019 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Applied Science: Environmental Technology))--University of Pretoria, 2020. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/77295 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:25.358Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/77295 Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I Brink, Hendrik Gideon jtendenedzai@gmail.com Chirwa, Evans M.N. Tendenedzai, Job Tatenda Bioremediation Kinetics Selenium Selenite Pseudomonas stutzeri NT-I UCTD Engineering, built environment and information technology theses SDG-06 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Dissertation (MSc (Applied Science: Environmental Technology))--University of Pretoria, 2020. Selenium (Se) in the aquatic environment is predominantly found as the soluble selenium oxyanions; selenate (SeO42-), and selenite (SeO32-). These oxyanions are toxic, and they readily bio-accumulate in the food chain. However, numerous studies have proven the viability of microbial remediation in reducing them to elemental selenium (Se0) which is considered to be biologically inert and relatively less toxic. Of the various microorganisms that have been employed in Se bioremediation, Pseudomonas stutzeri NT-I has shown great potential in removing high concentrations of SeO42- and SeO32-. Of these two selenium oxyanions, SeO32- is more toxic, is the most reactive and is usually found in mildly oxidising acidic environments. Therefore, the focus of this study is on selenite. In this study Pseudomonas stutzeri NT-I was used in aerobic batch reduction of various SeO32- concentrations (0.5 to 10 mM) to Se0 under already known optimum conditions of temperature 35±2 °C, pH 7 – 8 and salinity 5 g.L-1 NaCl. The selenium (Se) reduction efficiency of strain NT-I was assessed under varying conditions, such as the presence and absence added nitrogen and glucose substrates, inhibited metabolic activity and bacterial cells. Moreover, the variation in the different parameters such the oxidation reduction potential (ORP), metabolic activity (MA) and the concentrations of SeO32-, glucose and total organic carbon (TOC) were also monitored. Key results indicated that the rate and amount of SeO32 reduction was influenced by the concentration to be reduced. For an initial SeO32- concentration of 0.5 mM, reduction was gradual and after 36 h, approximately 75 % had been reduced to Se0 which was equivalent to 0.375 mM. In the reduction of 10 mM SeO32- however, the reduction rate was rapid and even though the overall percentage reduction averaged around 18 %, this was equivalent to 1.8 mM This indicated that the increased initial reduction rate was a result of increased biomass activity in response to increased selenite concentration. This response is likely a defence mechanism employed by strain NT-I to detoxify its surrounding in elevated SeO32- concentrations. The results of these biological experiments were modelled, and the non-growth kinetics were found to fit the adapted Monod equation with k_s and k_Se values of 4.723 mM and 2.869 mmol.(h.g)-1 respectively. Pseudomonas stutzeri NT-I’s capability of being able to survive in very high selenium concentrations make it an attractive and versatile microbial species suitable for the bioremediation of selenium laden industrial wastewater. mi2026 Chemical Engineering MSc (Applied Science: Environmental Technology) Restricted SDG-06: Clean water and sanitation SDG-09: Industry, innovation and infrastructure SDG-12: Responsible consumption and production 2020-12-07T10:33:41Z 2020-12-07T10:33:41Z 2021-04 2020 Dissertation * http://hdl.handle.net/2263/77295 DOI: 10.25403/UPresearchdata.16418871 en © 2019 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Bioremediation Kinetics Selenium Selenite Pseudomonas stutzeri NT-I UCTD Engineering, built environment and information technology theses SDG-06 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I |
| title | Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I |
| title_full | Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I |
| title_fullStr | Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I |
| title_full_unstemmed | Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I |
| title_short | Performance evaluation of biological selenium IV (Selenite) reduction by a pure culture of Pseudomonas stutzeri NT-I |
| title_sort | performance evaluation of biological selenium iv selenite reduction by a pure culture of pseudomonas stutzeri nt i |
| topic | Bioremediation Kinetics Selenium Selenite Pseudomonas stutzeri NT-I UCTD Engineering, built environment and information technology theses SDG-06 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 |
| url | http://hdl.handle.net/2263/77295 |