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The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor
Dissertation (MEng)--University of Pretoria, 2020.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2021
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| _version_ | 1867613729371193344 |
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| access_status_str | Open Access |
| author2 | Chirwa, Evans M.N. |
| author_browse | Chirwa, Evans M.N. |
| author_facet | Chirwa, Evans M.N. |
| collection | Thesis |
| dc_rights_str_mv | © 2020 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 (MEng)--University of Pretoria, 2020. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/79624 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:46.593Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| 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:2263/79624 The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor Chirwa, Evans M.N. u13303628@tuks.co.za Maharajh, Dheepak Mukwevho, Mukhethwa Judy UCTD Acid mine drainage Biological sulphate reduction Sulphate reducing bacteria Design Expert Response Surface Methodology 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 (MEng)--University of Pretoria, 2020. Biological sulphate reduction (BSR) has been identified as a promising alternative technology for the treatment of acid mine drainage. BSR is a process that uses sulphate reducing bacteria to reduce sulphate to sulphide using substrates as nutrients under anaerobic conditions. The performance of BSR is dependent on several factors including substrate, pH, temperature and hydraulic retention time (HRT). In a quest to find a cost effective technology, Mintek conducted bench-scale tests on BSR that led to the commissioning of a pilot plant at a coal mine in Mpumalanga province, South Africa. This current study forms part of the ongoing tests that are conducted to improve Mintek’s process. The purpose of this study was to investigate the robustness of Mintek’s process and to develop a tool that can be used to predict the process’ performance with varying pH, temperature and HRT. Design Expert version 11.1.2.0 was used to design the experiments using the Box-Behnken design. In the design, pH ranged from 4 to 6, temperature from 10 °C to 30 °C and HRT from 2 d to 7 d with sulphate reduction efficiency, sulphate reduction rate and sulphide production as response variables. Experiments were carried out in water jacketed packed bed reactors that were operated in a down-flow mode. The reactors were packed with woodchips, wood shaving, hay, lucerne straw and cow manure as support for sulphate reducing bacteria (SRB) biofilm. Cow manure and lucerne pellets were used as the main substrates and they were replenished once a week. These reactors mimicked the pilot plant. The data obtained were statistically analysed using response surface methodology. The results showed that pH did not have a significant impact on the responses (p>0.05). Temperature and HRT, on the other hand, greatly impacted the process (p<0.05) and the interaction between these two factors was found to be strong. Sulphate reduction efficiency and sulphate reduction rate decreased by over 60 % with a decrease in temperature 30 °C to 10 °C. Generally, a decrease in sulphide production was observed with a decrease in temperature. Overall, a decrease in HRT resulted in a decline of sulphate reduction efficiency and sulphide production but favoured sulphate reduction rate. This study demonstrated that Mintek’s process can be operated at pH as low as 4 without any significant impact on the performance. This decreases the lime requirements and sludge production during the pre-neutralisation stage by close to 50 %. There was, however, a strong interaction between temperature and HRT which can be used to improve the performance especially during the winter season. mi2026 Chemical Engineering MEng Unrestricted SDG-06: Clean water and sanitation SDG-09: Industry, innovation and infrastructure SDG-12: Responsible consumption and production 2021-04-22T10:33:19Z 2021-04-22T10:33:19Z 2020/09/29 2020 Dissertation Mukwevho, MJ 2020, The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor, MEng Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/79624> S2020 http://hdl.handle.net/2263/79624 en © 2020 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 | UCTD Acid mine drainage Biological sulphate reduction Sulphate reducing bacteria Design Expert Response Surface Methodology 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 The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor |
| title | The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor |
| title_full | The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor |
| title_fullStr | The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor |
| title_full_unstemmed | The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor |
| title_short | The Use of Design Expert in Evaluating The Effect of pH, Temperature and Hydraulic Retention Time on Biological Sulphate Reduction in a Down-Flow Packed Bed Reactor |
| title_sort | use of design expert in evaluating the effect of ph temperature and hydraulic retention time on biological sulphate reduction in a down flow packed bed reactor |
| topic | UCTD Acid mine drainage Biological sulphate reduction Sulphate reducing bacteria Design Expert Response Surface Methodology 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/2263/79624 |