Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery
Thesis (PhD(Eng))--University of Pretoria, 2011.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Published: |
University of Pretoria
2013
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613713201102848 |
|---|---|
| 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 | © 2011 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 | Thesis (PhD(Eng))--University of Pretoria, 2011. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/28663 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:40:31.230Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| 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:2263/28663 Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery Chirwa, Evans M.N. s22289985@tuks.co.za Ngwenya, Nonhlanhla Metallic fission products Sulphate Nuclear waste UCTD Thesis (PhD(Eng))--University of Pretoria, 2011. The performance of a growing sulphate reducing bacteria consortium for Sr2+, Co2+ and Cs+ removal from solution in a batch sulphidogenic bioreactor was investigated. Metal removal by the growing bacterial consortium, and microbial culture growth and metabolic activities (biological sulphate removal) were continuously monitored in the bioreactors over the duration of the treatment period. On the other hand, diversity changes within the bacterial consortium before and after bioreactor operation (28 days) were performed using the partial 16S rRNA fingerprinting method. In the original bacterial consortium, Enterococcus and Staphylococcus sp. were the dominant bacterial species. However, the presence of Sr2+, Co2+ and Cs+ in the growth media, resulted in the emergence of new bacterial species belonging to the Citrobacter, Paenibacillus, and Enterococcus and Stenotrophomonas genera, respectively. The Citrobacter and Paenibacillus sp. demonstrated high tolerance towards the presence of the divalent cations, Sr2+ and Co2+, respectively, while the Enterococcus and Stenotrophomonas sp., demonstrated Cs+ high tolerance. The bacterial growth and sulphate removal rate were significantly decreased at initial metal ion concentrations ≥100 mg/L. The toxicity and inhibitory effects of the metals on the present SRB consortium was observed in the order Sr>Co>Cs. The metal uptake capacity (qτ) of the bacterial consortium decreased with increasing initial metal concentration, and complete Sr2+, Co2+ and Cs+ removal was observed at initial metal concentrations ≤75 mg/L. Overall, the present SRB consortium demonstrated a superior Sr2+ removal capacity (qmax= 405 mg/g), and the least for Cs2+, where qmax = 192 mg/g. The present SRB culture exhibited a superior Sr+ and Cs+ binding capacity, compared to other studies in literature. Results from Sr2+, Co2+ and Cs+ biosorption kinetics indicate that initial concentration and solution pH played a vital role in determining the rate of metal removal kinetics. The experimental data was successfully analysed by the pseudo-second-order rate model, demonstrating that chemisorption is the main rate limiting step for the removal of Sr2+, Co2+ and Cs+ from solution. In this study, the adsorption behaviour of protons and of Sr2+, Co2+ and Cs+ onto the bacterial consortium cell surfaces was evaluated under anaerobic conditions as a function of pH (4-10), ionic strength (0.01, 0.05, 0.1M) and temperature (25, 50 and 75°C). Acid-base titrations of the bacterial suspension indicated that the titration data could be adequately described by a four site non-electrostatic model, with pKa values of 4.41, 6.69, 8.10 and 10. The Sr2+, Co2+ and Cs+ adsorption data could be fitted with a two site non-electrostatic model, involving the type 1 and 2 sites (carboxylic and phosphoryl sites). Increasing the ionic strength had a negative effect on the adsorption of metal ions from solution. There was no observed temperature dependence on the adsorption of Co2+ and Cs+ from solution. In summary, results obtained in this study have shown that the processes involved in microbial Sr2+, Co2+ and Cs+ removal from contaminated sources is a direct function of the microbial characteristics and efficiency, mass transfer and surface complexation effects under varying environmental conditions. One important goal to be achieved in future studies will be the determination of the intrinsic stability constants and the structure of the formed metal complexes species. These constants can be used directly in risk assessment programs. Chemical Engineering unrestricted 2013-09-07T14:02:52Z 2011-10-14 2013-09-07T14:02:52Z 2011-09-06 2011-10-14 2011-10-12 Thesis Ngwenya, N 2011, Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/28663 > D11/9/62/ag http://hdl.handle.net/2263/28663 http://upetd.up.ac.za/thesis/available/etd-10122011-151728/ © 2011 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 application/pdf application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | Metallic fission products Sulphate Nuclear waste UCTD Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery |
| title | Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery |
| title_full | Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery |
| title_fullStr | Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery |
| title_full_unstemmed | Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery |
| title_short | Bioremediation of metallic fission products in nuclear waste : biosorption and biorecovery |
| title_sort | bioremediation of metallic fission products in nuclear waste biosorption and biorecovery |
| topic | Metallic fission products Sulphate Nuclear waste UCTD |
| url | http://hdl.handle.net/2263/28663 http://upetd.up.ac.za/thesis/available/etd-10122011-151728/ |