This study examined biological mercury removal from soil using mercury-resistant bacteria in soil microcosms. Mercuric chloride was used to artificially contaminate Kidman soil to mercury concentrations of 5 ppm and 10 ppm. Soil moisture content was maintained at three levels, 20%, 30% and 50%. Mercury resistant-bacteria were added to soil samples and the mercury removal rate was compared to control samples without added bacteria. Mercury removal rate was initially enhanced by the addition of bacteria. After 30 days, no difference was observed between samples and controls with initial mercury concentration of 5 ppm when soil moisture content was 20%. At an initial mercury concentration of 10 ppm, soil samples had less mercury remaining than controls after 30 days. Autoclaved soil had a decreased mercury removal rate compared to soil not autoclaved. Addition of nutrient (sucrose) did not increase the mercury removal rate. A slurry-type bioreactor was found to be more efficient than a non-stir type. After 30 days of continuous stirring, 85-90% of the added mercury (10 ppm) was removed, while under the same conditions except no stirring, only around 60% of the mercury was removed.
Overall, biological detoxification of mercury from contaminated soil can be achieved by using a slurry-type bioreactor with additon of mercury-resistant bacteria.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-6440 |
| Date | 01 May 1991 |
| Creators | Zhang, Shiying |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
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