Biodegradación anaerobia y aerobia de DDT por fermentación en medio sólido
DDT is an organochlorine pesticide with a high resistance to degradation. Its use has been restricted in many countries because of both the environmental and health damages to which it is related. In Mexico , its use is still common in health campaigns to protect agricultural areas and as result of...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2000 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:x633f1375 |
| Acceso en línea: | https://doi.org/10.24275/uami.x633f1375 |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/DDT (Insecticide) -- Physiological effect info:eu-repo/classification/LEM/DDT (Insecticida) -- Aspectos sanitarios info:eu-repo/classification/LEM/DDT (Insecticida) -- Efectos fisiológicos info:eu-repo/classification/LEM/DDT (Insecticide) -- Health aspects info:eu-repo/classification/cti/3 |
| Sumario: | DDT is an organochlorine pesticide with a high resistance to degradation. Its use has been restricted in many countries because of both the environmental and health damages to which it is related. In Mexico , its use is still common in health campaigns to protect agricultural areas and as result of this, pollution by this compound has been observed in soils and sediments. This study proposes the degradation of DDT by bioaugmentation under anaerobic and aerobic systems in soild fermentation. The study was conducted using an agricultural soil of the Yucatan Peninsula, and texture and nutrients of the soil were characterized prior to the analysis. The sample was artificially contaminated with a known concentration of DDT. A factorial experimental design was carried out and it included the effect of inocula and culture conditions. The response variables were the concentrations of DDT, DDE and DDD, which were measured by gas chromatography. The aerobic inocula consisted of a mixed culture (commercial) and a pure culture of Phanerochaete chrysosporurn. Two culture conditions were tested: (i) aerobic conditions and (ii) an anaerobic pre-treatment in which activated sludges from a treatment plant of a softdrink facility were used, followed by aerobic condition. Total treatment lasted 28 days. Mixed cultures, including anaerobic and aerobic, were adapted to DDT for 40 days. These cultures were fed weekly with nutrients and 0.5 pg of DDT per mi of the culture media. It was demonstrated that degradation of DDT was more efficient with a combination of the anaerobic pre-treatment, and the use of the fungus under aerobic conditions. Maximum degradation was 84%. For DDE, the combined method was also the most suitable, with a 69% of degradation. The statistical analysis of the results for different times of culture showed significant differences during the anaerobic stage (from O to 14 days) and the final concentrations of DDT H(6, N=21) = 13.5152; p = 0.0356, which shows clearly that the efficiency of the anaerobic treatment in the biotransformation of DDT mainly oriented towards the formation of DDD, since an increase in the levels of this compound was obtained during this culture stage. No significant differences in DDE concentration between culture conditions were found; however, a decreasing tendency in concentration was observed during the 28 days treatment of anaerobic-aerobic culture. In order to observe the enzymatic activity related to microorganisms, reductase (qualitatively) and peroxidase (quantitatively) activities were evaluated during the culture. Reductase activity was only detected in the anaerobic stage and this group of enzymes was observed to be intracellular or linked to the membrane. The peroxidase activity present in the aerobic stage came from extracellular extracts. In both cases, a major increase of activity was observed in bioaugmentated culture. |
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