Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process

This study involved the degradation of dichloro-diphenyl-trichloroetane (DDT) using nano-zero valent iron and microbial biofilm as separate and combined processes. The nano-zero valent iron with size of less than 20nm and specific surface area of 45.2 m2 g-1 was synthesized using NaBH4 and FeCl3.6H2...

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Main Author: Tran, Ngoc Minh Quyen
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Language:English
Published: Animo Repository 2012
Online Access:https://animorepository.dlsu.edu.ph/etd_masteral/4348
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Institution: De La Salle University
Language: English
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spelling oai:animorepository.dlsu.edu.ph:etd_masteral-111862021-01-16T06:18:04Z Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process Tran, Ngoc Minh Quyen This study involved the degradation of dichloro-diphenyl-trichloroetane (DDT) using nano-zero valent iron and microbial biofilm as separate and combined processes. The nano-zero valent iron with size of less than 20nm and specific surface area of 45.2 m2 g-1 was synthesized using NaBH4 and FeCl3.6H2O. On the other hand, the biofilm having a thickness of 195.56 µm was developed on sand particles with the inoculum obtained from the sludge of the wastewater treatment facility of De La Salle University and a reactor that was used to treat polychlorinated biphenyls (PCBs). The NZVI treatment step was investigated to obtain the optimal conditions by response surface methodology following Box-Behnken design, with three factors such as initial DDT concentration, NZVI loading and cobalt loading. The response expressed as percent DDT degraded, a second order model with good agreement between experimental results and predicted values. The model terms showed that there is interaction between initial DDT concentration and cobalt loading due to their competition in receiving electron from iron. In addition, the increase in NZVI loading resulted in increased degradation rate, but only up to certain level because of iron agglomeration. The optimal conditions were found to be 20 ppm DDT concentration and 1g/L NZVI loading to obtain 57% DDT degraded. The agglomeration of NZVI was addressed by encapsulated NZVI, which degraded almost completely 20 ppm of DDT by using 1g l-1 NZVI. The kinetic study was conducted on both NZVI and ENZVI. Results showed that experimental data fit with both the power law of a homogeneous system and Michaelis-Menten equation for the heterogeneous system. The sequential treatment was conducted on 20 ppm DDT. Under NZVI process, only 57% of DDT was degraded by 1g l-1 NZVI. The decrease in DDT concentration resulted in the formation of dechlorinated metabolites, whose amounts increased during the NZVI treatment step. However, all DDT residues and its metabolites were degraded in the biofilm step. At the end of the sequential process, 20 ppm DDT was decomposed almost completely at 96.96%. The dechlorinated -iv- De La Salle University products were degraded by the biofilm. The biofilm process also resulted in the formation of metabolites believed to be polar compounds which did not appear under NZVI process. These metabolites could be ring-fission products which may contain hydroxyl (-OH) groups or carboxyl (-COOH) groups. The sequential NZVI-Biofilm process proved to be effective in treating DDT. This process could be applied to other chlorinated pesticides. 2012-01-01T08:00:00Z text https://animorepository.dlsu.edu.ph/etd_masteral/4348 Master's Theses English Animo Repository
institution De La Salle University
building De La Salle University Library
continent Asia
country Philippines
Philippines
content_provider De La Salle University Library
collection DLSU Institutional Repository
language English
description This study involved the degradation of dichloro-diphenyl-trichloroetane (DDT) using nano-zero valent iron and microbial biofilm as separate and combined processes. The nano-zero valent iron with size of less than 20nm and specific surface area of 45.2 m2 g-1 was synthesized using NaBH4 and FeCl3.6H2O. On the other hand, the biofilm having a thickness of 195.56 µm was developed on sand particles with the inoculum obtained from the sludge of the wastewater treatment facility of De La Salle University and a reactor that was used to treat polychlorinated biphenyls (PCBs). The NZVI treatment step was investigated to obtain the optimal conditions by response surface methodology following Box-Behnken design, with three factors such as initial DDT concentration, NZVI loading and cobalt loading. The response expressed as percent DDT degraded, a second order model with good agreement between experimental results and predicted values. The model terms showed that there is interaction between initial DDT concentration and cobalt loading due to their competition in receiving electron from iron. In addition, the increase in NZVI loading resulted in increased degradation rate, but only up to certain level because of iron agglomeration. The optimal conditions were found to be 20 ppm DDT concentration and 1g/L NZVI loading to obtain 57% DDT degraded. The agglomeration of NZVI was addressed by encapsulated NZVI, which degraded almost completely 20 ppm of DDT by using 1g l-1 NZVI. The kinetic study was conducted on both NZVI and ENZVI. Results showed that experimental data fit with both the power law of a homogeneous system and Michaelis-Menten equation for the heterogeneous system. The sequential treatment was conducted on 20 ppm DDT. Under NZVI process, only 57% of DDT was degraded by 1g l-1 NZVI. The decrease in DDT concentration resulted in the formation of dechlorinated metabolites, whose amounts increased during the NZVI treatment step. However, all DDT residues and its metabolites were degraded in the biofilm step. At the end of the sequential process, 20 ppm DDT was decomposed almost completely at 96.96%. The dechlorinated -iv- De La Salle University products were degraded by the biofilm. The biofilm process also resulted in the formation of metabolites believed to be polar compounds which did not appear under NZVI process. These metabolites could be ring-fission products which may contain hydroxyl (-OH) groups or carboxyl (-COOH) groups. The sequential NZVI-Biofilm process proved to be effective in treating DDT. This process could be applied to other chlorinated pesticides.
format text
author Tran, Ngoc Minh Quyen
spellingShingle Tran, Ngoc Minh Quyen
Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process
author_facet Tran, Ngoc Minh Quyen
author_sort Tran, Ngoc Minh Quyen
title Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process
title_short Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process
title_full Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process
title_fullStr Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process
title_full_unstemmed Degradation of dechloro-diphenyl-trichloroethane (DDT) by sequential nano-zero valent iron-biofilm process
title_sort degradation of dechloro-diphenyl-trichloroethane (ddt) by sequential nano-zero valent iron-biofilm process
publisher Animo Repository
publishDate 2012
url https://animorepository.dlsu.edu.ph/etd_masteral/4348
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