| Author | Tran Thi Thanh Thuy |
| Call Number | AIT Thesis no.EV-08-42 |
| Subject(s) | DDT (Insecticide)--Environmental aspects
|
| Note | A thesis report submitted in partial fulfillment of the requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Extensive use of POPs chemicals since last century has resulted a significant number of contaminated sites in the world, causing adverse impacts to human and environment. Although being considered as an environmentally friendly approach, only a few bioremediation technologies have been successfully applied in real scale. Several studies were conducted to evaluate degradation of POPs in synthetic soil and water. However, achieved results are not sufficient to have full scale picture on applicability of bioremediation for actual sites. The overall aim of this thesis was to evaluate the feasibility of bioremediation for contaminated site with 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT). Since some conventional technologies such as land farming, composting and biopiles have showed limitations, slurry bioreactor was targeted to discuss in this study. Principle of slurry bioreactor is to remove contaminants from soil by water. Then, contaminated water will be treated by physico or biological processes. A site in Tuyen Quang province, Vietnam was selected for the research. In the initial stage, investigation was carried out to identify whether the site is contaminated or not. Soil samples were collected from the site to determine concentration of POPs. Analytical procedure for POPs identification includes several steps from sample preparation, extraction, clean up to analyzing by Gas Chromatography. After finishing investigation stage, information on concentration of POPs in soil was used as input data for Fugacity model. Fugacity model provided more information to assess the situation of the site. In the second stage, experiment was conducted with soil from heavily contaminated area of the site. In order to aim at slurry bioreactor, removal of DDT from soil by water (leaching, washing) and degradation of DDT in water was studied. Investigation results indicated that the site is seriously contaminated with DDT. A disposal hole of DDT was identified with about 100m² area. Concentration of DDT in soil was around 300 ppm on the top of disposal hole; and 1 ppm in the surrounding area. The output of Fugacity also reported a very high concentration of DDT in sediment and biota (7.6 ppm in sediment and 15 ppm in biota). Physical treatment was studied with soil from heavily contaminated area. Washing with detergent gave higher removal of DDT from soil. Results of experiment showed that the efficiency of soil washing was dependent on pH of wash water. The removal reached 5%, 12%, 36% and 36% at pH value of 6, 8, 10 and 12 respectively. After physical treatment, biodegradation test was conducted with contaminated water. And, slow degradation of DDT and its metabolites in water was observed under both anaerobic and aerobic conditions. After two months treating under sequential anaerobic/ aerobic condition, concentration of DDT in water reduced from 0.59 ppm to 0.04 ppm resulting 93% reduction. The slurry bioreactor consist soil washing and biological treatment. Soil washing gave 36% of removal and biological treatment gave 93% of removal. Thus, the total removal efficiency of bioreactor is 33%. Slurry bioreactor is considered as a potential alternative to clean up sites contaminated with DDT. Further study should be conducted to improve efficiency of process. |
| Year | 2008 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Annachhatre, Ajit P.;Pham, Hung Viet; |
| Examination Committee(s) | Preeda Pakpian;Shipin, Oleg V.; |
| Scholarship Donor(s) | Ministry of Education and Training, Vietnam; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2008 |