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Bioremediation of Polychlorinated Biphenyls Contaminated Soils (with Emphasis on 4-chlorobenzoic acid) by Slurry Systems

Abad, Zahra | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54579 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Yaghmaei, Soheila; Ghobadi Nejad, Zahra
  7. Abstract:
  8. Polychlorobiphenyl compounds are a class of persistent organic pollutants consisting of two biphenyl rings and chlorine substations. Polychlorobiphenyls do not dissolve in water, are very stable at high temperatures, and are considered a good conductor. Due to the mentioned properties in the 1930s and 1940s, these compounds were widely used in various industries such as power plants, Painting industry, Plastics industry, etc. After years of use, these substances have been found to be very dangerous to the health of living organisms and the environment due to their high resistance to decomposition and the ability to accumulate in adipose tissue. Today, although the production and use of these products is prohibited, significant quantities of them are available in warehouses or equipment of various industries. Various ways to remove polychlorobiphenyls from nature have been suggested. One of these methods is bioremediation, which is more environmentally friendly and more economical than other methods. In this study, the 4-chlorobenzoic acid compound was degraded in the slurry system by the microbial strain Lysinibacillus macrolides DSM54T (previously isolated from contaminated native soil in the first phase of the project) and its degradation was investigated using an spectrophotometer. Also, in order to obtain the highest percentage of biodegradation, optimization by considering time, microorganism concentration, temperature, pH and pollutant concentration factors was performed by @Design Expert software and response surface methodology. The optimal response proposed by the software was 100% biodegradation at 25 ° C, initial concentration of contaminant 100 mg/kg, pH = 8, microbial inoculation of 16% v/v and time content of 240 hours
  9. Keywords:
  10. Response Surface Methodology ; Optimization ; Biodegradation ; Bioremediation ; Biological Degradation ; Lysinibacillus Macrolides ; Polychlorinated Biphenyls ; Slurry System

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