Phytoremediation of heavy metal polluted soil and utilization of hyperaccumulator plants via pyrolysis

In this thesis, it was aimed to remediation of soil polluted with lead (Pb), cadmium (Cd), Zinc (Zn) through phytoremediation techniques. The thesis was carried out in three stages consist of remediation of polluted soil through plants, evaluation of polluted plants via pyrolysis and comparison of remediation technologies by MCDM (Multi Criteria Decision Making) methods. In the first stage of the thesis, rape (Brassica napus), sunflower (Helianthus annuus) and corn (Zea mays) seeds were sowed in simulated soils which had been prepared with addition of Pb, Cd and Zn compounds in laboratory. In the second stage, initial plant compositions were determined by elemental analysis (C, H, N, S), moisture, ash, volatile matter, and fixed carbon analysis. The contaminated plants were pyrolyzed at 500 °C with the heating rate of 35 °C/min in a fixed bad stainless steel (380 S) 240 cm3 reactor. After pyrolysis, Pb, Cd and Zn content of solid and liquid products were determined. Toxicity Characteristics Leaching Procedure (TCLP) analysis was also utilized for the solid product. In the third stage, biological treatment, electrokinetic, phytoremediation, physical isolation, soil flushing and vitrification technologies were evaluated by Analytic Network Process (ANP) and ELimination and Choice Expressing the REality (ELECTRE III) methods, on the purpose of determination of the most appropriate remediation technology for soil polluted with heavy metals and assist to decision makers. In conclusion, the best metal removal efficiency from soil was obtained with rape. According to pyrolysis results, it was observed that heavy metals were stabilized at solid product, and phytoremediation was determined the most appropriate remediation technology, after the analyses of ANP (Analytic Network Process) and ELECTRE III (Elimination Et Choix Traduisant la Realité ) methods. Keywords: Cadmium, Lead, Multi Criteria Decisions Making, Phytoremediation, Polluted Soil, Pyrolysis, Zinc.