الفهرس 
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Abstract
1. Egyptian petroleum fly ash is highly rich in vanadium, nickel and iron besides traces of other heavy metals such as (Co, Zn, Cu and pb).
2. Ten fungal isolates were isolated from the fly ash sample. The most dominant fungal genera were identified as Aspergillus, Penicillium, Fusarium, Humicola, Epicoccum and Cladosporium.
3. The fungal isolates were screened for their acid productivity; since organic acids are one of the main agents in the bioleaching process.
4. The sensitivity of the tested fungal isolates toward the heavy metals present in the studied sample was determined in the term of dry wt. which were arranged as follow: A. niger < A. terreus < P. vermiculatum < A. flavus < Humicola hayalothermophila < Cladosporium cladosporioides < Penicillium sp. < Epicoccum nigrum < Cladosporium sp. < Fusarium moniliforme.
5. The maximum fungal growth was obtained with using two-step bioleaching method. The fungal biomass was the highest using sucrose in media (100 g sucrose/ L media).
6. The highest bioleaching efficiency for the target metals was achieved by using direct two – step bioleaching process with sucrose medium.
7. Among ten fungal isolates, Cladosporium cladosporioides and Humicola hyalothermophila achieved the highest bioleaching efficiency of vanadium. While, the highest bioleaching efficiency of nickel and total iron was achieved using Cladosporium cladosporioides and Epicoccum nigrum.
8. The fungal isolates were adapted to grow on a medium with pH value 3 in order to improve the fungal tolerance to grow in acidic culture medium (sample pH 2.8: 3).
9. Fly ash was involved in thermal pretreatment to upgrade the vanadium content which, had a positive effect on the bioleaching of vanadium, on the other hand it had a negative effect on the nickel and iron bioleaching. The optimum thermal pretreatment was roasting at 850 ºC for 3 hrs. with 90% Na2CO3.
10. The bioleaching process was optimized by studying the factors of carbon source, nitrogen source, fly ash concentration, incubation period and initial pH.
11. The optimum conditions were achieved with sucrose as carbon source, NH4Cl as nitrogen source, 1% (w/v) fly ash and incubation period of 10 days for vanadium, nickel and total iron.
12. The bioleaching efficiency was highly affected by the initial pH of the growth medium. However, the bioleaching was optimum at pH value of 6 for vanadium and 8 for nickel and total iron. Which gradually decreased through the bioleaching process.
13. Cladosporium cladosporioides was the best fungal isolate that was achieved the maximum bioleaching efficiency of V was 65.4%, Ni was 74.6% and Fe2O3 was 26.9%.
14. Organic acids were produced by Cladosporium cladosporioides in control and optimum culture filtrate were estimated by HPLC. Malic acid was the main organic acid which produced by 35.90, 40.32 and 15.22 (mg/ml) in pure culture, at the optimum conditions using roasted fly ash and at the optimum conditions using original fly ash, respectively.
15. The surface morphology and accumulation activity of the fungal biomasses and the microstructures of the fly ash particles were examined using scanning electron microscopy SEM before and after bioleaching process.
16. Morphological changes of Cladosporium cladosporioides, Humicola hayalothermophila and Epicoccum nigrum were observed after bioleaching due to accumulation of the heavy metals in the cell surface. The mycelial morphology and the visual appearance of the fungal colony were affected by the presence of the fly ash sample. These effects were varied according to the fungal species type and the growth conditions.
17. It was obvious that the effect of bioleaching process on the original and roasted fly ash was revealed the presence of very small particles adsorbed on them. SEM images of fly ash sample was showed rough surface in compared to the original sample.
18. Vanadium and nickel were recovered by direct precipitation. Vanadium was recovered with purity of 74.06%. While nickel was successfully precipitated with purity of 93.39%.
19. Vanadium and nickel were recovered by biosorption with different pretreated Cladosporium cladosporioides biomasses. The maximum biosorption rate was 32.895 and 43.871%, respectively for V and Ni, that were achieved by boiling in 0.5 N NaOH for 15 min. and then dried at 60°C for 12–15 hrs.
20. The obtained results from this study were revealed that the fungal isolates were able to biosorb various concentrations of the heavy metals and can be developed for the biosorption of contaminated soil.
21. This study indicated that bioleaching of heavy metals in the Egyptian petroleum fly ash using fungi could be applied before bulk reuse of the fly ash, simultaneously adding value to the by-product which may be considered as an artificial ore and minimizing the environmental hazard impacts.