Bioremoval of some heavy metals from aqueous solutions by two different indigenous fungi Aspergillus sp. AHM69 and Penicillium sp. AHM96 isolated from petroleum refining wastewater

Abstract

Myco-remediation of heavy metals using indigenous fungi of different petroleum refining areas in Egypt was applied. Among the physicochemical parameters determined in these refineries effluents, the highest levels of heavy metals were recorded for the most toxic heavy metals Fe³⁺ and Co²⁺. The fungal isolates under the isolation codes AHM69 and AHM96 isolated from the mycobiome of Mostorod and Tanta refineries, respectively showed the best bioremoval efficiency toward heavy metals from the real wastewater mixture and polycyclic aromatic hydrocarbons from aqueous solutions. Based on phenotypic and genotypic analysis they were identified as Aspergillus sp. AHM69 and Penicillium sp. AHM96. The optimum conditions for the best bioremoval of Fe³⁺ and Co²⁺ from aqueous solutions by Aspergillus sp. AHM69 were live biomass, temperature 45-55 °C, pH 4.5-5.0, contact time 180 min, metal concentration equal to 1000 and 400 mg/L of Fe³⁺ and Co²⁺ with live fungal biomass dose of 0.5% and 0.4% with Fe³⁺ and Co²⁺, respectively. Concerning to the biomass of Penicillium sp. AHM96, the optimum operation conditions for the best removal of Fe³⁺ and Co²⁺ were 45 °C, pH 5.0 and 400 mg/L of Fe³⁺ with 1.0% biosorbent dosage or 1000 mg/L of Co²⁺ with 0.5% biosorbent dosage for 180 min as process time. Furthermore, FTIR analysis showed masking, shifting, creating and absenting of different functional groups in the fungal biomass surface of AHM96 and AHM69 strains in the presence of Fe³⁺ and Co²⁺ compared to unloaded biomasses. Microscopy with Energy Dispersive X-ray analysis (SEM-EDX) indicated that the removal of Fe³⁺ and Co²⁺ by fungi AHM69 and AHM96 was via biosorption and bioaccumulation on the biomass surface. Our results suggested that in the near future, fungal treatment is likely to outperform and replace other chemical and biological treatments in industrial wastewater treatment for oil refining.

Keywords: Fungal biosorbents; Heavy metals bioremoval; Oil refining industrial wastewater; Process optimization.

Figure 1

Phylogenetic tree of selected fungal strains AHM69 and AHM96 based on rDNA-ITS sequences analysis.

Figure 2

Effect of various process temperatures on the bioremoval of Fe³⁺ and Co²⁺ (%) from aqueous solution by live and dead biomasses of Aspergillus sp. AHM69 and Penicillium sp. AHM96.

Figure 3

Effect of various pHs on the biosorption process of Fe³⁺ and Co²⁺ (%) from aqueous solution by live and dead biomasses of Aspergillus sp. AHM69 and Penicillium sp. AHM96.

Figure 4

FTIR absorptions analysis for functional groups of unloaded (a and c) and loaded (b and d) Aspergillus sp. AHM69 and Penicillium sp. AHM96 biomasses, respectively.

Figure 5

SEM-EDX of Aspergillus sp. AHM69 and Penicillium sp. AHM96 (a and c) control (b and d) in the presence of iron and cobalt, respectively.