Removal of heavy metals from waste water of tanning leather industry by fungal species isolated from polluted soil

Abstract

Seven fungal species (1237 colonies/g dry soil) belonging to three genera were isolated from soil sample (pH 8.7, total soluble salts 0.81 mS/cm, organic carbon 0.25%) located in the industrial city at Al-Madinah Al-Munawarah. Such soil receives a long-term application of untreated industrial effluents. The isolated species were Aspergillus candidus, Aspergillus carneus, Aspergillus flavipes, Aspergillus flavus var columnaris, Aspergillus unguis, Cephalosporium curtipes and Cylindrophora hoffmannii.
Genus Aspergillus, the most dominant, accounted for 95.1% of the total count and was represented by five species. A. candidus was the most prevalent species on the isolation plates (37.2% of the total count) followed by A. flavipes and A.unguis. The isolated fungi were investigated for their potential to remove heavy metals from wastewater effluent of tanning leather industry. Such effluent was alkaline (pH, 8.2) with high content of total soluble salts (30.6 mS/cm) and heavy metals including Pb⁺², Cu⁺², Fe⁺³, Mn⁺², Cr⁺⁶ and Sr⁺². The isolated fungi showed significant metal sorption capacity which was species and metal dependent. Almost all the fungi showed more affinity to Pb⁺² than Cr⁺⁶ and Sr⁺². The most dominant A. candidus on the isolation plates exhibited the highest activity for biosorption of heavy metals. The results indicate that fungi of contaminated soils have high level of metal biosorption capacities.

Keywords: Fungi, industrial wastewater, biosorption, heavy metals.

African Journal of Biotechnology Vol. 12(27), pp. 4351-4355