Abstract
Chromium toxicity is one of the major environmental pollutants. As conventional methods for heavy metal removal are very expensive, bioremediation using fungi is extensively explored. Therefore in the present investigation, out of 23 fungi isolated from tannery effluent, 4 Aspergillus species namely A. terreus, A. tamarii, A. flavus and A. niger were selected for evaluating chromium tolerance and biosorption potential. Growth of the fungi was tested using various concentrations of Potassium dichromate (Cr VI) viz., 1 mM, 3 mM and 5 mM amended in potato dextrose agar. For all the fungi, growth was observed only in 1 mM and 3 mM. No growth was observed in 5 mM. Biosorption efficiency of both live and alkali pretreated Aspergillus species was compared. In the present study, alkali pretreated form exhibited highest biosorption efficiency than the live biomass in which A. terreus showed highest chromium biosorption potential compared to the other fungi.
Highlights
Heavy metal pollution has become a worldwide environmental issue over the last few decades
Aspergillus sp. were observed to be the most commonly occurring in the heavy metal contaminated soils as reported by Ahmad et al [21] and Zafar et al [23]
Several Aspergillus species have been used for heavy metal ion adsorption such as A. niger [24], A. fumigatus [25], A. niveus [26], A. versicolor [27], A. flavus [28], A. terreus [29] and A. cristatus [30] etc
Summary
Heavy metal pollution has become a worldwide environmental issue over the last few decades. Chromium is one of the major pollutants present in waste waters from various industrial units such as electroplating, fertilizers, pigments, tanning, mining etc. Chromium exists in two stable oxidation states, i.e., trivalent Cr (III) and hexavalent Cr(VI) [2]. The latter is highly water soluble and reported to be a potent carcinogen [3]. Prolonged exposure to hexavalent chromium (Cr(VI)) causes serious health hazards such as cancer in the digestive tract and lungs, epigastric pain, nausea, vomiting, severe diarrhoea and hemorrhage [4].
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