Zinc Uptake by Fungal Biomass Isolated from Industrial Wastewater

Abstract

In the present work, the biosorption potential of a fungal strain isolated from industrial wastewaters contaminated with zinc and other heavy metals has been investigated. Zinc biosorption studies using the fungi were conducted in an optimized media under sterile as well as nonsterile conditions using batch bioreactors. Initial pH of the media was found to be 5.6. The growth of the fungi and specific metal uptake rates were studied in the liquid media with different initial concentrations of zinc ranging from 0 to 10,000 mg/L. The growth of the fungi was not affected at lower concentrations (up to 100 mg/L) of zinc. However, a further increase in the concentration of zinc increased the lag phase duration and decreased the substrate utilization rate. The specific metal uptake by the fungi increased with an increase in initial concentrations of zinc. The effect of a sugar concentration (5–100 g/L) on the growth of the organism and the specific metal uptake by the organism were studied. These studies were carried out using an initial zinc concentration of 100 mg/L. A maximum zinc removal of 18.4 mg/g of dried biomass was observed at 20 g/L sugar concentration. Further increase in sugar concentration did not increase the specific metal uptake by the organism. The effect of pH on the growth of the organism and the specific metal uptake by the organism were also studied in the pH range 2.5–6.5. The optimum pH for the growth and the specific metal uptake was found to be in the pH range 4.5. The effect of inoculum concentration (5–20%v/v) on the growth and the metal uptake capacity of the organism was also studied. A maximum zinc removal of 77 mg/g of dried biomass was observed within 36 h at 500 mg/L of initial zinc concentration and at 20 %(v/v) inoculum concentration. The growth of the organism was also monitored in the presence of other metals such as Pb, Cu, Ni, and Cr, separately. The organism was capable of growing in each case at 100 mg/L initial concentration. Batch studies were also conducted to examine the biosorption potential of the organism adapted to minimal media. The organism was also found to be effective for the removal of zinc from an actual effluent generated by a color picture tube manufacturing industry.