چكيده لاتين :
The different methods are used for the removal of heavy metals as important contaminants in water and
wastewater. Biosorption is an alternative to traditional physicochemical in removing toxic metals from
wastewaters and groundwater resources. In this study biosorption of lead and chromium ions from
solution was studied using Bacillus circulans isolated from Anzali wetland in batch and biofilter modes
and optimum conditions were determined. The experimental results showed 900-950 mg/L and 1050-
1100 mg/L, for minimum bactericidal concentration and minimum inhibitory concenteration for lead and
chromium, respectively. Results of metal concentration in solution containing 500 mg/L in batch culture
showed a reduction about 65% and 48% in five and four days for lead and chromium, respectively. The
highest value of lead and chromium uptake in solution with 500 mg/L was 78% and 40% in biofilter
mode, respectively. The biosorption of lead and chromium were increased up to pH=5.5, 6, 5.5 and 7,
respectively. In the other hand, maximum sorption occurred at neutral pH. There was a significant
decreasing of biosorption levels by lowering pH fewer than 3. Accumulation of lead and chromium was
determined by scanning electron microscopy analysis of the biofilm exposed to 500 mg/L metal
concentration. Based on this analysis, the highest metal concentrations were observed in regions with
including bacteria.
