Bio-removal of Zn from contaminated water by using green algae isolates

Abstract

Abstract Wastewater is one of the main sources of the heavy metals. These hazardous compounds find their way through water resources and consequently threaten human being’s life and other living organisms. Several solutions have been proposed to address this issue. Nowadays, using algae to eliminate these elements is the most effective method in terms of cost and time in comparison with other biological and chemical methods. This research was carried out to evaluate the capability of native algae species in Zn removal from industrial sewage. A split plot (in time) experiment which consists of one main factor (time) and three subsidiary factors including basic solution at two levels, algae isolates at three levels and Zn concentration at three levels of 0 (blank solution), 10, and 100 mg/L from ZnSO4.7H2O) was conducted. Firstly, the dominant and fast growing algae isolates were separated from the depth of 20 cm, in Botanical Garden of Tabriz University and Khalatpoushan Research Station, Tabriz, Iran. Then, three efficient isolates were selected for the second phase of the experiment. After sufficient growth of the superior selected algae isolates on minimal medium, algal suspension was prepared and the population adjusted to 3×104 cell per mL, and then the suspension was transferred to the Erlenmeyer flasks (100 mL) including Tabriz wastewater and basic solution. OD, pH and Zn concentration was measured in intervals of 3, 6, 9, 15 and 20 days. Based on the results, the highest Zn absorption by two algae isolates was recorded in the minimum medium with the blank solution and in the municipal wastewater with the concentrations of 10 and 100 mg/L which can be concluded that both isolates were capable of eliminating contamination effectively in the natural environment compared to the laboratory condition. At the concentrations of 0 and 10 mg/L, almost all Zn was removed from both medium and at the concentrations of 100 mg/L, approximately 90% of Zn was removed from both culture mediums. Accordingly, it can be concluded that both algal isolates can be considered as a suitable bio-remover for removing Zn form polluted waters.