Potential use of cyanobacteria Nostoc sp. in bioremediation of heavy metals-contaminated effluents

Abstract

Cyanobacteria are well known for their ability to a variety of pollutants from waters, including toxic heavy metals (HMs). This study investigated the potential remediation of wastewaters by cyanobacteria Nostoc sp. Five heavy metals ions were selected for the experiment including Cd2+, Cu2+, Pb2+, Ni2+, and Zn2+. Removal efficiencies of the investigated od HMs by cyanobacteria Nostoc sp. using bioaccumulation and biosorption processes were evaluated and compared. Results confirmed the high efficiencies of the investigated species of cyanobacteria for the removal of the target contaminants which were cocentration and contaminant-dependent.Live cells of Nostoc sp. have the highest affinity to bioaccumulate Pb (98.15%), and Cu (95.14%) from the solution. However, the biosorption capacity of dried biomass of Nostoc sp, besides Pb (92.27%), and Cu (96.00%), was high for Cd (91.00%) removal as well. Living cyanobacteria biomass absorbed 87% of Zn. In the case of Ni, cyanobacteria Nostoc sp. did not show significant bioremediation potential. Through the bioaccumulation process, removal of Ni was only 38%, while the biosorption process was more efficient 63.80% of Ni removal. These results indicate the potential of Nostoc sp. cyanobacteria as an efficient agent for pollution control. Furthermore, the data obtained represent a base for further investigation towards the development of a suitable biosorbent system that could be used for industrial effluent treatment.