Background Water pollution with heavy metals is a severe dilemma that concerns the whole world related to its risk to natural ecosystems and human health. The main objective was to evaluate the removal efficiency of Cd of various concentrations from contaminated aqueous solution by use of two cyanobacterial strains (Nostoc muscorum and Trichormus variabilis). For this purpose, a specially designed laboratory pilot-scale experiment was conducted using these two cyanobacterial strains on four different initial concentrations of Cd (0, 0.5, 1.0 and 2.0 mg L−1) for 21 days. Results N. muscorum was more efficient than T. variabilis for removing Cd (II), with the optimum value of residual Cd of 0.033 mg L−1 achieved by N. muscorum after 21 days with initial concentration of 0.5 mg L−1, translating to removal efficiency of 93.4%, while the residual Cd (II) achieved by T. variabilis under the same conditions was 0.054 mg L−1 (89.13% removal efficiency). Algal growth parameters and photosynthetic pigments were estimated for both cyanobacterial strains throughout the incubation period. Conclusions High Cd concentration had a more toxic impact on algal growth. The outcomes of this study will help to produce treated water that could be reused in agrarian activities.

No abstract

Background: Water pollution with heavy metals is a severe dilemma that worries the whole world related to its risk to nature ecosystem and human being health. The main objective is to evaluate the removal efficiency of Cd with various concentrations from contaminated aqueous solution by two Cyanobacteria species (Nostoc muscorum and Anabaena variabilis). For this purpose, a designed laboratory pilot scale was applied using two cyanobacteria species (Nostoc muscorum and Anabaena variabilis), four different initial concentrations (0, 0.5, 1.0 and 2.0 mg L−1) for 21 days. Results: N. muscorum was more efficient than A. variabilis for removing Cd (II), because the optimum value of residual Cd achieved by N. muscorum after 21 days at (0.5 mg L-1) was (0.033 mg L-1), where the removal efficiency was 93.4%, while the residual Cd (II) by A. variabilis under the same conditions was (0.054 mg L-1), and the achieved removal efficiency was 89.13%. Algal growth parameters and Photosynthetic pigments were estimated for both Cyanobacteria species through the incubation period. Conclusions: High Cd concentration had a more toxic impact on algal growth. The outcomes of this study will help to produce treated water that could be reused in agrarian activities.