Assessment of bioremediation potential of Microcystis aeruginosa for removal of cadmium and lead ions from aqueous matrices

Document Type: Research Paper

Authors

1 Science and Research University of Fars

2 University of Isfahan

Abstract

Capability of cyanobacterium Microcystis aeruginosa, isolated from effluent of a wastewater stabilization pond, for removal of cadmium and lead ions was investigated. Variation of removal efficiency as a function of metal concentration, pH, temperature and biomass dosage was studied. Also, use of closed reflux digestion technique as an innovative option for decomposition of cyanobacterial pellet was studied. A multi-phase washing method was developed in order to attain more elevated desorption efficiency. Maximum removal efficiency occurred in pH 7, temperature 28°C and biomass dosage 0.2g for Cd2+ and corresponding values of 6, 25°C and 0.1g for Pb2+. In all tested concentrations of lead and cadmium, extracellular absorption overweighed intracellular uptake with highest ratio of former to later of 172 for Cd2+and 143 for Pb2+. EC50 values attained for Cd2+and pb2+were respectively 20mg/l and 15mg/l. Closed-reflux digestion method was found as a good option for cyanobacterial pellet digestion. Three-stage consecutive washing procedure devised in our study gave desorption efficiencies of 92 and 86 percent for Cd2+ and Pb2+ respectively as compared with values of 52 and 44 percent for Cd2+ and pb2+ obtained by conventional washing procedure. This investigation verifies possibility of employing Microcystis aeruginosa for removal of Cd2+ and Pb2+ from aqueous and wastewater solutions.

Keywords