Biosorption of Heavy Metals from Aqueous Solution using Bacterial EPS

Abstract

Bioremediation of heavy metal pollution remains a major challenge in environmental Biotechnology. Some industrial processes results in the release of heavy metals into aquatic systems. This has led to increasing concern about the effect of toxic heavy metals as environmental pollutants. One of the approaches considered for application involves biosorption either to biomass or to isolated biopolymers, as a more economical, effective and safe alternative to processes such as precipitation, coagulation, ion exchange, electrochemical and membrane processes. Many bacterial polysaccharides have been revealed to join heavy metals with changeable degrees of specificity and resemblance The adsorption of heavy metals by extracellular polymeric substances (EPS) is energy independent, non-metabolism, and can be caused by contact between negative charge and metal cations of acidic functional groups of EPS. Isolated biopolymers have not been practical on a huge range for heavy metal remediation. In this work, a experiment was carried out to investigate the ability of adsorption of three different metals – Zn2+, Pb2+, Cr6+, Ni2+, Cu2+, Cd2+ and Co2+ by an EPS produced by consortium gram-negative bacteria. EPS concentration and adsorption time were wide-ranging, in order to determine the ultimate environment to remove these metal cations from aqueous solutions. Outcome showed that the EPS is proficient to adsorb cadmium, zinc, and copper from the system. The extracellular polymeric substance produced by consortium gram-negative bacteria were shown to be a good adsorbent, capable to remove zinc, lead, chromium, nickel, copper, cadmium and cobalt from an aqueous system, with removal efficiencies of 77.15, 78.18, 74.48, 66.63, 71.00, 72.71 and 76.12% of each metal, respectively.