Heavy metal pollution is a very serious threat to the natural environment and human health due to the fact that it cannot be remediated through chemical or biological processes. Although these persistent pollutants are harmful even in small concentrations, the problem becomes critical due to the significant issue posed by the bioaccumulation of these pollutants in various living organisms. Furthermore, the industries that generate large quantities of wastewaters containing heavy metals are in an increasing development. Sources of large fluxes of heavy metal wastewaters include electrical and electronic waste recycling, mining, electroplating and batteries, pesticides, pigments, dyes and textiles production. Hence, viable, environmentally-friendly, low-cost and efficient solutions are required in order to address this problem. Biomass-based removal methods represent a promising alternative to the conventional ones. The capacity of many biological materials for heavy metals removal from aqueous systems has been analyzed so far owing to the very good preliminary results obtained in related research studies. Microorganisms are very potent in this regard owing to their cells being highly adaptable to toxic environments. They have chemical structures with affinity to metals and the capacity to transform very toxic metal species into less harmful ones. The main processes that can be applied in wastewater treatment through the use of microbial organisms are biosorption for inactivated forms, bioaccumulation, biotransformation and biomineralization, respectively, for living forms. For these processes to be used successfully, different parameters such as pH, temperature, metal concentration and dosage of microbial biomass have been studied. The current paper gives an overview of the obtained lab-scale results of heavy metals removal from wastewater using both living and non-living microorganisms. Findings regarding process optimization and upscaling potential are presented. Different microorganisms are considered and compared. Advantages and disadvantages from technical, economic and environmental perspectives are presented. The main current issues and potential solutions are highlighted.

biosorption, bioaccumulation, lab-scale application, heavy metals, microorganisms

environmental engineering

Presentation: oral