Clorella vulgaris: formulazioni per il miglioramento dell'assorbimento di metalli pesanti da acque reflue

Water pollution caused by heavy metals dispersed in the environment is one of the major threats to all life forms on Earth. Classical physico-chemical technologies for heavy metals removal result to be incomplete, show low efficiency and lack of selectivity and produce large volumes of waste. Therefore, the scientific community has focused on bioremediation, a wide group of technologies based on organisms and microorganisms. Among the latter, microalgae have proved to possess high heavy metals removal capabilities, adsorbing heavy metals on functional groups on their cell wall and Chlorella vulgaris is one of the most used microalgal species in wastewater treatment, because of its rapid growth in simple media. The three studies taken into consideration show that the optimisation of formulation of C. vulgaris can be a powerful tool to increase its efficiency in heavy metal adsorption. Microalgae in powder, treated to induce cell wall chemical modifications and grown in optimal culture conditions, show higher adsorption capacity, compared to C. vulgaris biomass alone. The same goal is achieved increasing the area of contact between algal cell wall and metal ions, employing algal nanoparticles. They are a good strategy, but there is the need for sustainable disposal of nanoparticles loaded with heavy metals. Finally, immobilization of microalgal cells within alginate beads permits better stability and higher cell density, which lead to improved heavy metal removal. Future research efforts should try to further increase the adsorption capacity of microalgae by improving the existing formulations and answering to rising challenges about the environmental preservation, but also by implementing new integrated heavy metal removal technologies