Bio-mineral interactions: applications to mine waste

Giovanni De Giudici, Daniela Medas (University of Cagliari)

Carlo Meneghini (University of Rome 3)

Biominerals are the product of organism's activity leading to mineral formation within the cellules or in the neighbouring environment. Since the original work of Lowenstam (1981) biominerals have been extensively investigated and they are actually considered to play a pivotal role in environmental and geological processes. Biomineralization studies represents a wide and active research field, they are intrinsically multidisciplinary and require complementary competences in order to understand biomineralization processes and eventually reproduce them via engineered systems, being a central issue to develop new technologies in environmental sciences, medicine and sustainable technologies in general.

This chapter presents the state of the art of bio-mineral interaction and focuses on processes and impacts on the Environment. Generalities of biomineral processes will be presented to facilitate readers in understanding bio-mineral interaction applied to mine environment and industrial areas.

In aquatic environments, bacteria are ubiquitous microorganisms that can precipitate a great diversity of authigenic minerals, driving biogeochemical cycles from microenvironments to global scales. Indeed, bacteria have a remarkable potential to sequester and accumulate cations onto their surfaces and can use metals to build biomineralization in response to their physiological purposes. Bacteria and other microorganisms can form biofilms typical of their ecological niche and often may cooperate to the biomineralization processes in plants and living organisms, particularly in the aquatic ecosystems. Among the different functions of biominerals, detoxifying aluminium and metals has been reported in different plant species.

In this chapter, we will show some example of how biominerals can be seen as key components of resilient systems and can be a sink to decrease bioavailable metals and pollutants. The variability of biofilms and biomineralization can be observed from centimetric to catchment scale. In historical mine areas, bacteria behave as expert metallurgists with the capability to reduce or oxidize iron. These expert biometallurgists can control the mineralization of zinc carbonates or zinc silicates. Sulphur reducing bacteria can re-precipitate authigenic base metal sulphides in the hyporheic zone, thus leading to the formation of new small ores. Thus, biomineralization offers a key to understand mineral stability and evolution and, more and more, offer new tools for mine operations sustainability that can be used also in other industrial technology.