During the last years we have prospected new strategies for improvement of bioremediation in soils polluted by organic contaminants, taking polycyclic aromatic hydrocarbons (PAHs) as the most representative chemicals with bioremediation potential. Improvements are expected on the two main sources of risks that still remain challenging bioremediation as a cost-efficient approach for organic contaminants in general: 1) risks from pollution often increases initially due to an unmodulated biological processing, leading to the formation of byproducts eventually more toxic than the parent contaminants; and 2) residual concentrations remain above regulatory threshold levels and might still constitute an unacceptable risk to relevant ecological targets, what affects soil use. These two sources of risks require specific measures, based on the biological processes occurring, respectively, at high and low carbon flow regimes. They both will be the focus of this overview presentation. Bioavailability science provides sufficient knowledge on a variety of processes with a potential for risk reductions in the bioremediation of polluted soils, at both high and low carbon flow regimes. For example, we have studied the actions of biostimulants produced by microorganisms and plants, such as biosurfactants, on slow desorption PAHs (Sci. Total Environ. 668:790-796, 2019); cell positioning along the contaminant paths by chemotaxis (Environ. Sci. Technol. 52:10673−10679, 2018) and attachment (Environ. Sci. Technol. 51:11935–11942, 2017); metabolic interactions, including the poorly characterised co-metabolism (Sci. Total Environ. 717:137210, 2020); and the priming effects caused by plants (Sci. Total Environ. 720: 137608, 2020). It seems profitable to consider these functions attempting to improve the current protocols for bioremediation. We have just started a national project to integrate them into new bioremediation technologies. The main goal is to reduce the time execution periods (and costs), for the achievement of current bioremediation limits for risk reduction, and even reach lower end-points.

Towards a risk-based modulation of carbon fluxes involved in the biological removal of organic contaminants in soils: bioavailability

ACS Spring Meeting 2021

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