Multi-evidence approach for the optimisation and management of bioremediation in an ex-situ plant

Soil contamination from petroleum hydrocarbons is a widespread environmental problem requiring effective and sustainable remediation strategies. Biopile bioremediation is a widely used technology thanks to its operational adaptability and reduced environmental impact. However, conventional monitoring that is based solely on the quantification of hydrocarbons is often inadequate for reliably describing the evolution of the process due to the high heterogeneity of soils and the analytical limitations associated with measuring a composite parameter. This study applied a multi-evidence approach to evaluate the effectiveness of bioremediation treatments at a pilot scale plant, integrating chemical, respirometric, biomolecular and modelling evidence. The results demonstrate that hydrocarbon analysis alone can lead to misleading interpretations, particularly in the early stages, whereas compositional indicators, such as the isomeric ratios of linear alkylbenzenes, enable more accurate assessment of biodegradation processes. Respirometric measurements provided direct information on microbial activity, enabling the efficiency of treatments to be assessed, and operational thresholds for oxygenation management to be defined. Meanwhile, biomolecular analyses highlighted the role of selected microbial communities and their functional consistency with pollutant degradation trends. Kinetic modelling of oxygen concentrations and consumption supported a quantitative interpretation of the observed processes, enabling an objective comparison of different treatment solutions. Overall, the multi-evidence approach proved to be an effective tool for overcoming the uncertainties associated with traditional monitoring and improving the ability to interpret processes.