## 4 Conclusions  
The results from the batch experiments showed that hexadecane mostly adsorb on soil particles (>60%) for all the concentrations tested. Oxygen and nitrate are effective electron acceptors for hydrocarbon removal, with experimentally estimated biodegradation rates of 0.587 \(\pm\) 0.007 d\({}^{-1}\) and 0.114 \(\pm\) 0.023 d\({}^{-1}\), respectively. The mathematical modelling predicted well the expected biodegradation processes in soil. The activity of the different microbial groups is determined by the availability of the electron acceptors, following the classical redox cascade (aerobic degradation, to denitrification, iron (III) reduction, sulfate reduction and finally methanogenesis). In the baseline scenario, hydrocarbon degradation under methanogenic conditions, as well as adsorption/desorption and washout by the water flux, exert a higher influence on hydrocarbon removal. Physicochemical parameters such as porosity, soil density and adsorption isothermal parameters presented high sensitivity, thus requiring careful definition and, if needed, further investigation for real case implementation of the model. For practical purposes, this model can be used as a support tool for the management of contaminated sites, since it allows the simulation and comparison of different bioremediation strategies, namely the addition of different electron acceptors, including soil re-aeration (that can stimulate a specific microbial group, relative to the others) or surfactants addition (that may also accelerate soil bioremediation by increasing hydrocarbons bioavailability), among others. Different bioremediation scenarios were simulated and pointed to natural attenuation or soil re-aeration being the best strategies under the simulated conditions. The addition of surfactants will also accelerate soil bioremediation. Finally, this study demonstrates that a mathematical model capable of responding to environmental perturbation can work as a decision-supporting tool for the proper design of soil bioremediation strategies tackling petroleum hydrocarbon contamination. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app122111069/s1](https://www.mdpi.com/article/10.3390/app122111069/s1)]([https://www.mdpi.com/article/10.3390/app122111069/s1](https://www.mdpi.com/article/10.3390/app122111069/s1)), Table S1. Stoichiometry of the main processes involved in hexadecane biodegradation; Table S2. Stoichiometric (Petersen) and composition matrix for the bioremediation model; Table S3. Values of model parameters and constants; Table S4. Values of absolute-relative sensitivity (Sens AR) of model parameters on TPH concentration in the liquid and solid phases (expressed as mg/L and g/kg, respectively); Figure S1. Hexadecane mass recovered from solid (a) and liquid (b) phases, relatively to the mass added in the solid-liquid partition experiments; Figure S2. Variation of dissolved oxygen (A) and aerobic biomass (B) concentrations in depth; Figure S3. Variation of nitrate, sulfate and Fe (III) over time, and denitifying, sulfate reducing and iron reducing bacteria in depth; Figure S4. Variation of methane concentration over time (A), and of methanogenic biomass concentration in depth (B). References [60; 61; 62; 63] are cited in the supplementary materials. G.M. : Conceptualization, Investigation, Methodology, Data curation, Software, Formal analysis, Writing--original draft, Writing--review and editing. S.C.: Investigation, Software, Visualization. A.F. : Investigation, Software, Visualization. R.C. : Conceptualization, Investigation, Visualization, Writing--review and editing. M.S.D. : Conceptualization, Investigation, Visualization, Writing--review and editing. A.J.C. : Conceptualization, Investigation, Methodology, Data curation, Software, Formal analysis, Funding acquisition, Writing--original draft, Writing--review and editing, Writing--review and editing. All authors have read and agreed to the published version of the manuscript.