Petroleum extraction in the Ecuadorian Amazon has caused widespread soil contamination with total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH), threatening ecosystems and hindering responsible infrastructure development on brownfields. This study evaluated biostimulation and bioaugmentation for remediating such soils, bridging environmental bioremediation to practical construction applications. Contaminated clay-sandy loam soil from the Triboilgas facility (initial TPH: 73.45 mg/kg; 4-PAH subset: 4,521.10 mg/kg) was treated in triplicate over 21 days: biostimulation with molasses, bioaugmentation with a native Mojanda microbial consortium (Pseudomonas 35%, Bacillus 22%, Rhodococcus 18%, Mycobacterium 12%), and control (natural attenuation). Methods included maintaining 60-70% moisture, daily monitoring, and hydrocarbon quantification via gas chromatography. TPH remediation showed near-complete removal across treatments (biostimulation: 0.18 ± 0.03 mg/kg 95% CI: 0.12-0.24; bioaugmentation: 6.44 ± 0.52 mg/kg 95% CI: 5.42-7.46; control: 15.21 ± 1.15 mg/kg 95% CI: 13.21-17.21), with no significant differences detected (ANOVA: F₂,₆ = 0.458, p = 0.65; post-hoc power = 28%). Low-molecular-weight PAH removal varied significantly (F₂,₆ = 5.87, p = 0.042), with control most effective (82.65% to 784.19 ± 98.3 mg/kg 95% CI: 638-930). Results indicate indigenous microbes excel in natural attenuation for PAHs, while biostimulation optimizes TPH removal, though extended treatment (60-90 days), complete 16-PAH characterization, geotechnical testing, and leaching assessments are needed before brownfield redevelopment for construction reuse.
Mafla et al. (Sun,) studied this question.