SUMMARY

• This study investigated how the presence of lead (Pb) as a co-contaminant affects the performance of two bioremediation approaches, natural attenuation and biostimulation with RemActiv™, in soils contaminated with Total Petroleum Hydrocarbons (TPH).
• Over a 28-week study, biostimulation with RemActiv™ achieved a 96% reduction in TPH concentration in soils with TPH contamination alone, and an 84% reduction where lead was also present as a co-contaminant.
• Natural attenuation was significantly less effective, achieving only 56% and 59% TPH reduction in the single and co-contamination scenarios respectively.
• Lead co-contamination also significantly altered the soil’s microbial community profile. In biostimulated soils without lead, Alcanivorax spp. dominated at over 50% of the bacterial community by week 12. Where lead was present, Pseudomonas spp. became dominant, comprising approximately 45% of the bacterial profile at the same timepoint.
• The study confirms that biostimulation with RemActiv™ is more effective than natural attenuation for remediating TPH-contaminated soils, including those with heavy metal co-contamination.
• These findings support the use of RemActiv™, a biostimulation product designed to accelerate TPH degradation in soil, as part of a site-specific remediation programme that accounts for the full contamination profile.