Soil washing of total petroleum and polycyclic aromatic hydrocarbons from crude oil-contaminated ultisol using aqueous extracts of waterleaf.

Ultisols are acidic soils found in humid climates and are known for poor fertility. Crude oil impacted ultisols, therefore, require special treatment measures to account for nutrient loss during treatment. In this paper, we report the utilization of a food waste, aqueous extracts of waterleaf (Talinum triangulare), as a plant-derived surfactant to wash simulated crude oil-contaminated soils. The soils before and after washing were monitored for microbial loads, nutrient parameters, physicochemical characteristics, total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs). Although higher amounts of PAHs (up to 100%) were removed compared to TPHs (up to 95.7%), the results revealed that the efficiency of the waterleaf extracts was comparable to that of a commercial surfactant sodium dodecyl sulphate. However, soils washed with the waterleaf extracts retained some significant amounts of nutrients and favourable pH moderation. In both surfactants, soil microbial loads reduced significantly. Overall, the aqueous waterleaf extracts showed potential as ecofriendly surfactants and nutrients retainer during soil washing of contaminated ultisols.