Use of Ecopiling to Remediate PAH-Contaminated Storm-water Lagoon Sediment

Abstract

Polycyclic Aromatic Hydrocarbons (PAHs) are widely distributed in the environment originating from both natural and anthropogenic sources. Consequently, they are found ubiquitously in the lithosphere, hydrosphere, atmosphere and biosphere. They are of major concern due to their recalcitrant nature, ability to bio-accumulate and their toxic, carcinogenic and mutagenic effects on biological systems. One major anthropogenic source of PAHs is creosote which is used as a wood preservative and contains 85% PAHs (w/w). Industrial facilities carrying out creosote treatment activities can result in major contamination of soil and groundwater at these sites. The current study investigates the potential of Ecopiling as a bioremediation strategy for creosote contaminated soil/sediment at a former wood preservation facility. The study involved greenhouse experiments to assess the phytoremediation potential of perennial ryegrass (Lolium perenne L.) and onsite construction of two small-scale, trial Ecopiles. The greenhouse study showed that the creosote contaminated sediment had an inhibitory effect on plant growth and reduced the effectiveness of rhizoremediation. However, the use of a clean soil overlay led to a significant decrease in the phyto-toxicity experienced by the ryegrass plants and subsequently resulted in greater PAH degradation in these pots. The use of Ecopiling was found to reduce the sum of EPA 16 PAH concentrations in the sediment by 94-96% after 730 days. The incorporation of spent-mushroom compost into the Ecopile, did initially increase the rate of PAH degradation, however, after 730 days there was no significant difference between the PAH concentrations remaining in the two Ecopiles. Although Ecopiling is a slow process compared to thermal and chemical treatments it has proven to be an effective and low cost process for the remediation of PAHs from industrial sediments.