Ecopiling: a combined phytoremediation and passive biopiling system for remediating hydrocarbon impacted soils at field scale

Abstract

Biopiling is an ex situ bioremediation technology that has been extensively used for remediating a wide range of petrochemical contaminants in soils. Biopiling involves the assembling of contaminated soils into piles and stimulating the biodegrading activity of microbial populations by creating near optimum growth conditions. Phytoremediation is another very successful bioremediation technique and involves the use of plants and their associated microbiomes to degrade, sequester or bio-accumulate pollutants from contaminated soil and water. The objective of this study was to investigate the effectiveness of a combined phytoremediation/biopiling system, termed Ecopiling, to remediate hydrocarbon impacted industrial soil. The large scale project was carried out on a sandy loam, petroleum impacted soil [1613 mg total petroleum hydrocarbons (TPHs) kg-1 soil]. The contaminated soil was amended with chemical fertilizers, inoculated with TPH degrading bacterial consortia and then used to construct passive biopiles. Finally, a phyto-cap of perennial rye grass (Lolium perenne) and white clover (Trifolium repens) was sown on the soil surface to complete the Ecopile. Monitoring of important physico-chemical parameters was carried out at regular intervals throughout the trial. Two years after construction the TPH levels in the petroleum impacted Ecopiles were below detectable limits in all but one subsample (152 mg TPH kg-1 soil). The Ecopile system is a multi-factorial bioremediation process involving bio-stimulation, bio-augmentation and phytoremediation. One of the key advantages to this system is the reduced costs of the remediation process, as once constructed, there is little additional cost in terms of labor and maintenance (although the longer process time may incur additional monitoring costs). The other major advantage is that many ecological functions are rapidly restored to the site and the process is esthetically pleasing.

On-site and in situ remediation technologies applicable to petroleum hydrocarbon contaminated sites in the Antarctic and Arctic

“…Contaminated soil was amended with nutrients, inoculated with hydrocarbon degrading bacteria and then used to construct passive biopiles (Germaine et al 2014). Finally, perennial rye grass (Lolium multiflorum) and white clover (Trifolium repens) were sown on the soil surface to complete the ecopile.…”

“…Germaine et al (2014) investigated the effectiveness of a combined phytoremediationÁ biopiling system, termed ecopiling, to remediate petroleum hydrocarbon contaminated soils (1613 mg/kg…”

Importance of soil physical characteristics for petroleum hydrocarbons phytoremediation: A review

“…According to the EPA (US Environmental Protection Agency) the very hazardous chemicals like benzene, toluene, ethylbenzene, xylenes, and naphthalene are included in the petroleum hydrocarbons (Lehmann et al, 2006, Bojes and Pope 2007, Gao and Collins, 2009, Cook et al, 2010, Boonsaner et al, 2011, Fester et al, 2014, Germaine et al, 2015. These pollutants can affect soil physical characteristics like soil texture and structural status, compaction, saturated hydraulic conductivity, and penetration resistance (Hreniuc et al, 2015).…”

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

“…In the current study, a constructed functional microbiome of PAH degrading bacteria (previously isolated from the same site) were encapsulated in calcium alginate beads. It has been previously shown that this is a useful way of inoculating polychlorinated biphenyl and diesel degrading microbes into soil [14,16]. These beads degrade slowly over time, giving the inoculum time to adapt to the conditions of the soil and protecting them from predation and competition.…”

“…Germaine et al [14] reported the successful remediation of 4800 m 3 of soil containing low levels (<2000 ppm) of petrochemicals through Ecopiling over a 2 year period. The Ecopile process involves biostimulation of indigenous hydrocarbon degraders, bio-augmentation through inoculation with known PAH degrading consortia and phytoremediation, through the effect of root growth and penetration throughout the soil and the resulting stimulation of microbial activity in the rhizosphere.…”