Abstract
The presence of water-immiscible organic liquids—commonly called non-aqueous phase liquids or NAPLs—in soils and groundwater, is a worldwide environmental problem. Typical examples of NAPLs include: petroleum products, organic solvents and organic liquid waste from laboratories and industry. The molecular components of NAPLs present in soils, rocks and groundwater are readily transferred to the vapour and aqueous phases. The extent to which they do this is determined by their solubility (which is quite limited) and vapour pressure (which can be quite high). These molecular components, once dispersed in the vapour phase or dissolved in the aqueous phase, can provide a long-term source of harm to biotic receptors. The object of this lecture text is to examine how we can assess the degree of harm using quantitative risk assessment and how NAPL contaminated environments can be restored through the use of chemical, biological and physical remediation technologies.Graphical abstract
Highlights
A wide variety of water-immiscible organic liquids— referred to as non-aqueous phase liquids (NAPLs)—have been manufactured and used since the beginning of the twentieth century [1]
NAPL trapped in pore spaces by capillary forces as droplets or ganglia, which are immobile under normal water flow conditions
This can be a problem for the degradation of chlorinated ethene volatile organic compound (VOC) encountered, for example, in low-permeability zones [54], since capture of particles at pore throats or their accumulation in pores can severely reduce the permeability of the zone which in turn can result in the isolation of the VOC plume from further interaction with permanganate [55]
Summary
A wide variety of water-immiscible organic liquids— referred to as non-aqueous phase liquids (NAPLs)—have been manufactured and used since the beginning of the twentieth century [1]. Encountered examples include chlorinated hydrocarbon solvents, coal tar products
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