Thesis title: Application of synthetic and natural surfactants for mobilizing Polycyclic Aromatic Hydrocarbons (PAHs) for remediation purpose in the real case study of SIN Bagnoli-Coroglio (NA), Italy
During the 20th century, the expansion of industries, manufacturing processes and their applications without considering emissions and waste production have led to the release of significant amounts of pollution into the environment. This is also occurred in Italy, starting from the early 1900s, continuing through the 1960s economic boom, and up until the most recent warnings and obligations to reduce the pollution emissions. In order to prevent environmental and sanitary harm, in 2000, the Italian Ministry of Environment and Protection of the Territory (now Ministry of Environment and Energy Security) created a list of the so-called “Siti di Interesse Nazionale “SIN”, i.e. National Priority Sites. This list includes large areas throughout Italy so dangerously polluted that require remediation operations of the soil, subsoil, ground- and/or superficial- and/or sea water. Due to its widespread contamination, “ex ILVA” in Bagnoli (Naples) was included in the SIN list as one of the most seriously polluted site in Italy. This site’s unique and complicated history makes it a “unicum” case in the history of Italian industry.
In this site, amid the priority pollutants in soil and sediments, Polycyclic Aromatic Hydrocarbons (PAHs) are among the most toxic and carcinogenic compounds for the environment and human health. Because they can be produced by the partial combustion of organic matters, in addition to other types of emissions like oil spills and chemical production, organic compounds can be found in all matrices. Since they are Hydrophobic Organic Contaminants (HOCs), they have a strong interaction with organic matter, are barely soluble in water and are persistent and volatile in nature.
In this context, the aim of this research has been the assessment of the capacity of different commercial, non-ionic and biodegradable surfactants, synthetic or biosurfactants, to solubilize and mobilize PAHs, in order to remediate heavily contaminated sediments. These surfactants would be used in a soil washing process to increase the extraction’s efficacy by enhancing the solubility of PAHs.
In detail, the primary objective of my PhD thesis was to illustrate the huge potential of surfactants by comparing just their capacity to solubilize PAHs in contrast to water. Once this was determined, the focus shifted to figuring out their properties, performing multiple washing tests, modifying the temperature and the concentration of the surfactants in solution, with the scope to determine the best conditions for their application.
As last study, the best synthetic and natural surfactants have been tested in column to gauge their performance in a laboratory-scale soil flushing process. Their efficiency was further examined in the case of application in a soil washing process in addition to gaining better results on their capacity to mobilize PAHs.