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Browsing by Subject "NAPL"

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  • Niemistö, Emilia (2019)
    Diesel, which belong to the fossil fuels, have been exposed recently because of global warming and because of decrease of known fossil fuel reserves. It has been estimated that reserves of fossil fuels will last next 40-50 years. Burning of fossil diesels will cause not only carbon dioxide emissions but also particle and metal emissions. There have been attempt to develop alternative energy sources. Growing alternative, which have came to the market, is renewable diesels, which can be produced from many sources such as reeds and biowaste. Biodiesels differ from fossil diesels by their chemical structure. Contrary to fossil diesel, completely renewable diesels do not contain aromatic compounds and they burn more purely. Diesel might end up in soil in accidents. Behaviour of fossil diesels in a ground is well known, however, the behaviour of renewable diesels is not known so well. Even though solubility of renewable diesels is similar with fossil diesels, renewable diesels may have different behavior due to different chemical structure compared with fossil diesels. Soil removal and taking the soil to be cleaned up is the most popular way to clean diesel contaminated soil resulted from diesel leaking. Alternative way to clean diesel contaminated soil is to use bioremediation where the microbes are used. In bioremediation microbes are added to the soil or activity of the microbes is boosted by improving living conditions of microbes by adding nutrients and oxygen. In this master thesis spreading of three different diesels qualities in soil and with water in laboratory were viewed. Results of the laboratory experiment were compared to the result of Katariina Lahti-Leikas’ lysimeter experiment in Jokimaa. Diesel qualities used in experiment were completely fossil EN590, partly renewable ProDiesel and completely renewable NEXBTL. Experiment were executed in soil columns in laboratory conditions where pure lysimeter sand were exposed to diesel. Biostimulation were made to half of the soil columns using urea that every diesel had natural decomposition and biostimulation. Soil columns were watered and hydrocarbons C10-C40 from collected water below the column were analysed. In addition, soil samples were collected and hydrocarbons C10-C40 were analysed. The pH of the soil and water samples were followed throught the experiment. Biostimulation decreased concentration of hydrocarbons in the water in every diesel quality. Biggest concentration were in water from NEXBTL columns which move in soil mostly in NAPL. In soil samples there was not the same kind of decrease in hydrocarbon concentration as in water samples. Diesel moved from the upper part of the soil columns to the lower part of soil columns during the experiment. The reason why biostimulation did not decreased the hydrocarbon concentration in soil is probably because the experiment period was too short. Other things to affect the result are probably wrong comparison of nutrients or lack of oxygen, which have slowed down decomposition of hydrocarbons. The results of this study are consistent with the results of Katariina Lahti-Leikas’ lysimeter experiment in Jokimaa.