Biologisk in situ sanering av petroleumförorenad mark i Sverige : En analys av resultat från en utförd sanering, egna fältundersökningar och tidigare studier.

In this study, I examine the performance of an in situ bioremediation technique applied to petroleum-contaminated site in Sweden. The performance of the method was evaluated by analyzing the effects to the treatment on aliphatic- and aromatic hydrocarbon concentrations in soil and groundwater. In addition, I revisited the site and performed complimentary analyses of soil- and groundwater properties. In situ bioremediation can reduce the environmental impact and provide economic benefits. In situ methods are rarely implemented in Sweden and it is important to optimize its efficiency enabling reduced landfill and a nontoxic environment. I found that the in situ remediation was partly successful and degradation had occurred. At the treated site (area group 3) aliphatic hydrocarbons went below the detection limit after the second treatment with bacteria. I attribute the latter finding specific local conditions (oil spill, nutrient levels, pH and soil moisture). During the performed bioremediation neither moisture nor nutrients were added to the soil during treatment with bacteria, which may have affected the degradation. I recommend the function of bacteria and enzymes should be evaluated at a site-specific scale, before starting a bioremediation. Importantly, the bioremediation may have been influenced by fuel leakage and foam that was placed under the concrete slab, which creates further uncertainty about the weak responses by the treatment. Thorough evaluation of the local conditions prior to the treatment seems crucial and environmental factors can be just as important to examine as the content of the soil when applying in situ bioremediation