![]() ![]() ![]() Also, globally, the push towards sustainable land use and transportation require precautionary principles associated with in situ remediation to be re-considered (Smith 2019). It is, however, acknowledged that the current protocol needs to be questioned in the near to immediate future: In Finland, the landfill policies concerning contaminated soil masses are becoming increasingly restrictive (MOTE 2015). Approximately two thirds of the existing oil tanks are for residential use only (Soini 2014).ĭue to the low threshold values for contamination of soil in residential areas, alternative remediation methods are rarely being considered (Sorvari et al. Excavation of tanks and the contaminated soil tend to be the standard emergency protocol whereas this may be made difficult by buildings or associated underground structures (Dahl et al. In these cases, it may take time before the problem becomes noticeable, and large volumes of soil can already have been affected. In rare cases, these spills are associated with specific accidents, but more commonly result from normal wear and tear of the tank jackets (Puolanne et al. All in all, these low-profile occurrences amount to the biggest environmental concern in most parts of Finland. Incidents of spills reported to regional authorities annually count up to hundreds, and may involve a significant portion of individual sites regionally. The effect of CD on water solubility for different hydrocarbon fractions was tested to serve as the basis for risk assessment requirements for authorizing the use of the surfactant at the site.Īccording to the Finnish Oil Pollution Fund, there are 300,000 heating oil tanks in Finland (Soini 2014). The applicability of the surfactant was based on laboratory-scale tests demonstrating that CD promoted oil degradation and, unlike pine soap, was not utilized by the bacteria as a carbon source, and thus inhibiting degradation of oils regardless of the positive effect on biological activity. To further enhance the effect, methyl-β-cyclodextrin surfactant (CD) was added, resulting finally in a 98% reduction from the initial average level. By first adding live bacteria in a soil inoculum, and then oxygen and nutrients in different forms, an approximately 90% average reduction was achieved. ![]() Part of this was likely achieved through mobilization of oily soil into the tank, which was beneficial in regards to the following biological treatment. 50% reduction from the initial 25,000 mg/kg average oil concentration in the soil below the tank. First, hydrogen peroxide and citrate chelate was added for Fenton’s reaction–based chemical oxidation, resulting in a ca. The tank left emptied in the ground was used for slow infiltration of the remediation additives to the low permeability, clayey soil. A residential lot impacted by spills from a leaking light heating oil tank was treated with a combination of chemical oxidation and bioremediation to avoid technically challenging excavation. ![]()
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