The factors affecting the remediation of non-aqueous phase liquid (NAPL) contaminants in soils

The aim of this thesis is to identify the factors effecting the remediation of NAPLs in the soils. For this purpose, two major types of treatment systems -namely; slurry and fixed bed- were used for the physical and biochemical remediation of soils.The parameters of initial contaminant concentration, presence of local bacteria, and presence and amount of soil amendments are examined both in slurry systems, and in fixed bed systems, as well as the specific parameters related with the remediation technique. Solid waste compost was used as soil amendment and four different types of soil were used to examine their treatability. Diesel oil was used as a contaminant well represents the NAPLs. The treatment performances were followed by observing the TPHs and PAHs levels in the soils. The systems were also operated with sterile soils to define the extent of volatilization losses of NAPLs during the remediation.The major findings of the study are as follows; i) TPHs removal efficiencies are decreasing with increasing initial diesel concentration in systems, ii) the efficiencies of fixed bed systems are higher than the slurry systems, iii) by blocking the intersectional area between the soil and air & water because of high concentration of diesel contamination in the soil, treatment efficiencies are decreasing in fixed bed systems, iv) thermal volatilization is the dominant process to remove NAPLs from soils, and its efficiency is dependent both on contaminant properties and soil properties, v) the contamination age adversely effect the efficiency of NAPLs removal from the soils, vi) generally the TPHs removal efficiency increases with increasing CO2 production, vii) the removal rates of PAHs are decreasing with increasing number of benzene rings and PAHs removals are strongly correlated both with their water solubility and vapor pressure, which are determining the extent of their bioavailability and volatilities.