International Conference on Environmental Science and Technology (ICOEST’2013 – CAPPADOCIA), Nevşehir, Turkey, 18 - 21 June 2013, pp.230
Since nowadays soils are polluted by various ways such as agricultural activities, disposal of municipal and/or hazardous waste on it, there is a grown interest in soil remediation. It is a well-known issue that the contamination of soils by toxic pollutants is an environmental concern. Therefore, contaminated lands have to be remediated. For the remediation of contaminated soils, various technologies are used such as electrokinetic remediation, soil washing, thermal desorption, and bioremediation.
It is well known that remediation techniques for contaminated land depend on soil characteristics, contaminant characteristics, and legal and social requirements. Soil characteristics important for remediation are the particle size distribution (percentage of clay and silt), shear strength, porosity and permeability. Other important factors include the pH of groundwater and the soil and pesticide content. The depth of the water table and vadose zone, and the moisture content of the soil are other important factors.
These factors that may limit the applicability and the effectiveness of the process are also important in the determination of the appropriate soil remediation technique. As known, soil characteristics are efficient in remediation cost as well. For example, in soil washing, high humic content and large amount of silt and clay in the soil adversely affect the success of the process. If the soil contains a large amount of clay and organic material, the contaminants attach more easily to the soil, and therefore are more difficult to remove compared to a small amount of clay and organic material. As another example, in case of a soil matrix pohibiting contaminant–microorganism contact, the cleanup goals in bioremediation may not be achieved. Parameters affecting process performances in bioventing are water table close to the soil surface, saturated soil lenses, soil moisture content and soil permeability. It is known that low permeability and low moisture content soils, saturated soil lenses and the water table within several feet of the surface reduce bioventing performance.
Soil moisture and clay content, and buried metallic or insulating material and deposits (i.e. ore deposits) in soil have an important effect on the efficiency of electrokinetic remediation. It is known that the physiochemical composition of clay particles in soils is the basis for electrokinetic phenomena. Electrokinetic remediation technologies remediate faster in clays and silts than in sands and gravels. Soil pH should also be considered since acidic conditions and corrosion of the anode may create difficulties in in-situ efforts.
In soil vapor extraction, highly variable permeabilities or stratification, high organic content or extremely dry soil have important effects on the process performance and/or cost. It is known that soil that has a high percentage of fines and a high degree of saturation will require higher vacuums (increasing costs) and/or hinders the operation of the soil vapor extraction system. In thermal desorption, the parameters affecting the process performances and/or cost are the amount of clay and silt of soil, moisture and humic content of soil. Clayey and silty soils and high humic content soils increase reaction time as a result of binding of contaminants.
This review gathers some aspects of soil characteristics and its impact on soil remediation technologies including biological treatments, containment technologies, physical/chemical treatments, solidification/stabilization technologies, and thermal treatments. In geotechnical aspect, the methods used for soil remediation and the associated geotechnical fundamentals are reviewed.