Outcome of Field-Scale Experiments

Despite the fact that there were some major hindrances during the operation, some of the projects in literature were able to meet their remediation goals at least partially. This was true especially in the case of Geokinetics, which has pioneered in this field in Europe. The results of its field projects as published show that electrokinetics is a promising technology for the effective remediation of soil (Lageman, 1993). The field trials held in the Netherlands were for the removal of metals like lead, copper, zinc, arsenic, cadmium, nickel, chromium, and so on from different types of soil like peat and sand. 

This project was followed by an actual cleanup of an arsenic contaminated site in Loppersum in 1989, which was a partial success with three-fourths of the total soil volume remediated. Here, the presence of uncovered metallic objects inhibited the process. These metallic objects served as a path for the electric current and delayed the movement of metallic contaminants in the area. 

A similar kind of problem due to the presence of uncovered concretions of CdS acted as the bottleneck in the removal of cadmium during the cleanup of a temporary landfill in Stadskanal in 1990. Though initially the process was progressing well, there was an unexpected increase in the cadmium concentrations, and further analysis revealed the presence of these concretions, which were not identified during the earlier tests. The soil in this area was then pretreated to remove these, and further experiments yielded the desired results. 

In the USA, the first ever attempt to evaluate the technical feasibility of electrokinetic remediation was the field study at a Superfund site in 1988 (USEPA, 1998). The technology was studied in combination with pump and treat. The process was adopted for the remediation of a site heavily contaminated with chromium. This was carried out when the knowledge in electrokinetics was not sufficiently developed. However, the results were much encouraging, indicating the potential of electrokinetics as an effective means for the removal of metals from soil by desorbing the ions attached to the soil surface. 

The demonstration results indicate that approximately 200 g of hexavalent chromium was removed during about 700 h of system operation, and the average removal rate for the entire system was approximately 0.29 g/h. Nevertheless, a reasonable estimate of the chromium removal based on the pre- and posttreatment soil analysis was not possible in this case due to the nonhomogenous distribution of chromate concentration in pretreated soil and because the demonstration was not carried out until the completion. 

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