Microwave remediation of hydrocarbon-contaminated soils – Scale-up using batch reactors

This paper reports a study of two batch processing systems to assess scale-up of microwave treatment of contaminated soils. Two separate batch concepts were evaluated at a kilogram scale, and a comparative study was carried out using a laboratory microwave treatment system. The study was carried out on two samples of hydrocarbon-contaminated soils obtained from industrial sites within the UK. The levels of organic removal are shown to be dependent on the type of processing system used and the processing conditions. Over 95% removal of the organic contaminants are possible using a stirred bed system, whereas organic removal in fixed bed systems is limited to 30–50%. It is shown that the penetration depth of microwaves into the soil sample accounts for the varying performance and efficiency of the different systems.

► The ability of soils to absorb microwaves varies with time during batch processing.
► Large batches result in non-homogeneous treatment.
► Penetration depth and mass transfer are key process issues.
► Continuous processing is the preferable scale-up option.