Microwave heating is a potentially unique way of treating soils polluted by petroleum hydrocarbons and could reduce treatment times and energy implications. It has been shown that a more significant amount of water in soil generally increases the dielectric constant and loss factor, which indicates that higher water content in soil is beneficial for microwave heating. Batch remediation tests were performed using 2 kW, 2.45 GHz microwave generators to treat soils from several contaminated sites. The work investigated soil water content's influence on both the oil removal and the associated energy requirement. Soils with initial water content ranging from 1.6 to 12.6 % were heated within a treatment time of 1 to 7 min. Oil removal in the first 3min of heating is 38 %, 48 %, 38 %, and 42 % for sand, clay, loamy A, and loamy B soils. Soil. For soil with a water content between 14-18 %, oil removal in the first 3min is 45 %, 77%, 75 %, and 80 % for sand, clay, loamy A, and loamy B soils, respectively. The slight increase in energy requirement ranging between 6 to 20 % for all soils significantly impacted oil removal. However, optimizing the mass of soil resulted in a reduction in oil removal at the studied time. The achieved results confirmed promising data from laboratory tests for oil contaminants. Moreover, essential empirical knowledge is gained about this remediation technology that can determine practical limitations for further scale-up.

Removal of petroleum oil from soils during microwave heating

ACS Fall 2021

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