Soil washing enhancement with solid sorbents

Soil washing is a dynamic, physical process that remediates contaminated soil through two mechanisms: particle size separation and transfer of the contaminant into the (mostly) liquid stream. The performance of different sorbents and additives to remove motor oil from sea sand was tested. Hydrocyclone, attrition scrubber, and froth flotation equipment were used for the decontamination study. Sorbents and additives were mixed with soils in the attrition scrubber prior to flotation. Sorbents used were granular activated carbon, powder activated carbon, and rubber tires. Chemical additives used were calcium hydroxide, sodium carbonate, Alconox®, Triton® X‐100 and Triton® X‐114. When a froth flotation run was performed using no additive, washed soils “tails” contained 4000 ppm of total oil and grease (TOG). However, when carbon or rubber (6% by weight) was added to the contaminated soils the washed soils “tails” contained less than 1000 ppm of total oil and grease (TOG). The addition of sodium carbonate or calcium hydroxide (6% by weight) had same effects as sorbents. In both cases washed soil “tails” contained total oil and grease of less than 1000 ppm. The use of these non‐hazardous additives or sorbent can enhance the soil washing process and consequently saves on time (residence time in equipment) and number of stages (equipment design) required to achieve the target clean up levels.