Soil Flushing By Surfactant Solution: Pilot-scale Tests Of Complete Technology
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M. Šváb, M. Kubal & M. Kuraš
This paper relates to PCBs contaminated soil flushing process, in which the aqueous solution of anionic surfactant Spolapon AOS 146 was passed through the sandy soil having an average PCBs concentration of 34.3 mg/kg of dry matter. The laboratory part was focused in particular on the selection of a suitable surfactant for PCBs solubilisation from the soil and to the development of the soil extract processing technique which took place before the realisation of the pilot-scale demonstration of the soil flushing technology. The experimental pilot-scale facility used consisted of a steel column (3 m length, 1.5 m diameter) containing 1.7 m3 of polluted soil and a liquid circulation system, by which an aqueous solution of the surfactant was supplied to the soil. Spolapon solution (40 g/l) was passing through the soil column for 2.5 months. The concentration of surfactant and PCBs in the final aqueous extract was monitored during this time period. The final PCBs concentration profile in the soil was determined after stopping the liquid flow. After passing through the soil the PCBs containing aqueous extract was pumped out from the steel column bottom to a treatment unit, where it was processed by the adsorptive micellar flocculation followed by carbon black adsorption. The degree of PCBs removal from aqueous extract to coagulation sludge of 99.99% was observed. In terms of the mass balance all PCBs removed from the soil were concentrated in 14 kg of sludge with moisture content of 66%. A decrease in PCBs concentration to 15 mg/kg of dry soil was achieved, but it is certain that a decrease to level of units mg/kg could be achieved in the case of a longer duration of flushing. Keywords: soil, PCBs, surfactant, flushing.
soil, PCBs, surfactant, flushing.