Enhanced Soil Washing of PCB by Sophorolipids from Transformer Oil Contaminated Soil

Abstract

The effects of surfactants including synthetic surfactants and biosurfactants on 7 indicator PCBs removal from transformer oil-contaminated soil by using batch soil washing assessment were investigated. The sophorolipids (SLs) produced by Wickerhamiella domercqiae var. sophorolipid, especially lactonic SLs exhibited much higher PCB removal efficiency than SDS and Tween-80. The Σ7 PCB removal by 1.0 g/L lactonic SLs, 5.0 g/L of total SLs and acidic SLs was 30.2%, 30% and 25.4%, respectively. Removal efficiency of lower chlorinated congeners was significantly increased by adding sophorolipid, but higher chlorinated congeners removal efficiency was not further improved. 0.5 g/L lactonic SLs was efficient for PCB101 and 118 removal while 1.0 g/L lactonic SLs was efficient for PCB28 and 52 removal. The removal percentage was not increased with the increase of lactonic SLs concentration. The fermentation broth (yeast extract as nitrogen source) of W. domercqiae that was used directly on PCB removal was of superior efficiency.