Coal tar recovery using enhanced ‘pump‐and‐treat’

BACKGROUND Most experts acknowledge that low aqueous solubility results in low mass recovery rates using pump‐and‐treat (P&T), making such systems ineffective for coal tar (a multi‐component NAPL ) recovery. It is proposed to increase the apparent aqueous solubility of coal tar by orders of magnitude as an enhancement to conventional P&T schemes (or ‘P&T–E’), increasing coal tar recovery rates, reducing the pore volumes and time required for complete recovery, thus translating into cost savings . RESULTS Batch test results of aqueous solutions containing anionic surfactant, co‐solvent, and electrolyte are presented that were studied for both compatibility with a field‐obtained coal tar and effectiveness at solubilizing the coal tar above its aqueous solubility. Seven surfactants were tested at room temperature ( 23C ) in aqueous solutions containing the surfactant with co‐solvents and electrolytes. The most promising surfactant solution solubilized upwards of 40 000 mg L −1 coal tar. A 1–D column test resulted in 97% recovery using the promising surfactant . CONCLUSIONS P&T–E could significantly increase coal tar solubility without causing the formation of a rate‐limiting, solid‐like film and offers a promising approach for the remediation of coal tar from the subsurface. © 2013 Society of Chemical Industry