Case Study: Organoclay in BTEX Groundwater Remediation

Organoclay used in a permeable reactive barrier (PRB) successfully reduced BTEX concentrations in contaminated groundwater below regulatory limits at a refinery site.

The Challenge

A petroleum refinery site had groundwater contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX) at concentrations 15–80× above regulatory limits. Conventional pump-and-treat was considered cost-prohibitive for the 10-year remediation timeline.

Solution: Organoclay PRB

A permeable reactive barrier was installed using a sand/organoclay mixture (15% organoclay by dry weight) in a 45m long, 2m deep trench perpendicular to groundwater flow. The organoclay's hydrophobic surface preferentially adsorbed BTEX compounds from the aqueous phase as groundwater passed through the barrier.

Results (24-month monitoring)

ContaminantInfluent (avg)Effluent (avg)Reduction
Benzene2,400 μg/L38 μg/L98.4%
Toluene8,500 μg/L85 μg/L99%
Ethylbenzene1,200 μg/L24 μg/L98%
Total Xylenes5,600 μg/L112 μg/L98%

All effluent concentrations met regulatory discharge standards after 3 months of barrier operation.

Organoclay for Water Treatment Applications