SURFACTANT ENHANCED REMEDIATION OF SUBSURFACE CHROMIUM CONTAMINATION

The objective of this research was identification of optimal surfactan t systems for remediating chromate-contaminated subsurface environment s. Batch and column studies were conducted utilizing chromium contamin ated soil obtained from the U.S. Coast Guard Support Center, Elizabeth City, N.C. Results of the batch studies demonstrated that surfactants , when used alone, were able to enhance the extraction of chromate 2.0 -2.5 times greater than water. When a complexing agent, diphenyl carba zide, was solubilized by aqueous micelles the system was able to enhan ce the chromate elution by 9.3 to 12.0 times greater than water (or 3. 7-5.7 times greater than surfactant without the complexing agent). Col umn studies showed that when surfactants are used along with the compl exing agent, 213% of Cr(VI) can be removed relative to D.I. water in l ess than 20 pore volumes, whereas D.I. water took 35 pore volumes to r each the baseline removal. The economics of surfactant enhanced subsur face remediation will be affected by surfactant losses (e.g. precipita tion and sorption); batch and column studies were conducted to evaluat e the losses of surfactants due to such phenomena. Results of these la boratory studies demonstrated that the surfactant system containing Do wfax 8390 and diphenyl carbazide was most effective in remediation of the chromium contaminated soil.