Treatability Studies | Technology Evaluation Bench-Scale Treatability Testing for a 1,1,1-TCA/TCE Site

Project Highlights

• The study results were used by the client to select the most appropriate remedy for field implementation
• Study demonstrated that KB-1® Plus bioaugmentation promoted 1,1,1-TCA dechlorination and TCE dechlorination to ethene
• Study demonstrated that alkaline-activated persulfate promoted the complete destruction of TCE and partial destruction of 1,1,1-TCA

Sequential dechlorination of TCE through cDCE and VC to ethene and 1,1,1-TCA through 1,1-DCA to CA (left). Destruction of TCE and partial destruction of 1,1,1-TCA by sodium hydroxide-activated persulfate (right).

Problem Definition

Enhanced in situ bioremediation (EISB) and in situ chemical oxidation (ISCO) were considered as the preferred remedial technologies for field implementation. Bench-scale tests of the two technologies were performed to provide critical information to support the selection of the most efficient and effective technology. The primary site contaminants were 1,1,1-trichloroethane (1,1,1-TCA) and trichloroethene (TCE). Due to the contaminant mixture there was uncertainty as to how these technologies would perform. Specifically, 1,1,1-TCA is known to inhibit the reductive dechlorination of TCE if the requisite dechlorinating microorganisms are absent.

Solution

Bench-scale testing was performed by SiREM to evaluate (1) EISB; and (2) ISCO with alkaline- activated persulfate. Biotreatability microcosms were constructed to evaluate the rate and extent of 1,1,1-TCA and TCE reductive dechlorination under biostimulation (emulsified vegetable oil