SLOW-RELEASE PERMANGANATE GEL (SRP-G) AS AN ALTERNATIVE TECHNIQUE FOR TRICHLOROETHENE (TCE) PLUME TREATMENT IN GROUNDWATER

The contamination of groundwater by chlorinated solvents continues to be a pervasive problem and presents significant challenges for remediation. Specifically, trichloroethene (TCE) is one of the most ubiquitous organic contaminants impacting groundwater quality, posing significant risk to human health and the environment. Slow-Release Permanganate Gel (SRP-G) is a novel and promising in-situ remediation technique for TCE plume treatment. This study examined the gelation time of two SRP-G amendments, NaMnO₄ and KMnO_4, by comparing their gelling characteristics as a function of amendment concentration and colloidal silica content to ascertain their effectiveness for TCE plume treatment. Through this process, we hypothesize that colloidal silica mixed with either NaMnO₄ or KMnO₄ solutions will lead to variations in gelation times, allowing for optimal diffusional matrix permanganate release times to be determined for TCE plume treatment. SRP-G viscosity for different amendment ratios were measured to determine the solution transition time into gel and to help predict permanganate release times. 1-7 wt.% of a NaMnO₄ solution were mixed with 10 mL of 30 wt.% and 50 wt.% colloidal silica respectively. 30-90 mg/L of SRP-G solution were prepared from granular KMnO₄ mixed with 10 mL of 30 wt.% and 50 wt.% of colloidal silica solution. The preliminary results indicate that 1-7 wt.% SRP-G concentrations (NaMnO₄) with 50 wt.% colloidal silica solution showed a more rapid increase in viscosity compared to SRP-G concentrations in 30 wt.% colloidal silica. The 30-90 mg/L SRP-G concentrations using KMnO₄ showed little viscosity increase in 30 wt.% colloidal silica solution. However, a rapid increase in viscosity was observed for the KMnO₄ in 50 wt.% colloidal silica solution. Hence, 50 wt.% colloidal silica solutions were more effective for SRP-Gel formation with KMnO₄ and NaMnO₄ compared to the 30 wt.% colloidal silica solutions. Therefore, the higher silica content solutions (i.e., 50 wt.%) are expected to lead to more optimal gel formation and longer permanganate release times. The results of this research will provide relevant information to the development of SRP-G approach as a novel remediation strategy for dissolved plumes in groundwater.

Keywords: SRP-G, TCE, Colloidal silica, Gelation