Removal of 1,4-Dioxane in the Presence of Chlorinated Solvents and Other Substances: A Review on Current Strategies and Future Perspectives

Being classified as a suspected carcinogen, 1,4-dioxane (1,4-D) has been one of the most frequently detected organic contaminants in groundwater sites. Due to the common co-occurrence of 1,4-D with chlorinated compounds and a lack of comprehensive health advisory guideline standards established for potable water and other uses on a global scale, a new research emphasis to reflect more realistic situations needs to be placed onto the effects of common co-existing chemicals such as 1,1-dichloroethene, trichloroethylene, cis-1,2-dichloroethylene, and 1,1,1-trichloroethane on the environmental fate of 1,4-D. Additives (e.g., ions, nutrients, enzymes) are also introduced to enhance 1,4-D treatment efficiencies. To the best of our knowledge, however, there is no review article dealing with the removal of 1,4-D in the presence of chlorinated solvents and other interfering substances. Understanding its concurrent removal with the main chlorinated co-contaminants is necessary for more insightful and proper design of effective remediation strategies for 1,4-D. This review article will focus on the behavior, transport, and persistence of 1,4-D in the presence of other pervasive groundwater contaminants and substrates under diverse environmental conditions and treatment technologies. This review will also provide detailed information on currently available remediation technologies for 1,4-D (either individually or co-occurring) and potential key points to be considered for future technologies development.

1,4-dioxane (1,4-D) is an emerging toxic pollutant that is found as a contaminant in soil and groundwater. Despite its harmful nature, there are not many global standards regulating its levels in water. Therefore, finding effective ways to remove harmful pollutants is crucial for safer waters, requiring extended research and time. 1,4-D often exists together with other contaminants such as chlorinated solvents, making water treatment more difficult, costly, and less efficient. This review explains the physical and chemical behaviors of other co-contaminants when combined with 1,4-D as well as the current removal technologies as categorized based on physical, chemical, biological, or combination (hybrid) methods. It is found that each removal technique has its strengths and weaknesses but some failing to eliminate the co-solvents although they successfully removed 1,4-D. Thus, future research is warranted to further elucidate key reaction mechanisms between 1,4-D and other co-contaminants and to test real scale applications.