1,4-dioxane is an industrial chemical that is highly soluble in water. It is primarily used as a stabilizer of chlorinated solvents and is often found in contaminated groundwater sites. 1,4-dioxane can also be found in consumer products such as cosmetics, shampoos, and deodorants. It is also a byproduct in paint strippers, dyes, greases, antifreeze, and aircraft deicing fluids.
While 1,4-dioxane isn’t technically a “forever chemical” like PFAS, it’s sometimes referred to as one because of its unique chemical and physical properties, which make it resistant to traditional water treatment. The EPA has classified Dioxane as likely to be carcinogenic to humans, and data continue to show the dangerous health effects of exposure to 1,4-dioxane. Thus, it has been banned in various applications because of its potential risk to human health. Various jurisdictions require its removal to be less than 0.4 µg/L.
1,4-Dioxane Remediation
Due to its high solubility, 1,4-dioxane is not readily removed by air sparging or adsorbed on activated carbon. The most commonly practiced technology for 1,4-dioxane removal is ex-situ (sometimes referred to as pump and treat) advanced oxidation processes (AOP), either ultraviolet (UV) light-hydrogen peroxide (H2O2) or ozone (O3)-hydrogen peroxide.
An AOP is characterized by the production of hydroxyl radicals, which are short-lived, powerful oxidants. Molecular ozone alone is typically inefficient in removing 1,4-dioxane since the rate constant of 1,4-dioxane with ozone is only 0.32 M-1s-1 versus 2.5-3.1 x 109 M-1s-1 with hydroxyl radicals. However, ozonation of water containing various organic compounds can convert some molecular ozone to hydroxyl radicals.
Treatment Technologies for 1,4-Dioxane
Selecting an AOP (UV/Peroxide vs. Ozone/Peroxide) requires laboratory and/or pilot plant testing. Significant variations can exist from location to location and thus influence the appropriate advanced oxidation process selection, which can include the following:
- Bromide Ion – If bromide ion is present, UV-H2O2 may have advantages since it is less likely to produce bromate. However, some O3-H2O2 processes claim to be able to control bromate formation. This consideration also depends on whether bromate regulates the application and to what level.
- Fouling Factors – Certain dissolved species can cause fouling of the quartz sleeves in UV reactors, which results in frequent maintenance of the full-scale UV system to ensure the minimum UV light dosed between cleaning steps.
- Electrical Power Costs – UV is a more electrically intensive process, so higher power costs probably favor the O3-H2O2 process.
- UVT – UVT has a significant impact on both capital and operating costs.
Once testing is completed, a life cycle cost analysis should be conducted to select the lowest cost option.
Resource Links About 1,4-Dioxane and Treatment Technologies
The EPA profiles the occurrence and properties of 1,4-dioxane and summarizes the available remedial technologies.
- Download: Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications (pdf)
- Download: 1,4-Dioxane Technical Fact Sheet
Contact Spartan Environmental Technologies for a quote or questions about 1,4-dioxane remediation and treatment options.