Researchers at the New Jersey Institute of Technology recently discovered the bacterium Azoarcus sp. DD4 (DD4) and its ability to remove two co-existing contaminants from groundwater. 80% of groundwater sites contaminated with 1, 4-Dioxane also contain 1,1-Dichlorethylene (1,1-DCE). Both contaminants are toxic and difficult to treat in water using traditional methods. The discovery of Azoarcus sp. DD4 creates new possibilities for future water treatment.
What is 1, 4-Dioxane?
1, 4-Dioxane is an emerging contaminant, meaning little is known about the behavior and risks which makes treatment difficult. A maximum contaminant level for water has yet to be established by the EPA.
What we know about 1,4-Dioxane
- Likely carcinogen
- Found in thousands of groundwater sites in the U.S.
- Moves rapidly in water
- Industrial chemical from paint strippers, greases, waxes, shampoos, and cosmetics
- Enters the body through ingestion, inhalation, and skin contact
Side effects of 1, 4-Dioxane exposure
- Short-term exposure may cause nausea, drowsiness, and irritation to the eyes, nose, and throat.
- Long-term exposure may cause liver and kidney damage.
What is 1, 1-Dichlorethylene (1, 1-DCE)?
1,1-DCE is rarely detected in surface water but can spill into groundwater via industrial discharge and spread. According to the EPA drinking water regulations, the public health goal for 1,1-DCE in water is .007 (mg/L)2. Rapid separation makes this contaminant difficult to identify in water.
What we know about 1, 1-DCE
- Sweet odor like chloroform
- Used in cleaning solvents and plastic manufacturing
- Enters body through inhalation, skin contact, and administration of drugs
Side effects of 1, 1-DCE exposure
- Liver problems
- Kidney damage
- Central nervous system depression
Water treatment with Azoarcus sp. DD4 (DD4)
Biodegradation, the breakdown of substances into smaller particles, removes leftover contaminants after physical and chemical water treatment. 1, 4-Dioxane generally resists these remediation methods. Adding 1, 1-DCE in conjunction with 1, 4-Dioxane makes treatment even more difficult. Together, these two contaminants cause serious damage.
After applying the new microbe DD4, however, both contaminants decreased significantly. 1, 4-Dioxane decreased from 10 parts-per-million (ppm) to .38 parts-per-billion (ppb), and 1, 1-DCE decreased from 3 ppm to .02 ppm.
After 3 days of refrigeration, 80% of the bacterium survived, making it possible to deliver these microbes to infected water sites in the future.
Benefits water treatment with DD4
- Spreads easily in water
Researchers plan to conduct further study to understand how DD4 reduces contaminants. Using the bacterium in water treatment could begin within a year.
New Jersey Institute of Technology. "Newly discovered bacterium rids problematic pair of toxic groundwater contaminants." ScienceDaily. www.sciencedaily.com/releases/2018/10/181009115019.htm (accessed October 16, 2018).