Difference between revisions of "1,4-Dioxane"

Latest revision as of 02:45, 28 April 2022

1,4-Dioxane (14D) is a heterocyclic synthetic organic chemical that contains two ether bonds, is miscible with water, does not strongly sorb to natural or engineered materials, and does not biodegrade in many environments, all of which results in its persistence and rapid transport in aqueous environments. 14D is a suspected human carcinogen, which has resulted in relatively strict standards for drinking water sources. Advanced oxidation processes (AOPs) are the most well-developed technologies for removal of 14D from potable water supplies. Several treatment technologies are being developed for in situ treatment of 14D including chemical oxidation, cometabolic bioremediation, and thermally enhanced soil vapor extraction.

Properties, Fate and Transport

1,4-Dioxane (14D) is a heterocyclic organic compound, and the most commonly encountered of the three dioxane isomers (1,2-, 1,3- and 1,4-dioxane). Key physical and chemical properties of 14D are listed in Table 1. The heterocyclic, polar structure of 1,4-dioxane causes it to be miscible with water and also unable to strongly sorb or partition to aquifer solids or engineered sorbents (i.e. activated carbon). While 14D has a moderate vapor pressure, the high aqueous solubility results in limited volatilization.

Table 1. Properties of 1,4-Dioxane
Property	Value	Reference
Chemical Formula	C₄H₈O₂
Chemical Abstracts Service (CAS) Number	123-91-1
Appearance	Colorless Liquid	NIOSH, 2007^[2]
Molecular Weight	88.105 g/mol	NIST, 2018^[3]
Water Solubility	Miscible	NIOSH, 2007^[2]
Specific Gravity	1.03	NIOSH, 2007^[2]
Vapor Pressure at 25° C	38.1 mm Hg	US EPA, 2017^[4]
Henry’s Law Constant at 25° C	4.80 X 10^-6 atm-m³/mol	US EPA, 2017^[4]
Octanol-Water Partition Coefficient (log K_ow)	-0.27	US EPA, 2017^[4]
Organic Carbon Partition Coefficient (log K_oc)	1.23	Lyman et al., 1990^[5]

Biodegradation of 14D is limited in many environments including surface water, groundwater and wastewater treatment plants. Currently, there is little evidence that 14D biodegrades under anaerobic conditions^[6]^[7]. In contrast, under aerobic conditions, several bacteria and fungi^[8] can grow on 14D as a sole source of carbon and energy, including well-characterized strains such as Pseudonocardia dioxanivorans CB1190^[9]^[10] and other closely related actinomycetes^[7]^[11]^[12]^[13]. However, growth of these organisms on 14D is slow^[14], and as a consequence, 14D-metabolizing microorganisms are generally not effective in degrading 14D at the lower concentrations (≤100 μg/L) commonly observed in surface water and groundwater ^[15]^[16].

While 14D is not commonly used as a microbial growth substrate at ambient concentrations, there are a wide variety of microorganisms that can cometabolically biodegrade 14D when grown on a different (primary) substrate. During cometabolism, the primary substrate supports production of active biomass and induces the appropriate enzymes that can then fortuitously biodegrade 14D. Primary substrates that have been shown to support cometabolic biodegradation of 14D include tetrahydrofuran (THF), toluene, methane, ethane, propane, and isobutane^[10]^[17]^[18]^[19]^[20]. Recent field studies have demonstrated that propane-stimulated cometabolic biodegradation can reduce 14D to below 2-3 µg/L under appropriate conditions^[21]^[22].

As a result of the low sorption, low volatilization and low biodegradation, attenuation of 14D is often limited in groundwater^[23]^[24], surface water^[16] and traditional potable and wastewater treatment systems^[25]. In groundwater, the limited sorption of 14D results in relatively low concentrations in the source area and large dilute plumes^[15]. Under these conditions, much of the 14D mass will be present in the downgradient plume and aggressive treatment of the source area is generally less effective in reducing 14D migration.

Toxicity and Regulatory Standards (updated 2018)

The U.S. Department of Health and Human Services^[26] classifies 14D as a reasonably anticipated human carcinogen, and the International Agency for Research on Cancer^[27]^[28] regards 14D as possibly carcinogenic to humans (Group 2B). These classifications are primarily based on research on mice, rats and guinea pigs^[27]. One human epidemiological study reported no increased deaths from cancer in workers exposed to 14D^[29].

There is currently no maximum contaminant level (MCL) for 14D. However, tap water screening (0.46 µg/L) and drinking water equivalent levels (1 mg/L)^[30] have been established. For soil contamination, the US EPA has calculated a residential soil screening level (SSL) of 5.3 milligrams per kilogram (mg/kg), an industrial SSL of 24 mg/kg and leach-based SSL of 9.4 x 10^-5 mg/kg ^[31]. Many states have established drinking water and groundwater standards, which range from 0.25 (New Hampshire) to 9.1 µg/L (Texas)^[32].

History of Use and Release to Environment

Figure 1. Results of 14D plume length study.

The most common use of 14D has been as a solvent stabilizer for 1,1,1-Trichloroethane (TCA) utilized in metal degreasing operations. The addition of 14D to degreasing solvents such as TCA inhibits the formation of metal salts, which can result in solvent breakdown^[1]. Approximately 90% of 14D produced in the 1980s was used as a stabilizer for TCA^[1]. Following the phase-out of ozone depleting chemicals including TCA, the production and use of 14D has declined. Beyond its use as a solvent stabilizer, 14D has also been used in textile, paint and ink, cellulose acetate membrane and adhesive manufacturing operations^[1].

Figure 2. Effects of matrix diffusion processes on 14D concentrations in heterogeneous soils.

14D is an un-intended byproduct of some organic chemical synthesis processes^[1]. 14D can be produced during manufacture of alcohol ethoxylates which are used in a wide variety of consumer products including soaps and detergents, cosmetics and food. In 2001, ethoxylated raw materials were found to contain up to 1.4% 14D^[33]. Once this issue was recognized, measures were put into place to reduce 14D levels. 14D levels in the final product can be reduced by controlling the production process^[34] and by treatment of finished products by several approaches including vacuum stripping, steam stripping, and drying^[35]. 14D is produced as a byproduct during production of polyethylene terephthalate (PET), polyester and strong surfactants, as well as many other products^[36]. Treated industrial wastewater containing 14D may be released to surface water or groundwater^[16]^[37]^[38].

14D has been detected in air, potable water, wastewater and groundwater. 14D was detected in ambient air in several studies^[39]^[40]^[41]). In a survey of 4,864 public drinking water systems, 14D was detected in 21% of the systems and exceeded the health-based reference concentration of 0.35 μg/L in 6.9%^[42]. Municipal wastewater^[43]^[44] and landfill leachates^[45]^[46] also frequently contain 14D.

In groundwater, 14D is frequently observed as a co-contaminant with TCA^[15]^[47]. As 14D was often utilized as an additive to degreasing solvents^[1], its presence is positively correlated with other chlorinated organics such as TCA, trichloroethene (TCE), and 1,1-Dichloroethene (1,1-DCE)^[42]. In one study, TCA and/or TCE were observed in 94% of the monitoring wells with detectable 14D^[47].

A comprehensive evaluation of a large multi-site dataset^[48] found that 14D was detected, when analyzed for, at 52% of sites containing TCE, 70% of sites with 1,1,1-TCA, and 69% of sites with 1,1-DCE. The spatial extent of the 14D plumes typically fell within a similar or smaller footprint than the co-occurring chlorinated solvent plumes. The more limited migration of 14D, compared to chlorinated solvents, may be due to the timing of the 14D release. TCE was used at many sites prior to the use of TCA. As a result, TCE (and its by-products) may have been released before TCA and 14D and could have a “head-start”. The results were somewhat surprising given the high migration potential of 14D, as explained in the video shown in Figure 1. The maximum historical dioxane concentrations were below 365 μg/L for half of 194 sites with detectable 14D^[15]. Overall, 14D plumes are generally so dilute that source zones may be difficult to identify.

Also, modeling results^[48] indicate that matrix diffusion of 14D mass in and out of lower-permeability soils (i.e. silts and clays) can be an important fate and transport process for this compound as discussed in more detail in the video shown in Figure 2. The contribution of matrix diffusion processes to 14D concentrations within the source zone and the downgradient plume should be accounted for during site management.

The common presence of 14D in potable water supplies is a concern because 14D removal is low in many unit processes commonly employed in publicly owned treatment works (POTW) due to the high solubility, low volatility, and relative resistance to biodegradation (see section on physical/chemical treatment). 14D removal was not observed in several physical/chemical water treatment processes including coagulation, oxidation and air stripping processes^[49]. Activated carbon adsorption is somewhat more successful, with reported removal efficiencies ranging from 50 to 67 percent^[49]^[50]. Stepien^[25] reported that 14D removal was not observed in four domestic wastewater treatment plants in Germany. In a study of North Carolina water treatment facilities, 14D removal was not observed at two of the facilities, but was reduced by 65% at a third which employed ozonation of raw and settled water^[16].

Above Ground Treatment

Air stripping is generally not effective for removing 14D from contaminated water due its low Henry’s Law constant. While 14D can be removed from water by sorption to granular activated carbon (GAC), sorption capacities are low resulting in high capital and operating costs^[51]. In contrast, polymeric sorbents (e.g. Ambersorb^TM 560) are reported to have 5 to 10 times the sorption capacity of GAC, making sorption a more attractive alternative, though with additional operational requirements of adsorbent regeneration and proper disposal of spent waste^[51]. While 14D can be degraded by high energy UV radiation in high purity water^[52], direct ultraviolet photolysis is not economically viable due to operational challenges and high costs^[1].

Advanced oxidation processes (AOPs) using combinations of ozone (O₃), hydrogen peroxide (H₂O₂) and ultraviolet (UV) radiation produce highly reactive hydroxyl radicals (•OH) which are effective in destroying 14D. In the peroxone process (O₃ + H₂O₂), O₃ reacts with H₂O₂ giving rise to hydroxyl radicals^[53]. In a variation of this approach (HiPOx™ process), H₂O₂ is added first followed by high pressure O₃^[54]. Hydroxyl radicals are produced in UV + H₂O₂ systems by direct photolysis of H₂O₂ caused by absorption of energy from an ultraviolet lamp^[55]^[56].

AOPs are commonly employed for 14D treatment because of their high removal efficiencies with low contact times^[1]^[57]. The degradation mechanisms and kinetics of these processes are well understood, with multiple systems in current use^[1]. All of these systems are effective in destroying 14D, but have some limitations including the potential for bromate formation (when Br is present), reduced efficiency in the presence of free radical scavengers (e.g. HCO₃) and high capital and operating costs associated with energy and chemical consumption^[1]^[58].

Biological wastewater treatment has not been widely applied for 14D removal. While high concentrations of 14D will support growth of 14D degraders^[59] growth rates on 14D are slow^[37]^[9]^[60]^[61], and the low 14D concentrations in many systems are not sufficient to maintain an adequate level of 14D degraders for effective treatment. To overcome this problem, 14D degrading biomass was supported by addition of tetrahydrofuran (THF) to a continuously fed trickling filter for over one year. The system was effective in reducing 14D concentrations by 93–97% while influent 14D concentrations were varied from 200 to 1,200 µg/L^[62]. This basic approach was applied to full-scale treatment of leachate from the Lowry Landfill Superfund site where both THF and 14D were present as co-contaminants^[63].

In-Situ Treatment

A variety of methods have been attempted for in situ treatment of 14D impacted soil and groundwater including in situ chemical oxidation (ISCO), thermally enhanced soil vapor extraction, bioremediation, phytoremediation, and monitored natural attenuation (MNA).

ISCO can be used to degrade 14D in source areas with a variety of oxidants including permanganate^[64], persulfate^[65], Fenton’s reagent^[66] and ozone^[57]. However, ISCO treatment of 14D in source areas is not common because much of the mass is in the downgradient plume. Dilute plumes can potentially be treated using cylinders placed in wells that slowly release oxidant over time. In a field demonstration, a system of slow release persulfate cylinders was effective in reducing 14D and chlorinated solvent concentrations by over 99% for 119 days^[67].

Thermal remediation of source areas is not frequently utilized for 14D remediation because much of the 14D mass is in the dissolved plume. However, when applied to treat a source area, thermal remediation can be effective. Following electrical resistive heating of a chlorinated solvent source area, 14D levels in groundwater were reduced by >99%^[68]. 14D source areas can also be treated using a combination of heated air injection and focused air extraction from areas with elevated 14D concentrations. In a field demonstration, thermally enhanced soil vapor extraction reduced 14D levels by 94%^[69]^[70]. Modeling results indicate that removal increases with increasing air injection temperature and relative humidity and decreases with initial soil moisture content^[71].

In situ bioremediation has not been commonly applied to 14D treatment due to the slow growth of bacteria using 14D as a growth substrate. However, there has been some success in stimulating cometabolic biodegradation of 14D using gaseous substrates. In a biosparging pilot test, air amended with propane was injected into a single well that was bioaugmented with the propanotroph Rhodococcus ruber ENV425. 14D levels decreased by >99% in the sparge well and two nearby monitoring wells^[21]. A propane-stimulated groundwater recirculation system has also recently been reported to effectively reduce concentrations of 14D as well as several chlorinated aliphatics such as TCE and 1,2-dichloroethane^[22].

Phytoremediation has been reported as a viable treatment alternative for 14D^[72]. The primary removal process is via phytovolatilization, which involves transpiration of chemicals from the leaf surfaces to the atmosphere^[73]. Addition of 14D degrading bacteria (e.g. CB1190) and appropriate co-substrates can further enhance the removal of 14D in soil planted with poplar trees^[74].

Early microcosm studies indicated that 14D did not degrade in the presence of impacted aquifer material under in situ conditions^[38]. However, a statistical analysis of multiple Air Force and California sites found evidence of 14D removal in 19% of the sites^[75], similar to other chlorinated VOCs (TCE and 1,1-DCE). The decay rates were positively correlated to dissolved oxygen, and negatively correlated to high metals and chlorinated VOC concentrations^[75]. 14D decay has also been positively correlated to the presence of oxidizing enzymes^[76]^[77]. Native 14D degrading microorganisms have also been detected in field studies using a number of environmental diagnostic assays, such as microarray^[76] and stable isotope probing^[78]^[79], suggesting that monitored natural attenuation (MNA) may be a feasible and cost-efficient alternative to mitigate 14D at some sites.

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^ Stefan, M.I. and Bolton, J.R., 1998. Mechanism of the degradation of 1, 4-dioxane in dilute aqueous solution using the UV/hydrogen peroxide process. Environmental Science & Technology, 32(11), pp.1588-1595. doi: 10.1021/es970633m
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^ Woodward, C., Shulmeister, J., Larsen, J., Jacobsen, G.E. and Zawadzki, A., 2014. The hydrological legacy of deforestation on global wetlands. Science, 346(6211), pp.844-847. doi: 10.1126/science.1260510
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^ Zenker, M.J., Borden, R.C. and Barlaz, M.A., 2003. Occurrence and treatment of 1, 4-dioxane in aqueous environments. Environmental Engineering Science, 20(5), pp.423-432. doi: 10.1089/109287503768335913
^ Shangraw, T. and Plaehn, W. 2012. Full-scale treatment of 1,4-dioxane using a bioreactor. Federal Remediation Technologies Roundtable Meeting. Report.pdf
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^ Félix-Navarro, R.M., Lin-Ho, S.W., Barrera-Díaz, N. and Pérez-Sicairos, S., 2007. Kinetics of the degradation of 1, 4-dioxane using persulfate. Journal of the Mexican Chemical Society, 51(2), pp.67-71. ISSN 1870-249X
^ Kiker, J.H., Connolly, J.B., Murray, W.A., Pearson, S.C.P., Reed, S.E.R. and Tess, R.J., 2010. Ex-situ wellhead treatment of 1, 4-dioxane using fenton's reagent. In Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy (Vol. 15, No. 1, p. 18).
^ Evans, P., Hooper, J., Lamar, M., Nguyen, D., Dugan, P., Crimi, M. and Ruiz, N., 2018. Sustained In situ Chemical Oxidation (ISCO) of 1, 4 Dioxane and Chlorinated VOCs Using Slow release Chemical Oxidant Cylinders. ESTCP Cost and Performance Report, ER-201324. Report.pdf
^ Oberle, D., Crownover, E. and Kluger, M., 2015. In situ remediation of 1, 4‐dioxane using electrical resistance heating. Remediation Journal, 25(2), pp.35-42. doi: 10.1002/rem.21422
^ Hinchee, R.E., P.C. Johnson, P.R. Dahlen, and D.R. Durris, 2017. 1,4-Dioxane remediation by extreme soil vapor extraction (XSVE). Final Report ESTCP Project 201326 Report.pdf
^ Hinchee, R.E., Dahlen, P.R., Johnson, P.C. and Burris, D.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction: I. Field Demonstration. Groundwater Monitoring & Remediation, 38(2), pp.40-48. doi: doi.org/10.1111/gwmr.12264
^ Burris, D.R., Johnson, P.C., Hinchee, R.E. and Dahlen, P.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction (XSVE): II. Modeling. Groundwater Monitoring & Remediation, 38(2), pp.49-56. doi: 10.1111/gwmr.12277
^ Aitchison, E.W., Kelley, S.L., Alvarez, P.J. and Schnoor, J.L., 2000. Phytoremediation of 1, 4-dioxane by hybrid poplar trees. Water Environment Research, 72(3), pp.313-321. doi: 10.2175/106143000X137536
^ Ouyang, Y., 2002. Phytoremediation: modeling plant uptake and contaminant transport in the soil–plant–atmosphere continuum. Journal of Hydrology, 266(1-2), pp.66-82. doi: 10.2175/106143000X137536
^ Kelley, S.L., Aitchison, E.W., Deshpande, M., Schnoor, J.L. and Alvarez, P.J., 2001. Biodegradation of 1, 4-dioxane in planted and unplanted soil: effect of bioaugmentation with Amycolata sp. CB1190. Water Research, 35(16), pp.3791-3800. doi: 10.1016/S0043-1354(01)00129-4
^ ^75.0 ^75.1 Adamson, D.T., Anderson, R.H., Mahendra, S. and Newell, C.J., 2015. Evidence of 1, 4-dioxane attenuation at groundwater sites contaminated with chlorinated solvents and 1, 4-dioxane. Environmental Science & Sechnology, 49(11), pp.6510-6518.[ https://doi.org/10.1021/acs.est.5b00964 doi:10.1021/acs.est.5b00964]
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^ Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. doi: 10.1128/AEM.04162-13
^ Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. doi: 10.1039/C2EM30358B
^ Li, M., Liu, Y., He, Y., Mathieu, J., Hatton, J., DiGuiseppi, W. and Alvarez, P.J., 2017. Hindrance of 1, 4-dioxane biodegradation in microcosms biostimulated with inducing or non-inducing auxiliary substrates. Water Research, 112, pp.217-225. doi: 10.1016/j.watres.2017.01.047

@@ Line 1: / Line 1: @@
-[[wikipedia: 1,4-Dioxane | 1,4-Dioxane]] (14D) is a heterocyclic synthetic organic chemical that contains two ether bonds, is miscible with water, does not strongly sorb to natural or engineered materials, and does not biodegrade in many environments, all of which results in its persistence and rapid transport in aqueous environments.  14D is a suspected human carcinogen, which has resulted in relatively strict standards for drinking water sources.  [[wikipedia: Advanced oxidation processes | Advanced oxidation processes]] (AOPs) are the most well-developed technologies for removal of 14D from potable water supplies.  Several treatment technologies are being developed for ''in situ'' treatment of 14D including [[Chemical Oxidation (In Situ - ISCO) | chemical oxidation]], [[Biodegradation - Cometabolic | cometabolic bioremediation]], and [[Thermal Remediation | thermally enhanced]] [[Soil Vapor Extraction (SVE) | soil vapor extraction]].
+[[wikipedia: 1,4-Dioxane | 1,4-Dioxane]] (14D) is a heterocyclic synthetic organic chemical that contains two ether bonds, is miscible with water, does not strongly sorb to natural or engineered materials, and does not biodegrade in many environments, all of which results in its persistence and rapid transport in aqueous environments.  14D is a suspected human carcinogen, which has resulted in relatively strict standards for drinking water sources.  [[wikipedia: Advanced oxidation process | Advanced oxidation processes]] (AOPs) are the most well-developed technologies for removal of 14D from potable water supplies.  Several treatment technologies are being developed for ''in situ'' treatment of 14D including [[Chemical Oxidation (In Situ - ISCO) | chemical oxidation]], [[Biodegradation - Cometabolic | cometabolic bioremediation]], and [[Thermal Remediation | thermally enhanced]] [[Soil Vapor Extraction (SVE) | soil vapor extraction]].
 <div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 '''Related Article(s):'''
+*[[Biodegradation - 1,4-Dioxane]]
+*[[Biodegradation - Cometabolic]]
-*[[Biodegradation – 1,4-Dioxane]]
-*[[Biodegradation - Cometabolic]]
-'''CONTRIBUTOR(S):''' [[Matthew Zenker]], [[Dr. Shaily Mahendra]], and [[Dr. Michael Hyman]]
+'''Contributor(s):''' [[Matthew Zenker]], [[Dr. Shaily Mahendra | Shaily Mahendra]], and [[Dr. Michael Hyman | Michael Hyman]]
 '''Key Resource(s)''':
 *[https://doi.org/10.1201/EBK1566706629 Environmental Investigation and Remediation: 1,4-Dioxane and other solvent stabilizers]<ref name="Mohr2010">Mohr, T.K., Stickney, J.A. and DiGuiseppi, W.H., 2010. Environmental investigation and remediation: 1, 4-dioxane and other solvent stabilizers. CRC Press. Boca Raton. 550 pages. [https://doi.org/10.1201/EBK1566706629 doi: 10.1201/EBK1566706629]</ref>
 ==Properties, Fate and Transport==
-,4-Dioxane (14D) is a heterocyclic organic compound, and the most commonly encountered of the three dioxane isomers (1,2-, 1,3- and 1,4-Dioxane). Key physical and chemical properties of 14D are listed in Table 1.  The heterocyclic, polar structure of 1,4-Dioxane causes it to be miscible with water and also unable to strongly sorb or partition to aquifer solids or engineered sorbents (i.e. activated carbon).  While 14D has a moderate vapor pressure, the high aqueous solubility results in limited volatilization.
+,4-Dioxane (14D) is a heterocyclic organic compound, and the most commonly encountered of the three dioxane isomers (1,2-, 1,3- and 1,4-dioxane). Key physical and chemical properties of 14D are listed in Table 1.  The heterocyclic, polar structure of 1,4-dioxane causes it to be miscible with water and also unable to strongly sorb or partition to aquifer solids or engineered sorbents (i.e. activated carbon).  While 14D has a moderate vapor pressure, the high aqueous solubility results in limited volatilization.
 {| class="wikitable" style="float:right; margin-left: 10px;"
@@ Line 28: / Line 26: @@
 |Chemical Abstracts Service (CAS) Number||123-91-1||
 |-
-|Appearance||Colorless Liquid||NIOSH, 2007<ref name="NIOSH2007">Barsan, M.E., 2007. NIOSH pocket guide to chemical hazards. [//www.enviro.wiki/images/3/3b/2007-NIOSH_Pocket_Guide_to_Chemical_Hazards.pdf  Report.pdf]</ref>
+|Appearance||Colorless Liquid||NIOSH, 2007<ref name="NIOSH2007">Barsan, M.E., 2007. NIOSH pocket guide to chemical hazards. [//www.enviro.wiki/images/3/3b/2007-NIOSH_Pocket_Guide_to_Chemical_Hazards.pdf Report.pdf]</ref>
 |-
-|Molecular Weight||88.105 g/mol||NIST, 2018<ref>NIST, 2018. NIST Chemistry WebBook: Standard Reference Database 69. US Department of Commerce.</ref>
+|Molecular Weight||88.105 g/mol||NIST, 2018<ref>NIST, 2018. NIST Chemistry WebBook: Standard Reference Database 69. US Department of Commerce. https://webbook.nist.gov/chemistry/</ref>
 |-
 |Water Solubility||Miscible||NIOSH, 2007<ref name="NIOSH2007" />
@@ Line 36: / Line 34: @@
 |Specific Gravity||1.03||NIOSH, 2007<ref name="NIOSH2007" />
 |-
-|Vapor Pressure at 25&deg; C||38.1 mm Hg||US EPA, 2017<ref name="USEPA2017Z">US EPA, 2017. Technical Fact Sheet – 1,4-Dioxane. Publication number: EPA 505-F-17-001. [//www.enviro.wiki/images/2/2e/2017-USEPA-_Technical_Fact_Sheet.pdf  Report.pdf]</ref>
+|Vapor Pressure at 25&deg; C||38.1 mm Hg||US EPA, 2017<ref name="USEPA2017Z">US EPA, 2017. Technical Fact Sheet – 1,4-Dioxane. Publication number: EPA 505-F-17-001. [//www.enviro.wiki/images/2/2e/2017-USEPA-_Technical_Fact_Sheet.pdf Report.pdf]</ref>
 |-
 |Henry’s Law Constant at 25&deg; C||4.80 X 10<sup>-6</sup> atm-m<sup>3</sup>/mol||US EPA, 2017<ref name="USEPA2017Z" />
@@ Line 45: / Line 43: @@
 |}
-Biodegradation of 14D is limited in many environments including surface water, groundwater and wastewater treatment plants.  Currently, there is little evidence that 14D biodegrades under anaerobic conditions<ref>Shen, W., Chen, H. and Pan, S., 2008. Anaerobic biodegradation of 1, 4-dioxane by sludge enriched with iron-reducing microorganisms. Bioresource technology, 99(7), pp.2483-2487. [https://doi.org/10.1016/j.biortech.2007.04.054 doi: 10.1016/j.biortech.2007.04.054]</ref><ref name="Zhang2017">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2017. Advances in bioremediation of 1, 4-dioxane-contaminated waters. Journal of environmental management, 204, pp.765-774. [https://doi.org/10.1016/j.jenvman.2017.05.033 doi: 10.1016/j.jenvman.2017.05.033]</ref>.  In contrast, under aerobic conditions, several bacteria and fungi<ref>Skinner, K., Cuiffetti, L. and Hyman, M., 2009. Metabolism and cometabolism of cyclic ethers by a filamentous fungus, a Graphium sp. Appl. Environ. Microbiol., 75(17), pp.5514-5522. [https://doi.org/10.1128/aem.00078-09 doi:10.1128/AEM.00078-09]</ref> can grow on 14D as a sole source of carbon and energy, including well-characterized strains such as ''Pseudonocardia dioxanivorans'' CB1190<ref name="Parales1994">Parales, R.E., Adamus, J.E., White, N. and May, H.D., 1994. Degradation of 1, 4-dioxane by an actinomycete in pure culture. Applied and Environmental Microbiology, 60(12), pp.4527-4530. [//www.enviro.wiki/images/c/cd/1994-Parales-Degradation_of_1%2C4-Dioxane_by_an_Actinomycete_in_Pure_Culture.pdf  Report.pdf]</ref><ref name="Mahendra2006">Mahendra, S. and Alvarez-Cohen, L., 2006. Kinetics of 1, 4-dioxane biodegradation by monooxygenase-expressing bacteria. Environmental Science & Technology, 40(17), pp.5435-5442. [https://doi.org/10.1021/es060714v [https://doi.org/10.1021/es060714v doi: 10.1021/es060714v]</ref>) and other closely related [[wikipedia: Actinomycetales | actinomycetes]]<ref name="Zhang2017" /><ref>Yamamoto, N., Saito, Y., Inoue, D., Sei, K. and Ike, M., 2018. Characterization of newly isolated Pseudonocardia sp. N23 with high 1, 4-dioxane-degrading ability. Journal of bioscience and bioengineering, 125(5), pp.552-558. [https://doi.org/10.1016/j.jbiosc.2017.12.005 doi: 10.1016/j.jbiosc.2017.12.005]</ref><ref>Inoue, D., Tsunoda, T., Sawada, K., Yamamoto, N., Saito, Y., Sei, K. and Ike, M., 2016. 1, 4-Dioxane degradation potential of members of the genera Pseudonocardia and Rhodococcus. Biodegradation, 27(4-6), pp.277-286. [https://doi.org/10.1007/s10532-016-9772-7 doi: 10.1007/s10532-016-9772-7]</ref><ref>Kim, Y.M., Jeon, J.R., Murugesan, K., Kim, E.J. and Chang, Y.S., 2009. Biodegradation of 1, 4-dioxane and transformation of related cyclic compounds by a newly isolated Mycobacterium sp. PH-06. Biodegradation, 20(4), p.511. [https://doi.org/10.1007/s10532-008-9240-0 doi: 10.1007/s10532-008-9240-0]</ref>. However, growth of these organisms on 14D is slow<ref>Barajas-Rodriguez, F.J. and Freedman, D.L., 2018. Aerobic biodegradation kinetics for 1, 4-dioxane under metabolic and cometabolic conditions. Journal of hazardous materials, 350, pp.180-188. [https://doi.org/10.1016/j.jhazmat.2018.02.030 doi: 10.1016/j.jhazmat.2018.02.030]</ref>, and as a consequence, 14D-metabolizing microorganisms are generally not effective in degrading 14D at the lower concentrations (≤100 &mu;g/L) commonly observed in surface water and groundwater <ref name="Adamson2014">Adamson, D.T., Mahendra, S., Walker Jr, K.L., Rauch, S.R., Sengupta, S. and Newell, C.J., 2014. A multisite survey to identify the scale of the 1, 4-dioxane problem at contaminated groundwater sites. Environmental Science & Technology Letters, 1(5), pp.254-258. [https://doi.org/10.1021/ez500092u doi: 10.1021/ez500092u]</ref><ref name="Knappe2016">Knappe, D., Lopez-Velandia, C., Hopkins, Z. and Sun, M., 2016. Occurrence of 1, 4-Dioxane in the Cape Fear River Watershed and Effectiveness of Water Treatment Options for 1, 4-Dioxane Control. NC Water Resources Research Institute of The University of North Carolina, Report No. 478. [//www.enviro.wiki/images/a/a4/2016-Knappe-Occurrence_of_1%2C4-dioxane_in_the_Cape_Fear_River.pdf  Report.pdf]</ref>.
+Biodegradation of 14D is limited in many environments including surface water, groundwater and wastewater treatment plants.  Currently, there is little evidence that 14D biodegrades under anaerobic conditions<ref>Shen, W., Chen, H. and Pan, S., 2008. Anaerobic biodegradation of 1, 4-dioxane by sludge enriched with iron-reducing microorganisms. Bioresource technology, 99(7), pp.2483-2487. [https://doi.org/10.1016/j.biortech.2007.04.054 doi: 10.1016/j.biortech.2007.04.054]</ref><ref name="Zhang2017">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2017. Advances in bioremediation of 1, 4-dioxane-contaminated waters. Journal of environmental management, 204, pp.765-774. [https://doi.org/10.1016/j.jenvman.2017.05.033 doi: 10.1016/j.jenvman.2017.05.033]</ref>.  In contrast, under aerobic conditions, several bacteria and fungi<ref>Skinner, K., Cuiffetti, L. and Hyman, M., 2009. Metabolism and cometabolism of cyclic ethers by a filamentous fungus, a Graphium sp. Appl. Environ. Microbiol., 75(17), pp.5514-5522. [https://doi.org/10.1128/aem.00078-09 doi:10.1128/AEM.00078-09]</ref> can grow on 14D as a sole source of carbon and energy, including well-characterized strains such as ''Pseudonocardia dioxanivorans'' CB1190<ref name="Parales1994">Parales, R.E., Adamus, J.E., White, N. and May, H.D., 1994. Degradation of 1, 4-dioxane by an actinomycete in pure culture. Applied and Environmental Microbiology, 60(12), pp.4527-4530. [//www.enviro.wiki/images/c/cd/1994-Parales-Degradation_of_1%2C4-Dioxane_by_an_Actinomycete_in_Pure_Culture.pdf Report.pdf]</ref><ref name="Mahendra2006">Mahendra, S. and Alvarez-Cohen, L., 2006. Kinetics of 1, 4-dioxane biodegradation by monooxygenase-expressing bacteria. Environmental Science & Technology, 40(17), pp.5435-5442. [https://doi.org/10.1021/es060714v [https://doi.org/10.1021/es060714v doi: 10.1021/es060714v]</ref> and other closely related [[wikipedia: Actinomycetales | actinomycetes]]<ref name="Zhang2017" /><ref>Yamamoto, N., Saito, Y., Inoue, D., Sei, K. and Ike, M., 2018. Characterization of newly isolated Pseudonocardia sp. N23 with high 1, 4-dioxane-degrading ability. Journal of bioscience and bioengineering, 125(5), pp.552-558. [https://doi.org/10.1016/j.jbiosc.2017.12.005 doi: 10.1016/j.jbiosc.2017.12.005]</ref><ref>Inoue, D., Tsunoda, T., Sawada, K., Yamamoto, N., Saito, Y., Sei, K. and Ike, M., 2016. 1, 4-Dioxane degradation potential of members of the genera Pseudonocardia and Rhodococcus. Biodegradation, 27(4-6), pp.277-286. [https://doi.org/10.1007/s10532-016-9772-7 doi: 10.1007/s10532-016-9772-7]</ref><ref>Kim, Y.M., Jeon, J.R., Murugesan, K., Kim, E.J. and Chang, Y.S., 2009. Biodegradation of 1, 4-dioxane and transformation of related cyclic compounds by a newly isolated Mycobacterium sp. PH-06. Biodegradation, 20(4), p.511. [https://doi.org/10.1007/s10532-008-9240-0 doi: 10.1007/s10532-008-9240-0]</ref>. However, growth of these organisms on 14D is slow<ref>Barajas-Rodriguez, F.J. and Freedman, D.L., 2018. Aerobic biodegradation kinetics for 1, 4-dioxane under metabolic and cometabolic conditions. Journal of hazardous materials, 350, pp.180-188. [https://doi.org/10.1016/j.jhazmat.2018.02.030 doi: 10.1016/j.jhazmat.2018.02.030]</ref>, and as a consequence, 14D-metabolizing microorganisms are generally not effective in degrading 14D at the lower concentrations (≤100 &mu;g/L) commonly observed in surface water and groundwater <ref name="Adamson2014">Adamson, D.T., Mahendra, S., Walker Jr, K.L., Rauch, S.R., Sengupta, S. and Newell, C.J., 2014. A multisite survey to identify the scale of the 1, 4-dioxane problem at contaminated groundwater sites. Environmental Science & Technology Letters, 1(5), pp.254-258. [https://doi.org/10.1021/ez500092u doi: 10.1021/ez500092u]</ref><ref name="Knappe2016">Knappe, D., Lopez-Velandia, C., Hopkins, Z. and Sun, M., 2016. Occurrence of 1, 4-Dioxane in the Cape Fear River Watershed and Effectiveness of Water Treatment Options for 1, 4-Dioxane Control. NC Water Resources Research Institute of The University of North Carolina, Report No. 478. [//www.enviro.wiki/images/a/a4/2016-Knappe-Occurrence_of_1%2C4-dioxane_in_the_Cape_Fear_River.pdf Report.pdf]</ref>.
 While 14D is not commonly used as a microbial growth substrate at ambient concentrations, there are a wide variety of microorganisms that can [[Biodegradation_-_Cometabolic | cometabolically biodegrade]] 14D when grown on a different (primary) substrate. During cometabolism, the primary substrate supports production of active biomass and induces the appropriate enzymes that can then fortuitously biodegrade 14D. Primary substrates that have been shown to support cometabolic biodegradation of 14D include [[wikipedia: Tetrahydrofuran | tetrahydrofuran]] (THF), [[wikipedia: Toluene | toluene]], [[wikipedia: Methane | methane]], [[wikipedia: Ethane | ethane]], [[wikipedia: Propane | propane]], and [[wikipedia: Isobutane | isobutane]]<ref name="Mahendra2006" /><ref>Vainberg, S., McClay, K., Masuda, H., Root, D., Condee, C., Zylstra, G.J. and Steffan, R.J., 2006. Biodegradation of ether pollutants by Pseudonocardia sp. strain ENV478. Appl. Environ. Microbiol., 72(8), pp.5218-5224. [https://doi.org/10.1128/aem.00160-06 doi: 10.1128/AEM.00160-06]</ref><ref>Hatzinger, P.B., Banerjee, R., Rezes, R., Streger, S.H., McClay, K. and Schaefer, C.E., 2017. Potential for cometabolic biodegradation of 1, 4-dioxane in aquifers with methane or ethane as primary substrates. Biodegradation, 28(5-6), pp.453-468. [https://doi.org/10.1007/s10532-017-9808-7 doi: 0.1007/s10532-017-9808-7]</ref><ref>Bennett, P., Hyman, M., Smith, C., El Mugammar, H., Chu, M.Y., Nickelsen, M. and Aravena, R., 2018. Enrichment with carbon-13 and deuterium during monooxygenase-mediated biodegradation of 1, 4-dioxane. Environmental Science & Technology Letters, 5(3), pp.148-153. [https://doi.org/10.1021/acs.estlett.7b00565 doi: 10.1021/acs.estlett.7b00565]</ref><ref>Deng, D., Li, F., Wu, C. and Li, M., 2018. Synchronic Biotransformation of 1, 4-Dioxane and 1, 1-Dichloroethylene by a Gram-Negative Propanotroph Azoarcus sp. DD4. Environmental Science & Technology Letters, 5(8), pp.526-532. [https://doi.org/10.1021/acs.estlett.8b00312 doi: 10.1021/acs.estlett.8b00312]</ref>. Recent field studies have demonstrated that propane-stimulated cometabolic biodegradation can reduce 14D to below 2-3 µg/L under appropriate conditions<ref name="Lippincott2015">Lippincott, D., Streger, S.H., Schaefer, C.E., Hinkle, J., Stormo, J. and Steffan, R.J., 2015. Bioaugmentation and propane biosparging for in situ biodegradation of 1, 4‐dioxane. Groundwater Monitoring & Remediation, 35(2), pp.81-92. [https://doi.org/10.1111/gwmr.12093 doi: 10.1111/gwmr.12093]</ref><ref name="Chu2018">Chu, M.Y.J., Bennett, P.J., Dolan, M.E., Hyman, M.R., Peacock, A.D., Bodour, A., Anderson, R.H., Mackay, D.M. and Goltz, M.N., 2018. Concurrent Treatment of 1, 4‐Dioxane and Chlorinated Aliphatics in a Groundwater Recirculation System Via Aerobic Cometabolism. Groundwater Monitoring & Remediation, 38(3), pp.53-64. [https://doi.org/10.1111/gwmr.12293 doi: 10.1111/gwmr.12293]</ref>.
@@ Line 52: / Line 50: @@
 ==Toxicity and Regulatory Standards (updated 2018)==
-The U.S. Department of Health and Human Services<ref>ATSDR, 2012. Toxicological profile for 1,4-dioxane. Agency for Toxic Substances and Disease Registry [//www.enviro.wiki/images/d/df/2012-ASTDR._Toxicological_profile_for_1%2C4-dioxane.pdf  Report.pdf]</ref> classifies 14D as a reasonably anticipated human carcinogen and the International Agency for Research on Cancer<ref name="IARC1999">IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, International Agency for Research on Cancer and World Health Organization, 1999. Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide. IARC.</ref><ref>Stickney, J.A., Sager, S.L., Clarkson, J.R., Smith, L.A., Locey, B.J., Bock, M.J., Hartung, R. and Olp, S.F., 2003. An updated evaluation of the carcinogenic potential of 1, 4-dioxane. Regulatory Toxicology and Pharmacology, 38(2), pp.183-195. [https://doi.org/10.1016/S0273-2300(03)00090-4 doi: 10.1016/S0273-2300(03)00090-4]</ref> regards 14D as possibly carcinogenic to humans (Group 2B).  These classifications are primarily based on research on mice, rats and guinea pigs<ref name="IARC1999" />. One human epidemiological study reported no increased deaths from cancer in workers exposed to 14D<ref>Buffler, P.A., Wood, S.M., Suarez, L. and Kilian, D.J., 1978. Mortality follow-up of workers exposed to 1, 4-dioxane. Journal of occupational medicine.: official publication of the Industrial Medical Association, 20(4), pp.255-259.</ref>.
+The U.S. Department of Health and Human Services<ref>ATSDR, 2012. Toxicological profile for 1,4-dioxane. Agency for Toxic Substances and Disease Registry [//www.enviro.wiki/images/d/df/2012-ASTDR._Toxicological_profile_for_1%2C4-dioxane.pdf Report.pdf]</ref> classifies 14D as a reasonably anticipated human carcinogen, and the International Agency for Research on Cancer<ref name="IARC1999">IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, International Agency for Research on Cancer and World Health Organization, 1999. Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide. IARC.</ref><ref>Stickney, J.A., Sager, S.L., Clarkson, J.R., Smith, L.A., Locey, B.J., Bock, M.J., Hartung, R. and Olp, S.F., 2003. An updated evaluation of the carcinogenic potential of 1, 4-dioxane. Regulatory Toxicology and Pharmacology, 38(2), pp.183-195. [https://doi.org/10.1016/S0273-2300(03)00090-4 doi: 10.1016/S0273-2300(03)00090-4]</ref> regards 14D as possibly carcinogenic to humans (Group 2B).  These classifications are primarily based on research on mice, rats and guinea pigs<ref name="IARC1999" />. One human epidemiological study reported no increased deaths from cancer in workers exposed to 14D<ref>Buffler, P.A., Wood, S.M., Suarez, L. and Kilian, D.J., 1978. Mortality follow-up of workers exposed to 1, 4-dioxane. Journal of occupational medicine.: official publication of the Industrial Medical Association, 20(4), pp.255-259.</ref>.
-There is currently no maximum contaminant level (MCL) for 14D.  However, tap water screening (0.46 µg/L)  and drinking water equivalent levels (1 mg/L)<ref>U.S. Environmental Protection Agency (USEPA), 2018(a). Edition of the Drinking Water Standards and Health Advisories. EPA 822-F-18-001 [//www.enviro.wiki/images/3/36/2018-USEPA-Edition_of_the_Drinking_Water_Standards_and_Health_Advisories.pdf  Report.pdf]</ref> have been established.  For soil contamination, the US EPA has calculated a residential soil screening level (SSL) of 5.3 milligrams per kilogram (mg/kg), an industrial SSL of 24 mg/kg and leach-based SSL of 9.4 x 10<sup>-5</sup> mg/kg <ref>U.S. Environmental Protection Agency (USEPA), 2018(b). Regional Screening Level (RSL) Summary Tables. </ref>.  Many states have established drinking water and groundwater standards, which range from 0.25 (New Hampshire) to 9.1 µg/L (Texas)<ref>Suthersan, S., Quinnan, J., Horst, J., Ross, I., Kalve, E., Bell, C. and Pancras, T., 2016. Making strides in the management of “emerging contaminants”. Groundwater Monitoring & Remediation, 36(1), pp.15-25. [https://doi.org/10.1111/gwmr.12143 doi: 10.1111/gwmr.12143]</ref>.
+There is currently no maximum contaminant level (MCL) for 14D.  However, tap water screening (0.46 µg/L)  and drinking water equivalent levels (1 mg/L)<ref>U.S. Environmental Protection Agency (USEPA), 2018(a). Edition of the Drinking Water Standards and Health Advisories. EPA 822-F-18-001 [//www.enviro.wiki/images/3/36/2018-USEPA-Edition_of_the_Drinking_Water_Standards_and_Health_Advisories.pdf Report.pdf]</ref> have been established.  For soil contamination, the US EPA has calculated a residential soil screening level (SSL) of 5.3 milligrams per kilogram (mg/kg), an industrial SSL of 24 mg/kg and leach-based SSL of 9.4 x 10<sup>-5</sup> mg/kg <ref>U.S. Environmental Protection Agency (USEPA), 2018(b). Regional Screening Level (RSL) Summary Tables. https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables</ref>.  Many states have established drinking water and groundwater standards, which range from 0.25 (New Hampshire) to 9.1 µg/L (Texas)<ref>Suthersan, S., Quinnan, J., Horst, J., Ross, I., Kalve, E., Bell, C. and Pancras, T., 2016. Making strides in the management of “emerging contaminants”. Groundwater Monitoring & Remediation, 36(1), pp.15-25. [https://doi.org/10.1111/gwmr.12143 doi: 10.1111/gwmr.12143]</ref>.
 ==History of Use and Release to Environment==
-The most common use of 14D has been as a solvent stabilizer for [[wikipedia: 1,1,1-Trichloroethane | 1,1,1-Trichloroethane]] (TCA) utilized in metal degreasing operations.  The addition of 14D to degreasing solvents such as TCA inhibits the formation of metal salts, which can result in solvent breakdown<ref name="Mohr2010" />. Approximately 90% of 14D produced in the 1980s was used as a stabilizer for TCA<ref name="Mohr2010" />.  Following the [[wikipedia: Montreal Protocol | phase-out of ozone depleting chemicals]] including TCA, the production and use of 14D has declined.  Beyond its use as a solvent stabilizer, 14D has also been used in textile, paint and ink, cellulose acetate membrane and adhesive manufacturing operations<ref name="Mohr2010" />.
+[[File:14D_Plume_Length.mp4 | 600px | thumb | right | Figure 1. Results of 14D plume length study.]]The most common use of 14D has been as a solvent stabilizer for [[wikipedia: 1,1,1-Trichloroethane | 1,1,1-Trichloroethane]] (TCA) utilized in metal degreasing operations.  The addition of 14D to degreasing solvents such as TCA inhibits the formation of metal salts, which can result in solvent breakdown<ref name="Mohr2010" />. Approximately 90% of 14D produced in the 1980s was used as a stabilizer for TCA<ref name="Mohr2010" />.  Following the [[wikipedia: Montreal Protocol | phase-out of ozone depleting chemicals]] including TCA, the production and use of 14D has declined.  Beyond its use as a solvent stabilizer, 14D has also been used in textile, paint and ink, cellulose acetate membrane and adhesive manufacturing operations<ref name="Mohr2010" />.
+[[File:14D_Matrix_Diffusion.mp4 | 600px | thumb | right| Figure 2. Effects of matrix diffusion processes on 14D concentrations in heterogeneous soils.]] 14D is an un-intended byproduct of some organic chemical synthesis processes<ref name="Mohr2010" />.  14D can be produced during manufacture of [[wikipedia: Ethoxylation | alcohol ethoxylates]] which are used in a wide variety of consumer products including soaps and detergents, cosmetics and food.  In 2001, ethoxylated raw materials were found to contain up to 1.4% 14D<ref>Black, R.E., Hurley, F.J. and Havery, D.C., 2001. Occurrence of 1, 4-dioxane in cosmetic raw materials and finished cosmetic products. Journal of AOAC international, 84(3), pp.666-670. [//www.enviro.wiki/images/7/7d/2001-Black-Occurrence_of_1%2C4-dioxane_in_cosmetic_raw_materials....pdf Report.pdf]</ref>. Once this issue was recognized, measures were put into place to reduce 14D levels.  14D levels in the final product can be reduced by controlling the production process<ref>Ortega, J.A.T., 2012. Sulfonation/sulfation processing technology for anionic surfactant manufacture. In Advances in Chemical Engineering. IntechOpen. [//www.enviro.wiki/images/f/fa/2012-Ortega-Sulfonation_sulfation.pdf Report.pdf]</ref> and by treatment of finished products by several approaches including vacuum stripping, steam stripping, and drying<ref>Sachdeva, Y.P. and Gabriel, R.L., Pharm-Eco Laboratories Inc, 1997. Apparatus for decontaminating a liquid surfactant of dioxane. U.S. Patent 5,643,408. [//www.enviro.wiki/images/f/f0/1997-Sachdeva-Apparatus_for_decontaminating_a_liquid_surfractant.pdf Report.pdf]</ref>. 14D is produced as a byproduct during production of [[wikipedia: Polyethylene terephthalate| polyethylene terephthalate]] (PET), polyester and strong surfactants, as well as many other products<ref>Ellis, R.A. and Thomas, J.S., Wellman Inc, 1998. Destroying 1, 4-dioxane in byproduct streams formed during polyester synthesis. U.S. Patent 5,817,910. [//www.enviro.wiki/images/b/b3/1998-Ellis-Destroying_1%2C4-dioxane_in_byproduct_streams_formed_during_polyester.pdf report.pdf]</ref>. Treated industrial wastewater containing 14D may be released to surface water or groundwater<ref name="Knappe2016" /><ref name="Grady1997">Grady, C.P.L., Sock, S.M. and Cowan, R.M., 1997. Biotreatability Kinetics: A Critical Component in the Scale-up of Wastewater Treatment Systems. Environmental Science Research, 54, pp.307-322. [https://doi.org/10.1007/978-1-4615-5395-3_28 doi: 10.1007/978-1-4615-5395-3_28]</ref><ref name="Zenker 2000">Zenker, M.J., Borden, R.C. and Barlaz, M.A., 2000. Mineralization of 1, 4-dioxane in the presence of a structural analog. Biodegradation, 11(4), pp.239-246. [https://doi.org/10.1023/A:1011156924700 doi: 10.1023/A:1011156924700]</ref>.
+D has been detected in air, potable water, wastewater and groundwater.  14D was detected in ambient air in several studies<ref>Harkov, R., Katz, R., Bozzelli, J. and Kebbekus, B., 1981. Toxic and carcinogenic air pollutants in New Jersey volatile organic substances. Proceedings of the International Technical Conference of Toxic Air Contaminants, p.245. Pittsburgh, PA: Air Pollution Control Association</ref><ref>Shah, J.J. and Singh, H.B., 1988. Distribution of volatile organic chemicals in outdoor and indoor air: A national VOCs data base. Environmental Science & Technology, 22(12), pp.1381-1388. [https://pubs.acs.org/doi/abs/10.1021/es00177a001 doi: 10.1021/es00177a001]</ref><ref>Keel, L. and A. Franzmann, 2000. Downtown Bellingham air toxics screening project, 1995-1999 staff report. Northwest Air Pollution Authority (NWAPA). [//www.enviro.wiki/images/d/d0/2000-Keel-Downtown_Bellingham_Air_Toxics_Screening_Project.pdf Report.pdf]</ref>).  In a survey of 4,864 public drinking water systems, 14D was detected in 21% of the systems and exceeded the health-based reference concentration of 0.35 &mu;g/L in 6.9%<ref name="Adamson2017a">Adamson, D.T., Piña, E.A., Cartwright, A.E., Rauch, S.R., Anderson, R.H., Mohr, T. and Connor, J.A., 2017. 1, 4-Dioxane drinking water occurrence data from the third unregulated contaminant monitoring rule. Science of the Total Environment, 596, pp.236-245. [https://doi.org/10.1016/j.scitotenv.2017.04.085 doi: 10.1016/j.scitotenv.2017.04.085]</ref>. Municipal wastewater<ref>Abe, A., 1999. Distribution of 1, 4-dioxane in relation to possible sources in the water environment. Science of the Total Environment, 227(1), pp.41-47. [https://doi.org/10.1016/S0048-9697(99)00003-0 doi: 10.1016/S0048-9697(99)00003-0]</ref><ref>Westerhoff, P., Yoon, Y., Snyder, S. and Wert, E., 2005. Fate of endocrine-disruptor, pharmaceutical, and personal care product chemicals during simulated drinking water treatment processes. Environmental Science & Technology, 39(17), pp.6649-6663. [https://doi.org/10.1021/es0484799 doi: 10.1021/es0484799]</ref> and landfill leachates<ref>DeWalle, F.B. and Chian, E.S., 1981. Detection of trace organics in well water near a solid waste landfill. Journal‐American Water Works Association, 73(4), pp.206-211. [https://doi.org/10.1002/j.1551-8833.1981.tb04681.x doi: 10.1002/j.1551-8833.1981.tb04681.x]</ref><ref>Fujiwara, T., Tamada, T., Kurata, Y., Ono, Y., Kose, T., Ono, Y., Nishimura, F. and Ohtoshi, K., 2008. Investigation of 1, 4-dioxane originating from incineration residues produced by incineration of municipal solid waste. Chemosphere, 71(5), pp.894-901. [https://doi.org/10.1016/j.chemosphere.2007.11.011 doi: 10.1016/j.chemosphere.2007.11.011]</ref> also frequently contain 14D.
-D is an un-intended byproduct of some organic chemical synthesis processes<ref name="Mohr2010" />.  14D can be produced during manufacture of [[wikipedia: Ethoxylation | alcohol ethoxylates]] which are used in a wide variety of consumer products including soaps and detergents, cosmetics and food.  In 2001, ethoxylated raw materials were found to contain up to 1.4% 14D<ref>Black, R.E., Hurley, F.J. and Havery, D.C., 2001. Occurrence of 1, 4-dioxane in cosmetic raw materials and finished cosmetic products. Journal of AOAC international, 84(3), pp.666-670. [//www.enviro.wiki/images/7/7d/2001-Black-Occurrence_of_1%2C4-dioxane_in_cosmetic_raw_materials....pdf  Report.pdf]</ref>. Once this issue was recognized, measures were put into place to reduce 14D levels.  14D levels in the final product can be reduced by controlling the production process<ref>Ortega, J.A.T., 2012. Sulfonation/sulfation processing technology for anionic surfactant manufacture. In Advances in Chemical Engineering. IntechOpen. [//www.enviro.wiki/images/f/fa/2012-Ortega-Sulfonation_sulfation.pdf  Report.pdf]</ref> and by treatment of finished products by several approaches including vacuum stripping, steam stripping, and drying<ref>Sachdeva, Y.P. and Gabriel, R.L., Pharm-Eco Laboratories Inc, 1997. Apparatus for decontaminating a liquid surfactant of dioxane. U.S. Patent 5,643,408. [//www.enviro.wiki/images/f/f0/1997-Sachdeva-Apparatus_for_decontaminating_a_liquid_surfractant.pdf  Report.pdf]</ref>. 14D is produced as a byproduct during production of [[wikipedia: Polyethylene terephthalate| polyethylene terephthalate]] (PET), polyester and strong surfactants, as well as many other products<ref>Ellis, R.A. and Thomas, J.S., Wellman Inc, 1998. Destroying 1, 4-dioxane in byproduct streams formed during polyester synthesis. U.S. Patent 5,817,910. [//www.enviro.wiki/images/b/b3/1998-Ellis-Destroying_1%2C4-dioxane_in_byproduct_streams_formed_during_polyester.pdf  report.pdf]</ref>. Treated industrial wastewater containing 14D may be released to surface water or groundwater<ref name="Knappe2016" /><ref name="Grady1997">Grady, C.P.L., Sock, S.M. and Cowan, R.M., 1997. Biotreatability Kinetics: A Critical Component in the Scale-up of Wastewater Treatment Systems. Environmental Science Research, 54, pp.307-322. [https://doi.org/10.1007/978-1-4615-5395-3_28 doi: 10.1007/978-1-4615-5395-3_28]</ref><ref name="Zenker 2000">Zenker, M.J., Borden, R.C. and Barlaz, M.A., 2000. Mineralization of 1, 4-dioxane in the presence of a structural analog. Biodegradation, 11(4), pp.239-246. [https://doi.org/10.1023/A:1011156924700 doi: 10.1023/A:1011156924700]</ref>.
+In groundwater, 14D is frequently observed as a co-contaminant with TCA<ref name="Adamson2014" /><ref name="Anderson2012">Anderson, R.H., Anderson, J.K. and Bower, P.A., 2012. Co‐occurrence of 1,4‐dioxane with trichloroethylene in chlorinated solvent groundwater plumes at US Air Force installations: Fact or fiction. Integrated Environmental Assessment and Management, 8(4), pp.731-737. [https://doi.org/10.1002/ieam.1306 doi: 10.1002/ieam.1306]</ref>. As 14D was often utilized as an additive to degreasing solvents<ref name="Mohr2010" />, its presence is positively correlated with other [[Chlorinated Solvents | chlorinated organics]] such as TCA, [[wikipedia: Trichloroethylene | trichloroethene]] (TCE), and [[wikipedia: 1,1-Dichloroethene | 1,1-Dichloroethene]] (1,1-DCE)<ref name="Adamson2017a" />.  In one study, TCA and/or TCE were observed in 94% of the monitoring wells with detectable 14D<ref name="Anderson2012" />.
-D has been detected in air, potable water, wastewater and groundwater.  14D was detected in ambient air in several studies<ref>Harkov, R., Katz, R., Bozzelli, J. and Kebbekus, B., 1981. Toxic and carcinogenic air pollutants in New Jersey volatile organic substances. Proceedings of the International Technical Conference of Toxic Air Contaminants, p.245. Pittsburgh, PA: Air Pollution Control Association</ref><ref>Shah, J.J. and Singh, H.B., 1988. Distribution of volatile organic chemicals in outdoor and indoor air: A national VOCs data base. Environmental Science & Technology, 22(12), pp.1381-1388. [https://pubs.acs.org/doi/abs/10.1021/es00177a001 doi: 10.1021/es00177a001]</ref><ref>Keel, L. and A. Franzmann, 2000. Downtown Bellingham air toxics screening project, 1995-1999 staff report. Northwest Air Pollution Authority (NWAPA). [//www.enviro.wiki/images/d/d0/2000-Keel-Downtown_Bellingham_Air_Toxics_Screening_Project.pdf  Report.pdf]</ref>).  In a survey of 4,864 public drinking water systems, 14D was detected in 21% of the systems and exceeded the health-based reference concentration of 0.35 &mu;g/L in 6.9%<ref name="Adamson2017">Adamson, D.T., Piña, E.A., Cartwright, A.E., Rauch, S.R., Anderson, R.H., Mohr, T. and Connor, J.A., 2017. 1, 4-Dioxane drinking water occurrence data from the third unregulated contaminant monitoring rule. Science of the Total Environment, 596, pp.236-245. [https://doi.org/10.1016/j.scitotenv.2017.04.085 doi: 10.1016/j.scitotenv.2017.04.085]</ref>. Municipal wastewater<ref>Abe, A., 1999. Distribution of 1, 4-dioxane in relation to possible sources in the water environment. Science of the Total Environment, 227(1), pp.41-47. [https://doi.org/10.1016/S0048-9697(99)00003-0 doi: 10.1016/S0048-9697(99)00003-0]</ref><ref>Westerhoff, P., Yoon, Y., Snyder, S. and Wert, E., 2005. Fate of endocrine-disruptor, pharmaceutical, and personal care product chemicals during simulated drinking water treatment processes. Environmental Science & Technology, 39(17), pp.6649-6663. [https://doi.org/10.1021/es0484799 doi: 10.1021/es0484799]</ref> and landfill leachates<ref>DeWalle, F.B. and Chian, E.S., 1981. Detection of trace organics in well water near a solid waste landfill. Journal‐American Water Works Association, 73(4), pp.206-211. [https://doi.org/10.1002/j.1551-8833.1981.tb04681.x doi: 10.1002/j.1551-8833.1981.tb04681.x]</ref><ref>Fujiwara, T., Tamada, T., Kurata, Y., Ono, Y., Kose, T., Ono, Y., Nishimura, F. and Ohtoshi, K., 2008. Investigation of 1, 4-dioxane originating from incineration residues produced by incineration of municipal solid waste. Chemosphere, 71(5), pp.894-901. [https://doi.org/10.1016/j.chemosphere.2007.11.011 doi: 10.1016/j.chemosphere.2007.11.011]</ref> also frequently contain 14D.
+A comprehensive evaluation of a large multi-site dataset<ref name="Adamson2017b">Adamson, D., Newell, C., Mahendra, S., Bryant, D. and Wong, M., 2017. In Situ Treatment and Management Strategies for 1,4-Dioxane-Contaminated Groundwater. SERDP Project [[Media:2017Adamson_et_al_ER-2307.pdf | ER-2307]].</ref> found that 14D was detected, when analyzed for, at 52% of sites containing TCE, 70% of sites with 1,1,1-TCA, and 69% of sites with 1,1-DCE. The spatial extent of the 14D plumes typically fell within a similar or smaller footprint than the co-occurring chlorinated solvent plumes.  The more limited migration of 14D, compared to chlorinated solvents, may be due to the timing of the 14D release.  TCE was used at many sites prior to the use of TCA.  As a result, TCE (and its by-products) may have been released before TCA and 14D and could have a “head-start”.  The results were somewhat surprising given the high migration potential of 14D, as explained in the [[Media:14D_Plume_Length.mp4 | video]] shown in Figure 1. The maximum historical dioxane concentrations were below 365 μg/L for half of 194 sites with detectable 14D<ref name="Adamson2014" />. Overall, 14D plumes are generally so dilute that source zones may be difficult to identify.
-In groundwater, 14D is frequently observed as a co-contaminant with TCA<ref name="Adamson2014" /><ref name="Anderson2012">Anderson, R.H., Anderson, J.K. and Bower, P.A., 2012. Co‐occurrence of 1,4‐dioxane with trichloroethylene in chlorinated solvent groundwater plumes at US Air Force installations: Fact or fiction. Integrated Environmental Assessment and Management, 8(4), pp.731-737. [https://doi.org/10.1002/ieam.1306 doi: 10.1002/ieam.1306]</ref>. As 14D was often utilized as an additive to degreasing solvents<ref name="Mohr2010" />, its presence is positively correlated with other [[Chlorinated Solvents | chlorinated organics]] such as TCA, [[wikipedia: Trichloroethylene | trichloroethene]] (TCE), and [[wikipedia: 1,1-Dichloroethene | 1,1-Dichloroethene]] (1,1-DCE)<ref name="Adamson2017" />  TCA and/or TCE were observed in 94% of the monitoring wells with detectable 14D<ref name="Anderson2012" />.  In a review of groundwater results from 194 sites with detectable 14D, the median value of the range of maximal historical dioxane concentrations was 365 μg/L (10th percentile, 9 μg/L; 90th percentile, 13,460 μg/L)<ref name="Adamson2014" />.
+Also, modeling results<ref name="Adamson2017b" /> indicate that matrix diffusion of 14D mass in and out of lower-permeability soils (i.e. silts and clays) can be an important fate and transport process for this compound as discussed in more detail in the [[Media:14D_Matrix_Diffusion.mp4 | video]] shown in Figure 2. The contribution of matrix diffusion processes to 14D concentrations within the source zone and the downgradient plume should be accounted for during site management.
 The common presence of 14D in potable water supplies is a concern because 14D removal is low in many unit processes commonly employed in publicly owned treatment works (POTW) due to the high solubility, low volatility, and relative resistance to biodegradation (see section on physical/chemical treatment).  14D removal was not observed in several physical/chemical water treatment processes including coagulation, oxidation and air stripping processes<ref name="McGuire1978">McGuire, M.J., Suffet, I.H. and Radziul, J.V., 1978. Assessment of unit processes for the removal of trace organic compounds from drinking water. Journal‐American Water Works Association, 70(10), pp.565-572. [https://doi.org/10.1002/j.1551-8833.1978.tb04244.x doi: 10.1002/j.1551-8833.1978.tb04244.x]</ref>.  Activated carbon adsorption is somewhat more successful, with reported removal efficiencies ranging from 50 to 67 percent<ref name="McGuire1978" /><ref>Johns, M.M., Marshall, W.E. and Toles, C.A., 1998. Agricultural by‐products as granular activated carbons for adsorbing dissolved metals and organics. Journal of Chemical Technology & Biotechnology: International Research in Process, Environmental and Clean Technology, 71(2), pp.131-140. [https://doi.org/10.1002/(SICI)1097-4660(199802)71:2 <131::AID-JCTB821>3.0.CO;2-K doi: 10.1002/(SICI)1097-4660(199802)71:2<131::AID-JCTB821>3.0.CO;2-K]</ref>. Stepien<ref name="Stepien2014" /> reported that 14D removal was not observed in four domestic wastewater treatment plants in Germany.  In a study of North Carolina water treatment facilities, 14D removal was not observed at two of the facilities, but was reduced by 65% at a third which employed ozonation of raw and settled water<ref name="Knappe2016" />.
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 Air stripping is generally not effective for removing 14D from contaminated water due its low [[wikipedia: Henry’s law | Henry’s Law]] constant.  While 14D can be removed from water by sorption to granular activated carbon (GAC), sorption capacities are low resulting in high capital and operating costs<ref name="Woodard2014">Woodard, S., Mohr, T. and Nickelsen, M.G., 2014. Synthetic Media: A Promising New Treatment Technology for 1, 4‐Dioxane. Remediation Journal, 24(4), pp.27-40. [https://doi.org/10.1002/rem.21402 doi:10.1002/rem.21402]</ref>. In contrast, polymeric sorbents (e.g. Ambersorb<sup>TM</sup> 560) are reported to have 5 to 10 times the sorption capacity of GAC, making sorption a more attractive alternative, though with additional operational requirements of adsorbent regeneration and proper disposal of spent waste<ref name="Woodard2014" />. While 14D can be degraded by high energy UV radiation in high purity water<ref>Hentz, R.R. and Parrish, C.F., 1971. Photolysis of gaseous 1, 4-dioxane at 1470 Ang. The Journal of Physical Chemistry, 75(25), pp.3899-3901. [https://doi.org/10.1021/j100694a023 doi: 10.1021/j100694a023]</ref>, direct ultraviolet photolysis is not economically viable due to operational challenges and high costs<ref name="Mohr2010" />.
-Advanced oxidation processes (AOPs) using combinations of ozone (O<sub>3</sub>), hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and ultraviolet (UV) radiation produce highly reactive hydroxyl radicals (•OH) which are effective in destroying 14D.  In the peroxone process (O<sub>3,</sub> + H<sub>2,</sub>O<sub>2</sub>), O<sub>3</sub> reacts with H<sub>2</sub>O<sub>2</sub> giving rise to hydroxyl radicals<ref>Fleming, E.C., Zappi, M.E., Toro, E., Hernandez, R., Myers, K., Kodukula, P. and Gilbertson, R., 1997. Laboratory assessment of advanced oxidation processes for treatment of explosives and chlorinated solvents in groundwater from the former Nebraska Ordnance Plant. Technical Report SERDP-97-3 [//www.enviro.wiki/images/b/b5/1997-Fleming-Laboratory_assessment_of_advanced_oxidation_process.pdf  Report.pdf]</ref>.  In a variation of this approach ([http://aptwater.com/hipox/technology/overview-advanced-oxidation-process-for-water-treatment/ HiPOx™ process]), H<sub>2</sub>O<sub>2</sub> is added first followed by high pressure O<sub>3</sub><ref>Bowman, R.H., Lahey, T. and Herlihy, P., Applied Process Tech Inc, 2007. System and method for remediating contaminated soil and groundwater in situ. U.S. Patent 7,264,419. [//www.enviro.wiki/images/6/61/2007-Bowman-System_and_method_fo_remediating_contaminated_soil_and_groundwater.pdf  Report	.pdf]</ref>.  Hydroxyl radicals are produced in UV + H<sub>2</sub>O<sub>2</sub> systems by direct photolysis of H<sub>2</sub>O<sub>2</sub> caused by absorption of energy from an ultraviolet lamp<ref>Omura, K. and Matsuura, T., 1968. Photo-induced reactions—IX: The hydroxylation of phenols by the photo-decomposition of hydrogen peroxide in aqueous media. Tetrahedron, 24(8), pp.3475-3487. [https://doi.org/10.1016/S0040-4020(01)92645-6 doi: 10.1016/S0040-4020(01)92645-6]</ref><ref>Stefan, M.I. and Bolton, J.R., 1998. Mechanism of the degradation of 1, 4-dioxane in dilute aqueous solution using the UV/hydrogen peroxide process. Environmental Science & Technology, 32(11), pp.1588-1595. [https://doi.org/10.1021/es970633m doi: 10.1021/es970633m]</ref>.
+Advanced oxidation processes (AOPs) using combinations of ozone (O<sub>3</sub>), hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and ultraviolet (UV) radiation produce highly reactive [[wikipedia: Hydroxyl radical | hydroxyl radicals]] (•OH) which are effective in destroying 14D.  In the peroxone process (O<sub>3</sub> + H<sub>2</sub>O<sub>2</sub>), O<sub>3</sub> reacts with H<sub>2</sub>O<sub>2</sub> giving rise to hydroxyl radicals<ref>Fleming, E.C., Zappi, M.E., Toro, E., Hernandez, R., Myers, K., Kodukula, P. and Gilbertson, R., 1997. Laboratory assessment of advanced oxidation processes for treatment of explosives and chlorinated solvents in groundwater from the former Nebraska Ordnance Plant. Technical Report SERDP-97-3 [//www.enviro.wiki/images/b/b5/1997-Fleming-Laboratory_assessment_of_advanced_oxidation_process.pdf Report.pdf]</ref>.  In a variation of this approach ([http://aptwater.com/hipox/technology/overview-advanced-oxidation-process-for-water-treatment/ HiPOx™ process]), H<sub>2</sub>O<sub>2</sub> is added first followed by high pressure O<sub>3</sub><ref>Bowman, R.H., Lahey, T. and Herlihy, P., Applied Process Tech Inc, 2007. System and method for remediating contaminated soil and groundwater in situ. U.S. Patent 7,264,419. [//www.enviro.wiki/images/6/61/2007-Bowman-System_and_method_fo_remediating_contaminated_soil_and_groundwater.pdf Report.pdf]</ref>.  Hydroxyl radicals are produced in UV + H<sub>2</sub>O<sub>2</sub> systems by direct photolysis of H<sub>2</sub>O<sub>2</sub> caused by absorption of energy from an ultraviolet lamp<ref>Omura, K. and Matsuura, T., 1968. Photo-induced reactions—IX: The hydroxylation of phenols by the photo-decomposition of hydrogen peroxide in aqueous media. Tetrahedron, 24(8), pp.3475-3487. [https://doi.org/10.1016/S0040-4020(01)92645-6 doi: 10.1016/S0040-4020(01)92645-6]</ref><ref>Stefan, M.I. and Bolton, J.R., 1998. Mechanism of the degradation of 1, 4-dioxane in dilute aqueous solution using the UV/hydrogen peroxide process. Environmental Science & Technology, 32(11), pp.1588-1595. [https://doi.org/10.1021/es970633m doi: 10.1021/es970633m]</ref>.
 AOPs are commonly employed for 14D treatment because of their high removal efficiencies with low contact times<ref name="Mohr2010" /><ref name="Ikehata">Ikehata, K., Jodeiri Naghashkar, N. and Gamal El-Din, M., 2006. Degradation of aqueous pharmaceuticals by ozonation and advanced oxidation processes: a review. Ozone: Science and Engineering, 28(6), pp.353-414. [https://doi.org/10.1080/01919510600985937 doi: 10.1080/01919510600985937]</ref>.  The degradation mechanisms and kinetics of these processes are well understood, with multiple systems in current use<ref name="Mohr2010" />.  All of these systems are effective in destroying 14D, but have some limitations including the potential for bromate formation (when Br is present), reduced efficiency in the presence of free radical scavengers (e.g. HCO<sub>3</sub>) and high capital and operating costs associated with energy and chemical consumption<ref name="Mohr2010" /><ref>Woodward, C., Shulmeister, J., Larsen, J., Jacobsen, G.E. and Zawadzki, A., 2014. The hydrological legacy of deforestation on global wetlands. Science, 346(6211), pp.844-847. [https://doi.org/10.1126/science.1260510 doi: 10.1126/science.1260510]</ref>.
-Biological wastewater treatment has not been widely applied for 14D removal.  While high concentrations of 14D will support growth of 14D degraders<ref>Sock, S.M., 1993. A comprehensive evaluation of biodegradation as a treatment alternative for the removal of 1, 4-dioxane (Doctoral dissertation, Clemson University)</ref> growth rates on 14D are slow<ref name="Grady1997" /><ref name="Parales1994" /><ref>Roy, D., Anagnostu, G. and Chaphalkar, P., 1994. Biodegradation of dioxane and diglyme in industrial waste. Journal of Environmental Science & Health Part A, 29(1), pp.129-147. [https://doi.org/10.1080/10934529409376026 doi: 10.1080/10934529409376026]</ref><ref>Bernhardt, D. and Diekmann, H., 1991. Degradation of dioxane, tetrahydrofuran and other cyclic ethers by an environmental Rhodococcus strain. Applied Microbiology and Biotechnology, 36(1), pp.120-123. [https://doi.org/10.1007/bf00164711 doi: 10.1007/BF00164711]</ref>, and the low 14D concentrations in many systems are not sufficient to maintain an adequate level of 14D degraders for effective treatment.  To overcome this problem, 14D degrading biomass was supported by addition of tetrahydrofuran (THF) to a continuously fed trickling filter for over 1 year.  The system was effective in reducing 14D concentrations by 93–97% while influent 14D concentrations were varied from 200 to 1,200 µg/L<ref>Zenker, M.J., Borden, R.C. and Barlaz, M.A., 2003. Occurrence and treatment of 1, 4-dioxane in aqueous environments. Environmental Engineering Science, 20(5), pp.423-432. [https://doi.org/10.1089/109287503768335913 doi: 10.1089/109287503768335913]</ref>.  This basic approach was applied to full-scale treatment of leachate from the Lowry Landfill Superfund site where both THF and 14D were present as co-contaminants<ref>Shangraw, T. and Plaehn, W.  2012. Full-scale treatment of 1,4-dioxane using a bioreactor. Federal Remediation Technologies Roundtable Meeting. [//www.enviro.wiki/images/9/98/2012-Shangraw-Full-scale_Treatment_of_1%2C4-dioxane.pdf  Report.pdf]</ref>.
+Biological wastewater treatment has not been widely applied for 14D removal.  While high concentrations of 14D will support growth of 14D degraders<ref>Sock, S.M., 1993. A comprehensive evaluation of biodegradation as a treatment alternative for the removal of 1, 4-dioxane (Doctoral dissertation, Clemson University)</ref> growth rates on 14D are slow<ref name="Grady1997" /><ref name="Parales1994" /><ref>Roy, D., Anagnostu, G. and Chaphalkar, P., 1994. Biodegradation of dioxane and diglyme in industrial waste. Journal of Environmental Science & Health Part A, 29(1), pp.129-147. [https://doi.org/10.1080/10934529409376026 doi: 10.1080/10934529409376026]</ref><ref>Bernhardt, D. and Diekmann, H., 1991. Degradation of dioxane, tetrahydrofuran and other cyclic ethers by an environmental Rhodococcus strain. Applied Microbiology and Biotechnology, 36(1), pp.120-123. [https://doi.org/10.1007/bf00164711 doi: 10.1007/BF00164711]</ref>, and the low 14D concentrations in many systems are not sufficient to maintain an adequate level of 14D degraders for effective treatment.  To overcome this problem, 14D degrading biomass was supported by addition of tetrahydrofuran (THF) to a continuously fed trickling filter for over one year.  The system was effective in reducing 14D concentrations by 93–97% while influent 14D concentrations were varied from 200 to 1,200 µg/L<ref>Zenker, M.J., Borden, R.C. and Barlaz, M.A., 2003. Occurrence and treatment of 1, 4-dioxane in aqueous environments. Environmental Engineering Science, 20(5), pp.423-432. [https://doi.org/10.1089/109287503768335913 doi: 10.1089/109287503768335913]</ref>.  This basic approach was applied to full-scale treatment of leachate from the Lowry Landfill Superfund site where both THF and 14D were present as co-contaminants<ref>Shangraw, T. and Plaehn, W.  2012. Full-scale treatment of 1,4-dioxane using a bioreactor. Federal Remediation Technologies Roundtable Meeting. [//www.enviro.wiki/images/9/98/2012-Shangraw-Full-scale_Treatment_of_1%2C4-dioxane.pdf Report.pdf]</ref>.
 ==''In-Situ'' Treatment==
-A variety of methods have been attempted for ''in situ'' treatment of 14D impacted soil and groundwater including [https://enviro.wiki/index.php?title=Chemical_Oxidation_(In_Situ_-_ISCO) in situ chemical oxidation (ISCO)], thermally enhanced soil vapor extraction, bioremediation, phytoremediation, and [https://enviro.wiki/index.php?title=Monitored_Natural_Attenuation_(MNA) monitored natural attenuation (MNA)].
+A variety of methods have been attempted for ''in situ'' treatment of 14D impacted soil and groundwater including [[Chemical Oxidation (In Situ - ISCO) | ''in situ'' chemical oxidation (ISCO)]], thermally enhanced [[Soil Vapor Extraction (SVE) | soil vapor extraction]], bioremediation, phytoremediation, and [[Monitored Natural Attenuation (MNA) | monitored natural attenuation (MNA)]].
-ISCO can be used to degrade 14D in source areas with a variety of oxidants including permanganate<ref>Waldemer, R.H. and Tratnyek, P.G., 2006. Kinetics of contaminant degradation by permanganate. Environmental Science & Technology, 40(3), pp.1055-1061. [https://doi.org/10.1021/es051330s doi: https://doi.org/10.1021/es051330s]</ref>, persulfate<ref>Félix-Navarro, R.M., Lin-Ho, S.W., Barrera-Díaz, N. and Pérez-Sicairos, S., 2007. Kinetics of the degradation of 1, 4-dioxane using persulfate. Journal of the Mexican Chemical Society, 51(2), pp.67-71. ISSN 1870-249X</ref>, Fenton’s reagent<ref>Kiker, J.H., Connolly, J.B., Murray, W.A., Pearson, S.C.P., Reed, S.E.R. and Tess, R.J., 2010. Ex-situ wellhead treatment of 1, 4-dioxane using fenton's reagent. In Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy (Vol. 15, No. 1, p. 18).</ref> and ozone<ref name="Ikehata" />.  However, ISCO treatment of 14D in source areas is not common because much of the mass is in the downgradient plume.  Dilute plumes can potentially be treated using cylinders placed in wells that slowly release oxidant over time.  In a field demonstration, a system of slow release persulfate cylinders was effective in reducing 14D and chlorinated solvent concentrations by over 99% for 119 days<ref>Evans, P., Hooper, J., Lamar, M., Nguyen, D., Dugan, P., Crimi, M. and Ruiz, N., 2018. Sustained In situ Chemical Oxidation (ISCO) of 1, 4 Dioxane and Chlorinated VOCs Using Slow release Chemical Oxidant Cylinders. ESTCP Cost and Performance Report, ER-201324. [//www.enviro.wiki/images/7/7e/2018-Evans-ER-201324_Cost_%26_Performance_Report.pdf  Report.pdf]</ref>.
+ISCO can be used to degrade 14D in source areas with a variety of oxidants including [[wikipedia: Permanganate | permanganate]]<ref>Waldemer, R.H. and Tratnyek, P.G., 2006. Kinetics of contaminant degradation by permanganate. Environmental Science & Technology, 40(3), pp.1055-1061. [https://doi.org/10.1021/es051330s doi: https://doi.org/10.1021/es051330s]</ref>, [[wikipedia: Persulfate | persulfate]]<ref>Félix-Navarro, R.M., Lin-Ho, S.W., Barrera-Díaz, N. and Pérez-Sicairos, S., 2007. Kinetics of the degradation of 1, 4-dioxane using persulfate. Journal of the Mexican Chemical Society, 51(2), pp.67-71. ISSN 1870-249X</ref>, [[wikipedia: Fenton’s reagent | Fenton’s reagent]]<ref>Kiker, J.H., Connolly, J.B., Murray, W.A., Pearson, S.C.P., Reed, S.E.R. and Tess, R.J., 2010. Ex-situ wellhead treatment of 1, 4-dioxane using fenton's reagent. In Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy (Vol. 15, No. 1, p. 18).</ref> and ozone<ref name="Ikehata" />.  However, ISCO treatment of 14D in source areas is not common because much of the mass is in the downgradient plume.  Dilute plumes can potentially be treated using cylinders placed in wells that slowly release oxidant over time.  In a field demonstration, a system of slow release persulfate cylinders was effective in reducing 14D and chlorinated solvent concentrations by over 99% for 119 days<ref>Evans, P., Hooper, J., Lamar, M., Nguyen, D., Dugan, P., Crimi, M. and Ruiz, N., 2018. Sustained In situ Chemical Oxidation (ISCO) of 1, 4 Dioxane and Chlorinated VOCs Using Slow release Chemical Oxidant Cylinders. ESTCP Cost and Performance Report, ER-201324. [//www.enviro.wiki/images/7/7e/2018-Evans-ER-201324_Cost_%26_Performance_Report.pdf Report.pdf]</ref>.
-Thermal remediation of source areas is not frequently utilized for 14D remediation because much of the 14D mass is in the dissolved plume.  However, when applied to treat a source area, thermal remediation can be effective.  Following electrical resistive heating of a chlorinated solvent source area, 14D levels in groundwater were reduced >99%<ref>Oberle, D., Crownover, E. and Kluger, M., 2015. In situ remediation of 1, 4‐dioxane using electrical resistance heating. Remediation Journal, 25(2), pp.35-42. [https://doi.org/10.1002/rem.21422 doi: 10.1002/rem.21422]</ref>.  14D source areas can also be treated using a combination of heated air injection and focused air extraction from areas with elevated 14D concentrations.  In a field demonstration, thermally enhanced [https://enviro.wiki/index.php?title=Soil_Vapor_Extraction_(SVE) soil vapor extraction] reduced 14D levels by 94%<ref>Hinchee, R.E., P.C. Johnson, P.R. Dahlen, and D.R. Durris, 2017. 1,4-Dioxane remediation by extreme soil vapor extraction (XSVE). Final Report ESTCP Project 201326 [//www.enviro.wiki/images/9/99/2017-Hinchee-1.4_Dioxane_remediation_by_extreme_soil_XSVE_ER-201326_Final_Report.pdf  Report.pdf]</ref><ref>Hinchee, R.E., Dahlen, P.R., Johnson, P.C. and Burris, D.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction: I. Field Demonstration. Groundwater Monitoring & Remediation, 38(2), pp.40-48. [https://doi.org/10.1111/gwmr.12264 doi: doi.org/10.1111/gwmr.12264]</ref>.  Modeling results indicate that removal increases with increasing air injection temperature and relative humidity and decreases with initial soil moisture content<ref>Burris, D.R., Johnson, P.C., Hinchee, R.E. and Dahlen, P.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction (XSVE): II. Modeling. Groundwater Monitoring & Remediation, 38(2), pp.49-56. [https://doi.org/10.1111/gwmr.12277 doi: 10.1111/gwmr.12277]</ref>.
+[[Thermal Remediation | Thermal remediation]] of source areas is not frequently utilized for 14D remediation because much of the 14D mass is in the dissolved plume.  However, when applied to treat a source area, thermal remediation can be effective.  Following electrical resistive heating of a chlorinated solvent source area, 14D levels in groundwater were reduced by >99%<ref>Oberle, D., Crownover, E. and Kluger, M., 2015. In situ remediation of 1, 4‐dioxane using electrical resistance heating. Remediation Journal, 25(2), pp.35-42. [https://doi.org/10.1002/rem.21422 doi: 10.1002/rem.21422]</ref>.  14D source areas can also be treated using a combination of heated air injection and focused air extraction from areas with elevated 14D concentrations.  In a field demonstration, thermally enhanced [[Soil Vapor Extraction (SVE) | soil vapor extraction]] reduced 14D levels by 94%<ref>Hinchee, R.E., P.C. Johnson, P.R. Dahlen, and D.R. Durris, 2017. 1,4-Dioxane remediation by extreme soil vapor extraction (XSVE). Final Report ESTCP Project 201326 [//www.enviro.wiki/images/9/99/2017-Hinchee-1.4_Dioxane_remediation_by_extreme_soil_XSVE_ER-201326_Final_Report.pdf Report.pdf]</ref><ref>Hinchee, R.E., Dahlen, P.R., Johnson, P.C. and Burris, D.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction: I. Field Demonstration. Groundwater Monitoring & Remediation, 38(2), pp.40-48. [https://doi.org/10.1111/gwmr.12264 doi: doi.org/10.1111/gwmr.12264]</ref>.  Modeling results indicate that removal increases with increasing air injection temperature and relative humidity and decreases with initial soil moisture content<ref>Burris, D.R., Johnson, P.C., Hinchee, R.E. and Dahlen, P.R., 2018. 1, 4‐Dioxane Soil Remediation Using Enhanced Soil Vapor Extraction (XSVE): II. Modeling. Groundwater Monitoring & Remediation, 38(2), pp.49-56. [https://doi.org/10.1111/gwmr.12277 doi: 10.1111/gwmr.12277]</ref>.
-''In situ'' bioremediation has not been commonly applied to 14D treatment due to the slow growth of bacteria using 14D as a growth substrate (see [Biodegradation – 1,4-Dioxane]).  However, there has been some success in stimulating cometabolic biodegradation of 14D using gaseous substrates.  In a biosparging pilot test, air amended with propane was injected into a single well that was bioaugmented with the propanotroph ''Rhodococcus ruber'' ENV425.  14D levels decreased by >99% in the sparge well and two nearby monitor wells<ref name="Lippincott2015" />. A propane-stimulated groundwater recirculation system has also recently been reported to effectively reduce concentrations of 14D as well as several chlorinated aliphatics such as TCE and 1,2-dichloroethane<ref name="Chu2018" />.
+''In situ'' bioremediation has not been commonly applied to 14D treatment due to the slow growth of bacteria using 14D as a growth substrate.  However, there has been some success in stimulating cometabolic biodegradation of 14D using gaseous substrates.  In a biosparging pilot test, air amended with propane was injected into a single well that was bioaugmented with the propanotroph [[wikipedia: Rhodococcus | ''Rhodococcus ruber'']] ENV425.  14D levels decreased by >99% in the sparge well and two nearby monitoring wells<ref name="Lippincott2015" />. A propane-stimulated groundwater recirculation system has also recently been reported to effectively reduce concentrations of 14D as well as several chlorinated aliphatics such as TCE and 1,2-dichloroethane<ref name="Chu2018" />.
 Phytoremediation has been reported as a viable treatment alternative for 14D<ref>Aitchison, E.W., Kelley, S.L., Alvarez, P.J. and Schnoor, J.L., 2000. Phytoremediation of 1, 4-dioxane by hybrid poplar trees. Water Environment Research, 72(3), pp.313-321. [https://doi.org/10.2175/106143000X137536 doi: 10.2175/106143000X137536]</ref>.  The primary removal process is via phytovolatilization, which involves transpiration of chemicals from the leaf surfaces to the atmosphere<ref>Ouyang, Y., 2002. Phytoremediation: modeling plant uptake and contaminant transport in the soil–plant–atmosphere continuum. Journal of Hydrology, 266(1-2), pp.66-82. [https://doi.org/10.2175/106143000X137536 doi: 10.2175/106143000X137536]</ref>. Addition of 14D degrading bacteria (e.g. CB1190) and appropriate co-substrates can further enhance the removal of 14D in soil planted with poplar trees<ref>Kelley, S.L., Aitchison, E.W., Deshpande, M., Schnoor, J.L. and Alvarez, P.J., 2001. Biodegradation of 1, 4-dioxane in planted and unplanted soil: effect of bioaugmentation with Amycolata sp. CB1190. Water Research, 35(16), pp.3791-3800. [https://doi.org/10.1016/S0043-1354(01)00129-4 doi: 10.1016/S0043-1354(01)00129-4]</ref>.
-Early microcosm studies indicated that 14D did not degrade in the presence of impacted aquifer material under ''in situ'' conditions<ref name="Zenker 2000" />. However, a statistical analysis of multiple Air Force and California sites found evidence of 14D removal in 19% of the sites<ref name="Adamson2015">Adamson, D.T., Anderson, R.H., Mahendra, S. and Newell, C.J., 2015. Evidence of 1, 4-dioxane attenuation at groundwater sites contaminated with chlorinated solvents and 1, 4-dioxane. Environmental Science & Sechnology, 49(11), pp.6510-6518.[ https://doi.org/10.1021/acs.est.5b00964 doi:10.1021/acs.est.5b00964]</ref>, similar to other chlorinated VOCs (TCE and 1,1-DCE).  The decay rates were positively correlated to dissolved oxygen, and negatively correlated to high metals and chlorinated VOC concentrations<ref name="Adamson2015" />.  14D decay has also been positively correlated to the presence of oxidizing enzymes<ref name="Li2013">Li, M., Mathieu, J., Yang, Y., Fiorenza, S., Deng, Y., He, Z., Zhou, J. and Alvarez, P.J., 2013. Widespread distribution of soluble di-iron monooxygenase (SDIMO) genes in arctic groundwater impacted by 1, 4-dioxane. Environmental science & technology, 47(17), pp.9950-9958. [https://doi.org/10.1021/es402228x doi: 10.1021/es402228x]</ref><ref>Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. [https://doi.org/10.1128/aem.04162-13 doi: 10.1128/AEM.04162-13]</ref>. Native 14D degrading microorganisms have also been detected in field studies using a number of environmental diagnostic assays, such as microarray<ref name="Li2013" /> and stable isotope probing<ref>Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. [https://doi.org/10.1039/c2em30358b doi: 10.1039/C2EM30358B]</ref><ref>Li, M., Liu, Y., He, Y., Mathieu, J., Hatton, J., DiGuiseppi, W. and Alvarez, P.J., 2017. Hindrance of 1, 4-dioxane biodegradation in microcosms biostimulated with inducing or non-inducing auxiliary substrates. Water Research, 112, pp.217-225. [http://dx.doi.org/10.1016/j.watres.2017.01.047 doi: 10.1016/j.watres.2017.01.047]</ref>, suggesting that monitored natural attenuation (MNA) may be a feasible and cost-efficient alternative to mitigate 14D at some sites.
+Early microcosm studies indicated that 14D did not degrade in the presence of impacted aquifer material under ''in situ'' conditions<ref name="Zenker 2000" />. However, a statistical analysis of multiple Air Force and California sites found evidence of 14D removal in 19% of the sites<ref name="Adamson2015">Adamson, D.T., Anderson, R.H., Mahendra, S. and Newell, C.J., 2015. Evidence of 1, 4-dioxane attenuation at groundwater sites contaminated with chlorinated solvents and 1, 4-dioxane. Environmental Science & Sechnology, 49(11), pp.6510-6518.[ https://doi.org/10.1021/acs.est.5b00964 doi:10.1021/acs.est.5b00964]</ref>, similar to other chlorinated VOCs (TCE and 1,1-DCE).  The decay rates were positively correlated to dissolved oxygen, and negatively correlated to high metals and chlorinated VOC concentrations<ref name="Adamson2015" />.  14D decay has also been positively correlated to the presence of oxidizing enzymes<ref name="Li2013">Li, M., Mathieu, J., Yang, Y., Fiorenza, S., Deng, Y., He, Z., Zhou, J. and Alvarez, P.J., 2013. Widespread distribution of soluble di-iron monooxygenase (SDIMO) genes in arctic groundwater impacted by 1, 4-dioxane. Environmental science & technology, 47(17), pp.9950-9958. [https://doi.org/10.1021/es402228x doi: 10.1021/es402228x]</ref><ref>Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. [https://doi.org/10.1128/aem.04162-13 doi: 10.1128/AEM.04162-13]</ref>. Native 14D degrading microorganisms have also been detected in field studies using a number of environmental diagnostic assays, such as [[wikipedia: Microarray | microarray]]<ref name="Li2013" /> and [[Stable Isotope Probing (SIP) | stable isotope probing]]<ref>Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. [https://doi.org/10.1039/c2em30358b doi: 10.1039/C2EM30358B]</ref><ref>Li, M., Liu, Y., He, Y., Mathieu, J., Hatton, J., DiGuiseppi, W. and Alvarez, P.J., 2017. Hindrance of 1, 4-dioxane biodegradation in microcosms biostimulated with inducing or non-inducing auxiliary substrates. Water Research, 112, pp.217-225. [http://dx.doi.org/10.1016/j.watres.2017.01.047 doi: 10.1016/j.watres.2017.01.047]</ref>, suggesting that monitored natural attenuation (MNA) may be a feasible and cost-efficient alternative to mitigate 14D at some sites.
 ==References==
@@ Line 94: / Line 96: @@
 ==See Also==
+*[https://www.youtube.com/watch?v=y9hIBss4E5c&t=2s 1,4-Dioxane: Do We Have the Right Conceptual Site Model for Managing Contaminated Groundwater Sites?]
+*[https://clu-in.org/contaminantfocus/default.focus/sec/1,4-Dioxane/cat/Overview/ CLU-IN: 1,4-Dioxane]
+*[[wikipedia: 1,4-Dioxane | Wikipedia: 1,4-Dioxane]]

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