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Pesticides can migrate into the water supply through agricultural runoff.

 

 

Pharmaceuticals and personal care products, untreated at wastewater plants, can become environmental contaminants.

 

 

 

 


 

Industrial chemicals enter the water supply through a variety of pathways.

 

 

 

 

 

 


 

The UV-photolysis reaction

 

 

 


 

The UV-oxidation reaction

 

What are Environmental Contaminants?

The term “environmental contaminant” refers to harmful chemicals present in soil, in air, and in water. Trojan Technologies focuses on those present in water. Environmental contaminants may come directly from human activities such as industrial manufacturing, agriculture, and wastewater discharge; or they may originate from natural sources, such as the taste and odor-causing chemicals generated by algae blooms. Regardless of the source, environmental contamination is on the increase, and the health risks posed to humans is also growing. For example:

  • Researchers have attributed decreases in human sperm quality and quantity as well as significant increases in cancer rates to non-natural chemical compounds in the environment (1,2).
  • A recent United States Geological Survey (USGS) study of water quality in streams and rivers across the United States detected a wide variety of chemicals, including industrial solvents, pesticides, antibiotics, non-prescription drugs, fire retardants and insect repellants (3).
  • A study in Germany detected the presence of pharmaceuticals including diclofenac (a widely used anti-inflammatory drug) and clofibric acid in tap water (4). 
  • Another study detected other pharmaceuticals, including carbamazepine and gemfibrozil, in the tap water of a number of cities in Canada. 
  • Studies have linked low concentrations (0.1 parts per billion [ppb]) of atrazine, the most widely used pesticide in the United States, to developmental deformities in frogs, including the development of multiple sex organs and small, feminized larynxes (5). 
  • Atrazine can be found in the remotest parts of the world: high concentrations of atrazine have been detected in the Canadian Arctic, well away from its point of use.  
  • In another study of pesticides in the water supply, frogs exposed to the widely used pesticide, malathion, experienced a near total collapse of their immune systems, with antibody production as little as 1% to 2% of normal (6).
  • Disinfection by-product (DBP) chemicals, including N-nitrosodimethylamine (NDMA), trihalomethanes (THMs) and haloacetic acids (HAAs), are formed from naturally occurring substances during chlorination or chloramination. Studies show that exposure to certain DBPs can cause cancer, increase the risk of miscarriage in women, and adversely affect the brain, eyes and testes (7).  
  • Bromate is another DBP that is formed from the reaction of ozone with naturally occurring bromide.  Bromate is considered by the USEPA to be carcinogenic at a concentration of 0.05 ppb (8).
  • 87,000: The number of chemicals slated for screening for endocrine-disrupting effects by the USEPA’s Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC).

 

UV Treatment: An Affordable, Proven Solution

UV disinfection has been used, successfully, over the last century to disinfect municipal drinking water and wastewater. The same technology is now being applied to destroy chemical contaminants. As a treatment and disinfection method, UV offers significant advantages over traditional technologies:
  • UV, alone or in conjunction with hydrogen peroxide, can act as a barrier to organic contaminants in water.
  • UV systems cost less, and are easier to install and maintain than other treatment technologies such as ozone or membranes.
  • UV simultaneously provides superior disinfection of microorganisms while destroying toxic chemical contaminants in the water.
  • UV-oxidation does not result in bromate in treated water.
  • TrojanUV solutions are capable of cost-effectively treating a variety of chemicals such as NDMA, 1,4-dioxane, endocrine-disrupting chemicals and pesticides.

 

How Does UV Work?

TrojanUV solutions use a series of specialized lamps that efficiently produce UVC-range (germicidal) wavelengths of ultraviolet light. As incoming water flows past these lamps, UV (alone or in conjunction with hydrogen peroxide) breaks down toxic chemical contaminants while simultaneously exposing microorganisms to a sterilizing dose of UV energy.

 

UV-Photolysis

UV-photolysis is the process by which chemical bonds of the contaminants are broken by the energy associated with UV light. When light is incident on an object, the photons may be reflected, transmitted, or absorbed. When UV photons enter a medium (water, for example), they are both transmitted and absorbed by the medium and its constituents (dissolved species including organic and inorganic substances). Photons that are absorbed may initiate a photolysis reaction. In other words, the treatment of a contaminant starts with energy (in the form of photons from a UV light source) being absorbed by a contaminant molecule. A contaminant molecule will undergo the photolysis reaction if:
  • The contaminant molecules in water are capable of absorbing UV photons
  • The energy holding the chemical bonds in the molecule together is less than the energy of the UV photons absorbed.

In other words, the treatment of a contaminant starts with energy (in the form of photons from a UV light source) being absorbed by a contaminant molecule.

 

UV-Oxidation

UV-oxidation is performed using UV light in conjuction with hydrogen peroxide (or other oxidant). It is a photochemical process that breaks down organic constituents in water by the process of oxidation. The UV-oxidation reaction is initiated by the photolysis of hydrogen peroxide. When UV photons are absorbed by hydrogen peroxide dissolved in water, hydroxyl radicals are formed. Hydroxyl radicals are highly reactive chemical species that then attack the contaminant molecule, breaking it into its component forms. The UV/hydrogen peroxide process, or UV-oxidation, is one of the most efficient processes in a larger group of processes known as advanced oxidation processes. Next to flourine (a poisonous, corrosive and malodorous gas), the hydroxyl radical is one of the most reactive species known.
  • Trojan’s UV-oxidation systems rely on the in situ generation of hydroxyl radicals by way of the UV-photolysis of hydrogen peroxide. 
  • Exposure of hydrogen peroxide to UV light leads to the scission of the hydrogen peroxide molecule into two hydroxyl radicals.
  • Once generated, these radicals react unselectively with the target contaminant as well as with other species in the water. The rate of these reactions is described by a second order rate constant specific to each reaction. 
  • This UV-oxidation process augments any direct photolysis of the contaminant and, in most cases, has the effect of increasing the degradation rate of the contaminant. Many contaminants cannot be photolyzed, directly. The destruction of such contaminants depends on UV-oxidation.

 

Trojan UV Solutions – Putting Science into Practice

Trojan has devoted significant resources exclusively to providing environmental contaminant treatment solutions. In California, where water is especially scarce, more and more water providers have sought the assistance of Trojan to help them make the most of available water supplies. Using cost-effective UV systems, Trojan is addressing their specific requirements for the treatment of chemicals such as NDMA, 1,4-dioxane, pesticides, and pharmaceuticals in water re-use and drinking water treatment facilities.

TrojanUV offers two environmental contaminant treatment solutions, the TrojanUVPhox™ and the TrojanUVSwift™ECT. The TrojanUVPhox™ is an amalgam, monochromatic UV lamp-based reactor, while the TrojanUVSwift™ECT is a medium-pressure, polychromatic lamp-based reactor. Both are modular for increased flexibility and can be packaged with hydrogen peroxide delivery systems for turnkey, UV-oxidation solutions.

For more information about TrojanUV Solutions for ECT, please contact Christian Williamson, Ph.D. at cwilliamson@trojanuv.com.

 

  1. Carlsen, E., Giwercman, A., Keiding, N., and Skakkebaek, N. E.  1995.  Declining Sperm quality and
     increasing incidence of testicular cancer: Is there a common cause?  Environmental Health
     Perspectives 130.  Pgs. 137-139.

  2. EPA.  1997.  Special report on environmental endocrine disruption: an effects assessment and analysis. Office of Research and Development.  Washington, D.C.  February, 1997.  EPA/630/R-96/012.

  3. Kolpin, D. W., E. T. Furlong, M. T. Meyer, E. M. Thurman, E. D. Zuagg, L. B. Barber, and H. T. Buxton. Pharmaceuticals, Hormones, and other organic wastewater contaminants in U.S. Streams, 1999-2000: a national reconnaissance. 2002. Environmental Science and Technology. Vol. 36, No. 6. Pgs. 1202-1211.

  4. Heberer, T., K. Schmidt-Baumler, H.-J. Stan.  1998. Occurrence and distribution of organic contaminants in Berlin surface and ground water. Acta Hydrochim Hydrobiol. 26(5). Pgs 272-278.

  5. Hayes, T., A. Collins, M. Lee, M. Mendoza, N. Noriega, A. Stuart, and A. Vonk. 2002. Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at ecologically relevant doses. Proc. of Nat. Acad. Of Sci. (U.S.) 99: 5476-5480

  6. Mittelstaedt, M. 2002. Study finds DDT may spur disease. The Globe and Mail, April 24, 2002.

  7. Swan, S. H., K. Waller, B. Hopkins. A prospective study of spontaneous abortion: relation to amount and source of drinking water consumed in early pregnancy. Epidemiology (1998) No. 9. Pgs 126-133.

  8. EPA, 2001. Toxicological Review of Bromate. EPA/635/R-01/002. March, 2001.

 
 
     
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