About UV Advanced Oxidation

The UV advanced oxidation process – also known as UV AOP – is when ultraviolet light, in combination with an oxidant, destroys environmental contaminants in water. Environmental contaminants are harmful chemicals that may come directly from human sources such as industrial manufacturing, agricultural run-off, or wastewater discharge, or they may originate from natural sources, such as the taste- and odor-causing chemicals generated by algae and bacteria blooms.

Remediation of Groundwater and Surface Water

Drinking water sources we rely upon every day are increasingly at risk of chemical contamination. Many of these contaminants have been proven harmful or carcinogenic and must be treated and removed in order for the water to be considered safe and useable. UV AOP is a critical step in the process and is currently being used to treat groundwater and surface water for a variety of contaminants including pesticides, algal toxins, nitrosamines (e.g., NDMA) and 1,4-dioxane.

Potable Reuse

Potable reuse is the process of recycling wastewater for the augmentation of drinking water supplies. UV AOP is a key part of the potable reuse treatment scheme, working alongside microfiltration and reverse osmosis to ensure a high-quality water is produced – water that exceeds the standards for drinking water. The role of UV AOP is to destroy low-molecular-weight contaminants that can pass through RO membranes, such as 1,4-dioxane, NDMA, pharmaceuticals, endocrine disruptor chemicals or industrial solvents.

The UV Advanced Oxidation Process

UV AOP requires UV light and an oxidant, such as hydrogen peroxide or chlorine. The process occurs in the UV chamber instantaneously with oxidizing radicals attacking and decomposing contaminants, so they are no longer harmful.

Oxidation-process.jpg – UV oxidation process diagram

  1. When UV light is introduced into the water, oxidant molecules absorb the UV light. This converts oxidants into highly energetic and reactive oxidizing radicals.

  2. Oxidizing radicals break down the bonds of contaminant molecules and reduce the potentially harmful chemical to its safe, elemental components.

  3. At the same time, UV light disinfects the water.

UV-photolysis

UV-photolysis is a photochemical reaction in which only UV light (without an oxidant) is required to destroy a chemical contaminant. The contaminant molecule absorbs the UV light which breaks down its bonds so it is no longer harmful. In most cases UV AOP is required to treat chemical contaminants, but in some cases, as with NDMA, UV-photolysis is all that is required.

The Benefits of UV AOP

Simultaneous Disinfection

Our UV AOP systems can also perform disinfection to obtain log reduction credits for Cryptosporidium and Giardia. This is ideal for water providers needing to meet requirements of the Surface Water Treatment Rule, Long Term 2 (LT2) Enhanced Surface Water Treatment Rule, or the Groundwater Rule, in addition to their contaminant removal needs.

Elimination of Residuals

Many other treatment technologies merely transfer the contaminant from one phase to another (e.g. air stripping: from water to air) resulting in a potentially hazardous, contaminant-laden residual that requires further treatment or disposal.

Effective Removal of 1,4-dioxane

Not all contaminants can be easily removed from water using processes like microfiltration, granular activated carbon or reverse osmosis. For contaminants such as 1,4-dioxane and certain nitrosamines, UV AOP is the only practical and proven solution.

Compact Footprint

UV AOP occurs instantaneously within the UV chamber, eliminating the need for the large concrete contact basins or steel pipes commonly used in conjunction with ozone. This allows UV AOP systems to be easily retrofitted into existing water treatment facilities.

UV AOP Destroys a Range of Contaminants

Volatile Organic Compounds

  • 1,4-Dioxane
  • Trichloroethylene (TCE)
  • Tetrachloroethylene (PCE)

Pesticides

  • Metaldehyde
  • Atrazine

Taste and Odor Causing Compounds

  • 2-Methylisoborneol (MIB)
  • Geosmin

Disinfection By-products

  • N-nitrosodimethylamine (NDMA)

Algal Toxins

  • Anatoxin
  • Microcystin

Explosives

  • Hexahydro-1,3,5-trinitro1,3,5-triazine (RDX)

Hazardous Substances

  • Cyanide

Environmental Contaminant Treatment Testing

Our renowned team of scientists and researchers have analyzed thousands of water samples from around the world, and our industry-defining UV AOP systems have been installed at treatment plants from California to Australia to treat a wide array of contaminants.

It all starts with a water sample.

We will measure characteristics of your water critical to UV AOP performance – such as UV transmittance, pH, nitrate ion concentration, and radical scavenging – to determine if UV AOP makes sense for your treatment plant.

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