From: Public Services and Procurement Canada
Ultra-violet (UV) oxidation, also called advanced oxidation, is an ex situ treatment that destroys groundwater contaminants. The contaminated groundwater is pumped, mixed with one or two oxidizing agents and passed under ultraviolet light. Ozone and/or hydrogen peroxide are often the oxidizing agents used to accelerate contaminant decomposition. Oxidation can either be direct, using an oxidizing agent, or combined with ultraviolet radiation. This technology is principally used for volatile and semi-volatile compounds, but can also be applied to pesticide and explosives degradation. The principal advantage of this technique is the destructive nature of the reaction.
Source:
Groundwater extraction devices (wells, trenches, permeable drains or other) are used to collect contaminated groundwater that is conveyed to the treatment system, treated and discarded.
The implementation of a UV treatment system may include:
The implementation of the system could lead to the management of contaminated soils resulting from drilling or excavation activities. In this case, these soils must be removed off-site.
Treatment systems can generate large quantities of solids (inert salts), liquid and gaseous discharges.
Generally, treated groundwater meets the applicable criteria and doesn’t pose a high risk when discharged. Treated water that contains by-products or excess reactive agents, as well as unacceptable pH levels can be a source of danger for downstream receptors. Monitoring of the water quality is required.
Notes:
On-site treatment trials will establish the efficiency of the technology and the parameters that influence the treatment time and cost (e.g. residence time, pump flow rate, requirements for pre-treatment, etc.).
Treatment trials on site will establish the efficiency of the technology and the parameters that influence the treatment time and cost (example: residence time, pump flow rate, requirement for pre-treatment, etc.).
The extraction and treatment of groundwater is not always appropriate in remote areas that do not have access to public services or to local labour that can monitor and maintain equipment. During the installation of extraction points (wells, trenches or drains), deep freezing of the soil and seasonal changes in soil conditions will have to be considered. Treatment equipment should be designed considering the possibility of long periods without any intervention of the system operator.
Long-term considerations are related to pumping and treatment technology and not for the UV treatment technology as such.
The secondary products formed by the UV treatment are carbon dioxide, water and inorganic salts. Certain volatile organic compounds, such as trichloroethane, may not be completely destroyed by UV treatment and are volatilized. In this case, gas emissions from the UV treatment system must be collected and treated.
Groundwater pretreatment may be required to improve the efficiency of this technology, and may include:
In the presence of certain volatile organic compounds such as trichloroethane, produced gas vapours must be collected and treated.
In 1998, UV oxidation was used at the Bofors Nobel Superfund site, Michigan, to treat groundwater contaminated with volatile and semi-volatile organic compounds. The treatment was combined with activated carbon filtration, pH adjustment and air stripping techniques.
More information is available at the following websites:
This technology has been successfully applied in the remediation of contaminated sites with volatile or semi-volatile organic compounds.
The application of UV treatment on explosives is recent and more limited. Tests conducted by the USA Army Environmental Center have shown this technology to be 99.9% effective in destroying common explosives in groundwater (CPEO, 1998).
Optimization of the calendar to promote the sharing of resources and reduce the number of days of mobilization.
Use of renewable energy and energy-efficient equipment.
Main Exposure Mechanisms
Applies or Doesn’t Apply
Monitoring and Mitigation
Dust
Doesn’t apply (minor during mobilization and construction)
N/A
Atmospheric/Steam Emissions—Point Sources or Chimneys
Applies (in certain cases)
Emissions monitoring (choice of parameters, types of samples and type of intervention [source, risk or local requirements])
Atmospheric/Steam Emissions—Non-point Sources
Doesn’t apply
Air/steam—by-products
Runoff
Groundwater—displacement
Groundwater—chemical/ geochemical mobilization
Groundwater—by-product
Applies
Groundwater quality monitoring
Accident/Failure—damage to public services
File checks and obtaining pre-excavation or drilling permits, development of excavation or drilling procedures and emergency response
Accident/Failure—leak or spill
Risk assessment, elaboration of accident and emergency response plans, monitoring and inspection of hazardous conditions
Accident/Failure—fire or explosion
Other—Handling contaminated soils or other Solids
Risk review, development of accident and emergency response plans, monitoring and inspection of unsafe conditions
Composed by : Serge Delisle, Eng. M.Sc., National Research Council
Updated by : Karine Drouin, M.Sc., National Research Council
Updated Date : February 12, 2013
Latest update provided by : Nathalie Arel, P.Eng., M.Sc., Christian Gosselin, P.Eng., M.Eng. and Sylvain Hains, P.Eng., M.Sc., Golder Associés Ltée
Updated Date : March 22, 2019
