Ultra-Violet Disinfection

Needs Address

Supply of safe water for domestic use

Adaptation effects

• Diversity of water supply to provide a source of water when alternative sources become unusable – less time spent on water collection enables more time to be allocated to agriculture and other livelihood activities
• Increases water security
• Increase economic development and therefore heightens economic resilience

Overview and Features

Ultra-Violet (UV) disinfection involves the destruction of microbial DNA from water to prevent the spread of waterborne diseases to downstream users and the environment. The main components of a UV disinfection system are mercury arc lamps, a reactor, and ballasts. The source of UV radiation is either the low-pressure or medium-pressure mercury arc lamp with low or high intensities.

Figure: A UV disinfection system (Smet and van Wijk, 2002)

Cost

• UV disinfection with mercury lamps is more costly than chlorination
• Costs include equipment and electricity

Energy source

UV lamps require an electricity source

Ease of maintenance

• Most mercury lamps have a life span of 6000-10000 hours
• Operation and maintenance is fairly simple, though requires regular checking of the equipment

Technology performance

• UV disinfection has been proven as an efficient purification method, however the technology cannot disinfect water 100%.
• Treatment effectiveness might be reduced when there is an increased flow of water – effectiveness of disinfection is determined by wavelength, condition of the water, intensity of radiation, type of micro-organism, exposure time
• Pre-treatment increases the effectiveness of UV disinfection
• More recently, the technology is being more widely employed due to vast improvements in operation and quality of equipment
• Provides a source of pure water for drinking and other domestic and large scale use

Considerations

• Should be used as part of a multi-pillar approach to water management e.g. Singapore’s ‘Four National Taps’
• Appropriate storage is needed post-treatment to stop the water becoming re-contaminated
• Appropriate disposal methods for UV mercury lamps must be ensured

Co-benefit, suitability for developing countries

• Provides health and sanitation benefits, reducing disease and mortality
• UV treatment may not be affordable in many developing country contexts

Information Resources

Astra, Bangladesh. N.d. Technology Database. Available at: http://astradst.info/Tool/Technologies [19 January 2014]

EPA, 1999. Wastewater Technology Fact Sheet Ultraviolet Disinfection. Available at: http://water.epa.gov/scitech/wastetech/upload/2002_06_28_mtb_uv.pdf [23 March 2015]

INSEAD, n.d. Tackling Singapore’s Water Shortage. Available at: http://centres.insead.edu/innovation-policy/events/documents/Singapore-WaterShortage.pdf [20 January 2015]

Smet, J. and van Wijk, C (eds.) 2002. Small Community Water Supplies: Technology, People and Partnership. Delft, the Netherlands. IRC International Water and Sanitation Centre. (Technical paper Series 40). Available from: http://www.ircwash.org/sites/default/files/Smet-2002-Small_TP40.pdf [20 January 2015]