LED UV Water Disinfection
Water Disinfection: LED UV vs. Mercury Arc Lamp
An LED-based UV light to effectively and efficiently disinfect water supplies by deactivating micro-organisms, bacteria, spores, molds, and viruses.
Item ID: 480
Process Loads & Appliances--Municipal Processes
Small-scale, low-voltage LED UV disinfection systems have proven to be up to five times more efficient than conventional mercury-based UV disinfection systems, according to studies conducted by the University of North Carolina and the University of Colorado. As of mid-2013, the available LED UV disinfection units are suitable for point-of-use applications capable of treating flows of 2 to 5 gallons per minute (gpm).
The current generation of LED UV lamps is not as efficient as low-pressure mercury amalgam lamps because they have an electrical input/light output efficiency of only 8% to 12% versus 20% to 40%. The system efficiency, however, is superior because:
- LED UV wavelengths can be tuned to maximize destruction: 265 nanometers (nm) for cryptosporidium or 280 nm for proteins,
- A reflecting sphere is integrated into an in-line treatment chamber to “reuse” photons until they interact with micro-organisms,
- The optical efficiency of the LED UV equipment is superior to conventional mercury systems, and
- The LED units are mercury-free, an important characteristic in the food and pharmaceutical industries.
Current LED UV applications include producing ultra-pure water in swimming pools and spas, and providing pure process water for the food & beverage industry (breweries, dairies, wineries, juices, and syrups), microelectronics, pharmaceutical, marine and aquaculture industries. Within three to five years, it is expected that the technology will be scaled up for use for large scale wastewater treatment and sewage overflow applications. The EPA is currently evaluating decentralized disinfection to neutralize contaminants in water at the point-of-use in homes. A power-stepping feature adjusts input power as needed for adequate disinfection, further increasing energy savings potential.
Baseline Description: Mercury Arc Lamps
Baseline Energy Use: 500 kWh per year per million gallons
This estimate is derived from studies conducted by the University of North Carolina and the University of Colorado. The LED UV system has an energy requirement of 10 gpm/Watt. The Mercury Vapor system operates at 2 gpm/Watt. This means that the LED system uses 100 kWh to treat 1 million gallons (MG) while the Mercury Vapor system requires 500 kWh. Energy savings are 80% of the baseline usage.
Manufacturer's Energy Savings Claims:
"Typical" Savings: 80%
Savings Range: From 80% to 81%
Studies conducted by the University of North Carolina and the University of Colorado indicate an optical power efficiency or LED UV disinfection unit performance of 10 gpm/W, contrasting with the 2 gpm/W performance achieved with conventional mercury-based UV systems. This means that the LED UV unit will consume only 20% of the energy while treating an equivalent amount of water as a mercury arc lamp-based UV system. As of mid-2013, the available LED UV disinfection units are only capable of treating flows of 2 to 5 gpm.
Best Estimate of Energy Savings:
"Typical" Savings: 80%
Low and High Energy Savings: 80% to 81%
Energy Savings Reliability: 3 - Limited Assessment
Small-scale, low-voltage LED UV disinfection systems have proven to be up to five times more efficient than conventional mercury vapor UV disinfection systems. Studies conducted by the University of North Carolina and the University of Colorado indicate an optical power efficiency of 10 gpm/W, contrasting with the 2 gpm/W performance achieved with conventional mercury-based UV systems used to treat potable water. Input power and irradiance levels would increase when treating water with dissolved solids or turbidity.
Energy Use of Emerging Technology:
100 kWh per million gallons per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
This is a promising technology that, if successfully scaled up, can provide significant energy savings. It should be added to "Watch Lists".
Currently no data available.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.