Item ID: 13
Ultraviolet Disinfection of Water and Wastewater
Water Disinfectant: Ultraviolet vs. Chemical or Ozone
An alternative technique to chemical or ozone water treatment that can reduce environmental and human health impacts of the treatment process.
Public health departments recognize UV as an effective method for treating wastewater, reclaimed water and drinking water. By 2007, approximately 21% of municipal wastewater treatment facilities (WWTFs) in the U.S. were using UV for disinfection. UV systems are energy intensive, and UV disinfection can account for approximately 10% to 25% of total electrical energy use at a municipal WWTF.
Some states encourage UV disinfection methods, but saving energy is not the main driving force. Alternative methods of disinfection, including use of chlorine gas, sodium hypochlorite or ozone, can have adverse impacts on receiving water bodies due to the formation of chlorine residuals, have health and safety impacts due to toxicity or require energy-intensive ozone generators. UV disinfection eliminates the need to generate, handle, transport or store toxic, hazardous or corrosive chemicals. UV disinfection is user-friendly, although the lamps must be cleaned periodically to prevent algal growth.
WWTFs using low-pressure UV lamps consume 100 to 250 kWh per million gallons (MG) of wastewater treated. Medium-pressure systems require 460 to 560 kWh/MG. Chlorine gas system energy use ranges from 60 to 250 kWh/MG, depending on the chlorine dose delivered.
Energy use depends on UV system design. Medium-pressure lamps can require two to four times more energy to operate than low-pressure, high-output lamps. Energy use increases as more lamps are required to deliver effective disinfection, as when the water is unfiltered. Good design allows for UV lamp turn-down or routing flow through fewer channels to respond to changes in wastewater flow and water quality.
Energy Savings: 0%
Energy Savings Rating:
Limited Assessment What's this?
|1||Concept not validated||Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.|
|2||Concept validated:||An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.|
|3||Limited assessment||An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline. |
|4||Extensive assessment||Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions. |
|5||Comprehensive analysis||Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.|
|6||Approved measure||Protocols for technology application are established and approved.|