UV energy shown attacking the DNA of a sub-microscopic organism. Photo courtesy of Trojan Technologies

The main disadvantage of the use of UV radiation is that it leaves no residual disinfectant in the water and hence is not widely used in municipal water purification. It is an ideal disinfection process, however, for residential and small commercial applications. The effectiveness of a UV system in eliminating microbiological contamination is directly dependent on the physical qualities and/or clarity of the water supply. Suspended solids or particulate matter can cause a shielding problem in which a microbe may pass through the UV filter without actually having any direct UV penetration. Untreated iron and manganese may cause staining on the quartz sleeve that houses the UV bulb and may impair its disinfection capabilities. UV filters are best used after adequate sediment, turbidity, iron, and manganese filtration.

Turnkey Solutions
For both arsenic and uranium removal, turnkey solutions are available with dual tanks in a lead-lag configuration. When simple testing reveals that the removal media in the active tank is being depleted, the homeowner switches to the 2nd tank. The spent first tank is then harmlessly handled and shipped to the manufacturer, who disposes of the waste in a certified hazardous waste site and then regenerates the media for future use. Turnkey solutions are a promising trend in dealing with those contaminants that constitute both a risk to the consumer and a disposal risk to the environment. It is likely that awareness of both water supply shortages and environmental concerns will accelerate the development of new and sustainable technologies in water purification.

Stephen K. Wiman, Ph.D., is a geologist and owner of Good Water Company in Santa Fe. He was recently appointed to the City of Santa Fe’s Water Conservation Committee. His primary interest is in using water chemistry to determine the most sustainable methods for treating specific water purification issues. Stephen may be reached at 505-471-9036 or skwiman@goodwatercompany.com.