The Efficacy of a Combined Approach

In the U.S., 80 billion gal of groundwater are used daily, according to the National Ground Water Association. In fact, for the majority of Americans, groundwater is their primary source of potable water. As a result, these water supplies are routinely measured against the strictest metric of safety with respect to microbial and chemical contamination. But as emerging technologies present the promise of new and more effective ways to treat water, this metric is being debated. The very definition of “safe” is being challenged, and chlorination is no longer the final arbiter.

According to the U.S. Environmental Protection Agency (EPA), nearly half of groundwater treatment facilities in the country include a disinfection protocol as a part of the overall treatment process. The goal of this protocol is to reduce incidences of waterborne disease and to eliminate harmful microorganisms in water supplies.

The Center for Disease Control and Prevention reports that, between 1991 and 2000, groundwater systems were associated with 68 outbreaks, resulting in over 10,000 incidents of human illness. In nearly 80% of the cases, contaminated source water caused the outbreak. Precedence such as this has spurred not only invention in the field of water purification technology, but also increasingly stringent regulatory measures.

Progressive Purification Trend

In October 2006, the EPA promulgated the Final Ground Water Rule as a means to further protect consumers against dangerous waterborne viruses and bacteria. The rule, designed to identify and address deficiencies in groundwater sources of public drinking water that could lead to contamination, applies to 147,000 systems and approximately 100 million consumers. Specifically, the rule targets systems identified as high-risk (current treatment methods do not remove 99.99% of viruses) and proposes corrective action to destroy potentially harmful pathogens before they reach an unwitting consumer.

A popular water treatment strategy in recent years is the use of a multi-barrier disinfectant approach. The use of multiple disinfectants—either sequentially or simultaneously—to achieve 99.99% (4-log) virus inactivation has enjoyed tremendous popularity as of late, spurred on by research underscoring its efficacy over that of a singular disinfectant.

For example, a 2006 study undertaken by Magbanua, et al. demonstrated that the use of ultraviolet (UV) and ozone in combination destroyed E. coli bacteria in water at an enhanced rate compared to either UV or ozone when applied separately. The study’s finding is not lost on the International Ozone and Ultraviolet associations, who in August 2007 will host the first-ever joint world congress on their respective technologies. Certainly, this move further demonstrates the perceived efficacy of a combined approach and solidifies the trend toward more progressive purification strategies.

Chlorine Alternative
Arizona-based Vortex Corp. recently awarded a contract with the U.S. Department of Homeland Security to deliver chlorine-free water disinfection technology to the municipal market—leveraged the synergistic effects of UV light and ozone to develop its photo-oxidation technology. The latter mimics the natural water purification phenomenon that occurs in the environment.

Used widely as a primary disinfectant in water treatment, chlorine is known for its affordability, residual value and overall effectiveness as a viricide and biocide. In fact, nearly all U.S. drinking water today is purified via chlorine, according to the EPA.

In recent studies, however, the storage and transportation of chlorine gas have been identified as potential terrorism risks. What’s more, chlorinated byproducts—produced when chlorine reacts with natural organic matter in the disinfection process—have been linked to cancer.

In light of this, regulatory bodies (and the industry as a whole) have placed increasing emphasis on the use of alternative primary disinfectants. They’ve engaged companies like Vortex to add to the lexicon of water science by innovating natural treatment strategies that not only safeguard the public against microbial and chemical contaminants, but also provide added benefits to consumers.

By combining UV, ozone and photo-oxidation technologies to disinfect water, Vortex’s approach presents a more effective viricide than chlorine, is safer to implement and infuses water with fresh oxygen. Furthermore, it can potentially reduce a system’s footprint and capital costs, providing an important economic stimulus to supplanting chlorine as the principal water disinfectant in the U.S. Another key benefit is that UV is a physical process rather than a chemical disinfectant, and ozone is generated onsite, eliminating shipping and handling concerns associated with highly corrosive chemicals such as chlorine gas.

Selecting the most appropriate disinfection protocol is a site-specific decision best left to local officials familiar with the unique challenges posed by their plant infrastructure and source water. But it is a decision nonetheless—a consideration of more than one recourse. Today, there are options superior to chlorination. The question is how much a municipality is willing to invest in new, more progressive technologies; perhaps the answer resides in how the industry will ultimately define “safe.”