August 1, 2010
By Connie Sue Centrella
The wide acceptance of aquatic play features and interactive water designs is dramatically changing the science of disinfection. While these imaginative, family-friendly environments have captured the excitement of thousands of people across North America, they have also created new challenges for facility managers, requiring an added measure for bather protection.
Recreational water illnesses (RWIs) represent the number-one health challenge associated with these features. RWIs are disease-causing germs, such as Cryptosporidium (Crypto) and Giardia, which are introduced into the water environment by users due to lack of bather cleanliness. Crypto, a parasite spread by diarrhea from infected humans (or other mammals), is highly resistant to chlorine disinfectants commonly used in public swimming pools.
An overview of supplemental disinfection systems (SDSs), including ultraviolet (UV) and ozone technology, was presented in the April 2010 issue of Pool & Spa Marketing. Each of these methods provides an effective second layer of protection for treatment in pool and spas; both have been accepted as leading technologies that can combat Crypto. This article will discuss UV disinfection specifically for aquatic play features; a future article will study the value and benefit of ozone for these environments.
Water chemistry parameters in aquatic play features require attention to bather loads, as well as the unique considerations associated with these attractions. For example, interactive play features, such as misters, sprays, water jets and sprinklers, need adequate hydraulics to maintain circulation. They also demand higher sanitizer levels to keep the water free of dangerous germs. It may be impossible to assure adequate disinfection with traditional sanitization; thus the introduction of SDSs.
Research has shown chlorine cannot kill as efficiently or effectively in these interactive environments. The Centers for Disease Control’s (CDC’s) Model Aquatic Health Code (MAHC) endorses and highlights the importance of SDSs and proposes the use of UV and ozone as accepted supplemental technologies for commercial pool environments. Recommendations and rationale of the MAHC will be presented by members of the steering committee at the 2010 World Aquatic Health Conference (WAHC) in Colorado Springs, Colo., on October 7.
Ernest R. Blatchley, PhD and his research team at Purdue University’s School of Civil Engineering have presented scientific findings at the WAHC describing their extensive research that explores UV technology and disinfection byproducts. In his presentations at the 2007 WAHC, Blatchley discussed the effect of UV photodegradation of inorganic chloramines (monochloramine, dichloramine and trichloramine). These disinfection byproducts create irritants to mucous membranes, causing eye irritation and upper respiratory tract infections. The research, funded by the National Swimming Pool Foundation (NSPF), determined UV effectively degrades and improves water quality and bather comfort. The emission spectrum of the UV lamp is effective in the breakdown of chloramines.
In simple terms, UV technology works by targeting the nucleic acids of micro-organisms. Exposure to UVC light prevents the DNA/RNA from replicating, preventing the micro-organisms from reproducing and thus rendering them harmless.
While traditional pools can be maintained using chemical parameters based on bather load, water volume and usage time, the dosage and sizing requirements for UV systems are calculated on flow rate (gpm) and the type of micro-organisms to be inactivated. UV technology is a one-pass system; it should be sized large enough for the entire pool volume to be exposed to UV light within a 24-hour time period.
This proven treatment is now mandated for use on all interactive water features located on cruise ships through the Vessel Sanitation Program (VSP). The growing popularity of children’s activity pools and aquatic environments aboard cruise ships has required an increase in disinfection controls. The final draft of the new VSP is currently under review, but as it stands, UV disinfection will be required on specific types of aquatic play features where children are present. The latest draft can be found at www.cdc.gov/nceh/vsp/.
Ongoing education and study is a must, as these technologies play a vital role in the elimination of Crypto and other RWIs. The Aquatic Play Feature™ Handbook, published by the NSPF, describes different types of features and the unique requirements needed to operate them and maintain water quality. The book focuses on risk reduction to the users, employees and the facility itself and emphasizes the importance of increased disinfection and an understanding of SDSs.
With the growing popularity of these water environments, it is important that pool contractors, engineers and service technicians know how to design and retrofit these supplemental systems for new and existing water environments. All pool industry professionals must unite to help combat the waterborne pathogens that cause RWIs.
Over the past four years, this column has focused on providing busy pool professionals an education experience and a venue to express their ideas with other pool and spa professionals by interacting online with a Keiser University eCampus Aquatic Engineering instructor. Readers participate in the same way as students who are enrolled in the two-year online college degree program. The instructor presents a learning topic to which the reader may respond with research and discussion. The topic for this column: What are the benefits of providing UV systems on aquatic play features? E-mail responses to firstname.lastname@example.org; a communication thread will share responses and present a forum for ideas and further discussion.
World Aquatic Health Conference Seminars 2007; 2009; 2010 (http://www.nspf.org)
Dr. Ernest Blatchley presentations
Aquatic Play Feature Handbook (http://www.nspf.org)
Model Aquatic Health Code (http://www.cdc.gov/healthywater/swimming/pools/mahc/)
Vessel Sanitation Program (www.cdc.gov/nceh/vsp/)
Connie Gibson Centrella, MBA, is program chair and professor for the online Aquatic Engineering Program at Keiser University eCampus. She was recently honoured for the fourth time with the Evelyn C. Keiser Teaching Excellence Award as an ‘Instructor of Distinction.’ An industry veteran with more than 40 years experience, Centrella is a former pool builder with extensive knowledge in pool construction, equipment installation and manufacturing.
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