Abstracts from the 2nd Annual NSPI "Chemistry in the Pool/Spa Environment" Symposium

Sponsored by:

The National Spa and Pool Institute

with additional sponsorship by:

Autopilot Systems, Inc.

Balboa Instruments, Inc.

BioLab, Inc.

Buckman Laboratories

Church and Dwight

Construction Technologies Laboratories

DEL Industries

DuPont

Environmental Test Systems

Hasa, Inc.

Journal of the Swimming Pool and Spa Industry

LaPorte Water Technologies

Muskin Leisure Products

Occidental Chemical Corp.

Pool Chlor

PPG Industries, Inc.

Vanson

Zodiac North American Pool Care Sector

Abstracts:

Charles P. Gerba, Ph.D.

Peter Gerba

University of Arizona

Bacteriological Aspects of Swimming Pools and Spas

Disease outbreaks involving public pools and hot tubs have been reported frequently since their use became popular. Because public pools are often used by persons who have only transient contact, infections resulting from their use are often difficult to identify, and published reports probably represent only a small fraction of a larger public health problem. The organism most commonly published in outbreaks is the bacteria Pseudomonas aeruginosa. This bacteria can grow to high numbers in hot tubs if proper disinfectant levels are not maintained, causing skin, ear, urinary, and eye infections. Several major outbreaks are reviewed and likely causes are identified. Proper pool and spa maintenance and disinfectant levels are needed to prevent illness associated with this organism. To prevent outbreaks, chlorine levels must be maintained above 1.0 mg/l (pH 7.2–7.8). Most published outbreaks have reported Pseudomonas aeruginosa contamination as a result of failure to operate the pool according to recommended practices. Maintaining the microbiological quality of pool water and preventing infection require regular operation and maintenance, including monitoring and record keeping by qualified personnel.

Everett Nichols, Ph.D.

Vanson

Chitosan: Chemistry and Use in Water Clarification

Chitosan is a natural biodegradable biopolymer produced from the polysaccharide chitin, which is derived from the crustacean shells of shrimp, crab and lobster. The chemical properties of chitosan provide the necessary characteristics needed for safe and efficient clarification of recreational water. Colloidal suspensions of insoluble non–filterable particulates are responsible for the turbidity often encountered in pool and spa water. Removal of the fine particulate suspended matter is necessary in order to improve water clarity. This process is referred to as clarification, and requires the coagulation and flocculation of particulates which are subsequently removed by filtration. Metal salts serve as effective coagulating aids while polyelectrolytes are typically used as flocculents. Chitosan, a natural cationic polyelectrolyte structurally similar to cellulose, functions as an effective flocculent for a variety of both organic and inorganic substances. In addition, chitosan’s chemical structure contributes to its unique ability to flocculate oil and chelate transition metal ions. This combination of properties distinguish chitosan as a unique clarifier of recreational water.

Fernando del Corral, Ph.D.

Betty S. Johnson

Russ Fues

Buckman Laboratories

Recirculating Dynamics of Conventional Recreational Water Algaecides

The dynamics of conventional algaecides were studied in a recirculating tank equipped with filtration devices capable of housing various filtration media (silica sand, diatomaceous earth, perlite, zeolites, fibrous cellulose and polyester cartridges). Two distinct groups of algaecides were studied. The first group was the quaternary ammonium compounds (linear and polymeric quats) and the second group, was copper-based products (ionic and complexed). Results revealed that under dynamic (recirculating) conditions none of the quats adsorbed onto (un-fouled) silica sand, diatomaceous earth, synthetic polyester cartridges, or perlite. Significant algaecide sorption was observed with zeolite-1 and zeolite-2 (clinoptilolite) after 21 filter passages. Additional studies revealed that under static/passive conditions (no-recirculation), all filter media tested demonstrated sorption properties with all algaecides tested. Further studies under static conditions demonstrated that soil had a dramatic impact on residual algaecide levels as compared to residual levels when products were exposed to packed algal cells. Our experimental results indicate that the longevity or half-life of selected test algaecides in a recirculating system most likely is predominantly due to the level or degree of trapped organic particles such as soil, algae cells and other organic and/or inorganic debris. Certain filter media has also intrinsic sorption properties for algaecides, such as zeolites. Based on our results, copper-based products appear to be more susceptible to be taken out of circulation with most conventional filter media than quaternary ammonium products.

Howard M. Kanare

Construction Technology Laboratories

Safety of Cement - Leachability of Trace Toxic Elements

Many elements such as mercury, lead, and chromium exist in portland cements at very low levels. As the cement hydrates, these elements potentially become leachable from the concrete products. Results from studies will be presented to show the concentrations of leachable elements and implications for health effects.
(This presentation summarized material out of the previously published work “Leachability of Selected Chemical Elements from Concrete”, which was first published in the Proceedings of the Emerging Technologies Symposium on Cement and Concrete in the Global Environment, Portland Cement Association Publication #SP114T, 1993. The paper is reprinted here by permission and courtesy of the Portland Cement Association.)

Wolfram Hartwig, Ph.D.

Engineered Treatment Systems

The Ozonation of Swimming Pool Water: Process Selection and Material Requirements

Ozone is an excellent oxidant and disinfectant that is used in a wide variety of commercial and industrial applications, among them water, waste water and swimming pool water treatment, pulp and kaolin bleaching, water reclamation and food processing. The ozonation of pool water is a relatively new technology in the U.S.A., so special attention must be given to the design of the ozonation process and to the selection of ozone–resistant materials for all affected components. The presentation will review different pool water ozonation processes, from the European ozonation with dual filtration to the post–filter side stream ozonation common in the U.S.A. Because of the high reactivity and corrosiveness of both gaseous and aqueous ozone, pool water ozonation imposes material requirements and constraints not normally encountered in pool construction and operation. The impact of ozonation on treatment components will be discussed, and recommendations for material selection will be listed.
Note: These Lists, Figures and Tables are reproductions or extractions from Dr. Hartwig’s handout, which was distributed at the symposium. They are best understood in conjunction with the audiocassette recording of the presentation.

Beth Hamil

DEL Industries

Applying Ozone to Commercial Swimming Pools - Before or After the Filter

The mode of application of ozone to an existing or new swimming pool’s water can be considered the most important decision to the success of the system, second only to the amount of ozone produced by the chosen generator. In addition to properly sizing the ozone generator for a particular pool, the designer must also address the way it will be applied. It is generally accepted that the only way to safely apply ozone to a pool is with venturi injection (vacuum), but it is still open to discussion whether to apply ozone before or after filtration. We will review the pros and cons of both theories.
Note: These Lists, Figures and Tables are best understood in conjunction with the audiocassette recording of the presentation.

John A. Wojtowicz

Chemcon

Swimming Pool Water Buffer Chemistry

Buffering is the resistance of water to pH change. Pure water has little buffering. Buffering is necessary to prevent severe pH fluctuations that would otherwise occur when acidic or basic sanitizers are added to pool water. The presence of alkalinity in the form of bicarbonate and cyanurate imparts buffering to swimming pool water. A buffer system consists of a weak acid and its anion (e.g., carbonic acid and bicarbonate or cyanuric acid and cyanurate). Since a buffer can react with either acidic or basic substances that are added to swimming pool water it resists pH changes in either direction. However, because of the relatively low concentrations of buffering alkalinity (carbonate, cyanurate, or borate) in swimming pool water, the acid or base neutralizing capacity without significant pH change is limited. Although the buffers in swimming pools can neutralize minor quantities of acidic or basic substances with only small pH changes, significant pH changes will occur if large quantities of sanitizers (especially acidic) are added or if sufficient acid is added (e.g., during pH adjustment). Maximum buffering occurs at a pH where the molar ratio of acid to anion is one. At 80°F and 1000 ppm TDS, maximum buffering occurs at pH 6.3 and 6.8 for the carbonic acid/bicarbonate and cyanuric acid/cyanurate systems, respectively. By contrast, maximum buffering in the boric acid/borate system occurs at pH 9.2. On a molar basis, the cyanuric acid/cyanurate system provides more effective swimming pool water buffering at pH 7.5, 80°F, and 1000 ppm TDS because its pH of maximum buffering is closer to pool pH. However, on an equivalent ppm basis, the buffer intensity of the carbonic acid/bicarbonate and cyanuric acid/cyanurate systems are roughly comparable over the recommended pH range (7.2–7.8) and greater than that of borate at pH < 7.8. At pH 7.8, the buffering of the three systems are roughly comparable on a ppm basis. Borate significantly supplements swimming pool buffering at pH ³ 7.8.

Joe Grenier

Fountainhead Technologies

Improved Test Medium for the Evaluation of Algaecides and Algistats for Swimming Pools

An algaecide/algaestat test medium is proposed which contains sufficient nutrients for algal growth, has the hardness and alkalinity characteristics of properly balanced pool water and has an orthophosphate level more consistent with typical concentrations found in swimming pool waters. The chlorophyte alga Chlorella vulgaris was used to test the EC50 and Minimum Inhibitory Concentration (MIC) of ionic silver, copper and zinc in Allen’s medium and a proposed algal test medium (PATM). Results indicate that both the EC50 and MIC of all three toxicants tested were lower in the proposed medium than in Allen’s medium.

John Maziuk

Church and Dwight

Kim Skinner and Que Hales

Pool Chlor

Doug Latta

Aqua Clear

New Plaster Start-up Chemistry using Sodium Bicarbonate

A study was performed that compared the effects of different chemical start–up procedures on the surface of swimming pool plaster. Lab research was performed by simulating traditional start–ups and acid start–ups (both utilizing muriatic acid), and high alkalinity start–ups (using sodium bicarbonate) with plaster coupons, which were subsequently analyzed. Field research was also conducted to confirm consistency with the lab results. Experimental results and conclusions are given.
The study was performed by the authors, and the presentation, along with additional and unique data and hypothesis, was made by John Maziuk of Church & Dwight. The additional information is available by purchasing the audio cassette tape of the presentation.

Dick Vattimo

Occidental Chemical Corp.

Relationships Between Some Variables Affecting Pool Water Quality

In 1992 the Pinellas County Florida Public Health Unit under the direction of D. Michael Flanery, PE, Environmental Engineering Division Director, measured various properties of 486 public pools. Data was collected in the following categories: bacteria populations, water chemistry, turbidity, type of sanitizers used, environmental conditions (bather load, weather etc.), swimming pool characteristics, time and algae. The data was statistically analyzed under the direction of Dr. Lawrence Rakestraw (retired) of Occidental Chemical Corporation. This talk will describe the variables measured and their relationships to each other.
Note: These Lists, Figures and Tables are best understood in conjunction with the audiocassette recording of the presentation.

Ed Lightcap

DuPont

The Effect of Potassium Monopersulfate on ORP Measurement of Chlorine Sanitizer Residuals

Most public pools use chlorine sanitizers to control the growth and development of harmful micro–organisms. ORP analyzers are used to measure and control chlorine sanitizer levels in many of these public pools. In addition to sanitation, most public pools also practice some form of regular oxidation (shock treatment) to reduce bather waste and other organic contaminants that build up over time and exert a demand on, or consume, chlorine sanitizer. To alleviate problems associated with superchlorination, including the formation of combined chlorine compounds, chloramine odors and high chlorine residuals, a growing number of public pools are switching to potassium monopersulfate, an oxygen based oxidizer, for regular preventive oxidation. This discussion will review the effect of monopersulfate oxidation on the ORP measurement of chlorine sanitizer residuals.