Abstracts from the 1st Annual NSPI "Sanitizer Chemistry" Symposium

Sponsored by:

The National Spa and Pool Institute

with additional sponsorship by:

Amtrol

Aqua Biotechnologies

BioLab

Church and Dwight

Clearwater Tech

DEL Industries

DuPont

Eltech

Environmental Test Systems

Fountainhead Technologies

Hayward Pool Products

Journal of the Swimming Pool and Spa Industry

LaPorte Water Technologies

Muskin Leisure Products

N. Jonas and Co.

Pool Chlor

PPG

Teledyne Laars

Watkins Manufacturing

Abstracts:

S. D. Worley, Ph.D.

Auburn University

Novel N–Halamine Water Biocides

The use of a class of organic compounds known as N–halamines for disinfection and stabilization of free chlorine and free bromine in swimming pools and spa will be discussed. For those compounds soluble in water, the discussion will focus on their long–term stabilities while providing biocidal action in sunlight. For those compounds insoluble in water, the use in a cartridge filter application for disinfecting spas will be emphasized. Details about the novel compounds, for which the patent rights are owned by Auburn University, will be presented to include physical properties, synthesis methods, and biocidal and stability data. The most likely uses of the compounds in commercial applications will also be addressed.

John A. Wojtowicz

Chemcon

The Langelier Saturation Index – Overview and Update

It is a common misconception that the Langelier Saturation Index applies only to closed systems because it was developed for water in distribution lines. Since it based on calcium carbonate solubility equilibria, the Langelier Saturation Index is applicable to both open and closed systems containing dissolved calcium carbonate. The main difference is that in closed systems the alkalinity can vary at a given pH whereas in open systems alkalinity is fixed at a given pH. In addition, since alkalinities are much lower in open systems at comparable pH values, saturation hardness is much higher. Another common misconception is that swimming pools are open systems. Although swimming pools are open in a physical sense, they are not open from a thermodynamic (i.e., chemical equilibrium) standpoint. Periodic acid addition for pH control replenishes lost carbon dioxide, preventing equilibration with the atmosphere. Indeed, swimming pools exhibit the characteristics of closed systems, showing the expected range and variability of alkalinity which is also typical of many public water supplies. If swimming pools were open systems (i.e., in equilibrium with atmospheric carbon dioxide), they would contain only 4 to 18 ppm alkalinity over the 7.2 to 7.8 pH range. At a given temperature, swimming pool water chemistry must be balanced by adjusting pH, alkalinity, and calcium hardness in order to maintain the proper saturation with respect to calcium carbonate to avoid corrosion of metallic surfaces, etching of tile grout and plaster, scaling, and cloudy water. Water balance is determined by means of the “Calcium Carbonate Saturation Index” (SI), which was originally devised (Langelier 1936) to provide corrosion control for iron pipes in public water distribution systems by means of deposition of thin films of CaCO3. This paper discusses revisions to the Saturation Index equation due to more accurate values for the solubility product constant of calcium carbonate as a function of temperature and more realistic ionic strength corrections.

Roy D. Vore, Ph.D. and Michael J. Unhoch

Zeneca Biocides

The use of PHMB as a Sanitizer in Domestic Spas

The control of bacteria in spa water is much more demanding than pool water. The heated water, higher concentrations of both organic load and bacteria shed by bathers can result in unacceptable bacterial growth developing in spa water within a few hours of heavy use. To prevent health affecting bacterial outbreaks three approaches may be employed: continuous feed of the sanitizer, daily monitoring and addition of the sanitizer, and the use of a stable and non–load dependent sanitizer. Bromine and chlorine require daily monitoring and adjustment. Polyhexamethylene biguanide (PHMB or biguanide) is a non–oxidizing sanitizer that is minimally affected by high bather use. Prior to registration for use in spas by the U.S. E.P.A. the antibacterial performance of PHMB was measured in domestic spas with simulated use levels of one person per 125 gallons for 30 minutes per day. The spas were inoculated with high levels of bacteria implicated in spa related skin rashes (Ps aeruginosa and Staphylococcus aureus) and those shed in feces (Escherichia coli and Enterococcus faecalis) plus 2 pints of synthetic bather load per day. Throughout the study period the PHMB treated spa water had fewer bacteria than allowed by U.S. E.P.A. standards for recreational water as well as fewer bacteria than allowed in drinking water. A calcium hypochlorite spa exceeded E.P.A. standards for total coliforms on 13 of 14 days and had persistent levels of Ps aeruginosa. PHMB provided a significant improvement in the control of spa associated bacteria when compared to calcium hypochlorite.

Jacques M. Steininger, D. Eng. Sc.

Santa Barbara Control Systems

Comparison of Chlorine Testing Methods

Chlorinated water solutions were tested by amperometric titration and colorimetric analysis and with two commercial test kits. The results show good agreement between the first two methods and less accurate results with the test kits. The response curves of ten (10) new ORP sensors show that a minimum of 10 to 20 minutes of immersion time is required to obtain stable readings. After stabilization, the standard deviation for ORP readings is only 2 mV or about 0.2% of full scale value. The effects of Total Dissolved Solids, pH and temperature on ORP readings were also analyzed under laboratory conditions for varying chlorine concentration levels.

Tom Seechuk

LaMotte Company

MPS Interferences in the DPD Method

Monopotassium persulfate can appear as combined chlorine in the DPD test. A new test method was developed, in cooperation with Dupont, to not only eliminate the interference, but to allow the determination of monopotassium persulfate concentration.

Bonnie B. Sandel, Ph.D.

Olin Chemicals Research

Chlorine Disinfection Chemistry

Chlorine’s unique properties have been exploited for water disinfection for nearly 100 years, yet only recently, through comparisons with alternative methods, have scientists begun to understand the multiple features that make chlorination effective. This presentation deals with three features of chlorine disinfection for pools and spas: rapidity of action, persistence in the water and circulation system, and contributions to biostability of the treated water. Starting with the evidence of microbial risk and its relationship to the water circulation system, the discussion will proceed to a comparison of laboratory and field experiment results for a variety of chlorine and alternative sanitizer systems. Finally, guidelines for optimizing chlorine’s use will be discussed.

Rip G. Rice, Ph.D.

Rice International Consulting Enterprises

Wolfram Hartwig, Ph.D.

Engineered Treatment Systems

Gordon R. Finch, Ph.D.

University of Alberta

Potentials for Ozone to Control Cryptosporidium Oocysts in Pools

Knowledge that ozone is the strongest disinfectant and oxidizing agent available for controlling microorganisms in aqueous media is widespread and well understood. As such, ozone is quite capable of assuring the inactivation of cyst organisms, occasionally found in swimming pool waters, such as Giardia lamblia and Cryptosporidium parvum. However – to accomplish reliable inactivation of C. parvum and G. lamblia cysts, ozone must be present in sufficient concentrations in the waters containing these microorganisms and for sufficient periods of time so that the product of “C” (concentration of ozone in mg/L) times “t” (time of contact in minutes) is at least equal to the “Ct” product specified by the U.S. E.P.A. in the Surface Water Treatment Rule, promulgated in 1991 to ensure disinfection of municipal drinking water supplies. These requirements to meet a specified “Ct” value mean that ozone must be produced in the gas phase in sufficient concentrations so that when applied to the pool water, a sufficient level of ozone will be present to measure and monitor. The higher the concentration of residual ozone in the water, the shorter will be the reaction time necessary to assure attainment of the given “Ct” value for the specific cyst organism at the temperature of the water. This means that ozone generated by UV radiation cannot be effective for the inactivation of C. parvum oocysts (“Ct” value of ca. 5 min–mg/L) since the levels of ozone in the gas phase are so low as to preclude developing measurable ozone residuals in water for more than a few seconds in the immediate area of contact. On the other hand, ozone generated by corona discharge techniques (in concentrations above 1–2% using dried air as the feed gas, and 3–5% using oxygen–enriched air feed gas) can produce significant levels of measurable residual ozone in water (several tenths of a mg/L). If these levels of residual ozone are held for the several minutes, an appropriate “Ct” value for C. parvum can be achieved readily. The difficulties involved with the inactivation of C. parvum with ozone and chlorine will be discussed, and recommendations will be developed.

Ed Lightcap

DuPont

Peroxygen Compounds as Oxidizers

Peroxygen compounds are fast becoming integral components of many pool and spa water treatment programs. This presentation will review the primary peroxygen compounds used and discuss their application and reactivity.

Robert J. Kulperger

Natural Chemistry, Inc.

Natural Enzyme Technology Applied to Pools and Spas

Enzymes are organic protein molecules that act as biological catalysts to accelerate reactions in nature, such as the breakdown of organic molecules. Used in pools and spas, enzymes biodegrade organic molecules that traditionally require chemical oxidation to control. Natural enzymes are a preferred enzymes source because of the range of enzymes required in this application. Control of organics with natural enzymes reduces maintenance by eliminating scum build–up and waterline ring, chloramine’s cloudiness caused by organics, and rapid filter cycling due to organic fouling. A reduction in chemical shock usage and cleaning compounds is also observed.

Ray Kramer

ELTECH Systems Corp.

Electrolytic Chlorine Generation

The basic electrochemical reactions for swimming pool chlorination will be studied. Principal reactions at the anode and cathode will be discussed with regard to the species present. Special attention will be paid to the low level of salt present in pool water and the effects of low salinity on electrode performance. Furthermore, the basic failure mechanism for anodes involved with low salt chlorination will be discussed.

Robert A. Governal, Ph.D.

International Innovative Technologies

The Design of Advanced Pool and Spa Water Treatment Systems Using Catalytic Filtration Technologies

The design and application of novel and patented catalytic filtration technologies (CFT) will be presented towards the advancement of pool and spa water treatment systems. System designs to be presented include loop configurations as well as one–pass recycle/reuse/reclaim systems. CFT may become the next generation of water management and water treatment technologies, since they are a new science that can improve the technical and economic effectiveness of water treatment systems. A catalytic filter is a porous separation device in which the filtration surface has been activated to produce novel oxidation chemistries. Current filters available to end users today are made from surfaces that are inert, or can break down in extreme environments; these current filters are therefore designated as “passive filters”. Since catalytic filters can be manufactured from pore size ranges from reverse osmosis (molecular separations) through microfiltration (bacterial, parasitic, and bulk colloidal separations) regimes, CFT can be applied to a wide range of markets. CFT can be applied to pool and water treatment systems in conjunction with current and future chemistries such as muriatic acid, algicides, ozone, ultraviolet radiation, halogens and chloramines, etc., to minimize pathogenic and organic contamination potentials. CFT can increase the economic effectiveness of water treatment systems through the minimizing of operational costs such as filter replacement, chemical loading, and water replacement and disposal costs.

Carlos Enriquez, Ph.D.

Charles P. Gerba, Ph.D.

University of Arizona

Copper/Silver Ionization Disinfection

Proper disinfection of swimming pool water is essential to prevent the transmission of pathogenic microorganisms. Several viral, bacterial, and parasitic agents have been associated to outbreaks in poorly disinfected recreational waters. Chlorine is the most commonly used disinfectant of swimming pools. This chemical has proved to be a very efficient disinfectant when used properly. However, its use may result in eye and skin irritation, undesirable odor and, more importantly, in the formation of trihalomethane compounds derived from the reaction of chlorine with organic matter. Alternative disinfectants include the use of electrolytically generated copper and silver ions. These metal ions are effective disinfectants against viruses and bacteria of concern in swimming pools. Furthermore, enhanced microbial inactivation is achieved when these metals are used in combination with low chlorine levels. Use of copper and silver ions in water systems currently used in swimming pools and spas may provide an alternative to high levels of chlorination.

Fernando del Corral, Ph.D.

Betty S. Johnson

Buckman Laboratories

Recreational Water Algaecides

The uncontrolled growth of algae in recreational water systems can be aesthetically displeasing, and, if left unchecked, can be costly and very labor intensive to clean up. In some cases, algae growth can even provide a breeding ground for bacteria, creating unsanitary conditions. The use of algaecides has customarily been utilized to aid the sanitizer in preventing algal blooms. Currently, there are 152 registered, non–oxidizing algaecide formulations for recreational water use in the United States (Pestbank 1996). Only 2 active classes account for most of the registered formulations. Forty–six percent (46%) of all formulations are alkyl/diakyl/dioctyl dimethyl ammonium chloride type (ADAC) formulations, 40% are polymeric quaternary ammonium chloride formulations, and 12% are copper–based products. Only a small fraction (2%) comprise combination–type products (i.e., copper plus ADAC). There are other non–conventional, non–registered approaches for algal control such as ammonium sulfate and lanthanum carbonate. Very little information has been recently generated and disseminated to the industry as a whole regarding the efficacy of commercial algaecides. Therefore, the objective of this study is to evaluate the effectiveness (algaestatic and algaecidal properties) of nine commercial algaecides against axenic cultures of Chlorella pyrenoidosa, Phormidium faveolarum and Eustigmatus vischeri. In addition, the bacteriostatic properties of each product will be evaluated impedimetrically against a common capsule forming coliform bacteria, Enterobacter aerogenes and an unknown pigmented (pink) organism isolated from a pool biofilm.

Mary Costanzo

Brian C. Bokowy

BioLab, Inc.

Bromine and Ozone: Chemistry and Operational Challenges Encountered in the Treatment of Heavily Used Commercial Recreational Water Systems

Commercial recreational water systems such as large municipal pools, aquatic centers, health clubs and interactive aquatic theme parks are challenging water treatment environments. Organic and nitrogenous input from heavy swimming loads can rapidly disable available oxidizer/disinfectant levels necessitating constant chemical monitoring and the adoption of ancillary processes to maintain premium water quality. This presentation will begin with a brief, albeit detailed, assessment of true–to–life bromine:ozone chemistry encountered in commercial arenas followed by a review of the critical ancillary processes necessary to satisfy water quality objectives.

Allen Clawson

DEL Industries

Side or Slipstream Application of Ozone and Ozone Dosing for Commercial Swimming Pools The side or slipstream process of ozone application to the main stream pool circulation water is reviewed, discussing economic, safety and performance issues and advantages. Mass transfer efficiencies and injectors are analyzed. Ozone dose parameters with details of chlorine/bromine reduction are discussed, as determined by case studies and historical data.

Charles P. Gerba, Ph.D.

Peter Gerba

University of Arizona

Enteric Virus Outbreaks in Swimming Pools

Human enteric viruses cause a wide range of diseases including gastroenteritis, fever, rash, hepatitis and meningitis, as well as nose, eye, and respiratory infections. Enteric viruses originate from infected individuals who excrete them in feces and nose and throat secretions. They are more resistant to inactivation by chlorine than enteric disease–causing bacteria and have been sporadically isolated from community wading and swimming pools. Outbreaks most commonly occur when there has been a failure to maintain and adequate disinfection residual. Documented outbreaks have been most commonly associated with adenovirus eye and throat infections, although outbreaks of hepatitis A virus and enteroviral illnesses have been reported.