Water Conditioning & Purification Magazine

Untimely passing of Jeremy Holt

Wednesday, April 25th, 2018

On August 23, Jeremy Ray Holt of Gilbert, Arizona, passed away unexpectedly. He was born May 7, 1970 in Orem UT to Ray and Jeana Holt and graduated from Orem High in 1985. Known for his great sense of humor, Holt was an avid reader and especially loved spending time with his family. He enjoyed cooking for and entertaining his many friends and family.

Holt’s roots in the water treatment industry went deep. His grandfather, Albert M. Rowley, Sr. founded Intermountain Soft Water in the early 1950s. Holt was employed by B&R Industries at the time of his death.

Survivors include Holt’s wife Gina, sons Anthony and Benjamin, daughters Jessika and Chelsey; his parents, brother Jeffrey, sisters Jenifer Horn and Rhonda Stout; grandmother Lucy Rowley and many others. He was preceded in death by grandparents Albert M. Rowley, Sr. and Ernest and Thelma Holt.

Funeral services were held August 27 in Gilbert. Donations can be made at the Arizona Federal Credit Union, account #779984 in the name of Jeremy Ray Holt.

Electronic Testing: Is It For You?

Thursday, November 19th, 2009

By Joe Sweazy

Electronic testing devices for pool and spa water analysis are prevalent these days. Some pool professionals are using them and love them, while others have purchased such sophisticated equipment and allow them to collect dust in a box.

How do you know if an electronic testing tool is the right selection? After all, aren’t all the electronic testers faster, easier to use and more accurate and precise?

The answer is yes . . . and no. There is no single electronic tester available today, unfortunately, that measures 25 parameters, costs less than $50 and has no limitations. For now, the industry must focus on what is available and what should be considered when switching to electronic testing. This may include something as simple as a pocket-style TDS meter or as complex as a nineparameter photometer/colorimeter.

Before discussing the various types of instruments available to measure the quality of pool and spa water, some important factors need to be considered in purchasing an electronic testing device.


When evaluating a new electronic testing solution for your water analysis needs, know that the up-front cost is going to be considerably more than a couple of bottles of reagent or a whole new reagent test kit for that matter. Less expensive, singleparameter meters start out around $75 (USD). Multi-parameter instruments will set you back around $150 or more, with some instruments costing close to $1,000.

When considering the investment, also anticipate the cost of additional reagents, including calibration standards. It is often helpful to calculate the costs on a per-test basis, which will allow you to make a comparison to other testing methods or a competitive unit.

A single unit, for example, may be capable of measuring five different parameters. Each parameter may only require one reagent. In comparison, a liquid test used to test the same five parameters would likely require more than one reagent per test (some require as many as three). The costs of operating the electronic meter, therefore, may be better than you might expect by just comparing the costs of the reagents.


How easy does the instrument appear to operate? Review the activation and technique required to complete a test and consider how error may be introduced. This is an especially important question if you perform many tests in a day and/or share the testing responsibility with someone who would have difficulty using the instrument regularly.

Also consider the speed with which the testing is completed. Does it take more or less time than your existing method and what does that mean to you?

Many manufacturers will have operating instructions online. They may even have the complete manual available for free download. It can be very helpful to review this documentation prior to purchasing a new unit.


Accuracy and precision are always big factors when looking to upgrade to electronic testing. It is logical that when using electronic tests, more accurate and precise results should be achieved.

That may not always be the case. Fortunately, this should be easy to investigate. Most manufacturers will provide this information in some form.

Determine the expected accuracy (how close to the actual value) and precision (repeatability) by reviewing the sales materials available for any particular unit. If this information is not available, you may want to ask yourself ‘why not’?


Does the unit require periodic calibration and, if so, how difficult is it to perform? Many instruments require some form of calibration.Make sure to understand the recommended frequency of unit calibration. The cost of calibration standards should also be known in advance, in order to avoid the surprise of spending $40 or more on the appropriate calibration standards.


Like accuracy and precision information, the limitations of any instrument should be readily available. Pay careful attention to the operational ranges of the instrument to be sure that it will meet your testing needs.

Take note of any interfering substances that would affect test results. It would be a shame to purchase an instrument that is not recommended for use when hardness levels exceed 500 ppm if the hardness in your area is at least that high straight out of the tap.

Manufacturers may not be as forthcoming with the interference information, but this information is necessary and obtainable nonetheless. For example, pH and temperature limitations for ORP are well documented and plenty of information is available on this topic.

The instruments

Taking all of the noted factors into consideration, a wise decision can be made about the meter that best fits testing needs. Regardless of the instrument selected, the real benefit is that it can eliminate some of the guesswork that is typically required.

Many users find comparing a reacted color to a color standard very difficult, if not impossible. Instruments may be ideal for those with poor color acuity or some form of color blindness.

However, switching to electronics does not necessarily protect users from themselves. User error can still contribute to inaccuracies, as is the case with any testing method.


For some of the parameters regularly measured in pool and spa water, an analysis can be performed with a simple push of the button. For example, pH can be measured by a portable pH electrode that can be partially submerged into the pool or spa and the appropriate button pushed to activate the reading.

Unfortunately, this technology does not test all the important parameters in pool and spa water. These sensors typically measure pH, TDS, salt, ORP and temperature.

The latest in sensor/electrode technology allows some or all of these parameters to be measured on one unit at a price that is not a major investment. Several manufacturers now offer systems that are capable of measuring pH, TDS, salt, ORP and temperature in seconds, all with the same instrument. The least expensive of these instruments typically sells for around $350.

ORP and pH are measured in much the same way by these types of systems. Voltage is generated between a reference electrode and a measuring electrode with pool water in between.

A change in the current equals a change in the measured value. Even though there are two electrodes, these are often contained inside a single unit, giving it the appearance that it is just one probe. It is important to point out that ORP does not replace regular monitoring of free available chlorine. Regulations require testing free chlorine even in systems fit with ORP-monitoring ability.


Conductivity results are used to approximate total dissolved solids and salt. Conductivity is the measure of the water’s ability to conduct an electrical current.

A reference solution with known concentrations is used as a calibration standard. The unit then assumes the water ‘makeup’ is similar to that of the standard and measures its ability to conduct an electrical current that is converted into a salt or TDS reading, depending on the setting and calibration.

This is really just an approximation as conductivity, however, not a direct measurement of total dissolved solids or salts. But it is a fast and easy method that can provide a close approximation. Advantages include electrode systems that provide near instant results for the parameters that they are capable of measuring. Often the same unit can measure several parameters by switching modes. No additional reagents are needed for regular testing.

The results can also be highly accurate and precise depending on the instrument. These instruments are typically easy to use and operate with little or no training required. This technology is also suitable for continuous on-line monitoring.

The disadvantages are that electrodes require careful handling and cleaning/rinsing after each use with distilled or deionized water. It is also important to carefully follow the manufacturer’s recommendation for storage of the electrodes. These systems also require periodic calibration and it may be difficult to tell when they are not reading accurately.

Colorimetric tests

This type of electronic instrument is often referred to as a photometer or colorimeter. Either way, the basic technology is the measurement of light intensity at defined wavelengths as it passes through a reacted sample. A calculation based on a set calibration curve allows the measured value to be converted to appropriate value of the measured parameter.

This technology continues to improve as reagent technology improves. As great as these systems can be, they are reliant on the reagents (liquid, tablets or powder pillows) for getting accurate measurement. As reagents are improved and use life is extended, therefore, colorimeters become more accurate and reliable.

Additionally, the cost of these systems has dropped some in recent months, as low-cost optics and internal components become available. Some multi-parameter colorimeters can now be had for less than $150.

Most significant pool and spa parameters have the advantage that they can be measured with this technology, with several available in combinations with as many as 25 tests available on one unit. These instruments provide a high degree of accuracy and precision. They will typically meet all regulatory requirements for testing. Most parameters require only a single reagent for testing.

Disadvantages are that reagents are required for this testing. This adds cost and handling concerns. Additionally, these systems may take a longer time to complete tests due to the mixing and testing completion times.

Reflectance meters

Reflectance testing is the newest technology to enter into the pool and spa market. This type of system utilizes test strips instead of reagents to measure the intended water parameters.

A test strip is reacted and placed on the clear channel where light is reflected off of the reacted test pads. The reflected value is then read by an optical reader that allows for a colorimetric measurement. This measurement is then converted by complex algorithm to calculate concentrations of the measured parameters. Such technology has been used in the past in the medical industry for measuring blood glucose levels.

Advantages are that quick and easy tests for a few critical parameters can be done at one time. For example, a three-way test for free chlorine, pH and alkalinity can be completed in 30 seconds. The cost of replacement reagents is very low, as test strips are generally inexpensive. The up-front cost of these systems is also very inexpensive compared to other electronic testing

The technology is dependent on test-strip results in order to calculate the water analysis, which is a disadvantage. Test strips also will yield slightly more variation and, therefore, less precision than other comparable methods. Plus, not all parameters are currently available.

When selecting an electronic testing instrument there is much to consider. Keep the types of electronic testers in mind as well as their advantages and disadvantages to determine which unit is the best.

About the author

Joe Sweazy is Technical Sales and Services Manager for HACH Company/ETS Business Unit,  manufacturer of numerous water quality products and test devices in use around the world. He has published more than a dozen articles on pool and spa water chemistry and has presented numerous seminars at conferences of the Association for Pool and Spa Professionals (APSP) and at the World Aquatic Health™ Conference. He may be reached at jsweazy@hach.com.

Progress in Pool Chemistry Research Understanding Disinfection Byproducts and Combined Chlorine

Thursday, November 19th, 2009

By Susan B. Rivera, Ph.D., CPO

While researchers recognize the health benefits derived from swimming, others have identified exposure to the air above the pool water during swimming as a possible link to increased respiratory illnesses.

Swimming pools require disinfection for inactivation of waterborne microbial pathogens. In most cases, a halogen-based compound—usually chlorine—is used as the disinfectant. Chlorine also serves the function of oxidizing contaminants introduced by the swimmers.

These disinfection (biological) and chemical (oxidative) reactions are some of the most complicated water chemistry systems to understand and manage. Recent research has provided insight into how UV and chlorine react with the bodily fluids and microorganisms introduced into pools, predominately by swimmers.

Why chlorination?

Chlorine is the most cost-effective means of sanitizing a swimming pool. Recreational water outbreak analysis from the past 20 years demonstrates inadequately disinfected pools have been fully or partially responsible for the outbreaks since the chlorinesensitive organisms simply were not inactivated in the waters.1

In the early 1900s, prior to adequate disinfection, tens of thousands of people died from waterborne disease. The filtration and disinfection of drinking water is widely acknowledged to be responsible for a large part of the 50 percent increase in life expectancy in this century.

The US Centers for Disease Control (CDC) and Prevention recognizes the control of infectious diseases from cleaner water and improved sanitation as one of the top 10 public health  achievements of the 20th century.

Unlike water distribution systems that deliver water to your tap, pool water is recirculated every six to eight hours through some type of filtration system. During this time, swimmers’ activity provides a broad range of precursors with which disinfectants can react.

When chlorine reacts with these precursors, a variety of chemical reactions take place, including the formation of disinfection byproducts (DBPs). Standard pool filtration systems are ineffective at removing the precursors. In fact, it is the chlorine sanitizer that helps remove pollutants introduced by swimmers via oxidation reactions.

In the US, the accepted free available chlorine (FAC) concentration in pool water is one to five mg/L, but most operators maintain pools at two to four mg/L of FAC. FAC is defined as the sum of HOCl, OCl– and Cl2(aq) (all expressed as chlorine) and is commonly measured using a colorimetric method, known as the DPD method.

Several different pool test kits are available and utilize the DPD technology, either as a direct colorimetric measurement or a modification involving titration drop-wise to a colorless endpoint using ferrous ammonium sulfate (FAS). One of the concerns with chlorine is that the formation of chlorinated DBPs, especially volatile DBPs, may promote respiratory ailments.

The smell and irritant properties of swimming pool air have traditionally been attributed to inorganic chloramines, not free chlorine. Trichloramine has been reported to function as the irritant to the eyes and upper respiratory tract. However, studies have conflicted as to whether volatile chloramines are responsible for asthma and other respiratory illnesses linked to pools.

The reactions of chlorine with organic nitrogen-containing compounds (aka organic amines) in pool settings are still not well understood, but recent research is providing new insights into complicated pool chlorine chemistry. Historically, pool disinfection studies focused on the well-known reactions associated with the oxidation of ammonia, with trichloramine (NCl3) being the most infamous volatile DBP. It was not until 2007 that studies of chlorine reactions with organic amines were reported. Two of these papers provide insight as to potential directions forward in pool management.

Volatile disinfection byproduct analysis from model compounds known to be introduced by bathers

Air quality in indoor swimming pools has emerged as an area of concern with respect to human health. While researchers recognize the health benefits derived from swimming, others have identified exposure to the air above the pool water during swimming as a possible link to increased respiratory illnesses.

Dr. Ernest Blatchley and colleagues at Purdue University have recently made progress in developing a sensitive technique to measure DBPs. It is called membrane introduction mass spectrometry or MIMS. The technique may be used to detect and analyze volatile compounds in aqueous samples.

The membrane allows gases to enter into the mass spectrometer’s chamber where molecules are identified according to their mass and then quantified by selected ion monitoring. MIMS can measure a variety of volatile molecules, providing quantitative and structural data about volatile DBPs in aqueous samples.

Using this technique, these researchers evaluated the volatile compounds released during reactions of chlorine with four model organic compounds known to be introduced by bathers.2 The organic pollutants selected included urea, creatinine, L-histidine and L-arginine, all organic nitrogen-containing components found in human sweat and urine.

These results showed that common organic pollutants introduced during swimming activities contribute to the formation of trichloramine (NCl3). Other DBPs, including chloroform (CHCl3), cyanogen chloride (CNCl), dichloroacetonitrile (CNCHCl2) and dichlormethylamine (CH3NCl2) were also detected, as shown in Table 1. This was the first time another precursor other than ammonia had been demonstrated to produce NCl3.

Volatile disinfection byproduct analysis of chlorinated indoor swimming pools

The researchers went on to look at the distribution of disinfection byproducts in 11 different types of indoor pools over a six-month period.3 One of these was a spa.

The goal of the study was to identify volatile DBPs and their concentration ranges in chlorinated indoor swimming pools. Ten volatile inorganic and organic chloramines were identified as persistently existing, though the concentrations varied by nearly four orders of magnitude between the pools analyzed.

In addition to the volatile DBPs identified in the model study described above, brominated DBPs were also identified. It is thought that these compounds were derived from bromide that tends to accumulate over time unless water is exchanged.

Bromide is oxidized by chlorine to produce HOBr, the cousin to HOCl. HOBr can lead to the formation of brominated DBPs. Among halogenated DBPs, bromine-substituted compounds tend to display greater toxicity than their chlorinated analogs.

Free chlorine was also measured using DPD technology. This is the technology used in many pool test kits. The research indicated that 16.7 percent of the samples had a free chlorine concentration below 1.0 mg/L, the suggested lower limit by the National Swimming Pool Foundation (NSPF).

Several of the pool water samples had undetectable amounts of FAC, a cause for great concern. Pool operations rely on the presence of free chlorine to inactivate waterborne microbial pathogens and oxidize pollutants, even if other technologies such as UV are in place.

Combined chlorine (CC) was also measured using both DPD technology and MIMS, the more accurate analytical method. In the case of MIMS, direct quantitative measurements can be  made while with DPD, CC is calculated from the total chlorine (TC) and FAC measurements using the following equation: CC = TC- FAC


The methods showed that the DPD method consistently overestimates inorganic chloramine content in swimming pools. Using the MIMS method, 75.9 percent of the pools had inorganic combined chlorine concentrations that exceed the NSPF guideline of 0.2 mg/L for pools and 0.5 mg/L for spas.

Among the spa samples, 29.0 percent were above 0.5 mg/L. Using DPD, the number of pools over the 0.5 mg/L CC limit were 95.9 percent of pool samples and 96.8 percent of spa samples. The sources of interference of the DPD reactions are largely undefined, but their existence suggests that use of DPD-based methods as the only method to estimate inorganic chloramines may lead to inappropriate pool maintenance practices, particularly related chlorination was largely developed based on knowledge of the so-called breakpoint reaction where ammonia is oxidized to nitrogen gas, with mono-, di- and tri-chloramine as intermediates along the pathway.

Outcome goals

If the DPD reaction is also measuring organic chloramines, then the philosophy surrounding chlorine shocking may need to be adjusted. Possibilities include installing automated controllers to periodically increase chlorine concentrations overnight to help drive the breakpoint of the inorganic chloramines in the pool, allowing the FAC to return to acceptable levels prior to opening the next morning.

This type of strategy would avoid the need to dechlorinate. Another strategy is to install additional technologies to supplement the disinfection and oxidation properties of chlorine. These include UV, which has shown promise in photolysing inorganic chloramines in pools with good filtration.4

Another goal for industry leaders should be to actively promote the development and manufacture of a low-cost device to accurately measure volatile inorganic and organic compounds.

Specific goals for the industry might include:

1) Developing an affordable field-ready MIMS device 2) Guidance documents to assist pool operators and regulators to determine when a pool is truly out of compliance for combined chlorine
3) Additional third-party studies to evaluate DBPs associated with ozone, chlorine dioxide, monopersulfate, electrochemical methods of generating chlorine-based disinfectants and other commonly used disinfection and oxidation chemicals. These data can then be used to better understand the mechanism of formation for DBPs and the subsequent advantages and  disadvantages of each type of disinfection chemistry. Not all oxidants and chlorinebased disinfectants are equal.5

Great progress in understanding pool chemistry has emerged over the past few years. As technologies and analytical approaches improve, consideration of how to alter pool management guidelines and policies will follow. The information provided by the research will be beneficial in the development of multibarrier treatment technologies and control strategies to provide adequate disinfection in the pool while minimizing DBP formation.

Increased efforts have also been made to educate the public regarding the benefits of showering before entering the water and refraining from urinating in the pool. Minimizing precursor introduction (lotions, dried sweat, dirt, urine) will likely go a long way to improving swimming pool chemistry.


  1. Centers for Disease Control Healthy Swimming Website http://www.cdc.gov/healthySwimming/
  2. J. Li and E. R. Blatchley, “Volatile Disinfection Byproduct Formation Resulting from Chlorination of Organic-Nitrogen Precursors in Swimming Pools,” Environmental Science & Technology. 2007, 41, 6732-6739.
  3. W.A. Weaver, J. Li, Y. Wen, J. Johnston, M.R. Blatchley and E. R. Blatchley, “Volatile Disinfection By-product Analysis from Chlorinated Indoor Swimming Pools,” Water Research 2009, 43, 3308-3318.
  4. J. Li and R.R. Blatchley, “UV Photodegradation of Inorganic Chloramines,” Environmental Science & Technology. 2009, 43, 60-65.
  5. One of these technologies includes mixed oxidants and two include in-line salt water chlorinators and mixed oxidants. A summary of disinfection and oxidation advantages of mixed oxidants can be found in the document entitled “Master Features Summary.pdf” located in MIOX’s library at www.miox.com.

About the author

Dr. Susan Rivera is the Manager of Research and Development at MIOX Corporation. She holds a Ph.D. in biochemistry from the University of Utah and a Certified Pool Operator (CPO) certification from the National Swimming Pool Foundation. Rivera assists customers with pool disinfection management and has traveled overseas to consult on pool disinfection issues. She has been a member of the WC&P Technical Review Committee since September 2007.

About MIOX Corporation

MIOX Corporation, based in Albuquerque, NM, is focused on solving one of the world’s most pressing issues: the need for affordable, safe and healthy water. MIOX’s patented water disinfection technology replaces the need to purchase, transport and store dangerous chemicals. The company has over 1,500 installations, with equipment used in over 30 countries. MIOX equipment is used in recreational water venues, in hundreds of communities across the US for public drinking water systems, water reuse projects and a variety of commercial and industrial applications. More information is available at www.miox.com.

Situation Aeromonas

Monday, October 19th, 2009

By Kelly A. Reynolds, MSPH, Ph.D.

While driving my three kids to school this morning, the oldest (at 10 years of age) asked, “If you have to get a germ, what one would be best to get?” Indecision set in as I pondered various disease-causing organisms, their relative morbidity and mortality rates, population vulnerabilities, economic loss potentials, etc.

As their eyes glazed over, I continued thinking about the difficulties in ranking the importance of microbial pathogens. The process is not as straightforward as one would imagine. While the identification of any waterborne disease agent promotes the immediate need for control, careful consideration of an organism’s characteristics is necessary to develop effective and practical solutions. Aeromonas hydrophila is a great example of the difficulties encountered in prioritizing actions against waterborne pathogens.

The bacterium is surrounded by a significant amount of uncertainty relative to health effects and regulatory needs. POU devices, interestingly, complicate the story.

A repeat offender

As required by the 1996 amendments to the Safe Drinking Water Act, the US EPA must make regulatory decisions on at least five contaminants (microbial and chemical) every five years. In 1998 and again in 2005, Aeromonas hydrophila was one of more than 50 contaminants listed on the first and second issue of the US EPA’s Contaminant Candidate List (CCL 1 and CCL 2).1,2

The CCL is a list of unregulated contaminants known or suspected to occur in water and may
require federal regulation. A new, updated CCL is published approximately every five years.

Aeromonas’ repeated presence on the CCL led to the gathering of new and previous information to inform the US EPA about possible directions for understanding and controlling the bacterium in drinking water. Options included developing an enforceable regulation, developing suggested guidelines or to not regulate the organism.

The US EPA publication (2006), Aeromonas: Human Health Criteria Document provides an extensive review of the Aeromonas situation, including physical properties of the organism, transmission in humans and animals (fish, amphibians, reptiles, birds, domestic animals) and possible public health effects. A comprehensive description of what is known about the organism helps to identify key data gaps and inform best practices for appropriate controls.

Aeromonas is associated with human illness, including some severe infections. It is also readily found in just about any aquatic environment, including well water, treated drinking water and
purified drinking water.

Why then is this human pathogen not even listed on the CCL 3 list released in February 2008?

Is it a pathogen?

The US EPA website (http://www.epa.gov/ogwdw/ccl/basicinformation.html) lists three primary factors that are considered when determining whether or not to regulate a waterborne contaminant:

  • the extent of occurrence of the contaminant in drinking water
  • projected adverse health effects from the contaminant
  • whether regulation of the contaminant would present a ‘meaningful opportunity’ for reducing risks to health

Aeromonas bacteria are naturally present in all types of waters (ground, surface, marine, drinking and wastewater) around the globe. In drinking water systems, they are partially responsible for the development of biofilms that can alter the efficacy of treatment processes. They are also common contaminants of food (produce, seafood, deli meat, cheese, milk) and often present in feces and sewage even after treatment.

It is not uncommon, therefore, to be exposed to Aeromonas from a variety of sources. In fact, researchers believe that ingestion of Aeromonas is ‘continuous.’3

So, why aren’t more people getting sick? Concentrations in food are generally much higher than in drinking water and thus, control of exposures in water alone might not be meaningful
given other environmental transmission routes.

Health effects in humans related to Aeromonas infections have been specifically identified since the late 60s in both healthy and immunocompromised populations. Diarrhea, blood infections, meningitis, eye infections, pneumonia, wound infections and other illnesses are well documented.

Chronic exposure to untreated water and contaminated foods are suspected factors in known cases of illness. Despite consistent levels of the bacteria in treated drinking water, however, no waterborne disease outbreak due to Aeromonas in treated drinking water, from any point source, has ever been reported


This is where the story gets complicated. In an attempt to quantitate the infective dose of the bacterium (i.e., how many are needed to make you sick) researchers conducted a controlled human feeding study. The study, unfortunately, failed to identify significant illness rates in the test population even when 100 million colony forming units (CFU)—orders of magnitude higher
than typical water concentrations—were ingested.4

Such data inconsistencies complicated the understanding of Aeromonas. The development of new methods for isolation and characterization of the organism revealed genetic differences in the bacterial populations that coded for variable health effects.

These variations resulted in a previous misunderstanding of the importance of Aeromonas when isolated from a particular environment. New data showed that some species of the genus cause illness in animals and humans while others do not.

In fact, most strains found in the environment (including drinking water sources) are considered harmless for healthy populations. The strain used in the feeding study mentioned above was, in fact, one with minimal virulence factors.

Regrowth in POU devices

Improved characterization of aeromonads was a relief to the drinking water treatment industry as debate raged in the early 2000s regarding regrowth of ubiquitous bacteria in POU treatment devices. Aeromonas was a particular concern in POU purification devices utilizing carbon filtration where studies showed that counts of the bacteria post-treatment were often higher than in the influent.5 In both tap and purified water sources, however, levels were not high enough to cause gastrointestinal illness (10 CFU/mL in tap water and 29.5 CFU/mL in POU effluent) regardless of strain virulence.

Sand filtration and common disinfectants utilized in municipal drinking water treatment are effective at inactivating Aeromonas. Within the biofilm environment, however, populations remain protected and can persist in the drinking water distribution system.

Ubiquitous in soils, distribution systems are easily contaminated during routine maintenance practice. Regrowth is expected relative to nutrient and temperature increases (> 15°C/59°F) and low disinfectant residual (< 0.2 mg/L free chlorine).

Off the hook?

Regulatory standards for Aeromonas are in effect in The Netherlands (drinking water; 200 CFU/100 mL) and Canada (bottled water). No disease outbreaks, however, have been reported in relation to treated drinking water. Neither has a causal relationship with waterborne gastroenteritis and aeromonads been shown. Coupled with insignificant epidemiological data and inconclusive human feeding studies, little evidence exists for implementation of broad-spectrum controls.

Aeromonas is not necessarily off the hook as a pathogen of concern. Persons with diarrhea are more frequently colonized with the bacteria and shed higher numbers in the stool than those with asymptomatic infections. Peak isolation from human stools corresponds to seasonal peak concentrations in the environment during warmer months.

Infections in humans are caused by one of seven species but primarily due to either A. hydrophila, A. sobria or A. caviae. A. hydrophila causes about twice as much illness than each of the latter two. Infection typically occurs in children under five years old, the elderly or the immunocompromised, especially those with cirrhosis, cancer, diabetes or other serious ailment.

An understanding of individual host factors is now needed to determine the causal relationship between Aeromonas species and human disease. Normal flora of the gut is a complicated mixture of bacteria living in a delicate balance that differs among individuals in diversity and relative composition. Disruption or incomplete colonization of the gut flora whether due to age, chronic illness or antibiotic therapy likely plays a role in manifestation of Aeromonas infection.

Although untreated water supplies (specifically well water) have been traced to infection in humans in epidemiological studies, molecular analysis of strains isolated from the feces of ill individuals indicates dissimilar characteristics compared to common environmental isolates. This suggests a different source of infection.

What’s next?

After Aeromonas was listed on the CCL, nearly 300 distribution systems surveyed in the US were monitored for a year. Aeromonads were found in 14 percent of the samples and were more prevalent in smaller (< 10,000 customers served) municipalities and those with a groundwater source.

Typical concentrations in treated drinking water are low (< 10 CFU/100 mL). Concentrations in groundwater are also very low (< one CFU/mL) but are more likely to regrow and increase in the distribution system to > 200 CFU/mL.6 These values are still well below the infectious dose and several orders of magnitude below typical concentrations in food.

Several unidentified factors appear to be necessary to cause illness in humans as correlations with virulence factors or genetic characteristics are not evident. While the role of Aeromonas in human disease remains controversial and not well understood, treated and purified drinking water is no longer a primary area of concern for minimizing exposure of the general population.


  1. USEPA. 1998. Announcement of the drinking water contaminant candidate
    list; Notice. Federal Register. 63:10274-10287.
  2. USEPA. 2005. Drinking water contaminant candidate list 2; Final Notice.
    Federal Register. 70:9071.
  3. USEPA. 2006. Aeromonas: Human Health Criteria Document. Health and
    Ecological Criteria Division. Office of Science and Technology, Office of
    Water. Washington, D.C. pp. 1-198.
  4. D.R. Morgan, P.C. Johnson, H.L. DuPont, T.K. Satterwhite and L.V.
    Wood.1985. Lack of correlation between known virulence properties of
    Aeromonas hydrophila and enteropathogenicity for humans. Infection
    and Immunity. 50: 62-65.
  5. C. Chaidez and C.P. Gerba. 2004. Comparison of the microbiologic quality
    of point-of-use (POU) treated water and tap water.
  6. P. Holmes, L.M. Niccolls and D.P. Sartory. 1996. The ecology of mesophilic
    Aeromonas in aquatic environment. In: B. Austin, M. Altwegg, P.
    Gosling & S.W. Joseph (Eds.) The Genus Aeromonas. John Wiley & Sons,
    New York, NY, pp. 39-76.

About the author

Dr. Kelly A. Reynolds is an Associate Professor at the University of Arizona College of Public Health. She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds has been a member of the WC&P Technical Review Committee since 1997. She can be reached via email at reynolds@u.arizona.edu.

Monitoring Activated Carbon Drinking Water Filters

Monday, October 19th, 2009

By Henry Nowicki, George Nowicki, Wayne Schuliger and Barbara Sherman

More likely than not, your municipal drinking water has been filtered with activated carbon (AC). Municipal drinking water plants are mandated by the US EPA to purify drinking water supplies in major cities with activated carbon filters.

Domestic POU/POE devices rely on activated carbon adsorption. Pour-through pitchers, in-line filters on kitchen faucets or refrigerator cold water or ice-cube makers are becoming standard applications for AC purification.

Activated carbon POE units can protect a whole facility water supply, like restaurants or recreational vehicles. All of these applications use activated carbon, which is the best available technology (BAT) to treat drinking water.

These activated carbon filters require periodic monitoring to validate their performance. Activated carbon does not last forever and does need to be changed when it becomes exhausted.

The new concept presented here is for a low-cost and easy-touse monitoring tool. This has been dubbed the AC tester, which can help maximize performance (Figure 1).

Activated carbon

Activated carbon is a crude form of graphite, randomly oriented graphitic platelets.1 In drinking water applications, coconut shells and bituminous coal are the major raw source materials to manufacture AC.

These starting materials are sized and carbonized, which increases the materials’ percentage of carbon. After carbonization, they are activated to develop porous and microporous structures to provide surface areas of 800 to 1,200 m2/g.

This exceptionally high AC surface area is responsible for physical adsorption performance. It is also an asset to improving toxicity, taste and odor removal in water supplies and air streams. (A schematic representation for coconut and bituminous coal based AC is shown in Figure 2).

Initial starting granular activated carbon (GAC) adsorption spaces in AC applications have nanometer (nm) sized wall-to-wall spaces called micro-pores. These one to three nanometer-spaced (nm) graphitic platelets provide the strongest adsorptive forces to remove trace soluble contaminants from water or air.

Classically, activated carbon pores have been divided into micro-, meso- and macro-pores. Dr. Mick Greenbank has simplified the classical distribution of pores into adsorption and transport, which is functional, descriptive and easier to understand.2

Water treatment

Water treatment is done by passing water to be purified through fixed-bed adsorbers containing GAC. In municipal plants, these beds are typically three feet deep, but can go up to nine feet.

Historically, sand was used in these water filters to remove suspended solids. Most operations today use GAC as a replacement for sand or anthracite; GAC provides trace dissolved organics adsorption in addition to filtration of suspended solids. Many plants still leave a couple of inches of sand or anthracite underneath GAC.

Under the adsorber bed, media is the underdrain system that separates finished water from solid media. After GAC treatment, disinfectants are added. This is done to minimize the formation of disinfection byproducts and provide residual antimicrobial agent to consumers’ water tap.


Drinking water plants copiously wash initial GAC before putting it into services2 using American Water Works Association (AWWA) guidelines, as this organization provides much of the leadership for drinking water plant operations.

The GAC preliminary water washings remove fine dust and floaters and stratify the bed. This is done by backwashing the bed to suspend GAC particles. When the backwash valve is slowly closed, larger particles sink fastest and smaller particles are located on top of the stratified bed.

Backwashing is an important process parameter to remove GAC filtered particles accumulated from influent. Since these GAC filters operate by the force of gravity, removing accumulated fine particulate matter keeps them flowing and avoids development of head pressure.

Many GAC filter systems have automatic controllers to ensure routine backwashing. As the name implies, the GAC filter bed is raised by directing water up through the underdrain.

The stratified bed is raised about 50 percent to float away the low-density fine particulates filtered out by GAC. This dislodged filtered material is then carried away in a trough above the stationary filter bed. It is important to let backwashed suspended GAC particles settle slowly. This allows larger and heavier GAC particles to return to the bottom of the bed and the smallest, lightest particles to remain at the top when the bed is put back into service. Returning the bed to its proper original stratification maintains the mass transfer zone (MTZ), the region in which the concentration of adsorbate(s) in water decreases from influent concentrations to the lowest detectable concentration.

If the operators close the backwash valves too quickly, smaller particles (which have the highest adsorbate loadings) will become stratified throughout the settled GAC bed. Since GAC particles equilibrate with the surrounding water, a dislocated GAC particle deeper in the bed, loaded with adsorbates, can facilitate premature contaminant breakthrough.

AC tester

The original idea for an AC tester came from attending a short course3 by Dr. Milton Manes. He stated, “if you put a pound of activated carbon into a plastic bucket containing gasoline, the bucket would melt due to the exothermic adsorption heat.”

This idea was reduced to practical application for GAC monitoring.4 The original concept was scaled down to a handheld device (Figure 1).

It is easy to assemble an AC tester device. All you need is a reservoir to hold the solvent into which you immerse the AC specimen to be tested and a thermometer to measure the heatof-immersion (HOI) temperature rise.

We recommend using mineral oil as the solvent because it is readily available around the globe. It is inert, non-toxic, has relatively low competitive desorption capacity and has a high boiling point. Adsorption heat will thus be maintained in the liquid and not boiled away, if you use a low-boiling solvent.

The reservoir should have calibrated, graduated volume marks on its straight edge side . A 30-mL line needs to be marked on the AC tester.

A thermometer should be included which has calibrated, graduated marks from 10 to 30°C (50 to 86°F), with marked increments of 0.5°C (32.9°F). It is possible to estimate the AC heat-of-immersion adsorption temperature rise to a tenth of a degree in this simple device.

Test methods using this device have been continually used, with new applications still being found. Application for confirming incoming GAC quality and location of mass transfer zones in drinking water activated carbon beds has also been documented.

Test utilization

Using an AC tester is designed to be easy, with only low-cost equipment and operator skills required. Typically, a level tablespoon of GAC is sufficient to provide a good maximum temperature rise in about two minutes in the AC tester. It is easy to check incoming loads of activated carbon.

Do not rely solely on this easy test, however. Compliment it with official standard AWWA2 and ASTM5 test methods. Vendors provide these standard tests, which can be checked and verified with experienced and qualified laboratories.

Compare unused GAC with used GAC sampled from your operational adsorbers. Unfortunately, experience has shown that most activated carbon users do not retain a representative sample of media installed into the adsorbers. This is easy to fix by collecting GAC samples and storing them in clean, airtight containers similar to paint cans.

For example, if unused and used GAC both give a 4.0°C (39.2°F) rise in the starting mineral oil temperature, the carbon is like new. But if used GAC has only a 1.0°C (33.8°F) rise, the adsorption space is nearly filled and not likely to be working well.

Monitoring results

Core GAC samples were taken from two settled GAC beds at a municipal drinking water plant (Table 1). The core samples were placed on absorbent paper to remove bulk water. After air drying, composite samples were taken every four inches from the top of each bed to the bottom. HOI was determined in the AC tester, as well as densities according to ASTM5 (results are reported in Table 1).

Whether a large (20,000-pound/9,071-kilogram) AC municipal unit or a small (one pound/0.45 Kg) POU device containing AC is put into service, heterogeneous adsorption spaces are empty. As a water or air stream is passed through, adsorption spaces fill by taking materials out of the passing stream.

Eventually, useful adsorption spaces fill, with little or no adsorbate difference between influent and effluent streams. At equilibrium, used AC will have its smallest increase in temperature rise in the AC tester compared to the unused starting AC for that application.

AC monitoring tools

Prior articles have described other activated carbon monitoring methods.6,7 The method described with the AC tester is a low-cost approach within official ASTM and AWWA test methodology, 2,5 which are the cornerstones of the activated carbon industry. Such advanced test methods2,6,7 are pushing the carbon envelope.

Many more sophisticated test methods are relatively expensive compared to the AC tester. While a practical tool, it needs to be used in conjunction with classical and advanced test methods to help make the best decisions about purchasing and monitoring working activated carbon adsorption systems. AWWA, WQA and other consultants can provide educational programs to help explain these methods and what they provide users.

Gravimetric Rapid Pore Size Distribution (GRPD) method can be applied to the unused and used GAC to help reveal the pores which are filled during a particular application.6 Knowing which pores are filled can help select the best AC for the application by using a carbon which supplies the needed pores. The GRPD sister method7 helps to better understand fine micropores, which are the strongest adsorption pores.

Other applications

When users are purchasing large amounts of GAC, the AC tester makes it possible to run many samples at the job site. This test is fast and easy to do. It requires no sample preparation. Sending samples for ASTM and AWWA laboratory testing may take a few days or weeks to get the results back. The AC tester can yield results in a few minutes. By running a lot of incoming samples, this provides a statistical analysis of your newly installed GAC.

Manufacturers can use the AC tester at the production line. Getting product quality data in a few minutes after it comes out of the furnace allows operators to have timely information. Instead of sending samples to the lab for iodine numbers to get results the next day, it makes sense to have a nearby on-line quality check for AC products as they come out of the furnace.

The AC tester has been found useful for all forms of activated carbon: powder, granular, pellets, fabric, felts, composites and nanomaterials. Pellets are often used in vapor-phase applications because they provide the least resistance to drive air through the bed.

To get samples of pellets for the AC tester, lining up 150 to 200 millimeters (5.90 to 7.87 inches) of length provides a reproducible sample to deliver to the AC tester. Tablespoons of GAC are reproducible, but pellets do not pack in this small space reproducibly. Pelleted samples are reproducible on a linear (end-to-end) continuous segment.


  1. Greenbank, Mick. “New Model for Activated Carbons.” International
    Activated Carbon Conference. Pittsburgh, PA. October 2002.
  2. American Water Works Association (AWWA), Granular Activated
    Carbon ANSI Effective date: March 1, 2006.
  3. Manes, Milton. Two-day PACS Short Course “Activated Carbon Principles
    and Practices.” May 1998.
  4. Nowicki, Henry. “New test method for activated carbon remaining
    service life.” 6th International Activated Carbon Conference and Courses.
    Pittsburgh PA 1998.
  5. American Society for Testing and Materials (ASTM) under jurisdiction
    of Committee D-28 on Activated Carbon 2nd Edition 2000.
  6. Nowicki, Henry et. al. “GRPD Comparison of Unused and Used
    Drinking Water Activated Carbons” Water Conditioning and Purification
    April 2009 pg. 32-37.
  7. Nowicki, Henry et. al. “New Trace Capacity Test Method for Future
    Activated Carbon Applications” Water Conditioning and Purification June
    2009 pg. 22-27.

About the authors

Henry Nowicki, Ph.D. and MBA, provides the introductory course for the Activated Carbon School titled ‘Activated Carbon Adsorption: Principles, Practices, Applications and Opportunities.’ Dr. Nowicki directs the day-to-day routine and advanced testing, R&D, and consulting services for PACS. He can be reached at (724) 457-6576, by e-mail at henry@pacslabs.com or at the company web site at www.pacslabs.com.

Wayne Schuliger, P.E. provides the PACS short course titled ‘Design, Operation and Trouble Shooting Activated Carbon Adsorption Systems.’ He utilizes his 40 years of activated carbon adsorption engineering experiences to help solve client problems through on site and Internet consulting services. He can be reached via e-mail at wayne@pacslabs.com.

H. George Nowicki, BS and BA, is the manager for PACS Laboratories and new business developer for PACS. He can be reached by e-mail at george@pacslabs.com or by calling (724) 457-6576.

Barbara Sherman, BS and MBA, is the operational manager for PACS Testing, Consulting, R&D, Training and Conferences. She directs the day-to-day short courses, conference and business for PACS. She can be reached via e-mail at barb@pacslabs.com.

About the company

Professional Analytical and Consulting Services, Inc. (PACS) is in its third decade of providing activated carbon services and other services to engineers and scientists. PACS provides laboratory testing, R&D, consulting, training and expert witness services. PACS also provides 59 different one-to-three day short courses for scientists.

PACS hosts the bi-annual International Activated Carbon Conference and Courses programs in Pittsburgh, PA every October and a mid-year conference outside of Pittsburgh. Information about the firms services are available on its website www.pacslabs.com or by phone at (724)

The AC tester and its applications were conceived by PACS. Additional uses for the tester will be covered at upcoming PACS conferences, including October 6 and 7, at the 24th International Activated Carbon Conference.


Wednesday, October 14th, 2009

Let Us Hear From You!

One of my personal frustration points in life is to go shopping around Halloween (or the end of October) and actually see Christmas and holiday display items in retail stores. But, in talking to and working with retail marketing professionals, I know it is important to properly ramp up for the vital sales period.

So I usually curse under my breath, mutter something to myself about shopping ruining the holidays or life just not being like it was when I was a kid and let it go. Along the way I also start buying presents well before the season…just because.

At WC&P, we are already ramping up for our 2010 publication year. And we are asking you to do the same thing that frustrates me; think and respond outside of the season.

In both the September and October issues, as well as in the emailed POU-PoeNews, we have included readership surveys for 2010. We truly want to hear what you like, what you don’t like and any ideas you may have to help make the content of our publication even stronger.

The response has been very good, but we want even more! So please take a few minutes and share your thoughts; after all of the results are in, we will also be happy to share any key findings or suggestions.

Tell us about which feature story topics, technologies and applications you most like and least like to read about. Also tell us which regular columns you most like and least like to read.

We want to know which regular departments you most and least like to read. Likewise, we want to know what areas, topics or stories you would like to see more or additional coverage.

In 2009 we initiated out POU-PoeNews bi-monthly email newsletter and we would like your response on ideas and suggestions to improve that communication service. We also would like to hear about how you perceive the magazine advertisements relative to your purchasing decisions and what local or international trade shows are your 2010 priorities.

Our tabulation deadline is quickly approaching. You only have until October 16 to fax the survey to us at (520) 323-7412. Please see the survey on page ____ of this issue.

WC&P will then have a drawing of the names of all those submitting information. Two winners will each receive a $50 online gift certificate at amazon.com.

That is just a little way for us to say ‘thank you’ for your input and assistance.

And maybe the gift certificates will help you with your pending holiday shopping!

Controlling Contamination in Water Treatment Equipment—Part 3

Wednesday, October 14th, 2009

By Greg Reyneke, CWS-VI

The purpose of this four-part series is to discuss factors to consider when developing and implementing an effective disinfection protocol. It includes chemicals used for disinfection, their advantages and limitations; steps for developing an effective disinfection protocol; and procedures for maintaining ongoing system cleaning and disinfection. Part 3 of this series deals with classification of chemical disinfectants.

Disinfectants are classified by their chemical nature and each class has its own unique characteristics, hazards, toxicities and efficacy against various microorganisms. Environmental conditions, such as the presence of organic matter, pH or water hardness, will also impact the action of a disinfectant. Before using any chemical disinfectants, thoroughly read and follow manufacturer’s instructions.


Acidic disinfectants function by destroying the bonds of nucleic acids and precipitating proteins. Acids also change the pH of the environment, making it detrimental to many microorganisms.

Concentrated solutions of acids can be corrosive, cause chemical burns and can be toxic at high concentrations in the air. These characteristics limit their effective use. Antimicrobial activity of acids is highly pH- dependant.

Acids have a defined but limited use as disinfectants. Acetic acid is usually sold as ‘glacial’ acetic acid (95 percent acetic acid), which is then diluted with water to make a working solution concentration of five percent. The concentrated form is corrosive to the skin and lungs, but the typical dilution (five percent) is considered non-toxic and non-irritating.

Acetic acid is typically applied by spraying, misting or immersing an item into a diluted solution. Household vinegar is a four to five percent solution of acetic acid by volume. Acetic acid has poor activity in and around organic material.


Alcohols are broad-spectrum antimicrobial agents that damage microorganisms by denaturing proteins, causing membrane damage and cell lysis. Alcohols are used for surface disinfection, topical antiseptic and hand-sanitizing lotions.

Alcohols are considered fast-acting, capable of killing most bacteria within five minutes of exposure, but are limited in virucidal activity and are ineffective against spores. (Ethanol is considered virucidal; isopropanol is not effective against non-enveloped viruses.)

An important consideration with alcohols is the concentration used, with 70 o90 percent being optimum. Higher concentrations (95 percent) are actually less effective because some degree of water is required for efficacy (to denature proteins). Alcohols evaporate quickly but leave behind no residue.

Activity of alcohols is limited in the presence of organic matter. Alcohols are highly flammable, can cause damage to rubber and plastic and can be very irritating to injured skin. Due to the high concentrations, flammability risks and dilution concerns, alcohol is generally unsuitable for comprehensive disinfection.


Aldehydes are highly effective, broad-spectrum disinfectants, which typically achieve sterilization by denaturing proteins and disrupting nucleic acids. The most commonly used agents are formaldehyde and gluteraldehyde.

Aldehydes are effective against bacteria, fungi, viruses, mycobacteria and spores. Aldehydes are noncorrosive to metals, rubber, plastic and cement. These chemicals are highly irritating, toxic to humans or animals with contact or inhalation and are potentially carcinogenic; therefore, their use is limited. Personal protective equipment (nitrile gloves, fluid-resistant gowns, eye protection) should be worn if you ever use these chemicals.

Glutaraldehyde can provide sterilization at prolonged contact times. A two percent concentration is used for high-level disinfection. Glutaraldehyde efficacy is highly dependent on pH and temperature, working best at a pH greater than seven and at high temperatures. It is considered far more efficacious in the presence of organic matter, soaps and hard water than formaldehyde.


Alkaline agents work by saponifying lipids within the envelopes of microorganisms. The activity of alkali compounds is slow but can be increased by raising the temperature. Alkalis have good microbicidal properties, but are very corrosive agents and personal protection precautions should be observed.

Sodium hydroxide (lye, caustic soda, soda ash) is a strong alkali used to disinfect buildings but is highly caustic. Protective clothing, rubber gloves and safety glasses should be worn when mixing and applying the chemical. Never pour water into lye; lye should always be carefully added to water. Otherwise, a very violent reaction will occur as well as the production of high heat that can melt plastic containers.

Sodium hydroxide is corrosive to most metals. Ammonium hydroxide is an effective disinfectant against coccidial oocysts; however, strong solutions emit intense and pungent fumes. This substance is not considered effective against most bacteria. General disinfection should follow the use of this compound.

Sodium carbonate (soda ash, washing soda) can be used in a high- temperature solution (180oF/82oC). It is more effective as a cleanser than a disinfectant since it lacks efficacy against some bacteria and most viruses. This disinfectant has poor activity in the presence of organic material and can be deactivated by hard water. It can be irritating, requires protective clothing and is harmful to aquatic life.


Biguanides are detrimental to microorganisms by reacting with the negatively charged groups on cell membranes, which alters permeability. Biguanides have a broad antibacterial spectrum, however they are limited in their effectiveness against viruses and are not sporicidal, mycobacteriocidal or fungicidal.

Biguanides can only function in a limited pH range (five to seven) and are easily inactivated by soaps and detergents. These products are toxic to fish and should never be discharged into the environment.


Halogen compounds are broad-spectrum compounds that are considered low-toxicity, low cost and easy-to-use. They lose potency over time and are not active at temperatures above 110oF (43oF)or at high pH (> nine).

Since these compounds lose activity quickly in the presence of organic debris, sunlight and some metals, they must be applied to thoroughly cleaned surfaces for disinfection. Chlorine compounds function through their electronegative nature to denature proteins and are considered broad spectrum, being effective against bacteria, enveloped and non-enveloped viruses, mycobateria and fungi.

At elevated concentrations, chlorine compounds can be sporicidal. Sodium hypochlorite (bleach) is one of the most-widely used chlorine-containing disinfectants. (Commercial chlorine bleach contains 5.25 percent sodium hypochlorite in aqueous solution and 50,000 ppm available chlorine).

Biocidal activity of chlorine solutions is determined by the amount of the available chlorine of the solution. Low concentrations (two to 500 ppm) are active against vegetative bacteria, fungi and most viruses.

Rapid sporicidal action can be obtained at approximately 2,500 ppm;this concentration, however, is very corrosive so should be limited in its use. High concentrations are highly irritating to the mucous membranes, eyes and skin.

Chlorine compounds are rapidly inactivated by ultraviolet light and certain metals so fresh solutions should always be used. Hypochlorites should never be mixed with acids or ammonia as this will liberate chlorine gas out of solution.

Iodine compounds are broad spectrum and considered effective for a variety of bacteria, mycobacteria, fungi and viruses. Iodines function by denaturing proteins to interfere with the enzymatic systems of microorganisms.

Iodines are often formulated with soaps and considered relatively safe. Concentrated iodine compounds can be irritating to the skin, can stain clothes or damage rubber and many metals. Iodine agents are inactivated by quats and certain organic material.

Iodophors are iodine complexes that have increased solubility and sustained release of iodine. One of the more commonly used iodophors if povidone-iodine. They are good for general use and are less readily inactivated by organic matter than elemental iodine compounds. The dilution of iodophors increases free-iodine concentration and antimicrobial activity.

Oxidizing agents

Oxidizing agents are broad-spectrum, peroxide-based compounds that function by denaturing the proteins and lipids of microorganisms. Peroxygen compounds vary in their microbiocidal range, but are generally considered effective on hard surfaces and inside equipment. In their diluted form, these agents are relatively safe but may be irritating and damage clothing when concentrated.

Hydrogen peroxide in the home is in diluted form (three to 10 percent) whereas industrial use involves concentrated solutions (30 percent or greater). Hydrogen peroxide at a five to20 percent concentration is considered bactericidal, virucidal (non-enveloped viruses may be resistant), fungicidal and, at higher concentrations, sporicidal. Its activity against mycobacteria is limited.

Peracetic acid is a strong oxidizing agent and is a formulation of hydrogen peroxide and acetic acid. It is considered bactericidal, fungicidal, sporicidal and virucidal. It is also effective against mycobacteria and algae and has some activity in the presence of organic material. Extreme caution should be exercised when applying these disinfectants against ion exchange media, as irreversible oxidative damage can occur.


Phenols are broad-spectrum disinfectants that function by denaturing proteins and inactivating membrane-bound enzymes to alter the cell-wall permeability of microorganisms. Phenols can be coal-tar derivatives or synthetic formulations and usually have a milky or cloudy appearance when added to water and a strong ‘pine’ odor. Pine-Sol® is an example of a phenol found in the home.

Phenols are typically formulated in soap solutions to increase their penetrative powers and at five-percent concentrations are considered bactericidal, tuberculocidal, fungicidal and virucidal for enveloped viruses. Phenols are not effective against non-enveloped viruses and spores.

Phenols do maintain activity in hard water and in the presence of organic matter and have some residual activity after drying. Phenolic disinfectants are generally safe for humans but prolonged exposure to the skin may cause irritation. Concentrations over two percent are highly toxic to all animals, especially cats.

Quaternary ammonium compounds

These ammonium compounds–also known as quats or QACs–, are cationic detergents that are attracted to negatively charged surfaces of microorganisms, where they irreversibly bind phospholipids in the cell membrane and denature proteins, impairing permeability. Quats can be from different ‘generations’ depending on their chemistry, with later generations being more germicidal, less foaming and more tolerant to organic loads.

Quats are highly effective against gram-positive bacteria and have good efficacy against gram-negative bacteria, fungi and enveloped viruses. They are usually not effective against non-enveloped viruses or mycobacteria and are considered sporostatic but not truly sporocidal.

Quats have a residual effect, keeping surfaces bacteriostatic for a brief period of time after application. They are more active at neutral-to-slightly-alkaline pH but lose their activity at pH less than 3.5. Quats are considered stable in storage but can be inactivated by organic matter, detergents, soaps and hard water unless specially formulated.

Next Issue: Part 4—Disinfection action plan.

About the author

Greg Reyneke, CWS-VI, is currently General Manager at Intermountain Soft Water in Lindon, UT and serves on the WC&P Technical Review Committee. He also serves on the advisory board of the Smart Dealer Network, a trade association dedicated to helping independent water treatment dealers succeed in today’s changing world and reach their full potential.


Aarrow Promises Less and Delivers More

Wednesday, October 14th, 2009

By Denise M. Roberts

Aarrow Plumbing & Water Treatment
2159 Henderson Loop • Richland, WA 99354
Toll-free: (800) 260-5737
Tel: (509) 374-3333
Fax: (509) 371-1903
Websites: www.aarrowplumbing.com
and www.empoweredh2o.com
Email: matt@aarrowplumbing.com
Employees: 17 • Vehicles: 15

Established in 2001, Aarow Plumbing started as a small subcontracting outfit for a handful of custom homebuilders. The first month saw a mere five contracts for the company, but the housing boom quickly increased business to an average of 45 contracts per month.

Travis Mullins is sole proprietor of the company. His father Dave runs the Service Plumbing Division and company spokesman Matt Mahany oversees the Water Treatment Division. Rounding out Aarrow’s new construction and service plumbing divisions are 14 additional personnel who provide service to the tri-cities (Kennewick, Richland and Pasco) and surrounding areas from Yakima to Spokane in eastern Washington.

Mahany describes Travis as having two great passions: plumbing and motocross racing. “He is one of the hardest working plumbers in the tri-cities and enjoys getting his hands dirty,” says Mahany. “And Dave, with 35 years of experience, always has answers for the problems we encounter.”

Into the trenches

A former rep for Intermountain WaterTM, Mahany previously lived in Nampa, ID, but traveled regularly between Utah and Washington. His task was to help Aarrow and other builders and plumbers with water quality problems. On several occasions, Dave asked him to join the company and start a water division. In 2006, Mahany did just that with the blessing and goodwill of his former employer.

“Who better to treat your water than your plumber?” Mahany asks. “It’s important to help plumbers learn why water was so crucial to their business and why they needed to be the experts on water quality, not just how to get it from place to place.

“I’d helped many plumbers and have a passion for helping people get better water for their homes and businesses. I have lots of good friends in the plumbing and water treatment industry and I love what I do! But I hadn’t gotten into the trenches with them. After much thought and research, I decided it was the right move for me.”

Growth through change

Keeping up with the changing economy is the biggest challenge most companies face, including Aarrow. Credit restrictions, vendor cash-on-delivery policies and purchase reluctance from end-users have caused the firm to carefully hone its sales and marketing strategies. That includes greater use of digital media such as the Internet.

With the help of the Smart Dealer network, the company has raised its annual water sales 25-fold by adding a few quality products such as Mr. Smart Bottle®, PRO Series softeners and Next ScaleStop. Aarrow also maintains its strong presence in new home construction, remodels and commercial plumbing.

New water treatment model

“Aarrow will continue to focus more on high-tech water treatment options, periodic system service and disinfection, using products like Pur-Gard and following the SP-5000 disinfection protocol,” Mahany predicts. “Customers are beginning to realize that softeners grow bacteria and suffer attrition-based performance loss, requiring periodic maintenance and disinfection.

“As more people become aware of the need for cleaner water, they will expect the industry to have the answers to their water quality issues. Consumers who are unhappy with utility-grade city water and well water will want additional options and the environmentally conscious will demand alternatives, such as salt-free systems.”

Mahany says Aarrow is ready for the next set of challenges. The repair plumbing division continues to grow while the water treatment division is fast becoming the flagship of the business. “We believe in honesty, attitude, respect and order. We strive to make customers for life and to give them the service they deserve always promising less and delivering more.”


Product Certification, GFSI, HACCP and Training – The DNA of Beverage Quality

Wednesday, October 14th, 2009

By Chris Dunn

For decades manufacturers, retailers and trade organizations have promoted voluntary compliance of government food safety standards; initial focus was on product quality.

More recently, global retailers and manufacturers have been working to find common ground with schemes that focus on the underlying quality of management systems involved in the production of food. Better documentation correlation and more consistent methods with less defects and better quality are essential.

The double helix of DNA[1], with its two strands connected together for strength, represents a model to join quality of product with quality of management systems. Hazard analysis and critical control points (HACCP[2]), training and inspection (verification) become the links and together form a ladder for continually improving beverage quality.

First strand: product certification

Product certification started about 25 years ago. Non-profit organizations, such as NSF International, began to set consensus standards built around voluntary guidelines. These were designed to provide checks and balances inside the manufacturing process, which could then be verified through laboratory testing and plant audits. This type of standard is specific to a product and validates performance against governmental organizations requirements such as the US FDA, Health Canada or European Food Safety Authority (EFSA).

The foundation of product certifications is transparency of what is required and the independence of the certifying entity. Standards are validated by food safety expertise, scientific method, objective observation, quantitative measurement and physical inspection to verify compliance. The foundation is built on the verification of a functioning HAACP plan, physical plant inspection and laboratory testing of the product. Once the benchmark is achieved, there are re-inspections and re-testing at least once annually.

Governments recognize qualified third-party standards. They know that a product obtaining certification has a working HACCP plan supported by prerequisite programs built around good manufacturing practices (GMPs), sanitary and standard operating procedures (SSOPs and SOPs).

They also know a physical audit has been conducted and laboratory tests have been performed to verify product safety. While third-party standards are not a replacement for government oversight, they provide public affirmation of compliance. Some regulators reference third-party standards as guidance to people asking for help to meet government regulations.

Retailers value product certification because of the brand protection it offers their private label products. Because retailers often do not have the technical expertise in all product categories, their risk management strategy can use published standards to insure their co-packers are fully complying with all the regulations via third-party verification.

Manufacturers appreciate product certification as support in helping them achieve ‘best practice,’ as well as demonstrate to their customers they have world-class quality that has been validated by an independent third-party.

Faced with a plethora of choices, a certification mark on the product is a key factor in consumers choosing one brand over another. Knowing that a certified product has met all applicable requirements provides peace of mind for consumers.

Trade associations, such as the International Bottled Water Association (IBWA), have also helped to advance bottled water quality by promoting their Model Code and plant inspection programs, which impact the majority of the U.S. bottled water industry. NSF has been providing inspection and audits of IBWA member facilities since 1984. About half of the U.S. states use IBWA Model Code as the basis for their own regulations.

Second strand: Global Food Safety Initiative

Global sourcing and distribution of food and beverages has increased the complexity and interconnection required to produce consistency and uniformity. Retailers have in the past set their own criteria, especially for their own private-label brand, and have done their own inspections. While this benefited some individual retailers, it also resulted in redundancy.

Trying to reduce the negative impact on cost and efficiency, an organization called the Food Business Forum (www.ciesnet.com) took action. This Forum was founded in Europe by seven global retailers (Carrefour, Tesco, Metro, Migros, Ahold, Wal-Mart and Delhaize) and supported by major manufacturers like Kraft[3]. This group sought a solution that would reduce redundancy, while assuring members consistent, high-quality products.

The retailers chose their focus to be on the process (management systems) rather than individual products. This would result in a program that would be as applicable to fresh produce as to canned soup. Better systems would cause manufacturers to adopt better controls and thus improve quality.

The Forum harmonized minimum standards to insure competing programs delivered the same basic requirements. Under the banner of Global Food Safety Initiative (GFSI[4]), four schemes now exist and are deemed interchangeable: 1) British Retail Consortium (BRC[5]); 2) Safe Quality Food (SQF[6]); 3) International Food Standard (IFS[7]); and 4) Food Safety System Certification 22000 (FSSC22000[8]).

Each of the schemes covers all food and beverage categories, versus a specific product. They also promote systemization and documentation that guides a manufacturer in any food category to implement and manage a food quality and safety program focused on processes, measurement and documentation. These systems support complex product formulas and manufacturing processes, as well as upstream and downstream supply chains that often span the globe.

Similar to product certification, management systems are built on a HACCP foundation. With the intensity of processes and documentation, these programs start with a management commitment to provide the resources, as well as sign-off on system documentation. There is often linkage to corporate IT systems to collect and manage data.

These are complex programs that require in-house experts to implement and create the documentation. After everything has been systemized and documented according to the program guidelines, an approved auditor (certified by the GFSI program itself) does a desk audit of all documents and systems.

After verifying the systems and documents are in place, a verification of the system implementation takes place. This includes the physical plant inspection, as well as document review and usage.

Any non-conformances are noted and must be corrected before certification is granted. Annual follow-up visits are required to verify ongoing compliance.

What are the differences?

There are many points of difference on how each strand approaches quality. Some are defined by their nature — GFSI programs are generic, meaning the same manual and checklist apply to all categories of food.

There are references to ‘industry practices,’ but no product-specific requirements outlined. Product certification is tailored specifically to the product itself, thus it is naturally more proscriptive and clear.

In lighting for a plant, as an example, GFSI would say there shall be ‘adequate lighting’ tied to all types of activity performed. Product certification would be much more specific stating that there shall be 50 foot-candles of light in product areas and 20 foot-candles elsewhere.

The differences are driven by the nature of the programs – one tied to a specific product, the other tied to the systems generic to any food plant.

Common bonds

The underlying principle that both approaches share is HACCP.

Both systems place a heavy reliance on training. As part of product certification, a bottler is required to have provided HACCP, GMP, Food Security and Employee Hygiene training to all production workers.

Both approaches rely on inspections to verify implementation and efficacy of the programs. Product certification will devote more of the inspection to GMPs. The system audit will view the GMPs in the context of reviewing documentation.

Combined effect

When you use HACCP and training as connectors of the two strands and implement both programs, you form the spiraling double helix of beverage quality DNA. While symbolic, it is also a practical image of a ladder, which implies the best quality is achieved by continuously climbing upward.

As with real DNA, remove one of the strands or even one of the connectors and one is incapable of achieving best practice. Large operations often need both. The more complex an operation, or the more varied the products become, systems take on increasing importance.

Early proponents of GFSI once thought that GFSI was going to be the end-all solution. It is now of paramount importance to have product-specific programs, such as those found in NSF’s bottled water certification program to complement GFSI, HACCP and training initiatives. The best approach, therefore, is to infuse the manufacturing process with the strongest DNA possible so that it can replicate itself in the form of zero defect product quality.

References and Footnotes

  1. National Human Genome Research Institute: http://www.genome.gov/25520880
  2. Hazard Analysis and Critical Control Points (HACCP) is a systematic preventive approach to food safety and pharmaceutical safety that addresses physical, chemical, and biological hazards as a means of prevention rather than finished product inspection. http://en.wikipedia.org/wiki/HACCP
  3. The Food Business Forum started in 1953 and now has over 400 members in 51 countries. www.ciesnet.com
  4. The Global Food Safety Initiative (GFSI) coordinated by CIES – The Food Business Forum, was launched in May 2000
  5. BRC first introduced in 1998; now in Fifth Edition, published January 4, 2008.
  6. SQF launched August 2003 by SQFI; now in Sixth Edition, published in August 2008
  7. IFS started in 2003; now in Fifth Edition, published August 5, 2007
  8. FSSC22000 was approved by GFSI in June 2009 and will replace Dutch HACCP.Pull Quotes—The double helix of DNA, with its two strands connected together for strength, represents a model to join quality of product with quality of management systems.As people who were early proponents that GFSI was going to be the end-all solution are discovering, it is of paramount importance to have product-specific programs such as those found in NSF’s bottled water certification.
  9. Trade associations, like IBWA, have also helped to advance bottled water quality by promoting their Model Code and plant inspection programs which impact the majority of the US bottled water industry. About half of the individual US states use the IBWA Model Code as the basis for their own regulations.

About the Author

Christopher Dunn is General Manager of the Beverage Quality Program for NSF International, a public health and safety organization, based in Ann Arbor, Michigan. His program offers testing, auditing and certification of beverages including bottled water, natural mineral waters, flavored and functional beverages and packaged ice. Dunn is a 30-year veteran of the beverage industry. For over a decade, he has been involved with bottled water (IBWA) and packaged ice (IPIA) trade associations and is certified CWS-I by WQA. Dunn can be reached at cdunn@nsf.org.


Infrared Fiberoptic System for Online Monitoring of the Quality of Water

Wednesday, October 14th, 2009

By Professor Abraham Katzir

Globalization, rapid urbanization, urban waste generation, rising industrial and agricultural activities and other concerns have caused increased pollution of water resources. There has been a growing demand for sustaining the quality of water and maintaining public health.

It is essential that we monitor contaminants (such as volatile organic compounds [VOCs]), whose source is industry or agriculture and whose effects are ‘long term.’ It is also necessary to detect the presence of hazardous chemicals that may be introduced by accidental spills or by natural causes (such as hurricanes) and whose health effects are ‘short term.’ The threat of chemo-terrorism has also emerged worldwide during the last few years.

In each of these cases, monitoring systems should allow online monitoring in remote locations, be sensitive, selective, robust, affordable and easy to operate. There is a need to detect such contaminants in concentrations levels lower than one ppm. It would be extremely useful if the monitoring system could identify contaminants and distinguish between highly toxic ones (e.g. organophosphates) and less-toxic ones (e.g. halogenated hydrocarbons).

Most systems available today are based on sampling and not on continuous monitoring. Many of these systems are designed to detect only one type of pollutant.

Our research goal was to develop an infrared fiber-optic system that will continuously monitor the quality of water in situ and in real time. This system would, therefore, detect, identify and determine concentrations of contaminants that may pose a threat to public health. It would serve as part of an early warning system to monitor the quality of water in water supplies or distribution systems.

Fiberoptic infrared spectroscopy

The absorption of many organic and inorganic materials in the middle infrared (mid-IR) spectral range, from three to 25 µm, is highly characteristic and is often called a ’fingerprint.’ Water has a characteristic absorption spectrum, as does each of the above-mentioned contaminants.

By measuring the spectrum of an aqueous solution, one can distinguish between pure water and contaminated water. In principle, the absorption spectrum of the solution may reveal the nature of contaminants and their concentration; this is true even if there are many contaminants in the solution.

Several types of spectrometers can be used to measure absorption in the mid-IR, including grating spectrometers, Fourier transform infrared (FTIR) spectrometers and tunable IR lasers. In all these cases, one can in principal take a sample of polluted water, place it inside the spectrometer and carry out measurements.

The main problem is that water has an extremely high absorption in the mid-IR and, therefore, only a very thin sample must be used, which complicates the measurements. In addition, it would be infinitely better to carry out measurements on water in situ and in real time, rather than inside the spectrometer.

The solution we researched and developed is to use a method called fiberoptic evanescent wave spectroscopy (FEWS), which relies on optical fibers that are highly transparent in the mid-IR. The Applied Physics Group at Tel Aviv University (TAU) in Israel has developed special optical fibers made of silver halides (e.g. AgClBr), which are flexible, non-toxic, non-hygroscopic and highly transparent in the mid-IR.

There are very few groups that have similar fibers. These IR fibers can be coupled to mid-IR spectrometers, making it possible to measure the absorption spectra of aqueous solutions in an area remote from the spectrometer and in real time.

Development of a field deployable prototype

A schematic drawing of such a typical sensor for online monitoring (Figure 1) has been developed. The FEWS system for online monitoring of water is comprised of a mid-IR spectrometer, consisting of a tunable IR source, and an IR detector and a U-shaped sensor head.

Figure 1 The fiberoptic evanescent wave spectroscopy (FEWS) system for online monitoring of water.

One key element has been the development of the U-shaped sensor head (Figure 2). It has two arms that are well protected by a plastic tube, with the exposed AgClBr fiber segment at the center that serves as a sensing element. This element is brought in contact with water. The sensor head is easily connected to an FTIR system.

Figure 2

Figure 2

Figure 2 The sensor head. The yellow line on the right is the exposed segment of AgClBr fiber that serves as a sensing element.

Preliminary experiments

Experiments were carried out in boreholes in Munich, Germany and Vienna, Austria with participation of researchers from IPM in Freiburg, Germany and from the Technical Universities of Munich and Vienna. A fiber of six meters (19.68 feet) in total length was used. The fiber was shaped like a ‘U’ and 10 cm (3.94 inches) at its center served as the sensor element. This element was left exposed, whereas the two legs of the ‘U’ served as IR cables and were covered with a protective Teflon tube.

An FTIR spectrometer was used for the absorption measurements. The sensor element was introduced into the aquifer at the bottom of the hole. Tetrachloroethylene (TCE) was introduced as methanolic solution into a special compartment near the gravel-filled bed, which was already filled with cold water. Analyte eluted from the gravel bed into the well where the sensor head was placed.

Monitoring was carried out continuously for two days and the FEWS system proved effective. Measurements actually started after a delay of 200 minutes when the analytes first reached sensor. Then, naturally, the concentration of the chemicals was slowly increased.

In parallel, samples of water were periodically removed from the aquifer and the concentration of TCE was measured using standard gas chromatography (GC) (Figure 3). Quantitative results of the FEWS method were very similar to ones obtained by standard GC, with preliminary results indicating great potential of the system for online monitoring of pollutants in situ and in real time.

Figure 3 The black squares represent results obtained by gas chromatography and open circles represent results obtained by FEWS.

Pesticide measurements

Another example of the capabilities of the system was tested when aqueous solutions of highly toxic pesticides were injected into water. Solutions of 2,2-dichlorovinyl dimethyl phosphate (DDVP), parathion and diazinon in concentrations 0.5 to 30 ppm were prepared for the test.

In each case, IR absorption spectra were measured (Figure 4). It is clear that each pesticide has a characteristic absorption spectrum and that one can use the method for detecting and identifying pesticides in concentrations of less than one ppm (or possibly even lower).

Wavenumber [cm-1]

Absorbance [a.u.]



Figure 4 Absorption spectra of different concentrations of pesticides in water: (a) DDVP, (b) diazinon (c) parathion.

Future research

Initial research measurements were carried out using a large, expensive FTIR – not designed for fieldwork. Future research should be conducted with a smaller and more robust FTIR that is less sensitive to moisture. Such a mini-FTIR will make it possible to construct a compact and rugged FEWS system that can be used in the field.

There are also several ways of increasing the sensitivity of the FEWS system. Some of these depend on the geometry of the sensor element. For example, flattening the center of the element can increase the sensitivity by a factor higher than 10.

There are other methods that chemists use to increase sensitivity, which need to be researched. For example, the sensor element could be coated by an ‘enrichment’ layer that will allow molecules of pollutant to penetrate to the vicinity of the sensor element, but will not allow water molecules. This leads to an increased sensitivity. Several mathematical methods could also be used in order to increase sensitivity and also make it possible to detect one pollutant in the presence of others.

The infrared source (Figure 1) can be an FTIR or a tunable IR laser. The FTIR system covers a very broad range in the infrared spectrum and, therefore, can cover a broad range of contaminants. On the other hand, FTIR intensity is not very high and, as a result, the sensitivity of the system is not very high. Tunable IR lasers emit a very high intensity, but cover only a very limited range. They are, therefore, most suitable for detection of a specific pollutant, though they can detect this pollutant with a very high sensitivity.


It is expected that this novel FEWS system will have many applications. It will be highly useful for environmental protection and it will also contribute to water security in the face of global terrorism.

Such a system would be quite useful in many fields and in many countries, and could be used for monitoring of treated wastewater, irrigation water and drinking water. It could also monitor the quality of water online in water reservoirs, rivers, lakes and surface or groundwater. The miniature FEWS could also be lowered well below the surface of the water and be used for monitoring of pollutants at the bottom of the ocean.

About the author

Professor Abraham Katzir, a world-renowned expert in electro optics and biomedical optics, is the Head of the Applied Physics Group at Tel Aviv University, Israel. Previously, he worked in some of the top research laboratories in the US: a visiting scientist at the California Institute of Technology, a visiting staff member at ATT Bell Laboratories in New Jersey and a visiting professor at both Boston University and the Massachusetts Institute of Technology (MIT). Katzir’s work involves research and development of new methods and systems designed for medical applications, industrial applications, environmental protection and homeland security. He can be reached via email, Katzir@post.tau.ac.il, telephone + 972 3 6408301 or by fax at + 972 3 6415850. You can also visit the university website at www.tau.ac.il/~applphys.



©2019 EIJ Company LLC, All Rights Reserved | tucson website design by Arizona Computer Guru