Water Conditioning & Purification Magazine

Inline flow meter

Saturday, August 15th, 2020

Clack Corporation introduces the two-inch Plastic Inline Flow Meter, an economical, glass-filled, composite unit that offers many advantages. It is non-corrosive and has union-style adapters that have a small range of motion to assist with installation and to account for flex during operation. The meter has service flow ranges from 1.5 gpm to 150 gpm (5.67 to 567.81 L/m) and its accuracy is rated at +/- 5 percent. Available with 28-inch (71.12-cm) and 15-foot (4.57-meter) cable lengths, in both NPT and BSPT threads.
www.clackcorp.com/

Make-shift Pools and Essential POU Maintenance

Saturday, August 15th, 2020

By Kelly A. Reynolds, MSPH, PhD

With everyone stuck at home and community pools shut down, stock-tank pools are having a moment.1 These galvanized metal containers are staples on farms and ranches for watering livestock and are now being fashioned as backyard swimming pools. While they have a cute, rural-chic style, keeping them clean and preserving the water quality requires focused intention.

Designing your own
An inexpensive alternative to building a pool, stock tanks cost only a few hundred dollars compared to an in-ground swimming pool at tens of thousands of dollars. They can be purchased at your local animal feed or tractor supply store and will likely last longer than the plastic kiddie pools or above-ground alternatives. Stock tank shapes vary from oval, square and round options (with round tanks being the most popular for swimming) and range in size from six- to 10-foot (1.82- to 3.04-meters) diameters, holding 80 to 800 gallons (302.83 to 3,028.32 liters) of water. This makes for a weighty pool, so finding a solid, smooth or soft spot in the grass or sand to set the tank is important to avoid punctures and leaks.

Potential hazards
Harmful microbes naturally persist in tap water or hoses used to fill your stock-tank pool. Because swimming activities lead to exposures to harmful microbial contaminants (such as bacteria, protozoa and viruses) via ingestion, inhalation and skin and mucous membrane contacts, no one should swim in any pool until it is properly treated with chemical disinfectants and filtration equipment. Naturally occurring water-based organisms of concern include Naegleria fowleri (also known as the brain-eating amoeba) and Pseudomonas. Two cases of the almost always fatal Naegleria fowleri have occurred in previously healthy children swimming in untreated pools or bathtubs.2 The organism is readily found in lakes, holding tanks and water taps, particularly in warmer climates.3 Some strains of Pseudomonas cause ear infections (swimmer’s ear) and can infect hair follicles, leading to the well-known hot-tub rash.

Other microbes found on skin and in urine and feces may be introduced to the water by swimmers. Examples include, E. coli, rotavirus, norovirus and Cryptosporidium (which can cause mild to severe diarrhea and vomiting) and drug-resistant Staphylococcus bacteria (i.e., Staph and MRSA), which can cause unpleasant and sometimes serious skin infections. From 2000-2014, 493 disease outbreaks occurred due to exposure to treated recreational water, resulting in over 27,000 cases of illness and eight deaths.4 Treated recreational water outbreaks are most commonly due to chlorine-resistant Cryptosporidium or poorly maintained pools and spas. In a survey of over 13,000 public hot tubs/spas, about 20 percent had improper disinfectant concentrations. Home pools are subject to similar concerns.

In addition to microbes and algae, macro-organisms (such as mosquitoes) may take up residence in the standing water of stock-tank pools. Physical hazards may exist too, such as hot metal edges. Some creative owners have fashioned foam pool noodles to cover tank edges and create comfortable headrests.

Water quality maintenance
Maintaining the quality of treated recreational water is extremely important for the health of swimmers and to prevent microbes and algae from growing in the pool. Installing a pump to keep water circulating will discourage the accumulation of mosquito larvae and algal slime. The primary treatment methods are chemical disinfection and filtration. Filters may be purchased that are capable of removing chlorine-resistant protozoan and many bacterial pathogens, but viruses are too small to be efficiently removed by filtration. Chlorine or other sanitizers are necessary to kill harmful bacteria and viruses. Keeping the proper balance of essential chemicals and maintaining effective filtration, however, can be very difficult, particularly in smaller water volumes and during frequent use. Rain, debris (leaves and dust) and people (skin cells and oils) rapidly create chlorine demand in the water, depleting levels of chemicals designed to keep pools clean. If a small volume of water is contaminated by an infected individual, others can be quickly exposed, and before the water filter has a chance to do its job.

Chlorine tablets are widely available at pool supply stores and floating dispensers can provide consistent treatment. Concentrations of at least one ppm of free chlorine are recommended. At this level, most bacteria and viruses are inactivated within minutes, however, Cryptosporidium could still survive for a week at this concentration. Therefore, a combination of filtration and chemical disinfection is needed for optimal recreational water treatment. Even with routine treatment, stock-tank water should be drained and refilled periodically, maybe even monthly or more frequently, depending on how often it is used. Don’t wait until the water looks cloudy! Scrub any biofilm off the interior tank surface with a mild soap and brush to prevent any slime build-up.

Next steps
With proper care and maintenance, stock-tank pools can provide a great recreational water experience. Studies have shown that leisure swimmers consume hundreds of milliliters of water per swim and that splashes to the face correlated with the highest level of water ingestion.5 Children are at the greatest risk of infection due to their generally rougher pool play events that lead to splashing and increased water ingestion.6 They are also more likely to have a lack of healthy swimming habits, such as showering before swimming or handwashing compliance after using the restroom.7 Carefully monitoring contamination potentials and making sure pool water is properly treated before every swim is critical for good health and safe swimming.

References

  1. Murtaugh T. 5 of the Biggest problems People Have with Stock Tank Pools and How to Prevent Them. Country Living. https://www.countryliving.com/life/news/a44181/stock-tank-pool-problems/. Published 2020. Accessed July 12, 2020.
  2. Marciano-Cabral F, MacLean R, Mensah A, LaPat-Polasko L. Identification of Naegleria fowleri in Domestic Water Sources by Nested PCR. Appl Environ Microbiol. 2003;69(10):5864-5869. doi:10.1128/AEM.69.10.5864-5869.2003
  3. Sifuentes LY, Choate BL, Gerba CP, Bright KR. The occurrence of Naegleria fowleri in recreational waters in Arizona. J Environ Sci Heal–Part A Toxic/Hazardous Subst Environ Eng. 2014;49(11). doi:10.1080/10934529.2014.910342
  4. Hlavsa MC, Cikesh BL, Roberts VA, et al. Outbreaks Associated with Treated Recreational Water–United States, 2000–2014. MMWR Morb Mortal Wkly Rep. 2018;67(19):547-551. doi:10.15585/mmwr.mm6719a3
  5. Suppes LM, Abrell L, Dufour AP, Reynolds KA. Assessment of swimmer behaviors on pool water ingestion. J Water Health. 2014;12(2):269-279. doi:10.2166/wh.2013.123
  6. Suppes LM, Canales RA, Gerba CP, Reynolds KA. Cryptosporidium risk from swimming pool exposures. Int J Hyg Environ Health. 2016;219(8):915-919. doi:10.1016/j.ijheh.2016.07.001
  7. Castor ML, Beach MJ. Reducing illness transmission from disinfected recreational water venues: Swimming, diarrhea and the emergence of a new public health concern. Pediatr Infect Dis J. 2004;23(9):866-870. doi:10.1097/01.inf.0000138081.84891.30

About the author
Dr. Kelly A. Reynolds is a University of Arizona Professor at the College of Public Health; Chair of Community, Environment and Policy; Program Director of Environmental Health Sciences and Director of Environment, Exposure Science and Risk Assessment Center (ESRAC). 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 is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at reynolds@u.arizona.edu

Developing a New Contaminant Reduction Claim under NSF/ANSI 53

Saturday, August 15th, 2020

By Rick Andrew

One of the questions that I am asked from time to time is why there are requirements for claims of reduction of certain contaminants included in the NSF/ANSI DWTU Standards, whereas other contaminants do not have those requirements. This is a simple question with a complex answer that has several possible reasons associated with it. One of the main reasons why certain contaminants are included is because of market demand. If there is no market demand for products that reduce a certain contaminant, then it doesn’t make sense to develop requirements for a claim of reduction of that contaminant. If, however, a particular contaminant is becoming an issue in drinking water, such that consumer preference, regulations or other focus is being put on that contaminant, this potentially creates interest for the NSF Joint Committee on Drinking Water Treatment Units to consider development of requirements for a contaminant reduction claim.

Limitations
Even when there is market interest, there can be several limitations in the ability of the joint committee to develop a contaminant reduction claim. One of these limitations is lack of a regulatory level. If a specific contaminant does not have regulatory levels for drinking water, it can be difficult to establish an appropriate and defensible maximum allowable product-water concentration. For many years, the joint committee looked to US EPA and Health Canada as (basically) the only sources of regulatory levels, but in recent years they have begun to branch out and consider state regulatory levels for contaminants that are not currently regulated by US EPA or Health Canada. This can be tricky when multiple states or jurisdictions have developed regulatory levels that are different from each other. But this approach does offer an avenue to pursue a reduction claim for contaminants that are not yet regulated in drinking water by US EPA or Health Canada.

Another limitation is effectiveness of treatment. If a given treatment technology is not effective in reducing the contaminant to levels below the regulated level, then there is no point in developing requirements for contaminant reduction. Typically, the joint committee will seek at least some confirmation that treatment technologies are effective before initiating work on requirements for a contaminant reduction claim.

A third limitation is the availability of occurrence data of the contaminant in drinking water. The joint committee attempts to set the concentration of the contaminant in the test-challenge water at the 95th percentile of occurrence (such that 95 percent of impacted users would have the contaminant in their drinking water at the tested concentration) or lower. Typically when a contaminant has been monitored in drinking water for a period of time, there is sufficient occurrence data available to the joint committee to analyze and develop a challenge concentration that they can be confident will protect the vast majority of end users.

A new proposal
A proposal to add a new contaminant reduction claim was put forth at the annual meeting of the joint committee on May 13. This proposal was to consider development of requirements for reduction of 1,2,3-Trichloropropane (1,2,3-TCP) in NSF/ANSI 53 and possibly NSF/ANSI 58.
This proposal stemmed from reports that the state of California would like to move forward with a statewide initiative for use of certified POU/POE systems to help provide compliance with the Safe Drinking Water Act (SDWA) for public water supplies. Currently it is noted that one of the most frequent uses of POU/POE for SDWA compliance for small drinking water systems in California is for treatment of 1,2,3-TCP, but there are no requirements for reduction in the NSF/ANSI DWTU Standards.

Although 1,2,3-TCP is not regulated in drinking water by US EPA, it is a regulated chemical in California, with an established state maximum contaminant level (MCL) in drinking water of five ppt (or five ng/L). This MCL was adopted by the State Water Resources Control Board Division of Drinking Water on July 18, 2017. Quarterly sampling for 1,2,3-TCP in drinking water began in early 2018. It was detected in a number of water supplies, especially in small drinking water systems. This sampling effort plus previous sampling efforts provide occurrence data of 1,2,3-TCP in drinking water.

Focus on POU/POE as a solution
California is looking for an economical solution for these small communities that have detected 1,2,3-TCP in their drinking water and attention has turned to the possibility of using POU/POE products. They cannot, however, be utilized for a statewide program yet because there are no established criteria for these products to claim reduction of 1,2,3-TCP and therefore, there is no certification. Development of requirements for a reduction claim for POU/POE technologies will allow for conformity assessment of these products and for third-party certification. Once that certification can be achieved, regulators will be able to specify the use of certified POU/POE technologies for those end users being served by small water systems that are impacted by 1,2,3-TCP.

Stakeholders cooperating to improve water quality
The NSF Joint Committee is comprised of stakeholders from three main categories: regulators, product users and manufacturers. Each of these groups of stakeholders contributes to the development of the NSF/ANSI Standards by bringing their issues, expertise and concerns regarding the standards to the table and working through a consensus process to develop enhancements and advancements. In the case of 1,2,3-TCP, current end users with certain impacted water supplies have a contamination problem that needs to be solved. Regulators in California have developed a regulatory level that can be used as a defensible basis for a maximum allowable product-water concentration for a contaminant reduction requirement. Manufacturers have technologies currently being manufactured that can be tested to confirm that they meet the requirements, once those requirements are developed. Monitoring initiatives have resulted in the availability of the occurrence of 1,2,3-TCP in the drinking water.

All three groups of stakeholders will work together to develop the requirements and test method that will become part of NSF/ANSI 53 and potentially part of NSF/ANSI 58. This cooperation and collaboration is the key toward advancing the interests of all three groups of stakeholders and ultimately helping to improve public health by providing products that have been tested and certified to an American National Standard for effective reduction of 1,2,3-TCP, in addition to the other requirements of the standards for safety of materials and structural integrity.

About the author
Rick Andrew is NSF’s Director of Global Business Development–Water Systems. Previously, he served as General Manager of NSF’s Drinking Water Treatment Units (POU/POE), ERS (Protocols) and Biosafety Cabinetry Programs. Andrew has a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or email: Andrew@nsf.org

As Important as the Water We Drink Is the Air We Breathe

Saturday, August 15th, 2020

By Emma H. Peterson

There is no doubt that the prolonged presence of the COVID-19 pandemic has forced businesses to make risky, drastic changes, some being more successful than others. But with help from the flexibility and expertise of Ryan Richie, HealthWay Family of Brands took the initiative to adapt and ultimately triumph in these especially hard times. “At HealthWay Family of Brands, we understand the value of healthier air,” Richie says. HealthWay has had an advantage with the times because it manufactures technology to improve air quality. The company’s goal is to provide the best solutions in air quality, focusing on the ability to filter and kill airborne ultrafine particles that can carry infectious diseases, but Richie says: “It wasn’t until a global pandemic that people started to realize the need and benefit of healthier indoor air, as it relates to ultrafine particles.”

HealthWay is a family-owned, faith-based company that specializes in technology to keep indoor air clean and filter out particles that could make people sick. Founded in 1989, the company began producing many different technologies in air quality. It wasn’t until 2003 that HealthWay commercialized their patented DFS technology and started offering it through a network of educated dealers.

Though Richie is not related to the clan, he says he is “family by sweat, not by blood.” He began working at HealthWay 16 years ago after meeting the executive of the company. Richie was particularly intrigued by the products they manufactured and knew it was something he wanted to ‘get behind.’ He had a background in direct home sales and began at HealthWay as an independent dealer.

After finding its niche in the water conditioning and purification industry, Richie was brought on to have a more direct role in the company. He went through several sales positions and worked his way up to his current status as Executive VP. Today, most of his time is spent training and educating water professionals on how to incorporate air purification into their businesses.

Richie prides the company on being vertically integrated and ready to give their all to any product or person with whom they are dealing. “We have built a reputation around manufacturing the most innovative technologies available in this space,” Richie says. Though HealthWay may not be the leader (in size) of their field, being the leader in technology is surely enough of which to be proud.
With the uncertainty and challenges faced in the era of COVID-19, HealthWay had to adapt to unprecedented demand from markets that had not previously been focused on or anticipated. The team at HealthWay Family of Brands, led by CEO Vince Lobdell, navigated the company through these changes. They had to tweak their focus on what was relevant and necessary for the times and therefore, planned a new strategy for a COVID world. At the same time, they needed to keep a focus on their valued dealer network that was also facing increasing demands from their customers. “Providing our equipment to the front lines fighting COVID-19 is perhaps one of the greatest honors our team could be a part of,” Richie says. “Supplying hospitals from NYC to Dubai, Greece and the epicenter in Wuhan was certainly a logistical and supply strain, but we were glad to be a part of the solution.”

HealthWay was dubbed an essential business and was granted a waiver that kept them operating and open for their customers. The grant made it possible to correspond and take proper action to supply hospitals with high-end, air-quality technology in measure as never before. To do all of this, they had to double the staff, triple production and figure out how to respond quickly to shifting demands.

They are recommitting to the needs of their partners “to provide air purification equipment to the next battle front: homeowners,” he says. “It’s crazy. We have been in overdrive to keep up with the global demand for our systems.” But despite the insanity that Richie and his colleagues have gone through with at this time, there are many blessings in disguise. Through everything, the company’s partners responded with grace and leniency. “We could not be more grateful for their understanding and acceptance of longer lead times and shipping surcharges,” Richie says.

Richie says the next step for HealthWay now is to “expand our dealerships and reinforce relationships with the current partners we have. We have committed to a massive increase in production to fulfill these needs and want to extend an invitation to any water dealers who have thought of adding air purification to jump feet first into this space with us.” Richie says they need professional dealers to embrace their new model and be a part of the solution. “Utilizing our 16-year track record of supporting the water industry and armed with current data, the air purification market is going to take off,” he says. They will continue to encourage people to think of air purification as a necessity and only accept the highest-quality products that will fit their market.

Richie sees a lot of potential on the horizon, for how the water treatment industry will move forward and up from here. He believes that in addition to changes in the air-quality industry, “this will be a tipping point for the water treatment industry to be more transformative” and that there will be more “rapid expansion into using air-quality technology as well.” He considers that because of everything happening in an ongoing COVID-impacted world, people will be more aware of the need for cleaner, healthier air. This will mean expansion of the air purification industry. Because of that, however, there will be an increase in misleading data and dubious marketing claims from other companies that are simply looking to jump on the wagon and take whatever ‘piece of the pie’ they can get, as Richie describes it.

To be aware of the market and be educated on the products themselves is what HealthWay asks of their clients. “Make no mistake, the air purification industry is seeing rapid and massive growth as consumer demand continues to grow. We have always believed in an industry that prides itself on educating consumers on wellness solutions for the home,” Richie says. “After all, as important as the water we drink is the air we breathe. Wouldn’t you agree?”

Iron and Manganese Removal – Options and Cautions

Saturday, August 15th, 2020

By Matthew Wirth

Iron, manganese and hydrogen sulfide gas are all nuisance actors in water. They exist in various forms and they complex with other waterborne contaminants to create difficult compounds to control. Because of this, there cannot be a single-source solution for controlling these common water issues. The tools required to combat problem water nuisances vary with the form these metals and gases present themselves in a specific water supply. While science and theory abound on this topic, it sometimes helps to just look at working solutions, discuss how they work and what pitfalls exist with a particular technology. This article will concentrate on iron and manganese, but hydrogen sulfide plays a role in managing these metals.Read on.

The simplest forms of iron are ferrous (Fe2+) and ferric (Fe3+). Iron that is in solution (Fe2+) and remains in solution, is simply removed through ion exchange. Ferrous iron is divalent and will exchange for sodium using cation resin. Ion exchange is also effective in controlling manganous manganese (the divalent form of Mn2+.) It is also possible (and more environmentally responsible) to strip Fe2+ using catalytic collection. Catalytic collection allows the iron in solution to temporarily bond to the catalyst supported by the media substrate. During the service cycle, this form of iron is captured and held until backwash. The air scour and backwash cycle clean the media of the iron solids and send them to drain. This method of removing ferrous iron uses no chemicals or regenerants. It simply uses ambient air and O2 to recharge the media during the scour and backwash cycles to recharge the media.

When iron is oxidized into its ferric state (Fe3+), it requires mechanical separation for removal. Mechanical straining differs, depending on the particle size of the iron floc. A smaller floc requires tighter filtration; conversely a larger floc allows for larger micron solutions. Iron particles that are submicron and colloidal usually require a flocculant to increase the size of the floc or dead-end process filtration to control.

Dead-end filtration is a batch process where water is forced through a separation (filter) medium. Retained particles stay behind on the filter surface and in the case of a depth filter, within the medium while water flows through. Accumulated particles will eventually block or plug the filter, requiring its replacement. Process filtration allows for both nominal (approximate) and absolute (exact) micron filtration—an advantage when targeting a particular particle size. If 99.9-percent removal is not critical, nominal filters offer a less expensive option. If the targeted particle must come out, one uses absolute process filtration solutions.

Backwashing filter solutions range from natural zeolite (Clinoptilolite) that captures particulates in the 5- to 12-micron (µm) range to coarse media designed to catch particles over 20 µm. There is a large variety of media and mixed media available for particulates (Fe3+) larger than 12 µm. Multi-media filters generally trap particles down to 12-20 microns. Traditional commercially available filter media are effective on particles less than 20 µm (see Chart 1). Both of these applications, ion exchange and mechanical straining, are simple technologies and easily accomplished with standard equipment.

Ion exchange for ferrous (clear water) iron and Mn2+
Ion exchange for divalent cations is just another way to say water softener. Cautions with this application include limiting iron loading. Use compensated hardness calculations by adding four grains for every mg/L of Fe2+ and Mn2+. Being conservative with NaCl (salt) and attempting to maximize capacity throughput is fine for regular water softening applications. This practice may result in damage to the resin bed in water with high iron and manganese content. Be generous with the NaCl and conservative with the capacities in problem water.

Note: Softening resin prefers calcium (predominant hardness mineral) to iron 3.1 to 1.7 in selectivity respectively. This means the resin is 1.8 times more selective for hardness over divalent ferrous iron. Why is this important? Iron leakage can occur if the hardness penetrates too far into the resin column, thus driving off the iron and releasing it into the soft water. This is why a softener installed for Fe2+ and Mn2+ needs to regenerate more often and use more NaCl.

Do an iron speciation test to ensure that the Fe3+ is < 0.3 mg/L. A speciation test indicates how a tested substance exists in its different forms in a single sample. With iron, it will show how much is ferrous and how much is ferric. Manganese resists oxidation in pH < 8.4 (Hem, 1963). Therefore, in most waters it exists as Mn2+.

Use a resin cleaner to help control ferric iron build-up and help prevent fouling of the resin beads. Sulfite-based resin cleaners work in preventing ferrous iron from converting to ferric in the brine tank and system, while phosphate sequesters ferric iron and keeps it soluble. These resin cleaners are typically used in small doses and only partly compensate. They are seldom used at high enough doses to remove foulants already formed (Meyers, 2020).

Any standard softening resin will exchange Fe2+ and Mn2+ for sodium as it does hardness. Standard resin beads range in size from 16- to 50-mesh. The largest 16-mesh beads are over twice the size of the smallest 50-mesh bead. The larger the bead, the longer the flow (kinetic) path through the bead matrix (see Image 1).

An ion exchange resin bead is a porous structure with 99 percent of its exchange sites on the inside of the bead (see Image 2). The longer the Fe2+ is inside the bead, the more likely it will oxidize into Fe+3 and get trapped inside the resin bead structure, plugging it. Once the bead is plugged, it is no longer fully functional. A smaller bead has a shorter kinetic path through its matrix and iron is less likely to oxidize inside and create fouling. This makes smaller uniform particle size (UPS) resin beads, 30- to 50-mesh, a better choice in iron water because of its uniform particle size. This is also accomplished with a shallow-shell approach where the resin bead ion exchange matrix is introduced around a solid core center. By not allowing water to pass through the center of the bead, the diffusion path is limited to a narrowed exterior shell around the non-penetrable solid core (see Image 3).

This resin offers a number of economic advantages over conventional 16 x 50-mesh resins. The small, uniform bead size results in rapid ion exchange kinetics during operation, more complete regeneration of the resin and faster, more thorough rinse following regeneration. In addition, this predictability of outcome allows for greater accuracy in sizing, efficiency and throughput. If everything acts the same, outcomes are equivalent.

Captured air versus catalytic collection
Captured air systems are very popular today. They work by introducing O2 from an ambient air source—ambient air is 21-percent oxygen (which varies somewhat with elevation). The air is compressed inside the filter vessel and the O2 is consumed by the different constituents in the water that accept oxidation; i.e., H2S, Fe, Mn, etc. In chemistry, stoichiometric ratio equations calculate how much O2 is needed to oxidize the target elements in water.

In the O2 Required Calculator (Chart 2), the existing values for the target nuisance metals and gas of Fe2+, Mn2+ and H2S are loaded into the equation and the resulting theoretical O2 demand show this water needing 0.944 mg/L of O2 to oxidize the Fe, Mn and H2S to ferric, manganic and sulfur or sulfate. In these forms they will mechanically strain using a filter media. The calculator goes on to show the available O2 in either a two-tank or single-tank configuration for a particular tank size. The calculator looks at a standard 10 x 54-inch filter, after air loading and compression, has enough air to process 870 gallons (3,293 liters) of this challenge water in a two-tank system and 290 gallons (1,097 liters) in a single-tank system.

The cautions with this technique are as follows:
1. The time required for oxidation is pH and temperature driven. Acidic water inhibits oxidative reactions with these contaminants. Therefore, water with a pH less than neutral pH 7 slows reaction times. Conversion of the targeted constituents may be incomplete, allowing them to pass through filtration.
2. The required O2 demand becomes problematic if the demand is greater than reasonably satisfied by the system— throughputs are determined by available O2 in the vessel(s).
3. Oxidized metals begin to form solids when exposed to air and will collect in the upper diffuser along the side surfaces of the control valve and inside the control valve.
4. These filters require preventive maintenance. Best practice has preventive maintenance occurring annually or sooner as determined by the designer.

The water treatment industry has numerous choices for media that incorporates the use of a catalyst. A catalyst is a substance that accelerates or changes the rate of a chemical reaction without being consumed or chemically changed by that chemical reaction. Pyrolusite and manganese greensand are two natural medias that support a catalytic action. In addition, several manufacturers commercially produce specialized media designed to work in conjunction with a catalyst. Some of these media choices require regeneration and others work with naturally and/or introduced O2 in combination with the catalyst. One thing common to most filtration media is the requirement for high backwash flowrates: from eight to 25 gpm (30 to 94 L/m) per square foot. Systems using these media choices require considerable water (in the hundreds of gallons) to backwash, cycle and rinse.
In an application where only ferrous iron is present in the source water (where the Mn 2+ is < 0.05 mg/L and H2S is non-detect), consider using catalytic collection without the use of aeration. These systems function without captured air; it leaves the Fe2+ in solution. As Fe2+ passes through the filter, it encounters the catalyst on the media. Oxygen released by this hybrid exchanger reacts with Fe2+ to form insoluble red ferric oxide (Fe2O3). Ferric oxide precipitates on the surface of the substrate and is thus trapped in the media bed.

During use, oxygen atoms are gradually depleted from the catalyst and a ferric oxide crust forms on the surface of the media. Before all the oxygen is depleted, a cleaning cycle is initiated to remove the accumulated Fe3+ and to replenish the media with fresh O2. The cleaning cycle begins with an air scour, which breaks the iron oxide crust away from the surface of the media substrate and provides the oxygen (from the air) needed to replenish the catalyst. Air scour is followed by a backwash to remove the ferric oxide crust, then by a brief rinse. Following the cleaning cycle, the system is ready for its next service run.

The media substrate that supports the catalyst is a thermoplastic and very light-weight. The advantage to this is low backwash flowrates. This media backwashes at three gpm/ft2 making it an excellent choice for low-producing wells and water conservation. This media does require air scour to insure proper cleaning and recharge. In addition to using less water to cycle, this system eliminates the issues of iron oxide formation in the controls and diffuser related to captured air.
Because the system uses collection, it has a finite throughput. This is not a filter. Once the media is loaded with iron oxide, it must be scoured and backwashed. This throughput is governed by the water severity. It is therefore necessary to speciate the iron and know the ratio of Fe2+ to Fe3+. The ferric iron needs to be at or below the Secondary Standard for Fe of 0.3 mg/L, with the balance of the iron being ferrous to avoid staining issues downstream.

Cautions:
1. This technology is for ferrous iron only. While it can attract manganese, there are no claims to this effect. It is a clear-water iron solution.
2. If the Fe3+ is greater the 0.3 mg/L, the system may require process filtration downstream.
3. Once the media is loaded, it is no longer effective. The system requires meter-initiated operation and a liberal reserve.
4. This media is NOT compatible with ozone or chlorine.

Mechanical straining and ozone
Ozone (O3) technology is nothing new. On large-scale projects it is quite complex. Used in conjunction with low-voltage 12- and 24-VDC corona discharge generators, it is a useful tool for captured air filtration systems. The biocidal effects of O3 help in controlling biofilm buildup inside captured air filters. Biofilm collects iron oxides and creates plugging issues on these types of filters. In addition, bringing in untreated ambient air can introduce outside contaminants into the customer’s potable water. Ozone destroys airborne contaminants before they enter water systems, while the O3-charged air column inside the tank works to control biofilm and organic fouling.

Cautions:
1. Always ensure that the materials contacted by ozone are ozone compatible. O3 is a powerful oxidizer and will degrade some materials.
2. Be aware of the O3 levels introduced into the water. A small generator will produce a few tenths of a grams per hour. Their intent is not to treat continuous flow applications. That takes considerably more O3 and considerably more system components. See Chart 3 for an example of O3 demand for a typical 5-gpm (18-L/m) flowrate. The captured air system batch treat with ozone during regeneration. Continuous O3 treatment requires continuous introduction of ozone. In this example, the water requires 4.48 grams/hour (see Chart 3).
3. Ozone, while a powerful biocide, is not intended as a solution for microbiologically unsafe water when introduced in a batch application in captured air filters. In addition, while it can assist in the control of sulfur-reducing bacteria and iron bacteria in a batch application within the filter, its effectiveness downstream is marginal or absent.

Hydrogen sulfide as H2S
For this discussion, the presence of H2S in source water plays a role in consumption of available O2 for oxidation. Again, looking at Charts 2 and 3 see that hydrogen sulfide requires several times more oxygen to convert H2S to elemental sulfur and H2O. This reaction limits the available O2 needed for conversion of ferrous iron to ferric. Therefore, when sizing aeration/oxidation solutions, consider the effect H2S plays in the equation. H2S and SRB (sulfur-reducing bacteria) are detailed topics and best discussed in a dedicated article. For information on H2S, check out Bryan Swistock (Senior Extension Associate/Water Resources Coordinator) at Penn State. His article explains sources of hydrogen sulfide and solutions (https://extension.psu.edu/hydrogen-sulfide-rotten-egg-odor-in-water-wells).

Conclusion
The laws of chemistry, hydraulics and physics are static. Try as we might, one cannot fool science. There are solutions, but there is not one solution to controlling nuisance problem water issues. Do the testing, consult with the operating specifications and do the math. Miss one key piece of data and a solution quickly becomes a problem. Investigate and be skeptical of claims that sound too good to be true. To this author’s knowledge, a single-source answer does not exist for the many levels of water severity across the country. Do not be afraid to consult with people of knowledge in the effort to satisfy the needs of the end users who rely on experts for answers.

About the author
Matthew Wirth is an Industrial Water Specialist with 40 years of experience working with large process systems, including RO, IEx, process filtration and media filtration. He is the General Manager of Water at Pargreen Sales Engineering in Chicago, IL. Wirth received his engineering training at the South Dakota School of Mines and Technology in Rapid City, SD and earned a Bachelor’s Degree from Concordia University in St. Paul, MN. He can be reached via email, mwirth@pargreen.com or phone (630) 628-1330.

Back to the Basics: The Benefits of Liquid Sodium Hypochlorite for Swimming Pools

Saturday, August 15th, 2020

Photo courtesy of Brand Echo Marketing, Manhattan Beach, CA

By Terry Arko

Overwhelming product choices for pool water treatment
In today’s world, the consumer has become overburdened with product choices. Everything from food, beverages and clothing to media, technology and personal care products have a dizzying variety of personalized options available: when is the last time you ordered a plain, black coffee at a coffee shop? The same has occurred for the treatment of swimming-pool water. The primary task for a pool service professional, or even any DIY homeowner, is to ensure that the water in the pool is clean and safe for the swimmers. The very apparent failure of an off-balance pool when it goes green is a clear Don’t Swim sign, but we in the industry know that just as dangerous, invisible microbes and bacteria can leave a pool unswimmable, even though it may look okay.

Chlorine has been a long-standing workhorse to sanitize swimming pools and keep them free from bacteria or algae growth. Going back in time, the treatment of pool water was mostly simple. Two primary forms of chlorine compounds were widely used: liquid chlorinating compound (sodium hypochlorite, or bleach) and calcium hypochlorite dry, in both commercial and residential pools. The water was balanced primarily with muriatic acid. As swimming popularity increased, more pools were built and more swimmers entered the water. Longer hours at the aquatic facility and more swimmers in the backyard pool put a huge strain on the water quality. Products to address the surge began to fill the market.

More chlorinating options became available, led in the DIY market by trichlor tablets. Trichlor tablets differ from sodium hypochlorite and calcium hypochlorite because they are blended compounds that contain cyanuric acid (CYA). Cyanuric acid is a stabilizer that prevents chlorine in pool water from being broken down by sunlight. In the commercial realm, feeder systems became more prevalent and sophisticated. Ozone, UV and advanced oxidation processes (AOPs) soon became treatment options (joined by specialty chemicals) to handle everything from algae to evaporation prevention. The maintenance of the backyard pool evolved from a simple to a potentially complicated and confusing process.

How tablet convenience replaced liquid practicality
While calcium hypochlorite and liquid sodium hypochlorite were enjoying mainstream popularity in backyard pools, the fact remained that both forms of hypochlorite do not contain a stabilizer like CYA. That meant that in the summer sun, the free chlorine created by these compounds didn’t last very long. In fact, nearly all the chlorine from sodium hypochlorite or calcium hypochlorite could be destroyed in about four hours by direct summer sunlight. Since this problem began to be recognized, the practice of adding extra amounts of chlorine in the late afternoon or evening was incorporated. The issue was partially solved when Monsanto began to produce and distribute a chlorine stabilizer known as cyanuric acid (CYA). CYA stabilizer could be added to the pool to allow for longer residuals of chlorine during the sunny days of summer. The addition of the CYA stabilizer allowed chlorine from sodium hypochlorite or calcium hypochlorite to last up to eight times longer.

At levels of just 30 ppm, the CYA helped to significantly slow the degradation of chlorine from UV sunlight, which was an incredible benefit. Soon after, the trichlor tablets of stabilized chlorine (known as isocyanurates) began to make their way into residential swimming pools. The selling point of these tablets was convenience for the owner. The tablets could be added to an inline feeder or a floating container (floater). The main advantage of trichlor tablets was having the stabilizer that protects chlorine from the sun built right into the tablet, making it an instant convenience for the modern pool owner. As this system of treating backyard pools grew in popularity, liquid sodium hypochlorite was pushed out as the main source of pool sanitization. Liquid was now mainly used as a backup or shock.

Perceived dry chlorine convenience causes complications
While the two-in-one convenience of trichlor tabs continued to grow, there was something going on beneath the surface that pool pros and homeowners were beginning to observe. Early on there was a suspicion that higher levels of CYA could block the effectiveness of the chlorine, causing what was known as chlorine lock. Anecdotally, it was becoming certain that pools treated with trichlor tabs, with increasing amounts of CYA, were becoming a struggle to maintain. It seemed more of a challenge to keep free available chlorine levels in control and many pools had algae problems toward the end of the season. Users of trichlor tablets soon became aware of some side effects that led to complications in water treatment. The amount of CYA being released from the continual dependence on trichlor tablets as the primary means of chlorination bore a closer look. (More than half of an eight-ounce trichlor tablet consists of CYA. Over 54 percent by weight is CYA with the other 46 percent being chlorine and binders.) It was realized that too much CYA came from trichlor tablets with every application, which was far more than needed to stabilize a pool.

Despite the clear chemical argument for using (but limiting) CYA, there was a large contingent of users under the impression that more was better, while others were beginning to see the need to drain and dilute to keep CYA levels down. Regardless of the stance on the CYA debate, one point was clear: trichlor tablets made the maintenance of pool water more complicated and costly. Another important point was that they were very acidic, which led to using more soda ash to balance pool water. It was clear to see that the perceived convenience of trichlor tablets led to a lot of complications for both service pros and pool owners.

Liquid sodium hypochlorite and saltwater generators
Moving into the 90s, devices began to become more prevalent. A technology that became popular was the saltwater chlorine generator. These were sold to many new pool owners under the auspice of being a non-chemical pool product that relied only on salt to purify the water. Many of those new pool owners were not aware that the salt unit installed on their new pool was basically a small home version of a large-scale liquid sodium hypochlorite factory.

Liquid sodium hypochlorite is made at chemical plants by first using a process of electrolysis to split the sodium chloride molecule. Simple salt is divided into chlorine and sodium hydroxide, then blended with water to form liquid sodium hypochlorite. The saltwater generators on swimming pools do the same thing on a smaller (and less efficient) scale. So, they really are more correctly referred to as chlorine generators.

Liquid sodium hypochlorite is still recognized as one of the best back-up sanitizers for chlorine generator systems. The main reason for this is due to the byproduct that comes from the use of sodium hypochlorite. Let’s look at the different types of chlorine and their byproducts:

The only byproduct left from using liquid sodium hypochlorite to backup a chlorine generator pool is sodium chloride, better known as salt. Of all the types of assistive chlorine that can be used with a saltwater chlorine generator, liquid sodium hypochlorite is the simplest and most consistent with the system. The use of liquid sodium hypochlorite as a backup in a chlorine generator pool is best, due to the fact that it will not add any calcium scale or additional CYA to the system.

Like any type of chlorine-sanitized swimming pool, one using a chlorine generator will still need to maintain a certain level of CYA to prevent rapid burnout of chlorine from the sun’s UV rays. CYA levels in a salt pool are good at a level of 30-50 ppm. At times, a chlorine generator may need a backup of manually added chlorine to keep the water quality good. This could be due to heavy swimmer load, equipment failure or other inert items such as leaves and dirt being introduced into the pool water.

Liquid sodium hypochlorite and secondary systems
There are several sophisticated secondary sanitizer options that have gained in popularity recently: ozone, UV and AOPs. None are yet approved by US EPA as primary sanitizers, however. Even though they are beneficial to oxidize and inactivate many pool-water contaminants, they are unable to leave a measurable residual in the water. That means chlorine still needs to be the primary sanitizer, with a residual between one and four ppm. CYA levels need to be controlled in pools with these treatment types in order to get the desired residuals to ensure protection from bacteria in the pool.

As with nearly all other pool types, 30-50 ppm of CYA is the recommended level in these systems. At a CYA level of 60, it would take 4.5 ppm of chlorine to inactivate bacteria, which is outside what is required by US EPA rules. Since the main purpose of secondary devices is to allow for complete disinfection with lower amounts of chlorine, the use of trichlor in these treatment options is a less than ideal solution. Again, liquid sodium hypochlorite is a preferred choice for these systems because it provides manageable levels of free chlorine without byproducts that will reduce the effectiveness of UV, ozone or AOP.

The benefits of a simple liquid sodium hypochlorite system
Liquid sodium hypochlorite has been proven throughout the history of pool chlorination to be one of the most cost-effective, easiest and safest ways to disinfect pool water. Perhaps this is a good time to return to the simplicity of liquid for effective pool treatment. Benefits of liquid sodium hypochlorite include:

  • Affordable and easy
  • Safe for storage (as it is non-flammable and non-combustible)
  • Immediately available sanitizer
  • Leaves a measurable residual of free chlorine
  • Does not contain calcium or cyanuric acid
  • Very beneficial as a backup to chlorine generator systems
  • Ideal for use with secondary sanitizing systems like ozone, UV and AOP

Liquid sodium hypochlorite highly recommended for the COVID-19 summer
Most public aquatic facilities are reopening slowly and with restrictions. That means many families are choosing to stay home, making the backyard pool a center of activity. Liquid sodium hypochlorite is noted by the CDC as one of the most effective sanitizers for water disinfection and surfaces as well. The agency’s Safe Water page states: “Although a number of other disinfectants (calcium hypochlorite, ozone, UV, solar disinfection) and treatment processes (filters, slow sand filtration) have been investigated, sodium hypochlorite appears to offer the best mix of low cost, ease of use, safety, and effectiveness in areas where there is enough water to drink and water is not excessively turbid. These characteristics are the reasons why most water treatment systems in the US and Europe have been using chlorine for disinfecting drinking water for nearly 100 years.”

The liquid sodium hypochlorite used for swimming pools is a concentrated form of household bleach. The bleach used for laundry is typically a six-percent strength. Swimming-pool liquid sodium hypochlorite is available in strengths ranging from eight to as high as 12.5 percent. This is great for the swimming pool because liquid is ready to disinfect immediately without any need to dissolve or break down. That means that bacteria and algae are quickly disrupted. In relation to COVID-19, the CDC has stated that there is no evidence that the virus can be transmitted in treated swimming pools.

Conclusion
While there are several options for pool treatment, it’s important to make sure the right option is used. Liquid sodium hypochlorite (chlorine) for pools remains one of the most practical, effective and safest options for keeping pool water clean and clear this summer.

References
APSP Service Tech Manual, 5th Edition. Association of Pool and Spa Professionals. 2019

Lowry, Robert W. Basic Training Manual. IPSSA. 2016

The Condensed Chemical Dictionary, 10th Edition. Van Nostrand Reinhold Company 1981

Griffiths, Tom. The Complete Swimming Pool Reference. 1994

White, George Glifford. White’s Handbook of Chlorination and Alternative Disinfectants. 2010

About the author
Terry Arko has more than 40 years of experience in the recreational water industry, working in service, repair, retail sales, chemical manufacturing, technical service, commercial sales and product development. He has written over 100 published articles on water chemistry and has been an instructor of technical courses for over 25 years. Arko is a voting member on the board of the Recreational Water Quality Committee (RWQC) and serves as a board member for the California Pool and Spa Association (CPSA). He is also a Certified Pool Operator instructor with the Pool Hot Tub Alliance (PHTA). Arko is currently working as Technical Content and Product Training Manager for HASA Pool, makers of HASA Sani-Clor. He can be reached at terryarko@hasapool.com

Ozone Industry Sets Its Sights on Industrial Applications

Saturday, August 15th, 2020

Venturi injectors provide highly efficient transfer of ozone for water treatment in a wide range of industrial applications.

By Jim Lauria

Ozone has proven its efficacy, efficiency and value in drinking water treatment for years. Now ozone proponents are turning their sights on industrial applications, where the same benefits that have made ozonation so attractive in municipal water treatment can be applied across a much wider range of water quality challenges.

The International Ozone Association (IOA) Pan American Group has drawn together scientists, engineers and marketers from across the ozone industry to help suppliers from every corner of the business benefit from the growing interest in the power of the aggressive oxidant. The IOA’s Industrial Committee is actively advocating for the use of ozone, promoting research, educating the water industry about the use of ozone in an array of industrial applications and seeking case studies to help illustrate how ozone improves our lives daily.

Key benefits
Water treatment professionals have long recognized how effective ozone is in clean-in-place (CIP) systems, laundry, pulp and paper, mining and other industries. As ozone gains traction in industry after industry, certain key benefits float to the top. Of course, efficacy is first and foremost. Ozone works, and it works fast—even faster than peroxide. In just a few seconds, an ozone molecule will blast most organic contaminants, rendering them harmless. And because ozone dissolves readily in cold water, ozone treatment is extremely energy-efficient in processes like laundry and sanitation.

The powerful bleaching action of ozone has driven its extensive use in pulp and paper manufacturing, and the beneficiation of minerals like kaolin clay, where bright, white color is an indicator of quality. Other mining applications of ozone include the detoxification of compounds like cyanide into cyanate or the oxidation of selenium. As pressure increases to reuse water in mining—or any other industry—fast, efficient treatment will be a key part of the picture and ozone is proving itself to be a great fit. Another great strength of ozone systems is that they are largely self-contained, making them well adapted to remote applications. Generated on-site from oxygen or air, ozone does not require the storage or handing of dangerous chemicals.

In ozonation reactions or degassing processes, ozone is quickly converted to atmospheric oxygen. In terms of its chemical activity, ozone is like the perfect assassin. In its molecular ozone form, it is a specific oxidant that targets aromatic and aliphatic compounds—including pathogens and phenolic compounds that produce off-tastes and odors—kills quickly and effectively, then disappears into thin air. Converted into a hydroxyl radical, it storms a much wider range of contaminants in a flurry of oxidation before becoming neutralized.

Science emphasis
Members of IOA range from manufacturers of ozone generators and other ozone-specific machinery to the consulting engineers who design ozonation systems for their clients. The organization has a firm grounding in science and a mission to dig deep into the technology, so the emphasis is on rigorous testing, data sharing and detailed analysis.

Venturi injectors are widely used in efficiently injecting and mixing ozone into anything from pool water to winery CIP systems to massive treatment units at remote mining sites. Because IOA has drawn players from upstream and downstream in the market, their activities have proven to be fertile ground for collaboration, innovation, networking and letting ideas germinate and grow among colleagues involved in every aspect of ozonation.

In many marketing case studies, it is enough to know that ozone in a CIP system doesn’t require hot water and high pressure like conventional detergent CIP systems. In contrast, IOA’s online case study on CIP explains how analysis of a large ozone CIP system in a bottling plant saved $72,000 (USD) in energy costs and $300,000 in chemicals annually, while improving bacterial control. IOA’s page on ozone in pulp and paper applications links to dozens of peer-reviewed articles in Ozone: Science and Engineering on the topic.

Constant flow
IOA is continually sharing new information with members. As COVID-19 continued its spread in early summer, Barry Loeb, Editor-in-Chief of Ozone: Science and Engineering, alerted readers to promising trials of an ozone treatment for scarce N95 masks and studies of ozone-based decontamination systems for rooms in hospitals and hotels. Of course, the pandemic has put several IOA meetings on hold, including the Pan America Group conference scheduled for August in Las Vegas, NV. The organization is responding, however, by bringing members together online for conferences, such as a recent session on CFD or the upcoming presentation on ozone in mining applications. As IOA’s website notes: “We’re only beginning to discover ozone’s potential.” This is the time to get involved with the organization at the forefront of those discoveries.

About the organization
The International Ozone Association is a non-profit educational and scientific organization dedicated to the collection and dissemination of information on, and to promote research in, any and all aspects of ozone and related oxygen species technologies. Through the organization, members gain access to the most cutting-edge information on ozone technology. For more information, please visit the website https://ioa-pag.org/

About the author
Jim Lauria is Vice President of Sales & Marketing for Mazzei Injector Company, LLC. Since graduating with a Bachelor of Chemical Engineering degree from Manhattan College, he has traveled the world benchmarking the best global water management practices. Lauria is a member of the IOA-PAG Executive Operating Committee and co-Chair of their industrial committee. He can be contacted at jlauria@mazzei.net.

About the company
Mazzei Injector is a fluid design company that manufactures mixing and contacting systems for ozone injection and other municipal and industrial water treatment applications. The company, built by an engineer and driven by data-rich pursuits such as its in-house computational fluid dynamics (CFD) lab, is a perfect match for the International Ozone Association’s passion for science-based industry development. The company is a proud silver year-round sponsor of the IOA.

Residential Ozone Applications

Saturday, August 15th, 2020

By Greg Reyneke, MWS

Ozone is a highly effective technology for addressing numerous waterborne contaminants in commercial, industrial and recreational water usage environments. There are, however, relatively few dealers that use it on a consistent basis. This is usually because the dealer lacks the knowledge or confidence to recommend the technology. Ozone can be slightly intimidating to start using, since it is inherently more complex than a typical softener. As with softeners, though, if you know enough to get started and have a decent support network, you will be just fine. The key to success is to leverage the resources that you already have. Hopefully, you are already a member of WQA and your regional WQA, as well as enrolled in the MEP program. There, excellent information about ozone and problem water contaminants can be found.

Ozone generation
Ozone consists of three oxygen molecules and is highly unstable. This inherent instability is what makes it so very attractive for treating waterborne contaminants. It works hard oxidizing as much as it can for slightly less than a half-hour at room temperature and then degrades into safe, stable O2. This makes it very attractive for numerous oxidative applications. Ozone is naturally produced through solar radiation and lightning strikes. In the water-treatment industry, we simply imitate nature.

Ultraviolet light. Ozone is produced by reacting oxygen with ultraviolet light in the 185-nm spectrum. UV ozone generation has a lower up-front cost and is not very sensitive to ambient humidity, making it ideal for air-handling applications. (I prefer not to use it for residential water projects, since the UV lamp upkeep and sensitive ballasts make it cumbersome and electricity-intensive compared to other methods.)

Cold corona discharge. Also known as cold-spark corona discharge or simply corona discharge, this is my preference for residential applications. Simply put, corona discharge ozone production requires a high-voltage power source, anode, cathode and a suitable dielectric separator. Air passes between the electrodes over a dielectric, creating an electric field, or ‘corona,’ which induces O2 molecules to rearrange themselves as ozone (O3). Corona discharge produces a much higher concentration of ozone than UV, but is sensitive to ambient humidity. Always strive to maintain a dew point lower than -30°C (32°F) for optimum performance.

For residential applications, it is rare to see liquid oxygen feeds (or even oxygen concentrators), as you would in commercial and industrial applications, which keeps costs down, makes for a simpler installation and keeps maintenance costs reasonable. There may be times, however, that they are necessary, so be sure to discuss the options with your equipment vendor(s).

Ozone is an effective oxidizer when addressing the terrible trio in problem water: iron, manganese and hydrogen sulfide.

Iron, as one of the most abundant elements in the Earth’s crust, is commonly found in well-water supplies. While iron generally poses no health threat to humans and animals, it is a stain-causing and sediment-forming nuisance that feeds numerous strains of bacteria. Iron can exist in both soluble and insoluble forms. The ferrous iron (II) form is highly unstable and quickly develops insoluble iron (III) hydroxide when exposed to oxygen at elevated pH levels. Anaerobic groundwater can hold significant amounts. US EPA’s secondary MCL for iron is 0.3 mg/L; anything above 0.1 mg/L will typically cause staining over time. Iron-reducing bacteria (IRB) feeds on iron in water and presents its own set of unique challenges that can complicate your treatment options.

Manganese is far less abundant than iron, but still quite common and easy to recognize from telltale black staining. US EPA’s secondary MCL for manganese is 0.050 mg/L, with many states having an action level as high as 0.5 mg/L. The consumption of elevated levels of manganese has been linked to neurological disorders. Bathing and showering in water containing manganese has not been shown to pose an appreciable health risk to adults, but there is very little data on its effect on developing bodies. Therefore, it is prudent for pregnant women, babies and young children not to drink water containing manganese.

Hydrogen sulfide’s infamous rotten-egg smell distinguishes it from iron, manganese and most other contaminants that are found in well water. In addition to its unpleasant odor, hydrogen sulfide concentrations as low as 1.0 ppm are quite corrosive and even very low levels can tarnish silverware and stain porcelain fixtures. It is important to evaluate the water holistically when addressing hydrogen sulfide, since higher pH ranges (7-12) will include other species of sulfur (like sulfide or bisulfide) that do not have odor. Hydrogen sulfide can enter water from geothermal activity, decay of organic matter and, to further complicate issues, various strains of sulfur bacteria that commonly exist in groundwater supplies. They eat sulfur and their metabolic byproducts contain hydrogen sulfide gas. Sulfur-oxidizing bacteria will convert sulfide into sulfate, while producing a black slimy biomass.

The key to establishing an effective water treatment plan is to understand the nature of the problem, evaluate potential treatment options and then ensure it can be purchased, installed and maintained affordably.

Site survey and water test(s)
When performing a site survey, you should determine the following information at a bare minimum to ensure that you are able to provide a smart solution:

  • Type of water source
  • Type of storage and capacity (if any)
  • Floats and other controls in use
  • Peak water flowrate available to the water treatment system
  • Drainage facilities
  • Pipe size and material of influent water supply
  • Peak flow demand of the facility being treated
  • Space available for the system
  • Electrical power available for system
  • Dimensions of doorways and other entry ways
  • Daily water consumption habits
  • Client’s water quality concerns to be addressed
  • Water chemistry from a recent test

The biggest failures that I have witnessed and perpetrated in treating problem water have resulted from inadequate, incorrect or inaccurate testing. If any parameters seem strange or outside of the norm for what you have seen in the area before, don’t be afraid to test multiple times: “measure twice, cut once” is wise counsel.

You should always test for the following, using industry-standard test methods:

It is smart to also test for non-pathogenic bacteria with a Biological Activity Reaction Test (BART) to understand the overall situation better and anticipate interfering biological factors. BART is a simple, safe and effective method for predicting the population size and activity of specific groups of bacteria. Aerobic organisms grow around the ball, while anaerobic organisms will grow lower down in the water column. Results are determined by observing the rate of change of color/opacity (as well as variations in color on some tests) as the microorganisms at the bottom of the water column consume the nutrient mixture. A BART test usually takes two to eight days of incubation at room temperature, giving you the flexibility of performing the test without having to send a refrigerated sample to a testing laboratory.

BART kits contain specific sanitary nutrients in the base of a tube where the water being tested will be poured and a ball that will float at the top to restrict the amount of oxygen entering the water column. It is wise to test for slime-forming, iron-related and sulfate-reducing bacteria each time. Accurate water chemistry information will help you to calculate the amount of ozone required to provide appropriate treatment. Here are some helpful minimum dosage requirements used by our team (see Table 1):
Disinfection applications will require a minimum ozone dosage of 0.5mg/L in addition to any other established ozone demand.

Calculating minimum ozone generator production rate:
Grams of ozone per hour = water flow (liters/hour) x ozone demand
1. Calculate the flowrate to be treated in L/hr.
Convert from US customary units to metric as follows: (gpm x 60) x 3.785
For example: 1 gpm x 60 = 60 gallons per hour
60 gph x 3.785 = 227 liters per hour
2. Multiply minimum ozone demand by L/hr to calculate mg/hr minimum production rate.
3. Divide by 1,000 to determine the minimum grams per hour that the ozone generator needs to produce.

Complicating factors will interfere with textbook ozone demand calculations. Best practice is to include a reserve capacity of 30 percent beyond minimum to allow for flexibility in treatment. It’s better to throttle down your ozone production rate than to wish that you had more available. The next step is to calculate the volume of retention required to maximize contact time. You simply multiply the time required by the operating flowrate. If you are operating at 10 gpm (37.8 L/m) and require six minutes of contact time, you’ll need a total mixing/retention tank volume of at least 60 gallons (227 liters). Strive for a minimum contact time of one minute and maximum of 30 minutes, which is the half-life of ozone at room temperature (approximately 77°F/25°C).

Another perspective is to consider the dosage rate. Dosage rate factors time and ozone concentration to maximize oxidation and minimize cost. For example, a dosage of 0.5 ppm for two minutes is the same as 1 ppm for one minute and 2 ppm for 30 seconds. This dosage rate is important when evaluating the type of ozone injection.

Equipment selection and system design
Once you know what you’re dealing with and the challenges involved, you can begin the process of selecting an ozone injection configuration. Typical residential ozone installations are either atmospheric or in-line designs.

Atmospheric ozone injection
Atmospheric ozone injection can be quite cost-effective, especially if the homeowner is already planning on storing water and repressurizing it. A significant benefit of working with an outdoor atmospheric tank is that lower ozone dosages can be very effective due to increased contact time and the tank can safely vent gases and unused ozone to atmosphere. Some dealers will introduce the raw water into the tank through an aerating head to further assist in the oxidative process. Mixing nozzles can also be used to provide as much contact and movement as possible. A significant disadvantage of the atmospheric tank is that soluble precipitates will form at the bottom of the tank, necessitating periodic cleanouts. Further, if the tank installation does not include sanitary venting and protection of animal/insect ingress, it can become a source of bacterial contamination. An atmospheric configuration typically incorporates the following components, assuming that pump and fill controls are already in place:

Air pump. Sized to generate the pressure and flow needed to deliver the ozone to the desired point. The air will be pushed through an optional dryer, through the generator and then all the way to the tank where it will rise to the top and plunge down to the bottom (where it exits the diffuser), so take this into account and size accordingly.
Optional air dryer. The ozone installation will usually include an air dryer if ambient humidity is less than 20 percent. Air dryers can be passive-desiccant or active-heating dryers. Consult with your vendor to ensure that the pumped air is dry enough before entering the generator
Ozone generator. The generator is sized according to manufacturer’s guidelines along with your calculations. Be sure to discuss each application with your vendor to help minimize potential problems or complications.
Distribution tubing. One of the most common mistakes made in ozone installations is to use the incorrect tubing after the ozone generator. Remember that ozone is a very strong oxidizer and it can destroy vinyl and polyethylene fittings/tubing. Stick with proven tubing, like PVDF, FEP and PTFE. Always use the style and type of fitting that the tubing manufacturer recommends for the application. For example, most PVDF tubing manufacturers only advise barbed fittings, where PTFE can be used with barbed or compression fittings. Keep tubing shielded from direct sunlight/heat and keep the run as short as possible to minimize degradation.
Ozone diffuser. The diffuser introduces ozone to the water. This is not a place to be cheap; use a diffuser made of materials compatible with the water you are treating and select one that generates extremely small bubbles to enhance contact.

The most common failures that I see in atmospheric tank applications is where the O3 dosage is too low and you are then inadvertently promoting the growth of slime-forming aerobic bacteria. Remember that in warmer states, the water in an atmospheric tank can get quite hot, so your ozone will not be active for as long as it would in a northern climate.

In-line ozone injection
If there is no space for atmospheric injection, or the ambient temperature makes it unfeasible, an in-line injection design is appropriate. In-line injection requires a faster rate of ozone production and suitably designed injection, mixing, contact and ozone destruction. The preparatory steps are exactly the same as for atmospheric injection, with an air pump, air dryer, ozone generator and distribution tubing. The difference comes in with prefiltration, injection and contact times:

Prefiltration. Protect your injection system, mixer(s) and contact tank(s) from sediment and foreign material with a prefilter in the 30- to 50-micron range.
Backflow prevention. While check valves are important on all ozone installations, it is critically important to incorporate at least one ozone-compatible check valve and a Hartford Loop on a direct injection system after the ozone injector to prevent contamination of the ozone injection loop with water, as well as backflow of water into the ozone generator.
Injection. The injector type and location are important for ensuring that you inject as much ozone as possible into solution. Size the Venturi injector according to manufacturer’s specifications and plan on installing it so that it can be easily accessed for periodic maintenance and cleaning.
Static mixer. Static mixers allow for significantly improved contact between the ozone and the solution to be treated, and are well worth the added expense.
Ozone contact tank. A properly sized contact tank further ensures an appropriate ozone dosage while allowing off-gassing to an ozone destruct system and then to atmosphere.
Ozone destruct. Unused ozone in the contact tank indicates that there is sufficient ozone to fully oxidize the contaminants or more commonly insufficient contact time in solution because the contact tank is undersized. The contact vent can be routed to an ultraviolet or catalytic ozone destructor that will force it to revert back to the oxygen that is found in normal ambient air.

Dealing with the byproducts
Once the target contaminants have been oxidized into insoluble precipitates, it’s time to take out the trash. This can be effected with cartridges, bag filters or even a self-backwashing multimedia filter. Budget, required flowrate and the amount of contaminants to be removed will help to make the right decision. Think about the size of particulate to be removed and bench-test to establish the appropriate filter pore size that you will need.

It is also very important to plan for redundancy by installing parallel identical filters, or step-wise series filters. A successful approach is a self-backwashing multimedia depth filter followed by a one-micron post-filter, which ensures maximum removal of precipitates, while retaining the ability to properly clarify the water. You will minimize the potential for bacterial contamination of the post filters through good design, safe handling and disinfection procedures. It is sometimes appropriate to also soften the water at this point and then disinfect with 254-nm UV to provide peace of mind to the end user.

Installation and follow-up testing
Even the best-designed systems will fail if improperly installed. Make sure that you follow industry best practices while adhering to prevailing local codes and manufacturers’ guidelines. Locate equipment away from excessive humidity, direct rain, direct sunlight and freezing conditions. Dry, clean, cool equipment will provide the very best results.

Don’t plan on forgetting about your client once you’ve been paid. Instead, plan on returning within 30 days after installation to retest the influent and effluent waters and confirm that everything is working as promised. Discuss a sensible preventive maintenance plan with your client to help ensure that the system is properly maintained and that you are able to best serve them. Plan on visiting your client at least annually to maintain the system and ensure that their water is what they expect it to be.

Ozone safety notice
Ozone is an unstable and extremely powerful oxidizer. It can be deadly to humans and other animals. Concentrated ozone smells similar to chlorine and not surprisingly, they both act similarly against living organisms. Airborne ozone can cause:

  • Decreases in lung function
  • Aggravation of asthma
  • Throat irritation and cough
  • Chest pain
  • Shortness of breath
  • Susceptibility to pulmonary infections
  • Damage to eyes and mucosal membranes
  • Damage to skin

The US Occupational Safety and Health Administration (OSHA) guidelines for ozone in the workplace are based on time-weighted averages. Ozone levels should not exceed 0.1 ppm (parts per million) for each eight-hour-per-day period of exposure doing light work. The OSHA website cites several American Conference of Governmental Industrial Hygienists (ACGIH) guidelines for ozone in the workplace:

  • 0.2 ppm for no more than two hours exposure
  • 0.1 ppm for every eight hours per day exposure doing light work
  • 0.08 ppm for every eight hours per day exposure doing moderate work
  • 0.05 ppm for every eight hours per day exposure doing heavy work

Unlike OSHA, National Institute for Occupational Safety and Health (NIOSH) safety and health standards are not enforceable under US law, but they do have a strong influence in forming future policy and regulations, as well as being sensible. The NIOSH recommended exposure limit for ozone is 0.1 ppm. According to NIOSH, ozone levels of five ppm or higher are considered immediately dangerous to life and/or health. A good rule of thumb is that if you can smell ozone, then you should evacuate the area and properly ventilate before returning to work.

Conclusion
Ozone requires a little planning and effort, but the benefits can be dramatic. Learn more and take the plunge!

About the author
Greg Reyneke, Managing Director at Red Fox Advisors, has two decades of experience in the management and growth of water treatment dealerships. His expertise spans the full gamut of residential, commercial and industrial applications, including wastewater treatment. In addition, Reyneke also consults on water conservation and reuse methods, including rainwater harvesting, aquatic ecosystems, greywater reuse and water-efficient design. He is a member of the WC&P Technical Review Committee, currently serves as President of the PWQA Board of Directors and chairs the Technical and Education Committee. You can follow him on his blog at www.gregknowswater.com

People

Saturday, August 15th, 2020

Clark hired at IAPMO Oceana
The IAPMO Group announced the hiring of Graham Clark as Operations Manager of IAPMO Oceana, a new position within the organization. He is an engineering professional with 13 years of experience as a business and team leader. Prior to joining IAPMO Oceana, Clark spent four years with Rheem Australia, most recently as R&D Manager. Previously he was R&D Manager for CAMEC and Development Engineer for Davey Water Products. A graduate of Monash University in Melbourne, Clark holds dual Bachelor’s Degrees in engineering and commerce.

Sanderson named WEF Medical Officer
To ensure protection of the health and safety of wastewater workers during the coronavirus pandemic and into the future, Andrew Sanderson, MD, MPH of Howard University has been named Chief Medical Officer for WEF. He will guide and assist the organization in providing reliable medical information to wastewater utility managers and workers, as well as conduct research and serve as a spokesperson on medical issues for the sector. A gastroenterologist with Weatherby Healthcare, Sanderson is also an Associate Professor at Howard University. His previous positions include medical officer at the US Department of Health and Human Services, fellow at Harvard Medical School and Chief of the Division of Gastroenterology at Howard University Hospital. Sanderson received his Master in Public Health from Harvard University, Doctor of Medicine from Howard University and Bachelor of Science in biology from Morehouse College.

ACS honorees named
The American Chemical Society (ACS) has selected Paul Alivisatos, PhD, of the University of California (UC), Berkeley as the recipient of the 2021 Priestley Medal, the Society’s highest honor. The Samsung Distinguished Professor in Nanoscience and Nanotechnology Research and Professor of chemistry and materials science and engineering at UC Berkeley, he is being recognized for “foundational contributions to the chemistry of nanoscience, development of nanocrystals as nanotechnology building blocks and leadership in the chemistry and nanoscience communities.”

Mary Engelman will receive the ACS 2021 Award for Volunteer Service, presented annually to recognize the volunteer efforts of individuals who have served ACS by contributing significantly to the goals and objectives of the society. Engelman is being honored for her efforts in increasing public awareness of chemistry, mentoring young scientists and leading society activities.

AWWA President named, members appointed to boards
Melissa Elliott began her one-year term as President of the American Water Works Association (AWWA) during a gavel-passing ceremony at AWWA headquarters. She is Director of Strategic Communication Services at Raftelis, where she consults with utilities across the United States. Elliott has been an AWWA member for over 15 years, during which time she has served as Chair of the Public Affairs Council. She has also served as Trustee and Chair of AWWA’s Rocky Mountain Section. Two AWWA leaders have been appointed to the boards of non-profit water organizations. CEO David LaFrance has been appointed to the Board of Water Education Colorado (WEco) and Tracy Mehan, Executive Director of Government Affairs, was elected to the River Network Board of Directors. LaFrance’s term with WEco began in January. Mehan’s term with River Network officially begins October 1.

US Junior Prize winners announced
WEF announced Zoe Gotthold the winner of the 2020 US Stockholm Junior Water Prize, the nation’s most prestigious youth competition for water-related research. A student at Richland High School (Richland, WA), she developed prototypes of devices that promote oil flocculation at the surface and increase the efficacy of traditional oil-spill remediation techniques. Gotthold won $10,000 and will represent the United States at the international competition. The two US runners-up were Emily Tianshi (CA) and Emma Price (MO), who each received $1,000. Ishraq Haque (SC) received the Bjorn von Euler Innovation in Water Scholarship Award from Xylem Inc. Beatrice Youd (WI) received the James L. Condon Recognition for Environmental Stewardship.

‘Doc’ Nowlin, industry pioneer, mourned
Duane ‘Doc’ Nowlin, PhD, passed away June 15 in New Brighton, MN at the age of 83. A much-revered water treatment industry professional, he made a mark on the industry that cannot be matched. Nowlin spent countless hours serving the industry on numerous WQA science and technical committees, the Board of Directors and Board of Governors, WQRF and as a frequent presenter at WQA conventions. He also served on the US EPA Drinking Water Advisory Council and as a member of the American Chemical Society and American Water Works Association.
Nowlin served as 1988-89 WQA President and chaired the WQRF Board in 1991. Prior to his 2002 retirement, Nowlin was Senior VP of Science & Technology and Chief Scientist for EcoWater, where he had spent most of his career (including at the affiliated Lindsay Co. or Spectrum Labs). As a result of his intense involvement in the industry, Nowlin was honored multiple times throughout his career. In 1977, he received the WQA Award of Merit, followed in 1986 by the Key Award. In 1995, Nowlin received WQA’s highest honor, the Hall of Fame Award, followed by the WQA Lifetime Achievement Award in 2002.
Nowlin was preceded in death by his son, Carl and parents, Clarice ‘Sue’ and Denver ‘Shorty’ Nowlin. He is survived by his wife, Esther, sons David (Alba) and Mark, as well as six grandchildren. A Celebration of Life is to be held at a later date. In lieu of flowers, please make a donation to the charity of your choice.

Global Spotlight

Saturday, August 15th, 2020

North America
Calgon Mississippi plant expanded
Calgon Carbon Corporation announced that it intends to expand capacity at its Pearlington (MS) plant by adding a second virgin activated carbon production line. The expansion is expected to add 38 jobs at the plant when complete. The estimated investment will be $185 million (USD). When completed, Calgon Carbon’s virgin granular activated carbon capacity will exceed 200 million pounds per year.

IWSH welcomed by World Plumbing Council
The International Water, Sanitation and Hygiene Foundation (IWSH) announced it is the latest plumbing industry organization to join the World Plumbing Council (WPC). The WPC was established in 2000 and has at least one organizational (full or affiliate) member in 41 countries. Full members are mainly national-level plumbing industry associations and unions, while affiliate members include contractors, manufacturers, wholesalers, distributors, service providers and academic institutions.

US Water Alliance prize winners named
US Water Alliance announced the winners of the US Water Prize 2020: Denver Water was the winner of the Outstanding Public Sector Organization award while Marriott International was named Outstanding Private Sector Organization. Iowa Soybean Association took honors as Outstanding Nonprofit Organization and Flint Community Lab was named Outstanding Cross-Sector Partnership. National Correspondent Jose A. Del Real garnered Outstanding Journalism on the Value of Water for his series on California water issues and Outstanding Public Official was awarded to US Senator Ben Cardin (MD).

Ground Water Foundation changes announced
The Groundwater Foundation announced changes to its operations recently. Its work will mostly be consolidated into that of the NGWA, which operates the foundation. All correspondence should now be sent to 601 Dempsey Road, Westerville, OH 43081. If you have questions or concerns about how any of these changes may impact your efforts as a Groundwater Guardian, educator or foundation member, please contact Paul Humes, phumes@ngwa.org or (800) 551-7379, ext. 1520 or Terry Morse, tmorse@ngwa.org or (800) 551-7379, ext. 1504.

Water dispenser growth reported
The number of water dispensers in the US has been growing by around four percent a year and topped eight million for the first time in 2019, according to the US Water Dispense Market Report from Zenith Global. Revenue, however, fell by one percent to $4.1 billion after steady growth until 2017. Bottled water dispensers accounted for nearly six million units, 73 percent of the total, down from 78 percent in 2014. POU dispensers have grown from under 1.4 million to over 2.1 million during the past five years to take a 26-percent share.

Pool products for indoor disinfection announced
HASA Pool announced that its products can also be used to clean and disinfect indoor surfaces. The company’s liquid sanitizers are widely available to pool service professionals through a variety of distribution sources across the western US and to end-user customers at select retail dealer locations. These products can easily be repurposed in accordance with Centers for Disease Control and Prevention (CDC) guidelines for indoor disinfection.

ACS agreements announced
The American Chemical Society (ACS) and the Norwegian Directorate for ICT and Joint Services in Higher Education and Research (UNIT) have announced a landmark ‘read and publish’ agreement to advance open-access publication by researchers at the consortium’s nine member institutions. The agreement will run through the end of 2022, creating the potential for 100 percent of articles published by researchers in affiliated universities to be available open-access. ShanghaiTech University and the Publications Division of ACS announced their first publishing collaboration, creating a new journal for the worldwide research community, Accounts of Materials Research. This marked the first journal published by ShanghaiTech University and the first journal published by ACS in collaboration with an organization in China.

PWQA news
The Pacific Water Quality Association is seeking nominations to honor leaders in the water quality industry. Award recipients are selected from nominations submitted by members. Submissions may be made at https://pwqa.com/industry-awards/.

Europe
InnoBev awards for two water companies
The fourth annual InnoBev Awards, organized by Zenith Global, attracted over 120 entries from innovators across the worldwide soft drinks industry. Two water producers were honored with best-in-their-category awards: Essentia Water, LLC for Best Marketing/Social Media Campaign with its motto, ‘It Might As Well Be You’ and LUQEL, Best Technology Innovation for its Water Station Excellence.

Asia
ASTM, IAPMO agreement announced
ASTM International and IAPMO have signed a memorandum of cooperation (MOC) to promote collaboration in initiatives that advance public health and safety. The MOC relates directly to water sanitation and hygiene in Indonesia, the Philippines and other selected member nations of the Association of Southeast Asian Nations (ASEAN).

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