Using a naturally occurring plant to clarify water

by Sally Bouorm | October 1, 2011 2:59 pm

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By Samantha Luedke

Since the beginning of time, Sphagnum moss has been conditioning and clarifying various bodies of water (e.g. lakes, rivers and ponds) around the world where moss bogs exist. However, the idea to harness this natural process and test its capabilities in pool and spa water did not transpire until two seemingly unrelated events occurred.

Ten years ago, while flying home from a recent business trip, Dr. David R. Knighton, co-founder of Creative Water Solutions (CWS), a developer of natural water conditioning products in Plymouth, Minn., read a magazine article about the military’s use of Sphagnum moss to pack soldiers’ wounds during the pre-penicillin days of World War I. According to the story, soldiers whose wounds were packed with moss rather than cotton survived in larger numbers, leading Knighton to believe the moss had anti-microbial properties.

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After discussing this hypothesis with his research and business partner Vance D. Fiegel, a cell and microbiologist and co-founder of CWS, they obtained some moss from the bogs of northern Minnesota to perform preliminary tests.

Shortly thereafter, while on a plane over northern Minnesota, Knighton noticed the lakes in the northern half of the state appeared clearer than the southern lakes. After further research, he discovered the northern waters were often flanked by moss bogs. This realization led to another hypothesis Knighton tested on his swim spa, which was experiencing water quality issues. He took some Sphagnum moss, put it in a perforated plastic bag and placed it in his spa. Within a few days, the water started to clear and the foul smell diminished. This prompted further studies into the ability of sphagnum moss to clarify pool and spa water.

Finding the right moss for the job

Fiegel and Knighton’s initial research looked at the proliferation of bacteria in idealized liquid cultures with and without Sphagnum moss. It examined the effect of a number of species of Sphagnum moss on the proliferation of several types of bacteria, as well as algae, fungus and mould. The results demonstrated that certain species of moss were effective at inhibiting the growth of these micro-organisms without killing them.¹ If the moss was removed, the bacteria would continue to grow.

The role of biofilm

Whenever bacteria and water are combined, the bacteria always migrate to the surface initiating the formation of biofilm. The first bacteria that adhere to the surface produce and secrete a sticky matrix of complex sugar molecules called exopolysaccarides, which then incorporate proteins, nucleic acids and other compounds from the immediate environment.

In swimming pool and spa water, this biofilm matrix absorbs chlorine (Cl), bromine (Br) and other reactive ions into the sticky molecular matrix that covers the living bacteria. The ions may kill the bacteria closest to the surface, however, billions remain unharmed in the depths of the biofilm. These bacteria also quickly divide to replace the ones killed by the chemicals.

Studies reveal biofilm inhibiting properties

Laboratory studies revealed that extracts of Sphagnum moss significantly inhibit the growth of a number of planktonic bacteria including, Pseudomonas aeruginosa, a common bacterium found in water and soil that can cause disease in animals and humans. These studies further indicated that the inhibitory effect was bacteriostatic (restricted the growth and activity of bacteria without killing them) and not bactericidal (destroyed bacteria). These results led to additional laboratory investigations of the effects of Sphagnum moss extracts on biofilm formation and removal. The following results and conclusions were presented at the ‘Biofilms IV conference in September 2010:

• Extracts of Sphagnum moss inhibit P. aeruginosa biofilms;
• The inhibition of biofilm formation and removal of established biofilm is time and dose dependent;
• Biochemical studies would indicate the inhibitory activity is probably due to a combination of multiple chemical compounds;
• Inhibition of biofilm by Sphagnum moss extracts may involve the modulations of virulence factors such as pyocyanin (C₁₂H₁₀N₂O), which play a role in the control of the biofilm phenotype (an organism’s observable characteristics or traits); and
• The use of a natural, plant-based inhibitor of biofilm may be a useful alternative to current sanitizing methodologies.

Larger scale testing

In 2009, armed with this laboratory data and a working hypothesis that moss appeared to inhibit biofilm formation in small residential pools and spas, CWS pursued a public pilot test project with select partners in St. Paul, Minn.

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Titled ‘The City of St. Paul Public Pools Green Initiative[4],’ the project was performed by CWS in partnership with the city’s parks and recreation department at the Highland Park Aquatics Center (HPAC) and U.S. Aquatics, a swimming pool service and maintenance company hired by the city as an unbiased technical consultant on the project.

HPAC’s public outdoor facility comprises four pools, which provided an ideal setting to quietly conduct the test project, as it provided two control pools that were treated with Sphagnum moss and two that were not. The project’s purpose was to determine if the pools’ chemical loads could be lowered to save money and create more natural water conditions, while still providing a safe, healthy swimming environment that met all standards required by the Minnesota Pool Code, Minnesota Rules (Parts 4717.0150 through 4717.3975). Before the natural system was installed, the test was cleared with the Minnesota State Health Department and the facility’s experienced team of certified pool operators (CPOs) were trained on its operation and told to treat the water in accordance with the state.

Simulating a moss bog

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The Olympic-size 1,665,581-L (440,000-gal) main pool and 85,171-L (22,500-gal) children’s activity pool were set up as the Sphagnum moss test pools. All previous water treatment was left in place at the four pools.

Specially processed Sphagnum moss was used in customized strainer bags, enclosed in crates and tethered within the lap pool’s underground surge tank. The smaller children’s activity pool relied on the Sphagnum moss treatment in an arrangement more similar to a residential pool system, with offline tanks housing the necessary Sphagnum moss dosage.

1. Turbidity tests showed similar nephelometric turbidity unit (NTU) results similar to earlier tests performed on pool and spa water previously exposed to moss, with readings of 0.04 NTU.
2. After strainers were 60 per cent clogged due to unusually high cottonseed dispersal, turbidity started to increase above 1.0 NTU. Although the increase was well below the accepted clarity level for pools (3 NTU), once the strainers were cleaned, turbidity levels returned below 0.05 NTU.
3. Two weeks after the Sphagnum moss was introduced to the pools, a filtration pump automatically shut off due to back pressure in the system, which was also caused by the high levels of cottonseed. This went unnoticed overnight and the lack of filtration significantly clouded the pool. Once the system was operating again, the pool recovered within one day, without pool closure or use of additional chemicals.
4. An immediate increase in free chlorine was also noticed. At one point, levels reached 8 parts per million (ppm) with no combined chlorine. Pool engineers were reluctant to decrease oxidation reduction potential (ORP), fearing the free chlorine would plummet. However, ORP was decreased by increments of 10 millivolts (mV) when free chlorine was greater than 4 ppm. As the season progressed, ORP settled at 650 mV and free chlorine levels were between 2-3 ppm, with no recorded combined chlorine.
5. There was a gradual decrease in cyanuric acid (CYA, [CNOH]₃) delivery by 10 ppm each week. By the end of July, cyanuric acid was no longer being added to the pool and levels gradually decreased to zero at the water’s surface and 10 ppm at the bottom.
6. Concerned there would not be any free chlorine in the pool due to the decrease in cyanuric acid delivery, pool engineers were ready to add it manually if free chlorine levels decreased to 1 ppm. Throughout the remainder of the summer, however, free chlorine levels remained between 2-4 ppm without requiring cyanuric acid.
7. Calcium hardness, pH and total alkalinity (TA) were also stable throughout the study period. Even with 1,000-plus bathers per day and extremely hot temperatures, the pH required very little adjustment beyond the controller.
8. Calcium hardness levels remained at 500 ppm throughout the summer.

Overwhelming results and savings

By the end of the season, HPAC lowered its traditional operating, chemical and water costs and increased revenues. For instance, the City of St. Paul saved $36,000 in chemical costs over the previous year ($78,000), as well as $40,000 in staff overtime costs.

Previously, the pool maintenance crew accumulated many hours of overtime dealing with daily problems. These savings were a result of not having to hyperchlorinate the water or close the pool due to water issues.

The need to backwash the filters three times a week was also reduced, as the pools were able to be backwashed via pressure differential. By the end of the season, backwashing was required on a bi-weekly basis, which further reduced the city’s water costs.

The installation of the Sphagnum moss system also proved to be an effective marketing tool for HPAC. When the experiment was made public by the city’s mayor in mid-August, the ensuing media coverage and word-of-mouth referrals drove an increasing number of swimmers to the facility during the final weeks of the outdoor swim season. As a result, the city realized a $100,000 increase in pool revenues.

 

Samantha Luedke handles sales and marketing for Creative Water Solutions (CWS), a developer of natural water conditioning products in Plymouth, Minn. Prior to joining CWS, Luedke served as a laboratory technician for seven years with Embro Corporation, a biomedical research and development company. She can be reached via sluedke@cwsnaturally.com[6].

Source URL: https://www.poolspamarketing.com/trade/using-a-naturally-occurring-plant-to-clarify-water/

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