Teresa Orta de Velasquez, Neftali Rojas-Valencia, and Alberto Ayala

National Autonomous University of Mexico

Received: January 7, 2008

Accepted: May 16, 2008

Study Synopsis

The study was done to determine the effectiveness of ozone as a disinfectant against microorganisms in wastewaters that have developed high resistance to common disinfectants such as chlorine. Ozone was applied to Vibrio cholerae and Salmonella typhi bacteria, Acanthamoeba protozoa, total coliform (TC) and fecal coliform (FC). Results showed that at 14 minutes of ozonation, all bacteria and amoeba were completely destroyed.

Positive Findings from the Study

• “When ozone is applied, the synthetic samples show a clear decrease in the number of V. cholera, S. typhi, TC, FC and amoebae, at every stage of the ozonation process.”

• “It was noted that at 14 minutes of ozone application, 99.98% of bacteria were eliminated, and no free-living amoebae were detected. In addition, the inactivation of microorganisms gives first-order kinetics after the application of ozone.”

• “From previous experience and other research, it is known that ozone can break down cell membranes and protoplasm, and that this process impedes cell reactivation in bacteria, coliform, virus, and protozoa.”

• “Ozone inactivates bacteria by means of oxidation reactions. The cell membrane is the first site under attack; then the ozone attacks glycoproteins, glycolipids, or certain amino acids, and also acts upon the sulfhydril groups of certain enzymes; the effect of ozone on the cell wall begins to become apparent; the bacterial cell begins to break down after being in contact with ozone; the cell membrane is perforated during this process; and finally, the cell disintegrates or suffers cellular lysis.”

• “Ozone works by making the cell membrane permeable, and then aqueous ozone penetrates the cyst, and damages the cytoplasmic membrane. Further penetration affects the cell nucleus, ribosomes and other structural components.”

• “Ozone has been demonstrated as the most effective disinfectant for the inactivation of Cryptosporidum, and this is significant because Cryptosporidium is considered the most resistant of the protozoa, being as much as ten times more resistant than Giardia.”

• “In all cases, the microorganisms were very susceptible to ozonation, and a marked reducation of bacterial concentration was observed.”

• “It can be observed that most of the pathogenic microorganisms survice the application of chlorine, but they are significantly reduced in number, or eliminated altogether, when ozone is added.”

• “Ozone has the greatest germicidal power, followed by chlorine. Ozone is 25 times more effective than hypochloric acid; 2,500 to 3,000 times more potent and swifter than hypochlorite; and 5,000 times better than chloramine.”

• “Ozone thus effectively destroys bacteria and amoeba that are difficult to combat by other means. Of particular significance is that other disinfection methods involve the use of chemicals which are sometimes hazardous to human consumption, and always detrimental to the environment.”

Negative Findings from the Study

• “As with any other oxidizing agent, ozone has limitation when oxidizing organic and inorganic matter, depending on the nature and concentration of the constituents in the wastewater under treatment.” NOTE: The conditions set-forth in the study seek to replicate conditions in nature, but the laboratory tests are under perfect conditions. As the study states, some organic or inorganic material in wastewater might be resistant to oxidation, so the results might be slightly less than the 99.98% effectiveness seen in the controlled environment.

Thoughts and Comments

This study has combined full-scale laboratory tests and analysis with strong bibliographical resources to prove what has been known for more than a century: ozone eliminates bacteria.

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Logan Raub’, Christopher Amrhein”, and Mark Matsumoto2

‘Department of Environmental Sciences

Graduate Program in Soil and Water Sciences

University of California, Riverside

2 Department of Chemical Environmental Engineering

University of California, Riverside

‘Corresponding author: arnrhein@ucr.edu

Received for Review: 6 July 1999

Accepted for Publication: 10 March 2000

Do to formating eras the below report is missing some text, graphs, and tables. If you would like to see this complete report please click here.  

Abstract

There are reports that ozone in irrigation water can improve crop vigor, reduce insect and disease, enhance water penetration, and reduce fertilizer needs. It has been noted that ozone treated field soils seem spongier and have less standing water. Here we report on a laboratory column study on the effects of ozonated irrigation water on hydraulic conductivity, soil hardness (aggregate strength), clay dispersion, soil swelling, and changes to the chemical composition of the leachate water. Additional batch studies were conducted to characterize the factors affecting the rate of ozone loss in soil water suspensions and the results used in a mathematical model to predict ozone movement into a soil. We found that ozone increased the saturated hydraulic conductivity and decreased clay dispersion. 

In every soil tested, the drainage water from the ozone-treated columns had lower pH’s and higher electrolyte concentrations. This is attributed to organic matter oxidation and the weak acid properties of ozone. The rate of ozone degradation in soil water could be modeled using the total organic carbon content’ of the soil, the pH, and the soil water ratio.

Introduction

Ozone is a strong oxidant that has been used for over a hundred years to disinfect drinking water and to control undesirable color, taste, and odor in water. Ozone has also been used to oxidize and precipitate iron and manganese from groundwater. More recently, there has been an interest in the use of ozone in irrigation water. Farmers report that low doses (<1 mg L”) of ozone added to irrigation water improve crop vigor, reduce insect and disease, enhance water penetration, and reduce the need for fertilizers (Pedersen and Redsun, 1996).

There is good evidence that ozone can have an effect on the surface chemise of colloidal materials in water. Several drinking water treatment plants now preozonate the raw water to improve filtration. It has been found that the ozone helps “remove clay turbidity through coagulation”, although the mechanisms are not well understood (Langlais, etal., 199 1, chapter 1II.F). It has been hypothesized that ozone reacts with the organic coating on the clay and either removes or modifies the organic matter, thereby changing the surface charge of the clay.

The problems in soils of poor permeability, low hydraulic conductivity, crusting, sealing, and hard setting are largely attributed to changes in surface charge on clays and the interaction of adsorbed cations, anions, organic matter, pH, and ionic strength. The fact that ozone has an important effect on coagulation, flocculation, and filter performance suggests there may be a beneficial effect to water management in irrigation and soil filth.

Pedersen and Redsun (1996) interviewed farmers that had used ozone in their irrigation water and there was general agreement that the topsoil in ozone treated fields was more porous and spongy. These farmers also reported less standing water, decreased clotting, and deeper water penetration into the soils. All of these observations are in agreement with the effects one would predict from an amendment that increases clay flocculation.

In agriculture, the most common soil amendment to improve infiltration, soften hard soils, and reduce clotting and crusting, is gypsum (CaS0;2H20). Gypsum improves clay flocculation by increasing the CaZ’ concentration of the soil water, increasing the ionic strength, and replacing adsorbed sodium. Sodium on the surface of clays has a deleterious effect on soil structure and tends to increase the repulsive forces between negatively charged clay particles. Replacing exchangeable Na’ with divalent or trivalent cations reduces clay dispersion and swelling and improves the physical properties of soils.

In this project, we investigated the effects of ozonated irrigation water on the physical and chemical properties of soils in repacked columns. The properties measured were saturated hydraulic conductivity, aggregate strength, clay dispersion, soil swelling, and ,changes to the chemical composition of the leachate water. Batch studies with soil + water suspensions were performed to identify the factors that affect the rate of ozone loss in soil water. A mathematical model was constructed from the data to predict the rate of ozone loss in soils based on the soil water ratio, the initial ozone concentration, the total organic carbon in the soil, and pH. Other variables that were evaluated included the alkalinity, clay content, and specific surface area.

Materials and Methods – Experiment 1: Column Study

Three soil types were used to investigate the effects of ozone on the physical properties of soil in the column study. The first set of soil samples, identified as “Tulare”, came from an experimental field site in the Tulare Lake Basin of the San Joaquin Valley near Corcoran, CA. This soil is classified as a Tulare clay, a fine, montmorillonitic (calcareous), thermic Vertic Haplaquoll. The soil is typically cropped to cotton and safflower. The experimental field plots, from which the soil samples were collected, had been irrigated for six years with mixtures of low-salinity canal water and saline drainage water. The blended irrigation waters had total dissolved solids (TDS) of 400, 1500, 3000 and 4500 mg L1.

The second set of soil samples was collected from an experimental field site on the west side of the San Joaquin Valley, CA. The soil is classified as a “Milham” soil and characterized as a fine-loamy, mixed, thermic Typic Haplargid. This set of samples was collected from a pistachio orchard that was being used in a salt tolerance study. The field site had been inigated for two years with blended waters of varying electrical conductivities of 0.75, 2.0, 4.0, 6.0, and 8.0 dS m-I (approx. 500, 1300, 2600, 3800 and 5000 mg L’ TDS, respectively). For this experiment, the soils were labeled T-1, T-2, T-3, T-4 and T-5 for the varying treatment salinities.

The last soil studied using the columns, came from Riverside, CA area and is classified as “Ramona” and characterized as a fine-loamy, mixed, thermic Typic Haploxeralf. This soil is typically cropped to citrus and is distinct from the soils collected from the San Joaquin Valley because of the .fresh organic matter content.

All soils were air dried, crushed and passed through a 2-mm sieve prior to testing. Saturation extracts of the soils were analyzed for the major cations (calcium, sodium, potassium and magnesium), pH, and electrical conductivity (EC). The sodium adsorption ratios (SAR) were calculated from extracted solute concentrations and the exchangeable sodium percentages (ESP) were measured on the Tulare and Milham soils using 1.0 M ammonium acetate extract. The ESP of the other soils were estimated from the SAR’s, using a previously determined, average selectivity coefficient. Particle size analysis was determined using the hydrometer method (Klute, 1986). The alkalinity was determined by titrating a sample of the extract to pH 4.4 using 9.4 in M sulfuric acid. The total organic carbon in the soil was determined by a loss-on-ignition method (Sparks 1996), where the mass difference after heating at 400°C for 16 hours was taken as the amount of organic matter ignited. The surface area was determined using the ethylene glycol mono-ethyl ether (EGME) method (Klute 1986). The chemical and physical properties of these soils are listed in Table I.

The ozonated water was produced on an as-needed basis utilizing an Osmonics generator that produced ozone by feeding dry compressed air through a column where corona discharge produces atomic oxygen radicals that m h e r react with oxygen molecules to produce ozone. The ozone-enriched gas was then diffused into a beaker of water for 10- 15 minutes at a rate of 1 L ozonated air per minute to give concentrations of ozone of approximately 10 mg L-’. The concentration of ozone in the water could be varied by changing the flow of ozonated air into the water column or by varying the amount of voltage applied in the corona discharge. For an experiment with differing concentrations of ozone, it was found that varying the voltage gave the most consistent ozone concentrations.

Ozone concentration in’ the applied water was determined using the iodometric test for residual chlorine, which was modified to measure residual ozone. The iodometric test was used because it is quick, easy, and accurate (Greenberg et al., 1992). Because other oxidants like chlorine, oxides of nitrogen, and manganese species interfere with the iodometric test, the water was aged prior to ozonation by leaving it open to room air for a day to allow for dissipation of residual chlorine. Normally the iodometric test is done on an acidified sample, however there was interference from Mn in the leachate samples at low pH. Eliminating the acidification step reduced the interference from manganese and other oxidizing compounds without substantially affecting the ozone determination. In general, a 50-mL aliquot of ozonated water or leachate was reacted with 0.5 g of KI for five minutes. The sample was then titrated with a standardized thiosulfate solution to a colorless endpoint using a starch indicator. The reaction of ozone with KI is as follows:

O₃ + 2KI + H₂O = I₂ + O₂ + 2KOH

The iodine formed is then titrated with sodium thiosulfate:

I₂ + 2S₂O₃ à  2I + S₄O₆

The soil columns were constructed from glass cylinders with the dimensions 4.7 cm internal diameter and 20 cm length. Steel mesh was attached to one end of each column, and two layers of cheesecloth placed above the mesh to contain the soil during leaching. One hundred grams of soil was weighed, placed into each column and tamped to a bulk density of 1.3 g cme3. A small piece of filter paper (2-cm diameter) was placed on the soil surface to decrease the energy of the applied water, which would disturb the surface layer of the soil. The constructed columns were then placed in a wooden brace that was able to hold twelve soil columns side by side. Ozone treated and control columns were run alongside each other. A funnel was placed above to deliver irrigation water to the columns and another funnel was placed below the column to catch the leach-water, which was collected in 250-ml beakers for sampling and further analysis.

The soil columns were leached (irrigated) with aliquots of aged Riverside tap water or aged, freshly ozonated tap water in increments of 10 to 20 mL. Different soils received different aliquots of water, depending on the hydraulic properties of the soil. Water was applied at a rate that approximately matched the hydraulic conductivity. For some soils with high hydraulic conductivities, water was applied as often as every 20 minutes. For the soils with lower hydraulic conductivities, water was applied two or three times a day. Each soil received equal amounts of treatment water so that comparisons could be made between control and treatment. The treatments lasted approximately two to three days and a maximum of 200 ml/column applied. Some of the soils with high ESP’s received <lo0 ml because of very slow infiltration rates. All treatments were replicated fivefold. An average of 2.7 pore volumes of leachate was collected. The leachate from the columns was analyzed for electrical conductivity (EC,,), pH, and turbidity by light absorption at 500-nm wavelength. ‘ The leachate waters from the columns were also analyzed for calcium, magnesium, potassium, sodium, iron, and magnesium using the ICP-optical emission spectrophotometer.

To calculate a saturated hydraulic conductivity of the soil, the columns were pounded with 200 ml (giving a hydraulic head of approximately 12 cm) of water and allowed to percolate for a measured amount of time. Measurements were taken as to the height of the soil column, the height of the water at time zero and the height of the water after an arbitrary amount of time had passed. Saturated hydraulic conductivity, K,,, was then’ determined using the modified Darcy’s Law for a falling-head permeameter [K,, = (Wt,) * (In(b,+L)- ln@,+L))], where L is the length of the soil column, b, is the depth of water on top of the soil at time = 0, b, is the depth of water after time t, had passed.

Following leaching, the soils were allowed to drain overnight by gravity and then were weighed. The columns were then placed in an oven at 105°C for 24 hours, cooled and re-weighed. The differences between the weights were used to measure changes in water holding capacity, and assumed to give some measure of soil swelling.

The dried soil cores were subjected to tensile strength tests to determine if the soils had changed in hardness. The tensile strength test was performed using a Chicago Soil Test unit, which compressed the cores to the breaking point using the method of Dexter and Kroesbergen (1985). In this test, the cores were laid on their sides and the highest mass required to crush the cylindrical cores was recorded. The tensile strength is linearly proportional to the loading force at failure (Dexter and Kroesbergen, 1985).

All data for the column experiments were analyzed using the Student t-test for significant difference with a one-tailed significance distribution. Data entered into the tables are the means of the five columns run for each treatment.

Experiment 2: Batch Suspension Studies

This study was done because of the difficulties we encountered when trying to measure the loss of ozone with depth in column experiments with varying masses of soil. We concluded that to predict the penetration depth of ozonated water, we needed to measure the rate of ozone loss in a well mixed system containing samples of the soil. Once we knew the rate constant for ozone loss in a well mixed soil water system, a mathematical model could be used to predict the depth of ozone penetration into a soil.

An additional ten soil types (plus the three from the column experiment) were selected to study the rate at which ozone is lost from a well-mixed system of soil, ozone, and water (Table I). For the experiment, a 300-mL sample of aged Riverside tap water was ozonated for 10-15 minutes using the Osmonics ozone generator and then analyzed for initial 0, concentration. A weighed amount of soil (0.1 to 1.0 g) was introduced to the ozonated water and the soil /water suspension gently stirred with a magnetic stir bar while the ozone concentration was monitored with time. Ozone concentration was monitored by withdrawing, and filtering 10 ml of the solution into a beaker containing 0.5 g KI. The membrane filter excluded suspended colloids that might have interfered with the iodometric test. The acidification step was left out to reduce the interference from soluble manganese and oxides of nitrogen species. The sample was allowed to react for five minutes with the KI and then titrated with a standardized thiosulfate solution. The concentration of ozone in the sample was calculated and the loss of ozone with time was plotted. Soil solution pH was monitored throughout the experiment runs, noting a strong correlation of rate of ozone consumption to pH from preliminary experiments. The experiment was then repeated with a different soil mass.

Modeling

The model for ozone decomposition we used is based on a model constructed by Yurteri and Gurol (1988). The Yurteri and Gurol model was formulated to predict the rate constant of ozone consumption in municipal wastewater. Their model was based on the chemical properties of the wastewater, including pH, alkalinity, and total organic carbon (TOC). Our model initially used these parameters but was expanded to include suspension density (mass of soil to solution volume ratio), specific surface area of the soil, and clay content. Initially we hypothesized that to better predict the loss of ozone in our system; we needed to include the surface area of the soil in the equation, because of the potential interaction of ozone with surface coatings on soil minerals.

Results and Discussion – Experiment 1 : Column Study

The K,, values measured on this soil show that the ozone-treated irrigation water soaked into the soil somewhat faster than the unozonated water. Attributed to soil swelling and the plugging of conducting pores with dispersed clay. Soil swelling increases with increasing exchangeable sodium and. with decreasing solution ionic strength. Under conditions of high exchangeable sodium and low ionic strength, clay particles repel each other which leads to swelling and closure of large ,soil pores. When a soil swells, its water holding capacity increases because there is an increase in the fine pore space between clay particles and a decrease in the larger pores, which normally would drain under the force of gravity. Thus, changes in water holding capacity can be used as a quantitative indicator of internal soil swelling.

Clay dispersion and movement through soils has been correlated with reductions in hydraulic conductivity (Shainberg and Letey, 1984). In this study, clay in the leachate (turbidity) was determined by light absorption at 500 nm wavelength. Table V shows that the absorbance increased with increasing ‘exchangeable sodium in the Milham soil, which was expected. The ozone treated columns had significantly less clay in the leachate, suggesting that clay flocculation was improved as a result of ozonation. Surprisingly, the Tulare soil had large amounts of dispersed clay in the lowest salinity sample (400). This soil also had high variability in the saturated hydraulic conductivity measurements. There were no significant differences in dispersed clay from the Tulare soil samples in the ozone-treated and untreated columns. The Ramona soil showed no difference in dispersed clay, but this soil also showed no significant increase in hydraulic conductivity from ozonation.

 Analysis of the leach waters from the columns yielded significant differences between ozone treated and untreated waters. There was a significant increase in the leaching of salts from all of the ozone-treated soils, as measured by solution EC (Table VI). Cation concentrations in the leachate solutions were analyzed but are not presented. In all cases, the ozonated water leached more cations (Na, Ca, Mg, and K) compared to the untreated water. The changes in the SAR values were mixed, with no apparent decrease in SAR due to ozonation (Table VI). There was an increase in the total amounts of cations leached as a result of ozonation.

 There are two possible reasons for the, ‘higher electrical conductivities and higher cation concentrations in leach-water from the ozone treated soils. First, the ozone reacted with the organic matter of the soils, causing degradation and release of the cations and anions from the organic matter. Secondly, it is known that ozone behaves as a weak acid (Langlais et al., 1991), decreasing the pH of the irrigation water. Irrigation water pH values after ozonation were always lower than unozonated water, and the pH of the leach-water from the ozonated columns was lower in all cases (Table VI). This lower pH allowed for more dissolution of slightly soluble minerals (like calcite). Mineral dissolution reactions typically increase the Ca and Mg ion concentrations and lower the SAR. A decrease in the SAR results in cation exchange reactions with exchangeable Na. That is, the Ca and Mg released by mineral weathering compete for Na on cation exchange sites and the SAR is ‘buffered’ back towards its original value. The cation exchange capacity of the soil is a large reservoir for exchangeable cations that can strongly influence the composition of the soil solution. This possibly explains the increase in ion concentrations with only small changes in the solution SAR values.

 The benefits of ozone in the irrigation water, when  observed, might be attributed to the higher electrolyte concentration and lower pH of the soil water. Both of these factors can significantly increase the permeability and the saturated  hydraulic conductivity of soils. Other studies on the effects of SAR and the total electrolyte concentration on the saturated hydraulic conductivity of the Milham soil suggest that the small changes we observed in K,, could be attributed to this (unpublished data). Other studies with the Ramona soil, by Lebron and Suarez (1992), showed that decreases in pH increased clay flocculation and increased &a;,,. As a follow-up to this study, it would be interesting to compare the effects of ozone with small additions of acid to the irrigation water.

 Additionally, the concentration of oxygen and the oxidation/reduction potential (E,) of soil solutions were expected to increase as a result of ozonation, and these expected changes did occur. The aged tap water without ozone had an average Eh of 510 mV and the ozonated water at 10 mg L1 had an Eh of 1200 mV. At an ozone concentration of 1.4 mg L”, the E, was over 1000 mV. These high E,, values gradually decreased as the ozone decomposed. The dissolved oxygen concentration rose to -12 mg L-I. Improved crop vigor, which has been reported with ozonated irrigation water, may be attributed at least in part, to these two factors.

 In the pretreatment of drinking water to improve flocculation of suspended colloids, it has been found that a concentration of 0.5-1.5 mg L’ is the optimal range for flocculation (Maier, 1984). In this case, the water to solid ratio is very large, while in a soil the opposite is true. The ozone was rapidly lost once the water entered the soil columns, and we were unable to detect ozone in the leachate, even from very thin soil columns or in sand columns. We speculate that the higher concentrations of ozone were needed for ozone to move into the soil.

 Experiment 2: Batch Suspension Study

To, identify the factors that affect the rate of ozone loss from irrigation water and soil, we set-up a series of well-mixed batch suspension studies and monitored the loss of ozone from the system. It was found that the rate of ozone loss followed first order kinetics with respect to the concentration of ozone in solution. The reaction is first order because a plot of the natural log of the concentration of ozone versus time gave a straight line (Figure 2). The rate constant is also dependent on the suspension density.

 A plot of the rate constants versus the soil water ratios indicates that a linear relationship existed between the rate loss constant of ozone and the suspension density (Figure 3). A total of 13 soils were tested in this study and Figure 3 is representative of the data obtained. This figure shows that the rate constants were proportional to the mass of soil in contact with the solution, and that each soil had its own unique rate constant. The measured rate constants for all 13 soils were normalized for the suspension density and are reported’ in Table VII. The variability in the rate constants among the soils led us to examine the chemical and physical properties of the soils that might have affected the rate of ozone consumption.

 Modeling

Yurteri and Gurol (1988) proposed a mathematical model to predict the rate constant for ozone degradation in wastewater. Their model took into account the pH, total organic carbon (TOC), and alkalinity of the water. We attempted to formulate a model based on these parameters and other properties of the soil. The model initially included parameters for the specific surface area of the soil, which is related to clay content and texture, and the water-soluble alkalinity of the soil. Those terms did not add substantially to the model and were removed. The properties that we found which had a significant impact on the rate were the pH of the solution, total organic carbon in the soil (as measured by the “Loss-On-Ignition” method), and the soil to water ratio, or suspension density.

 Figure 4 is a plot comparing the measured and predicted rate constants for ozone degradation using the above equations. The trend line drawn depicts a one-to-one relationship between measured and predicted rate constants. The variability in the model indicates that there are still unknown parameters, which were not identified, that have a significant effect on the rate of ozone loss. It is likely that a chemical oxidation method for determining “ozone reactive organic matter” would give “a better prediction than the loss-on-ignition method. Restricted to the very surface of the soil. However, macrospore flow and the slower reaction kinetics during laminar flow could move ozonated water deeper into the soil.

 Conclusions

There appeared to be some benefits to adding ozone to irrigation water in these short-term studies.

The improvement in physical properties that was observed could be attributed to higher electrolyte concentrations in the soil water and lower pH values, both of which lead to improved clay flocculation and reduced dispersion. However, long-term studies are needed to determine if the gradual degradation of soil organic matter could lead to increased clay dispersion, surface crusting, and loss of structure. The surface of soils is typically very sensitive to changes in structure due to aggregate breakdown, which leads to crusting, sealing, and erosion. Organic matter is considered beneficial in holding soil aggregates together and binding clays.

 References

1. Dexter, A.R. and Kroesbergen, B. “Methodology for Determination of Tensile Strength of Soil Aggregates”, J. Agric. Engng. Res. 3 1 : 139- 147 (1985).
2. Greenberg, A.E., Clesceri, L.S. and Eaton, A.D. (Ed.), 1992. Standard Methods for the Examination of Water and Wastewater. Iodometric Method I. (Washington D.C.: Am. Public Health Assoc., 1992), p. 4-36 to 4-40.
3. Klute, A. (Ed.), Methods of Soil Analysir.’Part I . Physical and Mineralogical Methods. Second Edition. (Madison, WI: Am. Soc. Agron. and Soil Sci. Soc. Am., 1986), p. 4 16-42 1.
4. Langlais, B., Reckhow, D.A. and Brink, D.R. (Ed.), Ozone in Water Treatment. Practical Application of Ozone: Principles and Case Studies. Chap. 111. (Boca Raton, FL: Lewis Publishers, 1991), p. 133-316.
5. Lebron, I. and Suarez, D.L. “Variations in Soil Stability Within and Among Soil Types”, Soil Sci. Soc. Am. J.56:1412-1421 (1992).
6. Maier, D. “Microflocculation by Ozone”, R.G. RIP and A. NETZER (Ed.) Handbook of Ozone Technology and Applications, Volume I[ Ozone for drinking water treatment. (Boston, MA: Butterworth Publishers, 1984). p. 123- 140.
7. Pedersen, L, and Redsun, H. “Ozone Application for Agricultural Crop Production: Survey of Selected Manufacturers and Farmers”, (Report prepared for Pacific Gas and Electric Co., San Francisco, CA. by, Dantec Engineering, Inc. 605 Thornhill Rd., Danville, CA 94526. September 1996), p. 1 1 1.
8. Shainberg, I. AND Letey, J. “Response of Soils to Sodic and Saline Conditions”, Migardia 52 (2):l-57 (January 1984).
9. Sparks, D.L. (Ed.), Methods of Soil Analysis: Part 3, Chemical Methods (Madison, WI: Soil Sci. Soc. Am., 1996), p. 1002-1005.
10. Yurteri, C. and Gurol, M.D. “Ozone Consumption in Natural Water: Effect of Background Organic Matter, pH, and Carbonate Species”, Ozone Sci. Eng. 7:l-11 (1988).
11. Zahow, M.F. and Arnrhein, C. “Reclamation of Saline Sodic Soil Using Synthetic Polymers and Gypsum”, Soil Sci. Soc. Am. J. 56:1257-1260 (1992).

By Superintendent Glen Manly

I’m now finishing up my eighteenth year as Superintendent for Adobe Creek National Golf Course in Fruita, Colorado. I’d never seen our course come out of the winter looking better than it did in the spring of 2009. Every year since I’ve been here the course has emerged from the winter with a sodium cast, but this year was different. The course was greener, thicker, and healthier due to Mountain High Water’s Oxygen, Ozone, and CO₂ Gas Diffusion System. 

In March of 2008 I received a brochure in the mail from Mountain High Water about their Oxygen, Ozone, and CO₂ Gas Diffusion Systems. Among other information in the brochure, I was struck by the claim that their systems increase percolation rates and eliminate standing water. 

As you can imagine by the name “Adobe” Creek National, our facility was built on and with adobe clay and thus had very poor percolation. We had issues with standing water and black algae growth because of it. In April of 2008, I set up a meeting with my staff and Mountain High Water. After an entire afternoon of responding to all of our questions with complete, scientifically accurate answers, Mountain High had satisfied us, and we decided to purchase one of their systems in May 2008. 

There are many attractive things about the Mountain High’s System; it enabled me to reduce and stop the use of some costly, dirty, and time-consuming chemicals and surfactants. Below is a list of areas where we saved, spent, and earned money.

 Wetting Agents – We almost completly reduced the use of wetting agents. Previously, we were injecting one 55 gallon barrel of wetting agents per month in June, July, and August. Now, I only use wetting agents to occasionally to spray isolated hard spots on a couple of greens, that’s it. I attribute these remaining hard spots to a lack of sprinkler head coverage on those particular areas. 

Calcium Injection – We completetly eliminted calcium injection. Previously we were injecting one pallet of calcium each month, from May through September.  This year we didn’t use any calcium and the course stayed in great shape. We will be doing a soil test next year to make sure our soil’s calcium level is correct. 

Acid Injection – We completely eliminated all of our acid injection. Previously we were using one drum of acid each month from May through September to treat our greens. We were also using 75 gallons every three weeks from May to September to treat our fairways. The main reason for this acid use was pH control, which Mountain High Water’s CO₂ Injection has completely replaced with a much better result. We now purchase CO₂ gas instead of acid; the cost is about the same but with a better result. We are now able to lower our pH from 8.8 to under 7.0 on a nightly basis. 

Organic Spread – We completely eliminated our Organic Spread application this year. Our newest 9 hole usually gets a yearly organic spread, this year we forwent it, and still the turf remained healthy and thick. We will be conducting soil tests next year to make sure our soil and turf remain healthy in the absence of organic spread.

Poa Control – I have been battling Poa here for a while now. This year I was able to reduce my Poa control product by 25%. I believe this was directly related to Mountain High Water’s Oxygen, Ozone, and CO₂ Injection System. With the increase in oxygen going into the turf and soil nightly, the turf is healthier and able to uptake treatments more easily. This next year we hope to conduct tests to see if a reduction in fertilizer is possible. 

Fungicide – We almost completely eliminated the use of fungicides as well.  We were using a liquid fungicide to treat every green once a month May to September. Now we only use granular fungicide on a few greens with isolated hot spots. Treating these isolated spots is a minor problem and a minimal expense compared to having to treat every green. 

Hand Watering – I didn’t keep exact records on hand watering but it is safe to say that we eliminated at least 25% this year. Cooler weather was a factor, but I believe the hand watering reduction was due to Mountain High Water’s System. 

Zebra Mussel Shells – We completely eliminated the Zebra Mussel shells in our irrigation lines because of the ozonated water. The ozone killed all the bacteria in the water that the shells feed on, hence eliminating them. We never had a real difficulty with them, nor did we spend money to treat them, it’s just one additional benefit we noticed. 

Budget Surplus – According to our General Manger, Paul Graebner we saw an increase of over $100,000 in our R and M budget in 2009. We believe it is directly due to Mountain High Water’s System.

 On the right is me, Glen Manley, and on the left, Don Lease of Mountain High Water. We are taking the first round of percolation tests.

The system was installed in our pumping station and tied to our pump start, so when our system turns on, the Mountain High system turns on automatically. Also, the oxygen and ozone gas is created onsite from ambient air, so we don’t pay anything for the gases used. 

We also have a pH issue in our water that I’ve been battling for years, so I also wanted to use carbon dioxide because it lowers pH. The CO₂ is delivered weekly or bi-monthly depending on the time of year; it is clean and easy and I can lower my pH from mid to high 8’s to under 7. 

Before their system was installed we took percolation tests of our soil and tested our water for bacteria. These were our two biggest concerns, so we wanted to compare these initial results to later measurements after using the new system. 

In the first month, we started to see the turf becoming a brighter cast of green and standing water starting to disappear. This was due to the ozone chelating the iron and calcium already in our soil. For those of you who don’t know what chelating is, don’t worry, I didn’t know myself until last year. Chelating is a process that changes the molecules of light metals like iron, calcium, and magnesium to make them biologically available to plant life. 

I’m sure that all you superintendents know that most of your soils and water are full of calcium and iron already, but bicarbonates are tying them up so your turf and soil can’t use them. Well, this system allows the iron, calcium, and magnesium that already exist to be used in your soil and by your turf. 

After 68 days of having oxygen, ozone, and carbon dioxide injected into my irrigation water nightly we took another round of percolation tests. The result was that the percolation rate on our course increased by over 60%. We took another round of percolation tests 111 days after the system was installed and saw the percolation rate continue to increase. Meaning, we eliminated almost all of our standing water because the water penetrated the soil so much more effectively.

Above is one of my greens on May 15, 2008, below is the same green on July 22, 2008. The percolation rate increased, the black algae was gone, and the color was perfect.

Along with the percolation test a water test was taken for the purpose of determining bacteria levels in our irrigation water. Two water samples were taken on May 15, 2008, and sent to Colorado State University for Bacteria Coliform and Plate Count Tests. Another two samples were taken at the same location 68 days later.

The results were as-promised.  Virtually all of the bacteria was eliminated from or irrigation water. Without bacteria algae cannot exist, and thus, we saw the algae in our sprinkler heads and on our turf disappear as well. We also saw the zebra mussels in our pipes eliminated. Below are the results from the tests.

 The first water samples, in the table above, were taken from water around Adobe Creek National Golf Course to get a feel of the relationship between sample areas. Note the increases in the values from the pump lake to #2 and then to #5.  The first water tests taken were before any ozone had been used.

 *These samples have been treated with ozone 

The second round of water samples taken show a drastic increase in bacteria levels from the pump lake which was not treated by oxygen and ozone.  However, that untreated water was cycled through oxygen and ozone prior to arriving at the sprinkler heads #2 and #5. Note that the relationship between sample areas has changed.  The water from the infected pump lake exhibits a zero coliform count once ozonated, and the aerobic plate counts decrease from the lake to #2 to #5 instead of increasing, as in the first table. 

Many people don’t know this, but ozone is a powerful oxidizer. According to the EPA, ozone is more effective than chlorine in destroying viruses and bacteria, and there are no harmful residuals that need to be removed after ozonation because ozone decomposes rapidly. Using ozone is a win-win situation.

Now, I want everyone out there to realize that using this system is not a cure-all for your turf and water issues, but it does help, SIGNIFICANTLY. I have saved considerably in my budget on chemicals, surfactants, fertilizer, and labor. The use of Mountain High Water’s System has improved the look and quality of our course immensely. I’m glad we took a chance here at Adobe Creek National Golf Course on using this system.

Mountain High Water and/or it employees are proud members of the following Associations:

Golf Course Superintendents Association of America (national)

National Golf Course Owners Association (national)

International Ozone Association (international)

Rocky Mountain Golf Course Superintendents Association (Colorado/Wyoming)

Cactus & Pine Golf Course Superintendents Association (Arizona)

Rio Grande Golf Course Superintendents Association (New Mexico/Texas)

Golf Course Superintendents Association of Southern California

Southern Nevada Golf Course Superintendents Association

 Please look for us all year at your Associations outings. Mountain High Water staff attends functions all over the United States, so please let us know if you would like us to speak at your next outing.

Advertisements:

Look for a Mountain High Water ad in your chapters monthly news letter. Mountain High Water has ads in the following publications:

Sand and Sea

(Golf Course Superintendents Association of Southern California’s Publication)

Cactus Clippings

(Cactus & Pine Golf Course Superintendents Association’s Publication)

The Reporter

(Rocky Mountain Golf Course Superintendents Association’s Publication)

Rio Grande Newsletter

(Rio Grande Golf Course Superintendents Association’s Publication)

Phoenix Area Golf Course: Interpretation #1 of Ongoing

Testing to Monitor Ozone & Oxygen Diffusion 

Initial Tests Taken On September 8, 2009

Follow-up Tests Taken December 7, 2009

A. Standard Soil Tests

1. Sodium: Our September ’09 tests indicated that the harmful element, sodium, was found at unacceptably high levels. The December ’09 tests, following three months of ozone diffusion, showed a dramatic drop in sodium.Sodium is measured in two ways on a soil test: by actual amount (Ibs. per acre) and as a percentage of all the major elements in the soil that carry a positive charge (cations). The latter is also referred to as the ‘percent base saturation.’ 

For example, looking at #5T, in September the amount of sodium was 616 Ibs./acre. By December the amount had dropped to 378 Ibs./acre.(Ideal soil sodium levels are below 500 Ibs./acre.) When viewed as a percent of base saturation, the sodium on #5T dropped from 5.76% to 4.19%, a substantial drop over a three month period. (Acceptable sodium levels as a percent of base saturation are below 8%.) This sort of sodium reduction was consistent throughout all playing surfaces tested; please click here to see this report.  

2. Soluble Sulfur:The soil tests also reveal a dramatic reduction in soluble sulfur between September and December. Sulfur is a highly soluble element that leaches down through the soil profile readily if the soil is conducive to leaching (drainage). Sulfur is widely accepted in academic circles as a barometer for how good or bad the soil drainage is. This particular test result is the most positive indicator of improved drainage observed in any of the testing. 

Again, looking at #5T as an example, soluble sulfur in September was measured at 114 parts per million. By December this had dropped to 37 parts per million. Ideal sulfur levels are below 40 ppm, so this represents a dramatic improvement. 

Please click here to see this report with a graph that shows a significant decrease in sulfur levels on all surfaces tested. A decrease in soluble sulfur is an increase in percolation.This can be interpreted many different ways. Mainly it shows the ability to leach out harmful contaminates in irrigation water while allowing turf to up take nutrients easier. This increases root depth and mass by not only allowing oxygen, nitrogen, and nutrients to get  to the roots, but by ozone chelating elements like calcium so turf can uptake them more readily. 

B. Saturated Soil Analysis (also called “saturated paste extract tests”)  

1.      A Review of the ‘Saturated Paste Test’: The primary benefit of saturated paste tests is to measure the amount of salts in the soil which can be expressed as either “electrical conductivity” (E.C.), or “total dissolved salts” (TDS). 

This test also measures bicarbonate levels in the soil. Bicarbonates cause no harm to plant growth by themselves, but excessive bicarbonates do make it significantly more difficult to reduce unwanted sodium from the soil through standard management practices.

Finally, while soil sodium measurements are considered less credible on a saturated paste test than when measured in a standard soil test, there are, nonetheless, two meaningful measurements of the sodium hazard to be found on the paste test.

The first is the base saturation percentage of sodium. Ideally sodium, as a percent base saturation on a saturated paste test, should always be maintained below 35%. The other measurement of the sodium hazard is the sodium adsorption ratio or S.A.R. This sodium measurement should be maintained below 4.0.

2. Comparative Results Using Saturated Paste Testing: September ’09 – December ’09

 Levels of salts declined (improved) between September and December on all playing surfaces tested.

 The sodium hazard, when measured as S.A.R., also improved on all playing surfaces. The other sodium measurement, “sodium as a percent of base saturation” improved on #5F between September and December but remained the same on #5T and #5G. 

C. Tissue Tests  

It is still too early to draw to many conclusions from the plant tissue test, although there was a noticeable increase in nitrogen, phosphorous, and potassium.This is a benefit of the chelation process that is created by ozonation. The following are the mean test results for the most essential nutrients.

Please click here to see this report with the average changes between September ‘09 and December ‘09 of:

 Nitrogen (Note, this elemnet increased)

Phosphorous (Note, this elemnet increased)

Potassium (Note, this elemnet increased)

Calcium

Magnesium

Sulfur

Iron

Manganese

Please click here to see this report with a chart that shows the difference between plant tissue in September (before MHW system) versus plant tissue in December (after MHW system). Notice that there was a significant increase in nitrogen, phosphorus, and potassium. All of those nutrients were low in September and now they are at a good level. Calcium, magnesium, and sulfur stayed the same, at acceptable levels. 

D. Irrigation Water  

1.      Special Irrigation Water Testing: Dissolved Oxygen and Fecal Coliform.

 Two environmental tests were conducted on the water: “dissolved oxygen” and “fecal coliform,” each showing positive progress. Keep in mind that even the preliminary September tests showed both measurements were already well within acceptable levels. 

With dissolved oxygen, we have three test results: September (lake water); December (lake water); and December (irrigation water, with high ozone content). Both the September lake test results and the December lake test showed less dissolved oxygen in the water than the December irrigation test WITH ozone. As for fecal coliform, improvement also occurred. The highest reading was the September lake test, the December lake test showed a lower fecal coliform reading; and the December irrigation test with ozone was the lowest of the three.

 A reduction in fecal coliform is directly related to a reduction in algae. Also, an increase in dissolved oxygen is directly related to a reduction in algae, along with a healthier water environment. All water tests show progress in the right direction to eliminating lake algae.

 E. Summary

 1. Soluble sulfur, an excellent barometer of soil drainage, dropped precipitously between September and December, demonstrating that the soil had become more conducive to the downward movement (leaching) of water and soluble nutrients. The decline in total dissolved salts confirms this improvement in leaching/drainage.

 2. Unwanted sodium and salts, the two most serious soil chemical problems on irrigated Arizona soils, were reduced significantly between September and December.

 3. The irrigation water contained an increased amount of dissolved oxygen in December when compared to September.

 4.The irrigation water contained a reduced amount of fecal coliform in December when compared to September.

 5. Future testing:

1. Although there are many positive results in such a short time, further testing is still needed. Two further rounds of testing will be implemented. At the completion of those tests there will be a much clearer picture.

Do you have:

poor drainage?

standing water on your turf?

black layer algae?

sodium crust?

bicarbonate build-up in your soil?

Has your turf been destroyed by poor water quality?

Does your turf look less than perfect?

Mountain High Water will turn your turf into championship quality, using our ozone, oxygen, and CO₂ diffusion system.

Do you want to eliminate turf, water, and soil troubles while saving money?

Without any chemicals or additives, our system treats your water to produce the same effects as aeration, calcium and acids injection, algaecide, wetting agents, sulfur burning, and other classic water and turf practices.

The difference is Mountain High Water creates oxygen and ozone on-site, so there are no additional products needed.  Unlike the other turf treatments you might currently employ, with our system there is no risk of chemical harm to the turf or other expenses, inconveniences, and dangers that go along with storing and using chemicals.  And, our system works with all types of water, whether it is well, reclaimed, city, or brackish.

Installed at your pump station, our system creates the gases and then converts them into micro bubbles which are injected directly into your main line.  This process is used nightly in conjunction with your usual irrigation schedule.  You can actually see the improvement every morning, just like after a rain storm.

Mountain High Water offers full-service water and soil treatment with a single, simple, automated system. 

Are your lakes full of Algae?

Are you using your budget on algaecide, copper sulfate, or chlorine, monthly, with only temporary results?

Mountain High Water will turn your lake into crystal clear water, without using any chemicals.

Do your sprinkler heads have algae in them too?

Mountain High Water’s systems will eliminate sprinkler head algae. 

Do you want to know how we do it?

We use ozone & oxygen gas. Ozone is the tri-atomic form of oxygen. When the third molecule breaks loose, it starts eating the cell wall of bacteria, viruses, fungi, spores, and more. Without bacteria, algae and fungus cannot survive.

Ozone eliminates all bacteria in the irrigation water. So, clean, non-contaminated water is being used for irrigation.

Ozone is 50 times more powerful and over 3,000 times faster-acting than chlorine bleach.

Ozone gas offers the following advantages:

• Eliminates algae
• Eliminates black layer
• Eliminates Bryozoan
• Eliminates foul odors
• Kills fungus & bacteria

Ozone will chelate light metals such as calcium and iron, stopping bicarbonates from binding to them.  This makes these vital metals biologically available to your soil and turf.

We also diffuse pure oxygen, increasing the dissolved oxygen in your water by up to 400%, thereby creating an aerobic environment.

Oxygen injection offers the following advantages:

• Allows greater percolation
• Increases root depth
• Adds oxygen to soil
• Reduces aeration

When the turf is irrigated with highly oxygenated water it releases positively charged ions such as calcium in the soil. This will lower your soil’s Cation Exchange Capacity, creating increased percolation, eliminating sodium crust, and allowing salts to leech through.  High levels of dissolved oxygen in soil will also increase root growth and stop clay expansion.

With standard mechanical aeration, the removal of plugs allows oxygen to get into soil and helps to lower compaction.

Essentially, we are intensely aerating your turf using your irrigation water. Mechanical aeration only allows 10% of your soil to get more oxygen. Our system allows 100% of your turf & soil to get more oxygen daily.

The combination of light metals being chelated, increased percolation, and increased oxygen benefits the root zone immensely. It increases root density, depth, and health. When your roots absorb nutrients better, you can use less fertilizer.

According to industry experts, increasing the dissolved oxygen levels in water is beneficial to the root zone. The following advantages can be expected:

• Better root health, which will promote better absorption of nutrients
• Reduced incidence of diseases
• Better plant quality

We can also inject CO₂ to lower pH, with the following benefits:

• Safe to use
• Accuracy of regulation
• Low maintenance system
• Flexibility
• Safe for the environment

Do you want to know how it works?

• Carbon dioxide is a gas which produces carbonic acid, a weak acid, when dissolved in water.

CO₂+H₂O => H₂CO₃

• Carbonic acid is a mild acid present in water as H+ and HCO₃^-, which are highly reactive ions.

• The ions react immediately with alkalis such as caustic soda, sodium carbonate, and dissolved lime, turning them into neutral carbonates and bicarbonate salts.

H₂CO₃ + 2NaOH => Na₂CO₃ + 2H₂O

H₂CO₃ + Na₂CO₃   => 2NaHCO₃

Golf courses are increasingly required to use poor quality water for irrigation.  Whether using effluent, well, brackish, or city water, diffusing such gases as ozone (O₃), oxygen (O₂), and carbon dioxide (CO₂) will improve the quality of lakes and ponds, irrigation water, and soil.   Common golf course irrigation water issues such as high bacteria counts, high bicarbonates, lack of dissolved oxygen, and high pH levels can be eliminated with ozone, oxygen, and carbon dioxide diffusion. Ozone removes harmful contaminants and bacteria, and creates an aerobic environment that facilitates the decomposition of unwanted organic materials.  Oxygen creates an aerobic environment in the soil, which, among other things, will increase percolation and root growth. Carbon Dioxide controls pH levels. With the proper gas diffusion system, golf courses can substantially reduce the use of chemicals. This paper provides the science behind ozone, oxygen, and carbon dioxide as they relate to the effects on golf course irrigation water and soil.

 Ozone

Ozone is the tri-atomic form of oxygen.  Due to its structure, it is highly unstable, and thus is inclined toward returning to the stable molecule O_2.  The extra oxygen molecule then quickly binds with other components in order to stabilize, as illustrated below.  This property of ozone makes it a very powerful oxidant, with an oxidation potential of 2.07V, making it ideal for sterilization, enhancing fertilization, and removing odors. 

Golf course irrigation water frequently requires sterilization.  Often remaining in holding ponds for days before it is used on the course, it breeds bacteria, viruses, cysts, and fungi.  When this poor quality water is applied to turf it affects the health of the grass by importing unwanted algae and bacteria.  Typically, irrigation water would be sterilized with chemicals, and persistent algal or fungal growths on turf grass would be managed with the addition of algaecides or fungicides.  These solutions are not very environmentally friendly, can be harmful to the golfers, and require expensive and hazardous transport and storage.

According to the Environmental Protection Agency, ozone is more effective than chlorine in destroying viruses and bacteria.  When ozone is mass transferred into water with an inline diffusion system, removes pathogens and unwanted organic matter, killing algae, spores, and fungus by eliminating their food source, bacteria.  As ozone is generated onsite, the need for transport and storage is eliminated.  Additionally, no harmful residuals remain after ozonation, because ozone decomposes so rapidly. 

Chemical fertilizers added to golf courses are a considerable expense, and might not even be effective because in some areas the soil lacks metals or the soil conditions do not allow for easy metal uptake. Ozone makes fertilizer more efficient. For metals present in the irrigation water, such as iron, manganese, and calcium, ozone will also chelate the metals, making them more biologically available. Hence, you can apply less iron, calcium, and manganese but see better results due to the use of ozone injection. In addition, ozone causes heavy metals such as mercury or arsenic, which are undesirable in the turf, to react to their irreversible hydroxide forms, making them not biologically available.    

Ozone removes odors by oxidizing volatile organics and removing H₂S, without leaving behind a residual odor like chlorine.

In addition to its highly reactive properties being ideal for sterilization, fertilization and odor removal, ozonation also elevates the dissolved oxygen (DO) concentration of the effluent. The increase in DO can eliminate the need for re-aeration.

 Oxygen

When ozone is added to any system, it is only incorporated by a few percent by gas volume.  Thus, the remaining oxygen is added as O_2.  Furthermore, in some ozone reaction mechanisms, oxygen is reformed after it has reacted with organic molecules in solution.  Oxygen benefits the turf by aerating the soil and increasing dissolved oxygen levels, producing numerous benefits.

Golf course aeration has undergone many changes over the past 100 years as superintendents strive to relieve compaction and provide their turf with oxygen, the most crucial element for turf survival. Oxygen has two means of introduction into the soil: atmospheric introduction through mechanical aerafication, and dissolved oxygen in irrigation water. Mechanical means of introducing oxygen have become quite advanced, but the next generation of aeration technology will focus on water quality and how it affects soil oxygen levels.

When mechanical aeration takes place, only 10% of the soil surface is exposed to oxygen. When oxygen is diffused into irrigation water, 100% of the soil surface being irrigated is exposed to oxygen.

The ability to dissolve oxygen into water to create a stable oxygenated state which can be used for golf course irrigation systems is very beneficial.  This is accomplished by the use of an oxygen generator that conveniently concentrates oxygen on site. In doing so, the system ensures that oxygen is readily available in the soil/turf profile and prevents soil oxygen levels from becoming depleted by actively growing turf roots or soil microbes.  The resulting elevated DO levels in irrigation water lead to higher DO levels within the soil pore water.  This additional oxygen in the root-zone environment is then available for use by turfgrass roots and soil microorganisms.

Soil microorganisms are an essential part of the soil system since they are the main force driving nutrient movement in soils.  Providing an aerobic environment for soil microbes to flourish is essential in any turf management system. Oxygen diffusion systems can accomplish this by increasing irrigation water DO levels to well above the approximately 5mg/L needed in order to maintain an aerobic environment. 

By increasing the amount of oxygen available in soil pore space, oxygen diffusion supports critical soil microbial activity. Elevated oxygen levels within the soil pore space aid microbes in the mineralization of organic matter to useful forms of nutrients required for plant growth. Maintaining an aerobic environment not only helps break down organic matter, but also reduces the potential for formation of H₂S and CH₄ that prevail in anaerobic conditions. 

Soil microbes also aid in the aggregation of root-adhering soil at the soil-root interface.  This is the physical environment where roots take up O₂, water, and nutrients.  Since soil productivity is dependent on aggregate formation, soil microbes have a direct influence on both soil fertility and productivity.  By facilitating root growth and aerobic microbial activity, oxygen diffusion helps maintain a balanced turf/soil system and has the potential to reduce fertilizer requirements in the long run.

Partially decomposed organic matter or thatch is a major problem on turf, especially greens. This organic matter competes with the turf for oxygen at the soil surface. On many greens, the stress is so great that the turf can’t survive. Oxygen will break down the organic/thatch layer. Two results follow this breakdown of the organic layer.  First, the turf and soil will receive large amounts of oxygen producing the results mentioned in the preceding paragraphs, then this effect also allows nitrogen in the thatch layer to be released into the soil and the turf is able to use it.

Contrarily, if oxygen is not used, nitrogen applied to the soil in fertilizer will be wasted. Plant roots need oxygen as the terminal electron acceptor of the respiratory chain to gain energy for adenosine triphosphate synthesis.  If oxygen deficiency exists, a biologically mediated process called denitrification will use nitrate or other oxidized forms of nitrogen as the terminal electron acceptors for respiration instead of oxygen. In fact, when turf is watered through irrigation or from rainfall, small sites within the soil profile can become oxygen limiting. As soil temperatures rise, nitrogen losses will increase as the turf’s elevated respiration triggers more denitrification and a decreased efficiency in fertilizer use. Horgan’s study proved that fertilizer losses can be significant even after light irrigation because not enough oxygen is available.

Carbon Dioxide

Along with oxygen and nutrients, pH plays a significant role in turf health.  High pH soils promote unfavorable bacterial growth, whereas excessively low pH promotes fungal growth. Ideal turf pH should remain within 6.5-7.5 range (depending on the golf course).  For turf to fend off disease and promote healthy growth, and to maintain a proper soil structure, a constant pH, suited to the region, should be employed. Upsets in the pH adversely affect all organisms, including grass.  For most golf courses, water is one of the largest contributing factors for pH. For some courses, chemicals, either an acid or a base depending on the required adjustment, are used to control pH.  Alternatively, if CO₂ gas is dissolved in to the irrigation water, pH control can be achieved.

For a number of years, sulfuric acid was used in water treatment facilities to control alkalinity. It’s a product that works, but it also has many potential problems. Sulfuric acid can be difficult to apply and control. It is potentially dangerous to store and handle. Safety showers must be installed and readily available to operating personnel who must wear special clothing for their protection.  Additionally, the extremely corrosive acid requires special material for equipment and piping. Maintenance of the system demands frequent component repairs and replacement.  Other acids that are used to decrease pH of golf course water, such as HCl, H₂SO₄, and CH₃COOH are also hazardous to handle due to their corrosive nature.

Carbon dioxide, alternatively, is safe to handle, easy to apply, efficient, and ecologically safe. Controlling pH is critical to a golf course’s process and effluent quality, and CO₂ is the cheapest, cleanest, and easiest alternative to chemical methods.  The cost of carbon dioxide is very inexpensive, particularly when applied with efficient systems. 

Carbon dioxide is safe to use because, in the absence of water, it is inert and non-corrosive. It does not require mechanical transfer or handling equipment. It becomes active only when dissolved in water. CO₂ leaks dissipate safely into the atmosphere, leaving no residue to be neutralized, and having no hazardous effects. Furthermore, carbon dioxide does not corrode metal equipment. No special alloy or plastic distribution piping is required for the CO₂ system.

Application and maintenance of carbon dioxide is easy; it is done using compressed gas cylinders.  For most requirements, carbon dioxide is supplied with a 265 liter dewar, delivered by truck and stored on-site. The CO₂ storage tank is supplied, installed, and maintained by the supplier of the gas. Typically CO₂ is stored in pressurized vessels up to 300 psi which do not require feed or transfer pumps to supply the process. Systems are generally engineered to be pressure driven. With a minimum number of moving parts, this system offers continuous trouble free operation. Moreover, trained technicians can be rapidly dispatched to service the bulk CO₂ tank in the unlikely event of a problem.  The systems also offer flexibility, with a turndown ratio in control of the CO₂ injection rate exceeding 10:1, the pH control system will efficiently and rapidly respond to any fluctuation of flow rate or incoming pH.  Depending on the use at a given facility, a 265 liter dewar will last the course anywhere from one week to an entire month.

Using carbon dioxide is beneficial to the environment as well because there is no secondary pollution introduced into the treated water by salts such as chlorides (from HCl) or sulfates (from H₂SO₄). The introduction of CO₂ will contribute to the chemical equilibrium of water by forming neutral carbonates and bicarbonates.

Here is the chemistry behind CO₂; how and why it works. Carbon dioxide is a gas which produces carbonic acid, a weak acid, when dissolved in water. Carbonic acid is a mild acid present in water as ions H+ and HCO₃, which are highly reactive. 

CO₂ + H₂O  —>  H₂CO₃

The ions react immediately with alkalis such as caustic soda, sodium carbonate and dissolved lime, turning them into neutral carbonates and bicarbonate salts.

 H₂CO₃ + 2NaOH —> Na₂CO₃ + 2H₂O

 H₂CO₃ + Na₂CO₃ —> 2NaHCO₃

CO₂ is better than strong acids for controlling pH because it forms a mild but highly reactive acid which minimizes risks of overt acidification and rapidly responds to any variations of the incoming pH or water flow rate. Over or under treatment with mineral acids will often result in a pH which rapidly deviates from the compliance range.

Conclusion

The benefits that a golf course can see after diffusing ozone, oxygen, and carbon dioxide into its irrigation water are staggering. Diffused ozone removes all algae in lakes and sprinkler heads, reduces bicarbonate levels to under 50 ppm, replaces algaecide and sulfur burning, and increases the effectiveness of fertilizer. Oxygen diffusion increases percolation, root growth, and dissolved oxygen levels.  Effectively diffusing oxygen into irrigation water will provide over 500% more oxygen in the soil than aeration by mechanical means. Carbon dioxide diffusion will control pH levels. Though CO₂ will drastically increase bicarbonates in the water, ozone will counterbalance this effect, thus, in a golf course irrigation application it is recommended to use ozone injection in conjunction with CO₂. Calcium and acid injection can be replaced by diffusing CO₂, oxygen, and ozone at the same time. Now that the technology to economically and efficiently diffuse these gases into irrigation water is available, golf courses can stop using chemicals, improve their turf, and save thousands of dollars a year.

• A Cost Calculator
• Information about our pH Services
• New Golf & Turf and Lakes & Ponds pages

Please check back with us as we continue to add to our new features.