Comparing Disinfectants

Purifico

Comparing Disinfectants

Ozone leads the way in defending against water-borne pathogens like bacteria, fungi, and viruses. Pound-for-pound, ozone outperforms other chemicals due to its strong oxidizing power. Plus, it leaves no toxic residues, allowing operators to use whatever amount is needed to get the job done. With other chemicals, toxic residues are produced which constrains dosage, allowing certain pathogens to evade destruction. When it comes to safeguarding your crops or livestock from water-borne pathogens, Purifico ozone products provide unparalleled protection and peace of mind.

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Oxidative Power

Oxidation Potential is measured in volts (V) and measures the tendency for a chemical species to gain electrons. As shown below, ozone is a more powerful oxidant than other disinfectants like peroxide, chlorine or chlorine dioxide.

Substance	Oxidation Potential (V)
Hydroxyradical (OH)	2.86
Oxygen atom (O)	2.42
Ozone molecule (O₃)	2.07
Hydrogen peroxide (H₂O₂)	1.78
Chlorine (Cl)	1.36
Oxygen molecule (O₂)	1.23
Chlorine dioxide (ClO₂)	0.95

Treatment Comparisons

Ozone is the most powerful disinfectant, and is the best assurance against tough-to-treat pathogens. The tables below compares common water treatment systems and provides the CT values (read more about CT values) needed with each method to eliminate benchmark microorganisms. The dosages needed for disinfection vary with different temperatures, but ozone remains the best disinfectant in all conditions. The CT values are listed in mg*min/L for treatment at 20°C. UV dosage is provided for reference. Since UV cannot disinfect systemically like chemicals can, it provides relatively poor disinfection on its own.

Source: U.S. EPA (1991) Guidance Manual for Compliance with the Filtration and Disinfection Required for Public Water Systems Using Surface Water Sources, U.S. Environmental Protection Agency, Washington, D.C.

Viruses

CT values for 99.99% disinfection
Ozone	0.5
Chlorine Dioxide	12.5
Free Chlorine	3
UV	186 (mJ/cm)
Chloramine (99.90% inactivation)	746

Viruses are easily destroyed by ozone. To achieve the same results, you will need approximately…

25 times more chlorine dioxide
6 times more free chlorine
1500 times more chloramine

Cryptosporidium

CT for 99.90% disinfection
Ozone	0.72
Chlorine Dioxide	15
Free Chlorine	68
UV	11 (mJ/cm)
Chloramine (99.90% inactivation)	1100

Cryptosporidium are a type of disease-causing protozoa. They are easily destroyed by ozone but not other disinfectants. To achieve the same results, you will need approximately…

20 times more chlorine dioxide
100 times more free chlorine
1500 times more chloramine

Giardia Cysts

CT for 99.90% disinfection
Ozone	12
Chlorine Dioxide	347
UV	12 (mJ/cm)

Giardia cysts are a disease-causing type of protozoa. Compared to ozone, more than 10 times as much chlorine dioxide is needed for its disinfection.

Incomplete Disinfection

Chlorine Dioxide

Chlorine dioxide (ClO₂) is a popular disinfectant used to treat agricultural water. Chlorine dioxide is a fairly good option overall, but pathogen removal is likely to be incomplete for certain organisms such as fusarium or for removal of plant viruses . This method also leads to the build-up of chloride in irrigation water which can be harmful to plants and impede water recycling.

Residuals and Limited Recycling

Electrolyzed Water

Electrolyzed water is a system that aims to produce hypochlorous acid (HOCl), which is an oxidizer and sanitizer.

The hypochlorous acid is produced through the electrolysis of salt (NaCl) or hydrochloric acid (HCl).

Hypochlorous acid is useful for disinfecting water, but has some disadvantages compared with ozone:

Na or Cl residuals
Limits how many times water can be recycled
Doesn’t eliminate all plant pathogens
High upfront cost for generators
Like ozone, it is unstable and needs to be produced on-site. Generators and other equipment are required for its use.

Not Stand-Alone

Ultraviolet (UV) Radiation

Many producers recirculate their clean water through UV irradiation to kill microbes in solution. Since UV light is only able to kill microbes where it makes contact with them, this does not offer protection from microbial growth on the surface of your tanks and plumbing. UV radiation is a good way of reducing the microbial load circulating in solution, but is not the best choice as a stand-alone solution because it isn’t effective against all pathogens and will not completely eradicate them.

Free Chlorine

Studies have found that the amount of free chlorine levels needed to inactivate plant pathogens such as F.oxysporum is higher than phytotoxic thresholds. In other words, certain pathogens can’t be eliminated because the amount of disinfectant needed would be toxic to crops. In contrast, research shows that achievable working concentrations of ozone (~1.5ppm) yield 100% inactivation of F.oxysporum spores in less than a minute. Our personal experience backs up this science; after installation of Purifico ozone systems, our customers see drastic reductions in microbial counts on their water quality reports (typically complete elimination of detectable microbes).