Property	Ozone	vs. Oxygen
Molecular Formula:	O3	O2
Molecular Weight:	48	32
Color:	light blue	colorless
Smell:	- clothes after being outside on clothesline - photocopy machines - smell after lightning storms	- odorless
Solubility in Water (@ O-deg C):	0.64	0.049
Density (g/l):	2.144	1.429
Electrochemical Potential, V:	2.07	1.23

Gaseous Temp (C) half-life * -50 3-months -35 18-days -25 8-days 20 3-days 120 1.5-hours 250 1.5- seconds

Dissolved in Water (pH 7) Temp (C) half-life 15 30-minutes 20 20-minutes 25 15-minutes 30 12-minutes 35 8-minutes

* These values are based on thermal decomposition only. No wall effects, humidity, organic loading or other catalytic effects are considered.

The solubility of ozone depends on the water temperature and the ozone concentration in the gas phase: Units in mg/l or ppm.

3 GAS	5o C	10o C	15o C	20o C
1.5%	11.09	9.75	8.40	6.43
2%	14.79	13.00	11.19	8.57
3%	22.18	19.50	16.79	12.86

ORP is a term used frequently in the water treatment & food processing industry. ORP stands for Oxidation-Reduction Potential. So what is that? The best definition I can give is that “ORP is a measure of the cleanliness of the water & its ability to break down contaminants”.
It has a range of -2,000 to + 2,000 and units are in “mV” (millivolts).Since ozone is an oxidizer, we are only concerned with positive ORP levels (above 0 mV).

Ozone owes its excellent bactericidal, viricide, and sporicidal activities to its powerful oxidizing properties.

Ozone has an oxidation reduction potential of +2.07 volts as compared to HOCL (the active form of Chlorine in aqueous solution) which is +1.49 volts. It is reported to be 3000 times as germicidal as chlorine. It retains this strong oxidizing capability in aqueous solution, a property crucial for water disinfection and sterilization, as well as in high humidity air applications.

ORP sensors work by measuring the dissolved oxygen. More contaminants in the water result in less dissolved oxygen because the organics are consuming the oxygen and therefore, the lower the ORP level. The higher the ORP level, the more ability the water has to destroy

contaminants such as microbes, or carbon based contaminants.
The chart below identifies ORP levels for various applications:

ORP Level (mV)	Application
0-150	No practical use
150-250	Aquaculture
250-350	Cooling Towers
400-475	Swimming pools
450-600	Hot Tubs
600	Water Disinfection *
800	Water Sterilization **
*  Disinfection is destruction of specific pathogenic microorganisms **  Sterilization is the destruction of all microbial life

An ORP meter measures very small voltages generated with a probe placed in ozonated water. The electrode is made of platinum or gold, which reversibly looses its electrons to the oxidizer. A voltage is generated which is compared to a silver (reference) electrode in a silver salt solution, similar to a pH probe. The more oxidizer available, the greater the voltage difference between the solutions.

1. Ozone is 51% more powerful on bacterial cell walls than chlorine.
2. Ozone kills bacteria 3100 times faster than chlorine.
3. Ozone is the most powerful broad spectrum microbiological control agent available.
4. Ozone ELIMINATES the use of hot water and conventional sanitizer.
5. Ozone virtually eliminates all chemical usage.
6. Ozone is chemical-free; it produces NO toxic by-products.
7. Ozone has full FDA approval for direct-food contact application.
8. Ozone is clean and environment-friendly; its only by-product is oxygen.
9. Ozone is extremely effective as a disinfectant at relatively low concentrations.
10. Ozone is generated on site, eliminating the transporting, storing and handling of hazardous materials.
11. Ozone is very inexpensive to produce and has an unlimited supply.
12. Ozone is much safer for employees than conventional chemicals.
13. Ozone extends the shelf life of food products.
14. Ozone permits recycling of wastewater.
15. Ozone reduces Biological Oxygen Demand (BOD). Bacteria kill rate is up to three thousand times faster.

Ozone is an allotropic form of oxygen; each molecule contains three atoms of oxygen instead of the standard two. Ozone is a powerful disinfectant and has been used commercially for the treatment of potable water since 1904.

Ozone is formed naturally in the atmosphere, as a colourless gas giving a very pungent odour It is the ozone formed by lightening discharges during a thunderstorm which gives the air its characteristic fresh and clean smell afterwards. An ozone smell can also be detected around office copy machines and laser printers. In fact, ozone in air can be readily detected by smell at concentrations as low as 0.01 ppm

In the same way that ozone is formed naturally by the discharge of electricity during a thunderstorm, large quantities of ozone are produced in the modern electrical ozone generator This method of ozone generation is called corona discharge. A high voltage is passed across a gas stream containing oxygen. The energy of the high voltage splits an oxygen molecule (02); into two oxygen atoms (0) - which recombine with ordinary molecules of oxygen (02) to form ozone (03).

To improve the performance of the ozone generator, pure oxygen can replace the ambient air thus providing a greater percentage of oxygen in the airstream.

Ozone can also be formed in the proximity of certain types of ultra violet lamps, however this will only produce ozone at low concentrations. Since ozone is highly reactive and has a short half-life, it is very difficult to store and transport. Ozone must therefore always be generated on site for immediate use

Ozone is the most powerful oxidising agent permitted for use at this time (only fluorine is stronger - its use is banned in most countries).

As an oxidising agent it is 51% stronger than chlorine and has a kill rate of 3.125 times faster Ozone readily oxidises organic material in bacterial membranes which weakens the cell wall and leads to cell rupture causing immediate death of the cell.

Ozone oxidises most organics and reduced many inorganic materials to a lower state that is more biodegradable. Some organic materials can be completely oxidised to carbon dioxide and water.

Ozone kills all bacteria, viruses, spores, mould, mildew, fungi, amoebae and cysts. The amount of ozone, the concentration of ozone, the composition of the host environment and the contact time of ozone with the organism all play a role in calculating the level of ozone required to destroy each type of organic growth.

The maximum permissible continuous exposure limit to ozone in air is 0.1 ppm averaged over an eight-hour work shift. It is possible to detect ozone by smell at levels as low as 0.01 ppm. With sufficient concentrations of ozone, irritation of the eyes, dryness of the throat and cough may be experienced. Ozone is a potentially toxic material and the exposure limit guidelines must always be adhered to.

A properly installed ozone system will dissolve a high proportion of the ozone dosed into the water with the intention of building a residual level. As ozone can be detected at levels ten times smaller than the current Health & Safety Guidelines, any escaping ozone in an enclosed area can easily be detected and the necessary action taken to remedy the situation.

The temperature and humidity of the air and the chamber where ozone is made is very important in maximising ozone output. The cooler and dryer in the air, then the greater the ozone output. Most eltech Ozone Systems are therefore fitted with air dryers and filters to pre-treat and condition the air feed.

Ozone has a neutral pH (about 7.0) so it does not affect the pH of the system's water Ozone has no calcium or alkalinity, and has no dissolved solids; therefore it will not affect the water's balance.

Ozone does remove trace amounts of dissolved metals such as iron manganese and copper by oxidising them to their highest oxidation state. They will then precipitate out of the water and should be removed by filtration.

Ozone is highly reactive and because of this has a very short half life once dissolved into water The natural reaction for ozone (03) is to return to its oxygen form (02). This reaction time is typically 10-20 minutes at 20ºC. This means that any blowdown from an ozone treated cooling system will not contain any chemical biocides or corrosion inhibitors or toxic residues and thus will not be classed as effluent and may be disposed to surface drainage.

When ozone is injected to a properly designed ozone water treatment system there is very little ozone which is not dissolved. The ozone layer is located in the lower stratosphere between altitudes of 9 and 19 miles. What does escape would be like a drop in the ocean and would never reach this region.

The simplest form of ozone detection is smell. At levels as low as O.O1 ppm ozone can be detected by the human sense of smell. For a more accurate form of detection, several manufacturers promote devices that can detect ozone by means of light detraction or drop test chromatography.

There are methods for continuous ozone detection by means of Redox and direct ozone determination (Amperometric cell).

Ozone detection methods are very similar in design to other oxidising biocide monitors such as chlorine or bromine

Ozone has been scientifically proven to be most effective under almost all conditions at controlling bacterial, biofilms and other amoebae in cooling systems without the need for secondary biocide or biodispersant, as proven by the Department of the Environment and others. Documented test data is available

No. Ozone, when correctly applied, has been proven to maintain uniformly low corrosion rates, similar to and frequently better than systems treated with traditional chemicals.