Ozone Dosage vs Dissolved Ozone
The quantity of ozone applied to the water will always exceed the amount of ozone actually absorbed into solution.
Often times, due to system inefficiencies, a portion of the ozone off-gases without being absorbed into the water. This wasted ozone must then be vented outside or destroyed with an ozone destruct unit.
What are the Units of Ozone Dosage?
The units are also ppm or mg/l. But how can this be, if ozone has not actually been dissolved into solution? Remember that ppm is a ratio (1 ppm is one part ozone for every 1,000,000 parts molecules of water). An operator will know the quantity of ozone being produced. They will also know the quantity of water passing through a venturi (the typical method of injecting ozone). The ratio of generated gas to moving liquid will give us a value which can be expressed in ppm (or mg/l).
You might see an ozone system parameter which states 2.0 ppm ozone dosage. Do not confuse this with dissolved ozone. 2.0 ppm ozone dosage will often translate into 1.0 ppm, or less, dissolved ozone due to losses.
The amount of ozone that you place into the water will not remain that same value. The dissolved ozone will be reduced by the water conditions, such as the temperature, organic pathogens, etc. To obtain the desired dissolved ozone level, you must add ozone until you overcome the contaminants and the other ozone diminishing conditions.
The left picture represents dissolved ozone which is the amount of ozone measured in the water. The right picture represents ozone dosage which is the amount of ozone applied to the water.