The sizing of a system is depended on the desired
objective and the quality of the water to be treated. It is
always best the pre-treat the water to as high a standard as
possible, this will make it much easier to treat the water using
ozone and will give much better results. The pre-treatment
will reduce the COD of the water, it will reduce the ozone demand and this means that the size of the ozone generator
can be reduced.
If you wish to achieve complete disinfection of the water then the redox potential must be taken to 750mv and the hold at this level for a
period of at least 10 minutes. To achieve this level of oxidation, ozone application ates of approximately 1 mg/l will be required.
If UVc is used in combination with
ozone, the combined performance of the equipment can be many times greater than either ozone or
UVc on their own. This technique also permits the reduction of the size of the ozone generator to approximately 0.1mg/l. The
technique does not guarantee absolute disinfection of the water, but for most applications in aquaculture and water treatment, this is the
safest and preferred approach, especially for marine systems.
In the case of marine Ozonation systems, a high percentage of the ozone will oxidise chlorine and bromine in the water to form hydro-bromous acid.
The acid is itself highly reactive and unstable, and it will oxidise bacteria, viri and organic molecules etc. However hydro-bromous acid is
more stable than ozone and can have a long half life in marine systems. It is therefore best to treat the water by activated carbon after the
UVc system in order to remove any residuals. The carbon should be replaced, at approximately 1 year intervals.
