Functionality tests of the integrated system

Recent trials with the RAZone pilot plant has been concentrated around investigation of both seawater and freshwater exposure to intensive ozonation to test effects of water composition on the production of possible harmful by-products  such as bromine and redox potential, effects on removal of essential and non-essential nutrients ( such as iodide and copper) and  effects on removal of deleterious by-products of fish-farming (nitrite, nitrate, ammonia).  Trials have been run with seawater and fresh water loaded with waste from an experimental RAS stocked with sea-bass and trout respectively. Similar study was done on a control RAS (non ozonated) parallel with the ozonation trials.

Furthermore, a 30 day test has been run in the freshwater RAS with ozonated and a control system to study the effect of ozone dosage used in the experiments related to the water chemistry. The 30 day trials are aimed at investigating the impact of extended exposure to ozone on fish health.

Attained Findings

Ozonation was found to remove (oxidise) nitrite and iodide very quickly, but more slowly organic matter and copper  from seawater. The removal of iodide and nitrite is slowed down in the presence of organic matter indicating that this tends to absorb the  injected ozone. Sea-bass in the experimental fish farm was not affected by the ozonation indicating that all harmful ozonation products (if any) were rendered harmless within minutes and before the water is returned to the fish tank.

Copper is removed along with organic matter quite efficiently. Iodine removal is very fast in seawater, whereas no removal is observed in fresh water. Colour is removed much faster than by a good sand filter. While nitrite is removed much faster by ozone than by the biofilter in seawater, the effect in freshwater is slower in the ozonated freshwater system than in the control system. 

The trout stock that was exposed to the 30 day ozonation has not shown any sign of gill damage or behavioural irregularity during the trial period. There is no any significant variation in the condition scoring indexes (weight, Fulton condition, ISI, SSI, HIS or gill condition) either.



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