REWAQUA: an advanced technology for water purification in sustainable aquaculture based on photocatalytic ozonation

The present study has been undertaken in order to test the realpotential of photocatalytic ozonation in a bench-scale recirculating aquaculturesystem working on a 180 L reef coral aquarium. Notably, this choice may beconsidered representative. In fact, (i) the system is virtually closed so that freshwater turnover is practically negligible, (ii) the presence of living organisms ishighly diversified (corals, fishes, molluscs, echinoderms and crustaceans) andsome of them are particularly sensitive to water quality, (iii) high salinitystrongly puts a strain on the purification system. The hereby presented purificationmethod has been named REWAQUA, which stands for REcycling Waterfor AQUAculture and AQUAria. REWAQUA allows purification rates higherthan the sum of the rates of the single technologies (photocatalysis andozonation) operating in series. Furthermore the production of bromate ions,which are carcinogenic by-products of ozonation, is efficiently controlled. Twoyears observation of the reef coral aquarium reveals that photocatalytic ozonationis a good candidate for water purification in recirculating systems in view ofa sustainable aquaculture.