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 real potential of photocatalytic ozonation in a bench-scale recirculating aquaculture system working on a 180 L reef coral aquarium. Notably, this choice may be considered representative. In fact, (i) the system is virtually closed so that fresh water turnover is practically negligible, (ii) the presence of living organisms is highly diversified (corals, fishes, molluscs, echinoderms and crustaceans) and some of them are particularly sensitive to water quality, (iii) high salinity strongly puts a strain on the purification system. The hereby presented purification method has been named REWAQUA, which stands for REcycling Water for AQUAculture and AQUAria. REWAQUA allows purification rates higher than the sum of the rates of the single technologies (photocatalysis and ozonation) operating in series. Furthermore the production of bromate ions, which are carcinogenic by-products of ozonation, is efficiently controlled. Two years observation of the reef coral aquarium reveals that photocatalytic ozonation is a good candidate for water purification in recirculating systems in view of a sustainable aquaculture.