UV irradiation and micro filtration effects on micro particle development and microbial water quality in recirculation aquaculture systems

Abstract Recent studies have focused on micro particle build-up in recirculation aquaculture systems (RAS), and a correlation between micro particles and microbial activity has been shown. This study evaluated how micro particle build-up and microbial activity are affected by UV irradiation and micro filtration. Using 12 identical pilot scale RAS stocked with rainbow trout (Oncorhynchus mykiss), a two-factor factorial experiment was carried out testing in triplicate systems the effect of UV irradiation (systems with or without) in combination with cartridge filtration (1 or 200 μm pore size) on selected water quality parameters. The trial ran for 13 weeks. Water samples were obtained once a week, and the number and size distribution of micro particles was analysed. Microbial activity was derived from the hydrogen peroxide degradation rate, and concentrations of total and dissolved organic matter were measured as chemical oxygen demand (COD). Overall, both UV and cartridge filtration had significant effect (