Optimization and control of ozone use within recirculating aquaculture systems
University of New Brunswick
This research focuses on the development of a centralized ozone treatment system for improving water quality in recirculating aquaculture systems (RAS). The ozone system was tested in a commercial salmon smolt hatchery. An experimental reactor was also constructed to evaluate the effects of ozone on water quality and determine the reaction kinetics of ozone in RAS. Ozone treatment improves water quality by oxidizing dissolved organic compounds, which leads to lower refractory COD concentrations, improvement in UV light transmittance, and clear water. In addition, the reaction between ozone and the dissolved organic matter is nearly instantaneous. Based on these findings, a steady state model for the production and destruction of UV absorbing compounds was used to confirm that ozone dosing should not exceed 21.9 ± 2.8 g 0₃/kg feed to avoid ozone residuals. Finally, a control strategy is outlined which utilizes an ozone side-loop to infer the ozone demand within the RAS.