Numerical Modeling and Optimization of Open-Ocean Aeration Systems

Abstract

The coastal regions of Nova Scotia are prone to warmer ocean temperatures resulting in lower dissolved oxygen (DO) levels during the summer months. DO levels below 6 mg/L lead to reduced feed conversion, growth, and welfare of Atlantic salmon in open-ocean pens. An aeration system that allows for the delivery of supplemental oxygen to open-ocean aquaculture pens during conditions of low DO has the potential to improve key performance indicators of Atlantic salmon. A transient one-dimensional bubble plume model coupled with an ambient environment model was developed and validated using hydrodynamic and mass transfer case studies. The model was used to develop heuristics for the number of diffusers, spacing of diffusers, and the volume of air and oxygen-enriched air to maintain DO levels above the recommended minimum of 6 mg/L. Six trilobed diffusers using air are required to maintain the DO in an open-ocean pen above 6 mg/L.