Water Quality and Waste-Solids Dewatering at a Zero-Exchange Recirculating Aquaculture System
To meet growing demand, the aquaculture industry is building increasingly larger land-based farms. There are few locations which can provide enough fresh water for their operation and the industry is forced to reduce its water requirements further by modifying recirculating aquaculture systems (RAS) to incorporate zero-exchange technology. Cooke Aquaculture Inc. is currently constructing a zero-exchange RAS at Johnson Lake, located in Pennfield, New Brunswick to produce salmon parrs. This facility will be the first of its kind in the Americas. This research focuses on two possible problems which may arise with the new system. The first problem is with regards to the possible accumulation of waste metabolites in the water. A water quality monitoring program will be implemented throughout the first production cycle, and any accumulations will be remediated as they begin to arise. A model to predict nitrogen and phosphorus concentrations in the waste stream based on feed loading and measured equipment efficiencies will also be developed for optimization purposes. The second problem deals with the dewatering of waste solids generated in the system. The effectiveness of a centrifuge will be evaluated, first using lab-scale tests to optimize polymer dosing, then applying the lab-scale findings to an industrial centrifuge.