Testing of a passive foam fractionator prototype in a commercial recirculating trout farm

Foam fractionation has emerged as a technical solution to reduce the build-up of microparticles and dissolved organic matter in recirculating aquaculture systems (RAS). However, commercial application in freshwater RAS is challenging and expensive. In the present study, a simple, low-cost passive foam fractionation (PFF) prototype was developed and tested under commercial conditions. The prototype was tested in a Model Trout Farm (MTF) in three different production raceways during winter and spring to assess the operation and removal potential. A number of different water quality parameters, including organic matter, particles, bacterial activity, and phosphorus were examined in the system water and in the removed foamate. Overall, the PFF prototype removed particles as well as particulate and dissolved organic matter, reduced the amount of bacteria and total phosphorus in the water, regardless of sampling time and place. By utilizing the existing airlifts in the MTF, the associated cost of construction and operation was kept low. Overall, the results demonstrate that the passive foam fractionation has the potential to help address some of aquaculture’s pressing issues in a cost effective manner.