Foam fractionation is often considered an ineffective way of removing organic matter from freshwater due to the low surface tension of the water. There is, however, a lack of studies testing foam fractionation efficiency in replicated freshwater recirculating aquaculture systems (RAS). Foam fractionation can be applied with or without ozone. Ozone is a strong oxidiser previously shown to improve water quality and protein skimmer efficiency. To test the efficiency of foam fractionation and ozonation (20 g O₃ kg^-1 feed) separately and in combination in freshwater RAS, a two-by-two factorial trial was conducted with each main factor at two levels (applied or not applied). Each treatment combination was carried out in triplicates using 12 replicated pilot scale RAS stocked with juvenile rainbow trout (Oncorhynchus mykiss) and operated at a feed loading of 1.66 kg feed m^-3 make-up water. The trial lasted 8 weeks and samples were obtained once a week. Ozone applied by itself significantly reduced the number of particles (83%), bacterial activity (48%) and particulate BOD₅ (5-days biochemical oxygen demand; 54%), and increased ultra violet transmittance (UVT; 43%) compared to the untreated control group. Foam fractionation by itself lead to significant reductions in particle numbers and volume (58% and 62%, respectively), turbidity (62%), bacterial activity (54%) and total BOD₅ (51%). A combination of both treatments resulted in a significant additional improvement of important water quality variables, including a 75% reduction in total BOD₅, 79% reduction in turbidity, 89% reduction in particle numbers and 90% reduction in bacterial activity compared to the control. The removal efficiencies were within the same range as those observed in previous studies conducted with foam fractionators in saltwater systems (with or without ozone), corroborating that foam fractionation may become a useful tool for controlling organic matter build-up and bacterial loads in freshwater RAS.

由于水的表面张力低，泡沫分馏通常被认为是从淡水中去除有机物的无效方法。然而，在重复的淡水再循环水产养殖系统 (RAS) 中，缺乏测试泡沫分馏效率的研究。泡沫分馏可以在有或没有臭氧的情况下进行。臭氧是一种强氧化剂，先前已证明可以改善水质和蛋白质分离器的效率。测试泡沫分馏和臭氧化的效率 (20 g O ₃ kg ^-1饲料）分别和在淡水 RAS 中组合，对每个主要因素在两个水平（应用或不应用）进行了 2×2 的析因试验。每个处理组合使用 12 个重复的中试规模 RAS 进行三次重复，放养虹鳟鱼 ( Oncorhynchus mykiss ) 并在 1.66 kg 饲料 m ^{-3 补给}水的饲料负荷下操作。试验持续了 8 周，每周采集一次样品。臭氧本身可显着减少颗粒数量 (83%)、细菌活性 (48%) 和颗粒 BOD ₅（5 天生化需氧量；54%），与未处理的对照组相比，紫外线透射率（UVT；43%）增加。泡沫分离本身导致颗粒数量和体积（分别为 58% 和 62%）、浊度 (62%)、细菌活性 (54%) 和总 BOD ₅ (51%)显着减少。两种处理方法的结合显着改善了重要的水质变量，包括总 BOD ₅减少了 75%，与对照相比，浊度降低 79%，颗粒数量降低 89%，细菌活性降低 90%。去除效率与之前在盐水系统（有或没有臭氧）中使用泡沫分馏器进行的研究中观察到的相同，证实泡沫分馏可能成为控制淡水 RAS 中有机物积聚和细菌负荷的有用工具.