Startup and effects of relative water renewal rate on water quality and growth of rainbow trout (Oncorhynchus mykiss) in a unique RAS research platform

Kiuru

et al. 2020

Environ Sci Pollut Res

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In recirculating aquaculture system (RAS), ammonium excreted by the fish is typically transformed to less toxic nitrate by microbial activity in bioreactors. However, nitrate-nitrogen load can be harmful for the receiving water body when released from the RAS facility. A new type of water treatment system for a RAS was designed, including a passive woodchip denitrification followed by a sand filtration introduced into a side-loop of an experimental RAS, rearing rainbow trout (Oncorhynchus mykiss). In the process, woodchips acted as a carbon source for the denitrification, aiming at a simultaneous nitrogen removal and reduction of water consumption while sand filtration was used to remove organic matter and recondition the circulating water. A variety of chemical analyses and toxicological tests were performed to study the suitability of the process and to ensure the absence of harmful or toxic substances in the system. The results did not show increased toxicity, and no increased mortality was reported for the raised species. After the start-up of the system, the concentrations of fatty acids (e.g., hexadecanoic acid

Section: Methodsmentioning

confidence: 99%

Water quality in recirculating aquaculture system using woodchip denitrification and slow sand filtration

Lindholm‐Lehto

Kiuru

et al. 2020

Environ Sci Pollut Res

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“…Three PAA application levels (1, 2, or 4 times per week) and a control tank without PAA were applied in 8 individual RAS, using randomly allocated duplicate systems for each treatment. A more detailed description of the experimental RAS facility is reported by Pulkkinen et al (2018). In brief, each RAS consisted of a 500 L fish tank, separate water treatment and water quality control systems with total water volume of 760 L. The solids removal system included a waste feed collector, swirl separator, and drum filter with a mesh size of 60 µm.…”

Section: Experimental Setup and Peracetic Acid Treatmentmentioning

confidence: 99%

Effect of peracetic acid on levels of geosmin, 2-methylisoborneol, and their potential producers in a recirculating aquaculture system for rearing rainbow trout (Oncorhynchus mykiss)

Lindholm‐Lehto

Suurnäkki

Aquacultural Engineering

et al. 2019

In recirculating aquaculture systems (RAS)s, off-flavors and odors, mainly caused by geosmin (GSM) and 2-methylisoborneol (MIB), can accumulate in the flesh of fish from RAS water, reducing the profitability of production. In this study, peracetic acid (PAA) was applied in three application intervals to pump sumps of rainbow trout (Oncorhynchus mykiss) reared in RAS. Using a real-time polymerase chain reaction (qPCR), the potential off-flavor producers were quantified using geoA and MIB synthase genes. Streptomyces was identified as the major GSM producer, and biofilters showed the highest number of potential off-flavor producers. Concentrations of GSM and MIB were analyzed in the circulating water and in the lateral part of the fish fillet. In water, concentrations up to 51 ng L -1 (GSM) and 60.3 ng L -1 (MIB) were found, while in the fillet, these were up to 9.8 ng g -1 (GSM) and 10.2 ng g -1 (MIB), decreasing with increasing number of PAA applications. PAA applications reduced the levels of off-flavor compounds, although this was insufficient to fully prevent the accumulation of GSM and MIB.

“…Oxygen saturation was kept above 80% in the fish tanks. The system is described in more detail by Pulkkinen et al (2018).…”

Section: Methodsmentioning

confidence: 99%

The effects of different combinations of fixed and moving bed bioreactors on rainbow trout (Oncorhynchus mykiss) growth and health, water quality and nitrification in recirculating aquaculture systems

Aquacultural Engineering

Eriksson-Kallio

Aalto

et al. 2019

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