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Effects of formaldehyde on nitrification in biofilters of small‐scale recirculating systems
Author(s) -
Fredricks Kim T.,
Cupp Aaron R.,
Schleis Susan M.,
Erickson Richard A.,
Gaikowski Mark P.
Publication year - 2018
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/are.13785
Subject(s) - biofilter , nitrification , formaldehyde , nitrite , recirculating aquaculture system , biology , environmental chemistry , nitrifying bacteria , ammonia , microbiology and biotechnology , pulp and paper industry , toxicology , aquaculture , food science , nitrogen , chemistry , fish <actinopterygii> , environmental engineering , ecology , environmental science , fishery , nitrate , biochemistry , engineering , organic chemistry
Florfenicol (Aquaflor®) is the only U.S. Food and Drug Administration ( FDA ) approved drug for treating diseased fish reared in recirculating aquaculture systems ( RAS ). Treating diseased fish in RAS is challenging because of the potential to damage nitrifying bacteria in the biofilters. Impaired nitrification can lead to concentrations of ammonia and nitrite that compromise fish welfare. The objective of this study was to determine the effects of a FDA ‐approved parasiticide and fungicide, Parasite‐S ® (formalin), on biofilter nitrification. Stable biofilters were exposed once to 0, 9.25, 18.5, 37, or 55.5 mg/L formaldehyde. Total ammonia nitrogen ( TAN ) and nitrite nitrogen were monitored daily before and throughout the study to quantify biofilter function. Formaldehyde concentrations ≥37 mg/L increased TAN and nitrite nitrogen concentrations, and nitrification did not recover to pre‐exposure concentrations up to 8 day postexposure. On the basis of those results, a second trial was conducted. Stable biofilters were exposed once or on four consecutive days to 9.25 or 18.5 mg/L formaldehyde. Biofilters repeatedly exposed to formaldehyde showed signs of impairment and had variable recovery relative to single exposures. Results of this study may help identify formaldehyde concentrations that can be safely applied to RAS when treating diseased fish.