Location: Cool and Cold Water Aquaculture ResearchTitle: Low-dose hydrogen peroxide application in closed recirculating aquaculture systems Author
Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2011
Publication Date: 1/1/2012
Publication URL: http://handle.nal.usda.gov/10113/55784
Citation: Penderson, L., Good, C., Penderson, P. 2012. Low-dose hydrogen peroxide application in closed recirculating aquaculture systems. North American Journal of Aquaculture. 74(1):100-106. Interpretive Summary: Water recirculating aquaculture facilities in Denmark often rely on routine, high volume formalin treatments during the production cycle to reduce levels of external fish parasites. Hydrogen peroxide is an efficacious, environmentally-friendly alternative to formalin, but has been shown in the past to affect biofiltration in recirculation systems. Therefore, the aim of this project was to determine the effects of low-dose hydrogen peroxide on biofiltration in order to understand further whether this drug is a feasible alternative to formalin in Danish recirculation facilities. Our findings showed that biofiltration was not significantly affected by hydrogen peroxide at a low (but still efficacious) dosage, suggesting that this chemotherapeutant could be a viable alternative to formalin for treating external fish parasites in recirculation facilities. These results can assist farmers in selecting efficacious dosages of hydrogen peroxide for treating parasites while maintaining adequate biofiltration in their systems, and in a broader sense assist in significantly improving the environmental impact and overall sustainability of the water recirculation aquaculture industry.
Technical Abstract: The aim of the present work was to simulate water treatment practice with hydrogen peroxide (HP) in recirculating aquaculture systems (RAS). Six identical 1700 L pilot scale RAS were divided into two experimental groups based on daily feed allocation and were operated under constant conditions during a period of three months. The organic and nitrogenous loading of the systems differed four-fold between the two groups and was set by predefined constant daily feed load and constant make-up water. The fixed cumulative feed burden (CFB) were 1600mg feed/l in low intensity RAS and 1600mg feed/l in high intensity RAS. Decay of HP in rearing tanks and disconnected biofilter units were investigated by HP spiking experiments. The decay of HP in high intensity RAS rearing units and biofilters was orders of magnitude faster compared to HP decay in the respective compartments of low intensity RAS. Application of HP in low intensity RAS impaired biofilter nitrite oxidation; this effect was not observed in high intensity RAS. The impact of HP contact time on biofilter nitrification capacity was then assessed in biofilter bench scale experiments with nitrite spiking. HP exposure time was found to significantly inhibit nitrite oxidation. Compared to unexposed biofilter elements, nitrite oxidation was reduced more than 90 % following 3 hours exposure to 15 mg/l HP, whereas 30 minutes contact time only had minor negative effects on nitrite oxidation performance. The findings of this study demonstrate the potential for developing HP water treatment practices for RAS, and contradict prevailing notions that HP cannot be used safely in RAS that employ biofiltration. The development of new, effective therapeutic HP treatment protocols in recirculating aquaculture could be obe solution to reduce the current dependency on formalin to improve water quality and control parasitic loads.