A novel advanced oxidation process (AOP) that rapidly removes geosmin and 2-methylisoborneol (MIB) from water and significantly reduces depuration times in Atlantic salmon Salmo salar RAS aquaculture

Abstract

Atlantic salmon reared in RAS accumulate off-flavor chemicals in their flesh that must be depurated (“purged”) before the fish can be sold. The purpose of the present investigation was to evaluate the effects of a novel advanced oxidation process (AOP) on the removal of geosmin (GSM) and 2-methylisoborneol (MIB) from the depuration tanks of a commercial Atlantic salmon RAS operation, with the goal of speeding up the purging process while using less water. The technology, called the Exciton Advanced Oxidation Process® (eAOP®), works by multiple mechanisms of action including photocatalysis, ultraviolet (UV) photolysis, electrolysis, and UV/oxidant AOP. In chemical spiking experiments without fish, both GSM and MIB were almost completely removed from 18 m3 purge tanks by eAOP® in less than two hours. A 10-day experiment with market-sized Atlantic salmon was conducted to compare the rates of depuration of fish purged using traditional water flushing (control) or treated with eAOP®. In the eAOP®-treated fish, fillet GSM concentrations declined 60% faster than in the controls, and the fish were “on-flavor” in less than six days compared to ten days in the controls. The results indicate that eAOP® can be used to reduce depuration times in Atlantic salmon RAS aquaculture, saving water and minimizing the loss of fish biomass that typically occurs during longer depurations when the fish are not fed. These savings have significant positive economic impacts for commercial RAS operators, as well as positive implications for environmental impact and fish welfare.