PhD Proposal: Matthew Stromberg

Agenda:

To keep up with skyrocketing seafood demand, aquaculture in the US and abroad must expand beyond traditional coastal culture methods and dramatically increase production. The major bottleneck experienced when bringing aquaculture onshore is the development of the off-flavor compounds geosmin (trans-1, 10-dimethyl-trans-9-decalol) and 2-methylisoborneol (MIB)—particularly in recirculating aquaculture systems (RAS). These terpenoids give a “muddy” flavor to farmed fish, especially high value and popular fish like Atlantic salmon, (Salmo salar). Knowledge regarding the rates at which these compounds are taken up, eliminated, and biologically transformed remains unestablished. Depuration, the process of constantly adding fresh water to remove the taint prior to harvest, is the current industry standard. However, it remains an expensive, time-consuming, and an environmentally-unfriendly process due to the large amount of water used and discharged. Various advanced oxidative processes (AOPs) have been developed for commercial scale removal of off-flavor compounds and other applications. However, no comprehensive models exist to predict either the bioaccumulation or elimination of off-flavor compounds in RAS with integrated remediation technologies.

The proposed research aims to establish the basic rates surrounding off-flavor in Atlantic salmon, verify a new mathematical model for quantifying the impact of industry provided remediation technologies, and then use the model in development of a new remediation technique. Thus far, AOP research has been conducted using UV/TiO₂ photocatalyzed OH^- production for off-flavor mitigation. Briefly, the system proved ineffective in 15 ppt water, with the addition of O₃ producing unwanted perchlorate salts and an unsafe oxidative reductive potential (ORP). The most successful trials in 0 ppt water included direct O₃ dosing, O₃ dosing combined with AOP, and H₂O₂ with AOP. Similarly high ORP values were produced with O_3­ in fresh water. Future work with off-flavor mitigation technologies will use indirect ammonia electrooxidation and a novel method for physiochemical removal via ‘Synthetic Lipid Extraction’(SLE).

Agenda

WEBEX Meeting for virtual attendance