Aquaculture 2022

February 28 - March 4, 2022

San Diego, California

ENRICHMENT OF FISH WASTE WITH VODKA AND OTHER CARBON SOURCES TO INCREASE NUTRIENT MINERALIZATION IN AQUAPONICS AND RAS

Matthew Recsetar*, Kate Stalkfleet, and Kevin Fitzsimmons

 

Controlled Environment Agriculture Center

University of Arizona, Tucson, AZ

Tucson, AZ 85719

 msrecs@email.arizona.edu

 



Inadequate nutrient levels are o ne  of the drawbacks to  achieving success with aquaponics on a commercial scale. In fact, for many plants with higher nutrient demands such as tomatoes and hemp , nutrient supplementation must occur to maximize production.  When solid wastes are removed from an aquaponics system, many potential plant nutrients are also re moved in their non-bioavailable forms .  Important nutrients such as potassium and calcium as well as  micronutrients such as i ron, boron and zinc remain unavailable to plants outside of their ionic forms .  Therefore, m ineralization of solid fish wastes is an essential process to maximize plant production in aquaponics. It allows for nutrients that are initially removed from an aquaculture system a way to be added back to the system without compromising water quality or producing waste.  In essence, it allows for the existence of a truly zero- discharge aquaculture system.  In order for this to work, there has to be adequate resources for bacteria to digest solid wastes during the mineralization process.   While previous studies have documented  significant  increases in nutrient levels after aerobic mineralization, it is unclear if nutrient levels are being maximized or if there are factors limiting aerobic degradation of solids.  While the focus is generally to provide enough oxygen for the bacteria through aeration, it remains a bit of a mystery whether carbon availability is limiting.  Therefore, we proposed an experiment to examine nutrient levels after the addition of two carbon sources, ethanol (vodka) and citric acid to aerobic mineralization systems. Initial results were intriguing and analysis of results is underway.