(663c) Controlling Ammonia Levels with Natural Materials to Preserve Bait and Stored Fish in Fresh- and Seawater

Controlling ammonia levels with natural materials to preserve bait and stored fish in fresh- and seawater

Wen Zhao¹, Daniela Stebbins¹, Fei Guo¹, Sarina Ergas² and Norma Alcantar¹

1 Department of Chemical and Biomedical Engineering

2 Department of Civil and Environmental Engineering

University of South Florida

Fresh and seawater fishing are the most popular outdoor recreational activities in Florida and throughout the U.S.  Bait and fresh caught fish can be stored in tanks. Conventionally, tanks are aerated to maintain up to 99.5% saturation of dissolved oxygen. However, high ammonia level produced by fish waste can be lethal, even though enough oxygen is available for fish respiration. The aim of this project is to develop a commercial product that is user-friendly, sustainable, affordable, and able to extend the life of bait and fresh caught fish by removing ammonia safely.  The research approach has three steps. First, we identified the ammonia production rates when fish were stored in various volume aeration systems in fresh- and seawater environments. Second, we functionalized natural chabazite granules as an ammonia trapping agent that can work in both synthetic fresh- and seawater. Chabazite is an inexpensive chemical feedstock, which provides a high cation-exchange capacity. By controlling the temperature, pH, salinity and dissolved oxygen concentration separately in both fresh- and seawater systems, the conditions for its functionalization as well as optimal amounts of chabazite were determined. After laboratory simulation, we found that in freshwater, functionalized chabazite (30g) removed 49.6 ± 9.6% of NH₄⁺-N for up-to 4 days at high fish density. The same system removed 58.5 ± 8% of NH₄⁺-N for 4 days at low fish density.  In seawater, functionalized chabazite (30g) removed 49.2 ± 13.9% of NH₄⁺-N for up-to 4 days at high fish density. Third, by testing this product in real fish environment we could optimize the chabazite dosage. To better understand the influence of different treatments of chabazite, we are currently doing characterization of chabazite. This will allows functionalized chabazite to be commercialized and scientific as a high-efficiency, renewable ammonia removal product.