Performance of moving bed biofilm, periphyton, and halophyte biofilters in marine multi-trophic aquaculture systems

Title : Performance of moving bed biofilm, periphyton, and halophyte biofilters in marine multi-trophic aquaculture systems

Abstract:

Combining multi-trophic recirculating aquaculture system (MT-RAS) biofilter types leverages the strengths of different ecological biomes, benefits water treatment, resource recovery, economics, and environmental sustainability. The overall goal of this study was to determine the effects of different aquaculture biofilter combinations on MT-RAS. Three duplicate biofilter combinations were tested in a pilot scale MT-RAS with red drum (Sciaenops ocellatus): 1) periphyton (algae and bacterial biofilm) with halophytes (P+H), 2) periphyton with moving bed biofilm reactors (P+M), and 3) periphyton only (P²). Experiments were performed in two trials (spring and summer) with four replicates. Water quality tests validated that NH₃/NH₄⁺, NO₂^-, NO₃^-, and CO₂ were below fish toxic limits for all biofilter combinations. Fish mortalities were low, with food conversion ratios between 1.1 and 2.0. In all trials, periphyton added dissolved oxygen (DO) to the water (at an average of +3.95 ± 6.52 mg/(L*d)), thus reducing energy costs. Periphyton was also found to include valuable lipid content (4.55 ± 2.24 % of dry weight) with the detection of Ω-3 fatty acids. The P² trials maintained a stable alkalinity and pH balance.  The M+P trials removed NH₃/NH₄⁺ at a high rate; however, they also required more energy for DO. Edible sea purslane growth rates (1.0431 ± 0.3361 g/day/plant) were efficient in all P+H trials. The microbiome revealed abundance of Ignavibacterium bacteria, Chrysophyceae, Cyanobacteria, Haptophytes, Navicula and Chlorella algae, Nitrospira, Nitrospirae, Nitrosospharota, and Nitrosoarchaeum nitrogen cyclers. Overall, periphyton biofilter combinations nitrify, denitrify, stabilize pH, photosynthesize, and produce oxygen and a value-added product.

Biography:

Adam Bell entered into aquaculture as part of a group of ambassadors from the USA helping rural farmers raise tilapia in rural Zambia. After this he progressed into a PhD program at University of South Florida in the USA. He worked on marine recirculating aquaculture systems growing algae, fish, and plants at the pilot scale (2500L). He finished his PhD and then completed a postdoctoral on biomanufacturing at NASA.