Abstract Full Text:PDF Recommended articles Mail to Author How to Cite

¹ Aquaculture and Fisheries Management Program, Department of Biology, College of Natural Sciences, Jimma University, Jimma, Ethiopia
² Applied Microbiology, Department of Biology, College of Natural Sciences, Jimma University, Jimma, Ethiopia
³ Department of Biology, College of Natural Sciences, Dilla University, Dilla, Ethiopia DOI : 10.4194/AQUAST2731 Viewed : 410 - Downloaded : 1367 Efficient nitrification by microbial communities is crucial for maintaining water quality in aquaponics systems. This study optimized the performance of nitrifying bacteria-Nitrosomonas (Ns) and Nitrobacter (Nb) by investigating inoculum volume, bacterial ratio, and biofilter substrate configuration using fish wastewater. Initial tests with a 1:1 Ns:Nb ratio at inoculum volumes of 1.0, 1.5, and 2.0 mL L-1 showed that 1.5 mL L-1 achieved the highest nitrification efficiency. Further optimization revealed that a 2:1 Ns:Nb ratio (1.0 mL Ns: 0.5 mL Nb) maximized ammonia and nitrite oxidation (89.15% and 91.34%, respectively). Using this ratio, substrate type and volume fraction (12.5%, 25%, 37.5%) were evaluated, with plastic bottle caps (PBC) at 37.5% delivering superior nitrogen removal: NH4+ (98.5%), NH3-N (97.6%), NO2- (79.2%), and NO3- (96.1%). Water quality parameters remained within optimal ranges (DO: 1.2-3.9 mg L-1; pH: 7.18-8.53; temperature: 20.1-21.9C). The high surface area and buoyancy of PBC promoted enhanced microbial activity. These results offer practical strategies for improving sustainable nitrification and microbial efficiency in aquaponics systems. Keywords : Aquaponics Biofilter Media Wastewater Nitrosomonas Nitrobacter