In RAS and aquaponics, optimum system design is key to assure best results, defined by key performance indicators (e.g. removal of solid wastes , nitrification , NO2 and CO2 removal and O2-supply) . In this respect, a better understanding of the principles and performance of different functional components can improve robustness and performance of RAS.
The aquaponics team of Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) has developed a modular, Recirculating Aquaponics System.
The aim of this presentation is, to show how to calculate, design and build a robust and price effective RAS for aquaculture and aquaponics.
Materials and Methods
The system set-up includes 16 identical RAS specifically designed for aquaponic research trials. Each system is equipped with one fish tank a polyethylene sedimentation tanks, moving-bed nitrification bioreactor and pH stabilization. The modular approach of the design allows for high flexibility, e.g., by “by-pass” to synchronize bio filters flow rate, feces collection and valves for fresh- and wastewater usage, if needed . Furthermore, it is possible to adapt the system design towards altering research questions (figure 1). New water use was 10 % per day. p H was adjusted with NaOH by means of a medical drip applicator when needed and was kept at 7.8 ± 0.27 during the trial.
Furthermore, it is possible to customize the system for every new trial, if necessary. An outline of the system as it is in use at the moment can be seen in figure 1.
Robustness and performance of the system was demonstrated during first year of operation. During this time, different research trials were carried out, with main focus on development of aquaponics feeds for different fish species [1, 2] These studies demonstrated that physico-chemical parameters (e.g. oxygen concentrations, temperature, pH , and levels of ammonium and nitrite) , were within suitable ranges for fish tested.
During the trials oxygen and temperature could be kept constant in the defined limits of 7.11 ± 0.23 mg and 27.0 ± 0.3 °C. The values were measured once a day before feeding and water exchange. Solids were removed on a daily basis from each RAS from the sedimentation tanks.
Discussion and Conclusions
The authors believe, that the use of a low-budget but well-planned research system presents a chance to create something that opens up new possibilities for your future research and should be exploited more often. Through the above-mentioned study, it was possible to show that by controlled removal of waste water and aquaculture sludge the closing of nutrient streams between aquaculture and hydroponic can be supported. The ongoing development of aquaponics and the reuse of system-internal waste streams is becoming increasingly important.
We share our personal experiences on the design process -the planning, assembly, performance assessment and design improvement.
Shaw, Christopher; Knopf, Klaus; Klatt, Laura; Marin Arellano, Gabina; Kloas, Werner. (2023). Closing Nutrient Cycles through the Use of System-Internal Resource Streams: Implications for Circular Multitrophic Food Production Systems and Aquaponic Feed Development. Sustainability. 15. 7374. 10.3390/su15097374.
Shaw, Christopher; Knopf, Klaus; Kloas, Werner. (2022). Toward Feeds for Circular Multitrophic Food Production Systems: Holistically Evaluating Growth Performance and Nutrient Excretion of African Catfish Fed Fish Meal-Free Diets in Comparison to Nile Tilapia. Sustainability. 14. 10.3390/su142114252.