An innovative suction filter device reduces nitrogen loss in double recirculating aquaponic systems

Due to an immense loss of nitrogen caused by the primary sedimentation unit as connection between the fish and plant parts, the original DRAPS was modified by a new developed suction filter device to remove solid particles at minimal nitrogen loss. The nitrogen loss was significantly reduced by that system modification (≈43%) and thus resulted in a quite large reduction of greenhouse gas emissions due to the reduced need for manufacturing of nitrogen fertiliser. The combined production of African catfish and tomatoes in aquaponics revealed similar fruit yields of tomatoes as for the control using artificial fertiliser, while the overall fertiliser use in aquaponics was about 13.2-77.7% lower. However, fertiliser saving was highest after modification and replacement of the sedimentation unit by the new suction device. In addition, in comparison to already existing aquaponic systems, the total biomass output was significantly increased. The results were evaluated under consideration of intensive crop production in hydroponics.