Production of flathead grey mullet (Mugil cephalus) and lettuce 2 (Lactuca sativa) in a coupled aquaponic system under winter conditions

The experimental coupled aquaponic system used in this trial is shown in Figure 1. In brief, the system was composed of three replicate aquaponic units within a greenhouse,  being each aquaponic unit an experimental replicate. Each aquaponic unit consisted of a 2,000 L tank for holding fish, followed by a sedimentation tank where suspended particles like uneaten pellets and fish faeces settled down and were removed. Then, water flew into a 125 L biological filter tank filled with bio-balls, where nitrifying bacteria converted ammonia into nitrites and nitrates, adapted from IRTAmar® system. Water flew by gravity into the hydroponic unit where lettuces were supported on polystyrene rafts that covered the entire surface. Strong aeration was provided by a 0.3 Kw h air blower to ensure sufficient oxygen for the growth of plant roots. Finally, water was pumped (2,470 L/h; 0.1 Kw h) from the hydroponic unit 101 back to the fish-rearing tank through a submerged water pump (SERA Pond Precision SP2000, SERA GmbH, Germany). The total volume of each aquaponic unit is 7.1 m3, with a water turnover time for an entire circulation cycle of ca. 3 hours. Water and air temperatures were ambient since no thermal control was provided neither for the aquaponic water nor the greenhouse air. 

SOMMAR Platfom

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