Performance and optimization of recirculating aquaculture system combined with integrated vertical-flow constructed wetland

This study investigated the purifying efficiency, culture performance and design optimization of a recirculating aquaculture system (RAS) combined with integrated vertical-flow constructed wetland (IVCW). The results showed that the IVCW effectively removed total suspended solids (85%), chemical oxygen demand (50%), five-day biochemical oxygen demand (44%), total ammonia (53%), nitrite (83%) and nitrate (54%) from the aquaculture wastewater at a hydraulic loading rate (HLR) of 420mm/d. The channel catfish (Ictalurus punctatus) were bred up from fry (1.8 cm, 0.08 g) to juvenile (15.9 cm, 33.9 g) after five months. The survival ratio was 92.6%. A simple model for estimating the area ratios of wetlands to culture ponds was developed to optimize the design of the RAS combined with IVCW.