Performance of a constructed wetland treating intensive shrimp aquaculture wastewater under high hydraulic loading rate

A water treatment unit, mainly consisting of free water surface (FWS) and subsurface flow (SF) constructed wetland cells, was integrated into a commercial-scale recirculating aquaculture system for intensive shrimp culture. This study investigated performance of the treatment wetlands for controlling water quality. The results showed that the FWS–SF cells effectively removed total suspended solids (55–66%), 5-day biochemical oxygen demand (37–54%), total ammonia (64–66%) and nitrite (83–94%) from the recirculating water under high hydraulic loading rates (1.57–1.95 m/day). This led to a water quality that was suitable for shrimp culture and effluent that always satisfied the discharge standards. The area ratios of wetlands to culture tank being demonstrated (0.43) and calculated (0.096) in this study were both significantly lower than the reported values. Accordingly, a constructed wetland was technically and economically feasible for managing water quality of an intensive aquaculture system.