Flow-through land-based aquaculture wastewater and its treatment in subsurface flow constructed wetlands

Abstract

The growing of finfish, crustaceans, molluscs, and aquatic plants is termed aquaculture and it is currently the fastest growing animal food producing sector in the world. Flow-through aquaculture facilities are the most commonly used production system for the culture of salmonids. Flow-through land-based aquaculture facilities place great demands on water resources because they require large volumes of high quality source water to grow fish and they also discharge their wastewaters into the aquatic environment. The main source of waste in aquaculture wastewaters is the addition of formulated feed to the culture structure. Discharge of untreated aquaculture wastewaters can lead to physicochemical and biological degradation of receiving waters. Despite advances in feed quality and feeding practices, the treatment of wastewaters from flow-through land-based aquaculture facilities is a necessary practice. Conventional wastewater treatment from flow-through land-based aquaculture facilities has focused on gravitational sedimentation and mechanical screening of the wastewater, which successfully addresses the particulate fraction of the waste. In the past decade, the use of subsurface flow constructed wetlands (SSFCWs), which treat both the particulate and the dissolved fraction of the waste have been gaining attention for the treatment of wastewater from flow-through land-based salmonid farms. Existing studies have demonstrated that SSFCWs have the potential to successfully remove solids, oxygen demanding materials and nutrients from flow-through land-based salmonid wastewaters.