ABSTRACT
Aquaculture has become a major source of food, generating more than 45% of global fish production (FAO, 2011). This success comes with a heavy environmental price, as aquaculture requires huge quantities of water for operational uses, discharges heavy loads of organic and inorganic contaminants to water bodies, and consumes natural coastlines and their ecosystems (Subasinghe et al., 2009). Inland water recycling systems help reduce this environmental burden, shifting the operations away from sensitive areas, and diminishing the demand for water. Yet, pollutants are still discharged into the environment, as organic and inorganic nitrogen compounds are mostly untreated (van Rijn, 2013). In zero discharge systems (ZDS) where fish basins (FBs) and treatment compartments are connected
to form continuous water recycling units, nitrogen, sulfate and organic matter are removed by microbial processes (Neori et al., 2007). ZDS are thus based on structured but connected environments that form mesocosms reflecting rather varied ecological conditions. This structure brings about continuous and efficient water purification leading to adequate water quality conditions for aquacultural needs over time, with water requirements limited to compensation for evaporation losses. Significantly, high fish yields are obtained under relatively disease-free conditions (Shnel et al., 2002; Gelfand et al., 2003).
