Trace elements, anions, and carbohydrates in the recirculating aquaculture system using woodchip denitrification, constructed wetland, and sand infiltration

Abstract A recirculating aquaculture system (RAS) aims to achieve fish production with negligible discharge into the environment. RASs have been applied for in several countries, but nitrate removal is often a limiting factor increases. In this study, pilot-scale RAS (10 tons of fish/year) was connected water treatment field which consisted denitrifying woodchip bioreactor (9 m × 14 m) filled birch woodchips (Betula pendula), constructed wetland (7.5 6 m), and sand infiltration (16 31 high quality low-maintenance units. wetland, perennial common reed (Phragmites australis) used well-drained soil nutrient re-use. Concentrations different elements, diluted anions, selected hydrocarbons were monitored quantified. Some Mn leaching occurred during stage. However, concentrations decreased towards end experiment. total-Fe increased up 2.75 mg L?1 5 stage field, probably due anoxic conditions fine particles. This type process design offers effective circulating water.