Start-up of a “zero-discharge” recirculating aquaculture system using woodchip denitrification, constructed wetland, and sand infiltration

Recirculating aquaculture systems (RAS) discharge management limits the development of sector, because RAS do not automatically result in low nutrient emissions. Research has helped develop such as wetlands and woodchip bioreactors that have been adopted by Danish commercial model trout farms. To further concept, we modelled built a novel “zero-discharge” recirculating system with an annual capacity approximately 14 tonnes. The aim this paper is to describe entire concept present results from start-up phase whole system. includes treatment effluent (overflow sludge supernatant) using hybrid solution bioreactor, constructed vertical wetland, sand infiltration. Using three-step process, nitrate, phosphorus, organic matter are decreased acceptable levels reuse water process reducing need for new raw water. In first nine months operation, field was used end-of-pipe ensure safe recirculate fish. During winter, temperature dropped 2.7 degrees filter, but frost did reach any processes. It therefore appears can operate sufficiently even winter conditions. year bioreactor remove 97 % although slow caused be N-limited. On average, 79 92 inflow phosphate concentration removed respectively. wetland filter (35 %), longer than designed actual residence, it leached more expected. Further experimentation needed identify financial applicability performance during higher feeding rates.