Woodchip bioreactors as treatment for recirculating aquaculture systems’ wastewater: A cost assessment of nitrogen removal

•Denitrifying woodchip bioreactors are a viable treatment option for RAS wastewater.•Capital costs were estimated from a full-scale bioreactor designed for RAS effluent.•Pilot-scale bioreactor data was used to estimate system lifetime N removal costs.•Bioreactor cost efficiencies ranged from $2.83 to $13.35 per kg N removed.•Cost estimation describes an alternative N treatment option for aquaculture farmers.