Nitrogen removal of mine-influenced water in a hybrid bioreactor with floating hook-moss (Warnstorfia fluitans) in cold climate conditions

To remove nitrogen in cold conditions, we studied new nature-based treatment solutions using six pilot-scale reactors. The pilots were woodchip bioreactor (WBR), aquatic floating hook-moss (Warnstorfia fluitans) (MBR), and a combined hybrid unit (HBR) with an improved hydraulic design. experiment was run climate room at temperatures of 10 °C 5 mine water from two sites located northern Finland. Unlike traditional horizontal flow bioreactors, this study the efficiency poor (λ = 0.06) to satisfactory 0.51) by inserting inner plates along adding hook-moss. revealed highest capability removal all inorganic forms T ≤ mean HRT 70.5 h. On average, 30–78 % dissolved removed unit, which 2 3 times more than units consisting only or maximum NO−3-N rate 1.0–5.2 g m−3 d−1 21.8–99.7 for average incoming load 40 d−1. NH+4-N 75.6 53 took place HBR MBR, respectively, when 23.6 ± 0.7 °C. Over 154 days experiment, total 2.95 kg DIN-N, 0.8 higher sum DIN-N mass individual (1.7 kg) moss (0.55 kg). content compared showing contribution N plant uptake. Overall, our results suggest that combining woodchips walls may enhance conditions.