Agricultural production is a major source of diffuse pollution, which in Europe, mostly is due to excessive emissions of nutrients (nitrogen (N) and phosphorus (P)). N removal from agricultural drainage water in woodchips bioreactors is relatively well established, however, Addy et al. (2016) concluded in a meta-analysis, that more field-based studies of the performance of woodchip bioreactors are needed to determine removal rates in different landscapes, nitrate loading, and climate. Hence, the main objectives of the present study were to i) present results on N and phosphorus (P) removal in five field-based woodchips bioreactor facilities receiving agricultural drainage water and located in different geo-regions in Denmark and ii) to present the results of a cost-effectiveness analysis iii) further, to assess from experiments in a novel woodchip bioreactor test center at which hydraulic residence time (HRT) with winter cold water resulted in the most efficient N removal. Two years data from the five field based bioreactors showed N removal rates varying from 1.49 to 5.37 g N m-3 d-1 and a mean across all bioreactors and years of 2.90 g N m-3 d-1. The loss of phosphorus was relatively high the first year after establishment varying at rates from 298.4 to 890.8 mg P m-3 d-1. However, in the second year most bioreactors retained phosphorus at rates varying from 12.2 to 77.2 mg P m-3 d-1. The investments and the costs of the bioreactors were larger than expected based on the standard investments for bioreactors used in Denmark. The cost efficiency analysis pointed to larger investments in the bioreactor itself as well as more advisory costs as key issues. The N removal cost for the four bioreactors considered in this study was around 350 DKK per kg N (€47 per kg N) which is higher (+50%) than the standard cost per kg N used by Danish authorities. From several investigations in a novel woodchips bioreactor test center with a water temperature of 5 °C and an inlet concentration of 60 mg nitrate per liter, the maximal nitrate reduction rate was found at HRTs of 20-30 h. Further studies needs to be done under controlled environments to assess the most efficient design of woodchip bioreactors under varying drainage water temperatures and flows, and as well how to retain the initial release of phosphorus.