Bioreactor-Biochar (B2) Treatment System: A Novel Design to Remove and Capture Nutrients from Agricultural Drainage Water

Developing effective edge-of-field technology to reduce nutrient loss from tile-drain farmlands is an important strategy to meet the national water quality goals. In this work, an innovative bioreactor and biochar (B2) treatment system was developed to remove and capture nutrients from tile drainage water. The performance of B2 treatment system was comprehensively evaluated over a 9-month field-scale operation. The results demonstrated that the B2 treatment system greatly captures nutrient losses (>80%) from tile drainage. The total removals of dissolved nitrate (NO3), ammonia (NH4), dissolved phosphorous (P), and total phosphorous (TP) were 2.19 kg, 2.11kg, 2.85kg, 4.02kg, from the drainage water, respectively. This study also observed that a high content of total and dissolved P was released from the woodchip bioreactor, while two-stage biochar systems can significantly reduce the amount of leached total and dissolved P to the receiving water body. Therefore, this study proposed that B2 treatment system could be a promising edge-of-field practice to achieve nutrient removal and offset the negative effect (P release) of woodchip bioreactor.