| Water quality in agricultural watersheds is under greater scrutiny as the landscape and hydrologic pathways are altered to increase the production of affordable food. Agricultural best management practices (BMPs) are common tools to improve water quality on a local scale. This study examined the effectiveness of two-stage ditches using field data and the efficacy of bioreactors in a lab setting. In the field, the physical stability and nitrate removal of an alternatively designed drainage ditch in southern Minnesota (the Mullenbach Two-Stage Ditch) were assessed. Two-stage ditches are more stable than traditional, trapezoidal designs and may adjust slightly overtime to produce the most sustainable shape. This BMP is also effective at removing nitrate, although variably as it relates to temperature, hydraulic residence time, and influent nitrate loading. In the lab, a system to determine nitrate removal under reduced temperature conditions was used to evaluate novel media for bioreactors, including walnut shell biochar and Brotex(TM) material. A flow characterization and nitrate removal model was created in MS Excel(TM). Additionally, the model incorporated microbial processes found by a quantitative polymerase chain reaction (qPCR). This design is 2X more effective than traditional, woodchip only configurations. Multi-media bioreactors may have great potential for future applications by enhancing nitrate removal and microbial activity. Constant innovation is the key to sustainability, which can be achieved by creating optimized systems that highly effective under a range of environmental conditions and scenarios. |
