Development of a process-based subsurface bioreactor model

Subsurface Bioreactors are used to reduce nutrient transport from agricultural fields, mainly in the Midwestern United States. They are cost effective, have long lives, and can be operated to have no effect on drainage effectiveness. At present in Illinois, an empirical model, which relies on performance curves, is used to estimate bioreactor efficiency and nutrient reduction levels. Although temperature has a significant impact on denitrification, the model does not consider tile water temperature. This study introduces a process-based, daily time step, bioreactor simulation model that incorporates water temperature from DRAINMOD simulation with historical weather data. This model has a user-friendly interface, developed in Microsoft Excel using Visual Basic for Applications (VBA).