Effect of Carbon Supplementation on Denitrifying Bacteria in Woodchip Bioreactors

California’s agricultural sector is fundamental to the state’s economic growth and responsible for supplying a large portion of the country’s produce. An abundance of nutrient-rich irrigation is required to meet these high demands, and the resultant agricultural effluent is a source of increased nutrient content in California’s watershed and groundwater systems. This promotes eutrophication, and negatively impacts local ecosystems and human health. Effective remediation of waterways using bacteria in woodchip bioreactors can be achieved by maintaining the system within ideal conditions for productivity of the microbial populations. Bioreactor systems used wood chips to provide both substrate and a carbon source, and relied on insulated structures to maintain temperatures within the active range of the mesophilic bacteria. Corn starch was introduced to one system as a carbon supplement, as results had indicated the system was carbon-limited. A second bioreactor system acted as a control with no carbon supplement. Single pass and recirculatory experiments were conducted over a period of six weeks. More denitrification occurred in the experimental bioreactor than the control, suggesting corn starch serves as a viable carbon supplement to facilitate the metabolic processes of denitrifying bacteria