Marta Roser is a second-year Master’s student in the Department of Soil, Water, and Climate at the University of Minnesota. Hailing from Albert Lea, MN, Marta has a B.A. in Environmental Studies from Pacific Lutheran University in Tacoma, WA. In her semi-existent free time, Marta enjoys camping, gardening, cooking, and playing guitar.
To improve water quality, my lab is focusing on bioreactors that sit next to agricultural fields. A bioreactor is a device with material inside that supports biological processes which remove unwanted substances from an effluent. Often wastewater treatment facilities use a series of bioreactors to breakdown various substances. In this project, we are focusing on agricultural tile drainage as the effluent and the bacterial denitrification process – the conversion of nitrate to gaseous nitrogen – to take excess nitrogen out of the waterways. We also are determining if bioreactors can take up phosphorus from the effluent as well as nitrogen. Both of these nutrients in excess can lead to environmental problems such as algal blooms and low oxygen levels in water bodies. These conditions in turn create situations like the Gulf of Mexico’s Dead Zone.
From the outside, the bioreactors in our lab look like very ordinary PVC pipes. However, on the inside they are teeming with microbial life. The bioreactors are packed with carbon sources such as woodchips and corn cobs that the bacteria feed on and use to support their biofilms. Biofilms form when singular microorganisms clump together on a surface and form a multi-cellular colony. These often give the bacteria advantages such as increased nutrient access and protection. In our study, we want to determine how well the bacteria can carry out denitrification with various carbon sources and under different flow rates. We wanted to see how the bioreactors would hold up under storm events in the field, so tried to imitate the rise and decline of flow rates from actual drainage data. Once we have determined promising treatments in the lab for both warm and cold temperatures (15°C and 5°C), the other investigators on this project will test them in field bioreactors.