Research

Mine water remediation

Mineral-Enhanced Biochars for Removal of Sulfate and Metals from Mine Water

Biochar is a recalcitrant, aromatic carbon material, generated by heating biomass to temperatures between 300-1000°C under low oxygen supply. It can be produced from a variety of biomass feedstocks, such as agricultural residues, wood chips, or manure. Recently, biochars have found application as low cost sorbent material in environmental remediation. In this project we evaluate the effect of different mineral-enhanced biochars on microbial sulfate reduction and compare the sorptive properties of biochars for heavy metals associated with copper/nickel sulfide mining activities in NE Minnesota. Ongoing research is also investigating the electron shuttling capabilities of mineral enhanced biochars in microbial bioelectrical systems for mine water treatment. The aim is to develop a biochar-mineral composite material that promotes microbial electron shuttling and growth but also served as effective sorbent for heavy metals and metal sulfides in order to improve current biotechnologies for the efficient, low-cost, environmentally-friendly treatment of mine drainage in biofilters, bioreactors and permeable reactive barriers. The project is conducted in collaboration with Dr. Kurt Spokas, USDA ARS and Department of Soil, Water, and Climate, University of Minnesota.

Biochar

Tile drainage/agricultural runoff

Microbial Community Dynamics and Functional Resilience in Denitrifying Bioreactors

Denitrifying bioreactors as nitrate mitigation strategies hold promise for improving water quality in agricultural watersheds by effectively removing nitrate through stimulation of microbial denitrification. A better understanding of microbial community structure and bioreactor function is required in order to optimize reactor design and management. Because functional responses of microbial communities can vary strongly depending on temperature, hydraulic residence time (HRT), and bioavailability of organic carbon, an understanding of the fundamental links between population dynamics, functional resilience and community interactions in denitrifying bioreactors will improve our ability to predict and increase the stability of reactor performance. This project is conducted in collaboration with the laboratory of Prof. Bruce Wilson and graduate student Lori Krider from the Department of Bioproducts and Biosystems Engineering.

Denitrifying bioreactor

Wastewater

The microbiology of wastewater treatment

Biological wastewater treatment relies on microorganisms. Wastewater treatment plants operate large bioreactors, in which microorganisms are responsible for the conversion of nutrients (nitrate, phosphate) and degradation of organic carbon and pollutants. Any malfunctions of bioreactor performance are usually associated with disturbances of its microbial processes. A comprehensive understanding of a plant's microbial community composition and resilience to disturbances will enable us to better control the microbial processes essential for wastewater treatment.

Seasonal changes in microbial community structure and variations in activities of different functional population have been observed in natural microbial ecosystems, but have not been studied in great detail in wastewater treatment bioreactors. Despite the reliance on the cooperative behavior of different functional groups of microorganisms, relatively little is known about the population dynamics and interactions of microorganisms that reside in full-scale wastewater treatment bioreactors. The goal of this project is to analyze the dynamics of microbial populations and their activities in activated sludge bioreactors in response to seasonal fluctuations in plant operational conditions such as temperature and wastewater chemical composition. Routine monitoring of microbial populations and their activities in wastewater treatment plant bioreactors will allow timely intervention before process problems affect discharge water quality. This will contribute to the prevention of any consequences of operational problems, increased plant safety, improvement a plant's economic efficiency, and ultimately protect the environment. We closely collaborate with Prof. Timothy LaPara from the Department of Civil, Environmental, and Geo-Engineering on this project.

Wastewater banner

Single cell microbiology

Hunting biological “dark matter” by microfluidics and fluorescence activated cell sorting

Because 99% of most microbial species can currently not be cultivated (based on most estimates) the advancement of single-cell technologies has a huge impact on studies in microbial ecology. Uncultured species are also referred to as biological “dark matter” because they can only be studied indirectly using marker-gene based sequence surveys. Metagenomic approaches can provide large inventories of genes from complex environments, however the fundamental link between a microorganism’s identity (taxonomic classification) and functional capability (gene content, physiological activity) is often not preserved. Only through single-cell approaches the direct connection between a unicellular organism’s identity and function can be conserved and studied. In order to further elucidate the enormous genetic and evolutionary diversity on earth we develop single cell technologies with high-throughput capabilities. Among a suit of currently available and rapidly developing single-cell technologies our research focuses on the integration of droplet microfluidics and fluorescence activated cell sorting (FACS) for a variety of fundamental and applied questions in environmental microbiology and biotechnology.

Single cell technologies