MS Thesis Defense


Daniel Takaki
Master's Student, Water Resources Science

June 6, 2018


Enhanced Microbial Sulfate Removal Through a Novel Electrode-Integrated Bioreactor

In northeast Minnesota, high sulfate levels in water systems is a topic of interest due to its potential adverse impacts to wild rice ecosystems. Sulfate may also contribute to methylmercury production and eutrophication in certain conditions. Increased interest has emerged for developing low-cost technologies to treat the high levels of sulfate in the circumneutral water. Biological sulfate reduction is a promising and economically viable plan for maintaining low levels of sulfate and sulfide, but its performance is highly variable.

In this project, a low electrical potential applied to creek sediment and sulfate impacted artificial mine water (1000 ppm sulfate). This aimed to enhance and sustain biological sulfate reduction by continually supplying electron donor substrates to sulfate-reducing bacteria. Sediment bioelectrochemical reactors were developed to carry out this process in both batch and flow-through systems. Porewater sulfate was measured throughout experiments, resulting in over 90% reduction of sulfate in batch reactors due to enhanced microbial activity. The microbial community structure and relative abundance were examined to show that species associated with biological sulfate reduction were impacted by the application of a low electrical potential. This study demonstrated that the use of bioelectrochemical reactors to enhance the performance of biological sulfate reduction is a promising technology to treat sulfate impacted waters.