WRC funds three research grants for 2016

The Water Resources Center awarded funding to three research projects for 2016. Researchers will investigate cost-effective methods of controlling sulfate levels in Minnesota waters, protecting well water from arsenic infiltration and creating best management practices for farmers that balance agricultural production and water quality.

Enhanced Microbial Sulfate Removal and Recovery through a Novel Electrode-Integrated Bioreactor Research

Seeking cost-effective strategies to combat elevated levels of sulfate in Minnesota surface waters, PI ChanLan Chun (UMD, NRRI) will employ continuous electron donor substrates to sustain biological sulfate reduction. Chun and co-PI Daniel Jones (CBS) hope to determine the efficacy of electrolysis of water and/or iron to enhance microbial sulfate reduction and sulfur recovery from high sulfate waste streams. Additionally, they hope to discover how the microbial community responsible for the biological transformations (sulfate reduction, elemental sulfur production) responds to electrochemically-stimulated production of reductants and oxidants. Using electrode-integrated fixed-bed bioreactors in which cathodic hydrogen production stimulates sulfate reduction near the influent, and anodic oxygen or reactive iron species production will facilitate sulfide precipitation near the effluent. Sulfur and iron species produced and consumed will be monitored during reactor operation to compare performance under different conditions, and changes in the anaerobic and microaerophilic microbial communities will be examined by culture-independent methods.
“Alternative cost-effective treatment options like this will benefit both mining industries that need to meet water quality standards, municipal wastewater facilities and tribal communities that require clean water and a healthy environment for sustainable wild rice production,” said Chun.

sulfate pic

Preliminary result of stimulation of sulfate reduction and iron sulfide precipitation (black band near cathode) in batch sediment electrochemical cell with the applied voltage of 2.0 V and iron electrodes vs. control (no applied voltage).

 

Development of a Reactive-transport Model for Arsenic Mobility in Glacial Aquifers using Arsenic and Iron X-ray Absorption Spectroscopy Data

Solving the mystery of why seemingly random wells across western Minnesota are contaminated by arsenic, and creating a strategy for placement of wells to improve drinking water quality, is the focus of PI Brandy Toner’s (SWC) research. Toner, along with co-PI Gene-Hua Ng (Earth Sciences), has identified a correlation between well construction and arsenic concentrations, suggesting the interface between an aquifer and aquitard is a geochemically active zone releasing arsenic into groundwater.

Toner and Ng’s research revealed three release mechanisms for arsenic:

  • Desorption from aquifer sediments
  • Reductive dissolution of iron (Fe) oxyhydroxide minerals to which arsenic is sorbed
  • Oxidative dissolution of arsenic-bearing sulfide minerals

Recently the researchers confirmed arsenic speciation in aquifer (sand and gravel), aquitard (till) and aquifer-aquitard interface sediments obtained by rotosonic drilling using X-ray absorption spectroscopy (XAS). They will use this new data to develop a reactive –transport model to extend the application to larger geographic areas.

“The complex distribution of elevated-levels in wells found in Minnesota glacial aquifers is a long standing public health problem,” says Toner. “Our research, using our previously accumulated data and XAS will assist our goal of improving drinking water quality.”

 

Making Farm-Scale Decisions to Improve Watershed-Scale Environmental Quality: Policy Comparisons Based on Farm-Level Abatement Costs

Excessive nutrient runoff from agricultural land has been a hot topic in the Midwest, threatening water quality in the Mississippi and other surface waters, as well as being the source of a lawsuit between the Des Moines Water Works and a local cannery. PI Jay Coggins (Applied Economics) and co-PI Brent Dalzell (SWC) have selected 10-15 of the most feasible and promising best management practice (BMP) combinations in a sample area  of Minnesota and Iowa. The influence of these BMP combinations on agricultural production and nutrient runoff has been simulated through the Soil and Water Assessment Tool. The relationship between agricultural profitability and water quality improvement is analyzed through a detailed economic model and econometric method. Cost functions will be estimated for each hydrologic response unit, AKA a farmer, who is the fundamental agent making decisions on farming practices.               

Coggins and Dalzell will estimate the trade-off between agriculture and environment for different policies, including uniform reduction, uniform BMP implementation over the whole area, taxes and water quality trading.

“In particular, we will also explore questions such as, how can the target on nutrient runoff reduction be achieved under different policy scenarios? What are the monetary cost and benefits associated with it?” said Coggins.