Browsing by Subject "biochar"

Now showing 1 - 4 of 4
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    Effects of biochar on drought tolerance of Pinus banksiana seedlings, 2021
    (2023-04-05) Reuling, Laura F; Toczydlowski, Alan J Z; Slesak, Robert A; Windmuller-Campione, Marcella A; lreuling@umn.edu; Reuling, Laura F; University of Minnesota Silva Lab
    This data set was collected in 2021 as part of a greenhouse study on the effects of biochar as a soil additive for seedlings planted in sandy soil. Data includes information on seedling survival, growth, and physiological activity for two experiments, one relating to timing of drought onset, the other relating to watering treatment.
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    Electrochemical Stimulation of Denitrification In Woodchip Bioreactors and Wetlands
    (2020-10) Ramrattan, Kevin
    Elevated concentrations of nitrate in agricultural runoff can contribute to nutrient enrichment in coastal environments and when ingested can result in methemoglobinemia, a potentially fatal condition in infants. Woodchip bioreactors are ditches constructed at the edge of fields to create anaerobic environments replete with woodchips as carbon and electron sources to promote the growth of denitrifying bacteria to reduce nitrate to inert nitrogen gas. In the Midwest snow melt coincides with fertilizer application, creating a large volume of water with a high nitrate load that limits the efficiency of woodchip bioreactors. The lower temperatures also restrict microbial nitrate-reducing metabolism. One avenue for improving denitrification is the implementation of current-carrying electrodes to supply electron donors to the bacteria. Pyrogenic carbon (Biochar) has been demonstrated to sorb the water-soluble nitrate and acts as an electron shuttle. It is unknown how these two variables in tandem affect denitrification rates, and the microbes associated with these substrates remain uncharacterized. Here, we use batch bioreactors to test the nitrate removal capabilities of woodchip reactors amended with biochar and electrochemical stimulation. Aliquots were collected to measure nitrate removal using a continuous flow analyzer and bacterial communities were characterized based on 16S rRNA gene analysis. Electrode-containing reactors were significantly (p-value < 0.05) less efficient at treating nitrate during the first 8 hours following nutrient injection, but by 24 hours all reactors performed comparably with respect to nitrate removal. Electrode biofilms also had less α-diversity and in terms of β-diversity. Microbiome samples under the influence of electrodes were different from those that were not exposed to any electrochemical stimulation. The difference is bacterial community and the performance lag during the first 8 hours of operation may be a result of increased oxygen concentration in the reactors as a result of O2 evolution during electrolysis in the electrode-containing bioreactors. Biochar had no discernable effect on nitrate removal and did not have a significantly different microbiome from woodchips and water. Electrode biofilm samples were found to enrich Cyanobacteria while the biofilm on the biochar enriched Acidobacteria. Using the results of our experiment we propose the construction of a benchtop-scale electrochemically stimulated constructed wetland reactor.
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    Limiting Factors Of Nitrate Removal in Mesoscale Denitrifying Wood Chip Bioreactors
    (2018-04) Hackshaw, Nadine
    The use of woodchip denitrifying bioreactors holds promise as a simple, efficient and cost-effective system to reduce nitrate loads in agricultural runoff through stimulation of microbial denitrification. While bioreactor performance at colder temperatures and under varying hydraulic residence time (HRT) has been investigated, the correlation to functional microbial communities has not been studied in great detail. In this study, we quantified denitrifying functional gene copy numbers throughout the course of a three-month study within mesoscale [1.83m x 0.3m x 0.61m] denitrification bioreactors that were operated at three temperature regimes and two HRT. We found that with increasing temperature and HRT there was a significant increase in percent nitrate removed. Temperature and HRT had little effect on nirK and nosZ clade I gene copy numbers throughout the length of the bioreactors, however, they had a significant effect on 16S rRNA and nosZ clade II gene copy numbers at the inflow locations of the bioreactors. Utilizing a hydraulic flow model developed for the denitrifying bioreactors in this study, a decrease in nitrate concentration along the length of the reactors was calculated. We correlated a decrease in 16S rRNA, nirK and nosZ clade II gene copy numbers to the decrease in nitrate concentrations predicted by the hydraulic flow model. Our results suggest that at temperatures of 14.5°C and 12-hr HRT, denitrifying bioreactor microbial communities are limited by variables other than temperature and HRT. It is suggested that carbon availability is the most likely limiting factor, indicating a need to further investigate the role of both denitrifying and decomposing communities in denitrifying bioreactors. These findings contribute to a better understanding of the microbial functional communities in denitrifying wood chip bioreactors, allowing us to optimize the design and performance of these reactors in agricultural midwestern states.
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    Optimizing Biofiltration Media for the Capture of Phosphate and the Support of Vegetation Growth
    (2022-06) Kramarczuk, Kathryn
    AbstractBiofiltration is a stormwater management practice designed to treat runoff for harmful contaminants. A critical component of these systems is the granular media. In this study, I investigated six different types of base media (10% leaf compost, 20% leaf compost, 10% food compost, 20% food compost, sphagnum peat, reed sedge peat) and four different amendments (spent lime, biochar, iron and sphagnum peat) in various combinations with sand to test their capacity in mitigating phosphate release and supporting the growth of Switchgrass (Panicum virgatum) as an indicator of potential to support vegetation. The study consisted of an outdoor mesocosm experiment over three years, with 34 events total where 30 seeded mesocosms containing various media mixes received water from the Mississippi River (near downtown Minneapolis, MN, USA) that was spiked with phosphorus to simulate stormwater inputs. Soluble reactive phosphorus and nitrate concentration, pH, Switchgrass height over time, and Switchgrass biomass at senescence was measured each year. In general, mixes containing food compost, leaf compost, biochar with compost and spent lime with compost leached phosphorus whereas mixes containing peat, iron with compost, and sand adsorbed phosphorus. The mixes that leached phosphorus supported the most plant growth. Spent lime mixes and biochar mixes had the highest effluent nitrate concentrations indicating effects on N mineralization or nitrification. The iron and leaf compost layered media mix performed the best of all the mixes tested in terms of mitigating the release of phosphate and having the potential to support vegetation. Future research is necessary to determine if it can continue preventing phosphorus leaching and support vegetative growth with a higher percentage of compost and different plant species. Keywords: phosphate, nitrate, biofiltration, stormwater treatment, switchgrass (Panicum virgatum), compost, peat, biochar, water treatment residuals, iron