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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Impact of Substrate on Nutrient Removal in In-Ditch Bioreactors

Dubner, Anne Noe 04 August 2022 (has links)
Drainage ditches, or grassed waterways, collect nutrient-laden runoff from agricultural fields and transport it to nearby waterbodies. The high nitrogen and phosphorus content in this water leads to negative effects, such as eutrophication in the receiving waters. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors are intended to reduce flow rate and stimulate denitrification and sedimentation. Using experimental ditch segments and simulated runoff, this study evaluated nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors and 3) vegetated ditches with combination woodchip and biochar bioreactors. Biochar was added in an effort to increase phosphorus removal. Inlet and outlet concentrations of nitrate, ammonium and phosphate were measured for each of the three treatments in triplicate. There were no statistically significant differences between treatments on load removed for any of the three nutrients of interest. Issues in measuring outlet flow rate made drawing definitive conclusions on nutrient load reductions difficult. Further experimentation using adjusted outlet flow measuring methods and bioreactor design would help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology in agricultural grassed waterways. / Master of Science / Drainage ditches, or grassed waterways, are located at the edge of agricultural fields where runoff migrates naturally. These ditches help to direct runoff from the field to receiving waterbodies while reducing erosion. Agricultural runoff often contains high levels of nitrogen and phosphorus from fertilizer added to promote crop growth. When runoff with a high nutrient content reaches a waterbody, it reduces the quality of the water for the plants and animals that live in it and for human recreation or consumption. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors have the potential to remove nitrogen from the water by creating optimal conditions for the microorganisms that transform nitrogen in the water to nitrogen in the air. Phosphorus removal has the potential to be enhanced by in-ditch bioreactors that reduce flow and allow for phosphorus to settle out of the water. In addition, settling of phosphorus may be increased by adding a material, such as biochar, that phosphorus can attach to. Using experimental ditch segments and simulated runoff, this study looked at nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors installed and 3) a vegetated ditch with combination woodchip and biochar bioreactors installed. Concentrations of two nitrogen compounds and one phosphorus compound were measured before and after passing through each ditch. There were no significant differences between any of the three ditch types on how much of each compound they could remove. These results are inconclusive due to inaccuracies in measuring flow rate at the outlet of the ditches. Further experimentation using improved flow measuring techniques and bioreactor designs would likely help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology.
2

Effet de la salinité sur la compétition entre le roseau (Phragmites australis) et les quenouilles (Typha spp.)

Paradis, Étienne January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
3

Effet de la salinité sur la compétition entre le roseau (Phragmites australis) et les quenouilles (Typha spp.)

Paradis, Étienne January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
4

Studie rekonstrukce železničních stanic Jindřichov na Moravě a Branná / Upgrading of Jindřichov na Moravě and Branná Railway Stations

Kubina, Jiří January 2014 (has links)
The master thesis "Upgrading of Jindřichov na Moravě and Branná Railway Stations" deals with designing new platforms that are suitable for people with reduced mobility in accordance with applicable laws and standards. Platforms with the platform edge height of 550 millimetres above the top of rail were designed. The speed limit was increased from the original 40 km/h up to 50 km/h. Moreover, the thesis design reconstruction of railway superstructure and railway substructure and deal with the drainage system.
5

Rekonstrukce železniční stanice Jeseník / Upgrading of Jeseník Railway Station

Francová, Aneta January 2015 (has links)
The master thesis "Upgrading of Jeseník Railway Stations" deals with designing new platform that is suitable for people with reduced mobility in accordance with applicable laws and standards. Platform with the platform edge height of 550 millimetres above the top of rail were designed. The speed limit was increased. Moreover, the thesis design reconstruction of railway superstructure and railway substructure and deal with the drainage system.

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