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Treatment of Rainbow Trout (Oncorhynchus mykiss) Raceway Effluent Using Baffled Sedimentation and Artificial Substrates. The treatment performance of a 6 m wide by 67 m long by 0.8 m deep, baffled sedimentation basin receiving rainbow trout <i>(Oncorhynchus mykiss)</i> raceway effluent was evaluated with and without the installation of artificial substrates (Aquamats®). Treatment efficiency was also determined using normal rearing condition effluent loading versus cleaning and harvesting events. Total suspended solids (TSS) removal for the total basin averaged 79% and 71% during normal rearing conditions, as compared to 92% and 79% during cleaning and harvesting operations, when the Aquamats® were installed versus removed, respectively. Total phosphorus (TP) removal by the total basin, with and without Aquamats®, was 20% and 23% during normal rearing conditions as compared to 55% and 65% under cleaning and harvesting conditions, respectively. Higher TP removal during cleaning operations was attributed to sedimentation of particulate fractions. Dissolved nutrient removal (ortho-phosphate (OP), total ammonia nitrogen (TAN), nitrate, nitrite, and total organic carbon (TOC)) was not consistent throughout the basin and did not improve when the Aquamats® were installed. A short contact time and periphyton grazing by isopods may have limited the capacity of the Aquamats®. Calculated retention times with and without Aquamats® for the first half and total basin were 37% and 32% and 27% and 17% less than theoretical values, respectively based on a rhodamine WT dye study. Average surface overflow rates were adjusted accordingly and measured 19.1 m³/m²-day when the Aquamats® were installed, versus 14.8 m³/m²-day when the Aquamats® were removed for the overall basin. These rates are lower than previous recommendations for treating aquaculture effluents, but resulted in with high solids removal and consistently low TSS effluent (average < 2 mg/L) which may be necessary for strict discharge permits. Use of the overall basin minimized the occurrence of TSS measurements > 2 mg/L by 50%. For the first half of the sedimentation basin, the overflow rate averaged 44.1 m³/m²-day with Aquamats® versus 35.8 m³/m²-day without Aquamats®. The majority of effluent treatment occurred within the first half of the basin, which was responsible for 84% and 94% of total TSS removal, 42% and 100% and 61% and 80% of total TP removal during normal and cleaning/harvesting conditions, respectively.> Characterization of Nutrient Leaching Rates from Settled Rainbow Trout <i>(Oncorhynchus mykiss)</i> Sledge The leaching of nutrients from settled rainbow trout <i>(Oncorhynchus mykiss)</i> sludge into overlying water was evaluated over a 7 day period. Nutrient leaching was assessed in a stagnant reaction tank and one agitated by aeration to simulate turbulent conditions in stocked production raceways. Leaching of total phosphorus (TP), ortho-phosphate (OP), total Kjeldahl nitrogen (TKN), total ammonia nitrogen (TAN), and total organic carbon (TOC) occurred rapidly during the first 24 h in both stagnant and agitated conditions. The highest 24 h leaching occurred in the agitated tank, and power regression equations accurately described the varying rates of increasing TP, OP, TAN and TKN. In the stagnant tank, linear increases of TP, OP, TKN and TAN concentrations occurred during the first 24 h. These linear increases continued from day 2-7, but at slower rates than occurred during the first 24 h. Average nutrient leaching rates (mg leached/g sludge-h);(dry weight basis) were calculated based on linear concentration increases. In the agitated tank, nutrient concentrations decreased after 60 h, as aerobic bacterial uptake and/or chemical precipitation was suspected. Therefore, average leaching rates could not be determined. These findings reveal that daily cleanout of settling areas could eliminate the release of TP, OP, TAN, TKN, and TOC from settled solids by 66%, 65%, 39%, 76% and 51%, respectively, as compared to weekly cleanout schedules. Sustained leaching rates indicate nutrient release will likely continue beyond 7 days. This information suggests aggressive and continuous sludge management is most beneficial for maintaining high water quality and regulatory discharge compliance in fish production. / Master of Science

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The purpose of this investigation was to determine the effectiveness of the leaching streams from waste copper ore dumps as a nutrient solution for subsequent biological oxidation and solubilization of sulfide minerals. The copper in the leaching streams is precipitated by displacement with iron. As a result of this procedure the solution is high in ferrous iron concentration and has a pH of near 3.7. The bacteria in the leaching streams are capable of oxidizing ferrous iron to the ferric state and sulfide minerals to sulfates. The effects of temperatures, pH, urea, and aeration rate on the oxidation of the ferrous iron in the stream were studied. The effect of oxidized and reduced forms of the solutions, pyrite, urea, and pH on the solubilization of chalcopyrite were investigated. It was found that an increase in the rate of bubbling air through the ferrous solutions greatly increased the rate of oxidation of the solution. The optimum pH was found to be near 3.2. The optimum temperature was near 35°C. Added urea had little effect on the rate of oxidation of the ferrous solution. The presence of pyrite slowed the rate of solubilization of chalcopyrite. This was interpreted as being due to the lower pH caused by the oxidation of pyrite. Copper was found in the effluent leachates from the mineral samples when the pH was near 3.0. Little copper was found when the pH was below 2.5. Raising the pH with CaCO3 increased the rate of solubilization of chalcopyrite. Added urea had little effect on the rate. It was concluded that the reduced form of the leaching stream is an effective leaching fluid for the biological solubilization of chalcopyrite because of its relatively high pH and nutrient content. Pyrite is preferentially oxidized in the presence of chalcopyrite in tailing solution.

<p>Validerat; 20111223 (anonymous)</p>

Thiamethoxam and clothianidin are two neonicotinoids used in seed coatings for crops such as corn and soybeans. Both neonicotinoids have high solubility in water, so they are prone to transport via leaching and runoff. This thesis is comprised of two studies that evaluated potential solutions to mitigate neonicotinoid transport from fields. The first study examined the relationship between soil organic carbon content and neonicotinoid transport in a field planted in soybeans. Soils with increased organic carbon leached less thiamethoxam and clothianidin during early growing season leaching peaks; however, at the end of the season, higher organic carbon content only decreased leached mass of clothianidin. The second study was to determine neonicotinoid uptake of different ground covers used as cover crops or edge-of-field buffer strips, as well as the partitioning of thiamethoxam and clothianidin throughout the plants. Ground covers, such as crimson clover, had the highest recovery of applied thiamethoxam, meaning that it may be a good candidate to retain this pesticide in fields. Thiamethoxam and clothianidin concentrations were higher in leaf tissues than in stems or roots, indicating that above-ground biomass removal may be an effective way to reduce neonicotinoid loading in the environment. From these studies, I concluded 1) practices that raise the amount of organic carbon in the soil may help decrease early-season neonicotinoid transport, resulting in lower concentrations in surrounding waterways, and 2) careful selection of plant species, such as crimson clover, may help reduce neonicotinoid transport in the environment, while potentially reducing exposure to beneficial insects. / Master of Science / Pesticides called neonicotinoids are commonly applied to seeds in row crops, such as corn and soybeans, before they are planted. These pesticides are highly soluble in water, which can lead to them exiting fields through runoff or leaching. This thesis is comprised of two studies that examined several potential solutions for decreasing the amount of neonicotinoids available for transport. The first study examined the relationship between organic carbon in the soil and neonicotinoids, and whether this relationship helps to retain neonicotinoids in a soybean field. Soils with high organic carbon content decreased the amount of neonicotinoids exiting the field during early growing season storms; however, at the end of the season, high organic carbon content only decreased losses for one of the pesticides studied. The second study was to determine which of six plant species and two mixes used as cover crops or buffers were the most effective at removing neonicotinoids from soil, as well as where in the plant these neonicotinoids go after uptake. Ground covers, such as crimson clover, had the highest recovery of applied neonicotinoids, meaning they would be good candidates for planting around fields. Ultimately, neonicotinoid accumulation was higher in leaves than in stems or roots, meaning that removing and disposing of leaves in an environmentally safe way could be an effective way to decrease neonicotinoid pollution. From these two studies, I found that 1) increasing organic matter in the soil can stop neonicotinoids from exiting the area it was applied in, and 2) careful consideration of plant species in or around the field may help intercept neonicotinoids before they exit the field.

Silver nanoparticles (nanosilver) are gaining significant attention from the academic and regulatory communities, not only because of their antimicrobial effects and subsequent product applications, but also because of their potential health and environmental impacts. Although some human health effects of silver nanoparticles have been reported, realistic exposure levels from the use of consumer products are still largely unknown. The objective of this work was to characterize the release of silver and silver- containing particles during the normal use of silver nanotechnology consumer products. Specific objectives were to review the environmental and human health risks of airborne, engineered nanoparticles, to characterize aerosol emissions from nanosilver spray products, and to characterize nanosilver that may be released from childrenʼs consumer products under conditions of normal use. We identified possible routes of aerosolization of nanosilver from the production, use, and disposal of consumer products and estimated that about 14% of silver nanotechnology products that have been inventoried could potentially release silver particles into the air during use. The spray products investigated emitted 0.24 – 56 ng of silver in aerosols per spray action, and the plurality of aerosols were 1 – 2.5 μm in diameter, easily inhaled, for two products. Both the products' liquid characteristics and the bottles' spraying mechanisms played roles in determining the aerosol size distributions, but the size of silver-containing aerosols was largely independent of the liquid phase size distributions. We compiled an inventory of 82 children's consumer products that claim to contain nanosilver, of which 13 products were examined for presence of silver and tested for release of silver into liquid media and air, and onto skin. All products contained some form of silver, but silver-containing particles were observed in only four products, with sizes ranging from nanoscale up to 10 μm in size. Silver leached preferably into synthetic biological media with higher chloride concentrations, such as sweat and urine. We determined that levels of silver to which children would be exposed during normal use of these products are likely to be low, and bioavailable silver is expected to be in ionic rather than particulate form. / Ph. D.