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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.
131

Microbial Phosphorus Removal in Waste Stabilisation Pond Wastewater Treatment Systems

Mbwele, Lydia Ambakisye January 2006 (has links)
<p>Waste Stabilisation Ponds (WSPs) are characterised by low phosphorus (P) removal capacity. Heterotrophic bacteria are principal microbial agents in WSPs in addition to algae. As treatment proceeds in WSPs, algal growth increases and pH rises, this has lead to believe that P removal is mainly through sedimentation as organic P algal biomass and precipitation as inorganic P. In activated sludge treatment plants (AS), microbial P removal has been improved and is termed as enhanced biological phosphorus removal. There was a need to establish whether it was possible to enhance P removal in WSPs. A performance assessment of pond system at the University of Dare s Salaam (UDSM), Tanzania, has shown that 90% of the P removed was in the primary pond (facultative) and the rest in the maturation pond (aerobic).</p><p>In these studies, a pure strain A. hydrophyla was isolated from an activated sludge wastewater treatment plant in Sweden. This plant has a train that functions with enhanced biological phosphorus removal. The strain was tested for P uptake in minimal media supplemented with glucose, succinate or acetate, grown aerobically and anaerobically/aerobically. This strain was able to take up P without having been subjected to the anaerobic phase. It was observed that P uptake was enhanced after the anaerobic phase with media supplemented with glucose, but not with succinate or acetate. Phosphorus uptake repeatedly followed the bacterial growth pattern with correlation coefficients of more than 95%. Therefore P removal has a direct correlation with bacterial growth.</p><p>Two isolates Acinetobacter sp. (isolated from the primary facultative pond) and E .coli (isolated from the maturation pond) were obtained from a tropical WSP treatment system at the UDSM. They were subjected to aerobic P uptake experiment similar to those of A.hydrophyla. The uptake per unit absorbance of bacterial growth was found to be comparable to that of A.hydrophyla, isolated from AS. These results showed that heterotrophic activity is important in WSPs. It is possible to enhance P removal in these systems by designing the primary ponds for maximum heterotrophic activity and probably enrichment.</p>
132

Cattle access affects periphyton community structure in Tennessee farm ponds.

Middleton, Robert Gerald 01 August 2010 (has links)
Cattle farming is vital to the economy of the United States. Frequently, cattle are given access to ponds and streams for water. The relative impacts of cattle access in natural water sources on the periphyton community have been rarely investigated. Periphyton is the basis of the aquatic food web, and community composition can serve as a bioindicator of pollution. Thus, my objectives were to quantify the effects of cattle access in aquatic lentic systems on periphyton community structure and biovolume, identify taxa that were associated with cattle access, and identify abiotic mechanisms that might be driving assemblage changes. I conducted my research in 4 cattle-access (CA) and 4 no-access (NA) farm ponds on the University of Tennessee Plateau Research and Education Center from May 2005 – April 2006. Periphyton community composition and water quality were measured every 2 weeks using standard environmental monitoring procedures. I documented 181 new periphyton taxonomic records (7 phyla, 52 families, and 132 genera) in Cumberland County, Tennessee. Periphyton species richness was greatest in NA ponds. Mean biovolume of pollution-sensitive diatoms (e.g., Achnanthidium minutissimum, Cymbella sp., Eunotia sp., Fragilaria crotonensis and Tabellaria fenestrata) was greater in NA ponds. In contrast, pollution-tolerant diatoms (e.g., Gomphonema sp. and Navicula sp.) and non-diatoms (e.g., Oscillatoria sp. and Scenedesmus sp.) were more abundant in CA ponds. Turbidity, pH, conductivity, and concentrations of the total Kjeldahl nitrogen, total phosphorus, potassium, periphyton phosphorus, silicon, iron, magnesium and aluminum were greater in CA ponds. Thus, changes in water quality associated with cattle-access likely mediated changes in the periphyton community. Considering that changes in periphyton community composition can destabilize higher trophic levels, I recommend that cattle farmers take advantage of USDA conservation programs that provide funds for fencing cattle from watersheds and developing alternate water sources. My results also provide evidence that monitoring the periphyton community is a reliable technique to detect water pollution from cattle.
133

Quantifying CO2 emissions from lakes and ponds in a large subarctic catchment

Salimi, Shokoufeh January 2013 (has links)
Quantifying carbon emissions of water bodies at regional scale is required as recent studies revealed their contribution in carbon cycling is significant. This demands to scale up water bodies carbon emissions from local to regional scale using as accurate approach as possible. In this study data of carbon (CO2-C) fluxes for 80 sampled lakes were used to scale up to more than 3000 lakes and ponds over the catchment. The most appropriate method for upscaling was the one in which two factors of water body size and location (altitude) were involved and the uncertainties were quantified in an advanced approach (Monte Carlo model). Based on the estimates obtained in this method, the annual carbon emission from all water bodies (~ 500 km2) was about 2900 ton C yr-1 . About 62% of this annual emission was related to the large lake Torneträsk (334 km2) and another 38% to all other lakes and ponds (166 km2). Water bodies in subalpine region dominated (90%) total water bodies area and were the major contributor (97%) to the total carbon emissions of all water bodies. The remaining small contribution (3%) was for water bodies in the alpine region, which contains only 10% of total water bodies area. These data indicate that all water bodies smaller than the large lake Torneträsk especially the ones in the subalpine region have considerable contribution to the annual carbon emission of all water bodies. Considering water body size and altitude factors in the advanced upscaling method was appropriate to obtain accurate estimates.
134

Benthic Responses to Nitrogen and Phosphorus Deposition on Alpine Ponds in Banff National Park: A Replicated Whole-Ecosystem Experiment

Porter, Lisa, L. Unknown Date
No description available.
135

Water harvesting through ponds in the Arco Seco region of the Republic of Panama : decision support system for pond storage capacity estimation

Desrochers, Anne January 2004 (has links)
The 'Arco Seco' or 'Dry Arc' region of the Republic of Panama is considered to be the driest in the country, where many areas of this region experience severe water stress during the months of January through May. This study was conducted to develop a tool for the assessment of sustainable implementation of water harvesting through ponds for agricultural purposes in the region. A computer based Decision Support System (DSS) has been developed specifically for the Arco Seco region in order to facilitate pond storage capacity estimation. As part of the DSS, four computer programs have been designed for four different case scenarios; the first one is for sites that have high water demand and no topographical restrictions for pond size; the second is for fairly high water demand, no topographical restrictions for pond size, and for farmers who wish to have a backup of water to use mostly during drier years; the third is for low water demand, usage during the dry season only, and topographical restrictions for pond size, and finally the fourth is for constant water demand throughout the year, and for sites where runoff is the only water source.* / *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation).
136

Pramoninės žuvininkystės tvenkinių ūkių veiklos įtaka vandens kokybei / Industrial fishing ponds farm activities on water quality

Kračka, Deividas 17 June 2014 (has links)
Baigiamajame darbe nagrinėjama keturių Lietuvos pramoninės žuvininkystės ūkių į aplinką išleidžiama tarša (tiekiamo ir išleidžiamo vandens) pagal skendinčias medžiagas, BDS7, bendrą azotą ir bendrą fosforą ir pateikiamos rekomendacijos tvenkininių ūkių vandens kokybei gerinti. Darbo objektas: paviršinis vanduo. Darbo metodai – vertinama paviršinio vandens kokybė žuvininkystės ūkiuose aukščiau ir žemiau tvenkinių (tiekiamo ir išleidžiamo vandens). Darbo rezultatai. Išanalizavus daugiamečius žuvininkystės ūkių vandens kokybės tyrimų duomenis, gauti tokie rezultatai: 1. Skendinčiomis medžiagomis labiausiai užteršti: 1.1. UAB „Daugų žuvis“ tvenkiniai: (priimtuvas – Varėnės upė – 38,0 mg/l, 2009 m.) – žemiau tvenkinių; (priimtuvas – Žižmos upė – 37, 0 mg/l, 2007 m.) – žemiau tvenkinių. 1.2. AB „Išlaužo žuvis“ tvenkiniai: (priimtuvas – Jiesios upė – 47,0 mg/l, 2009 m.) – aukščiau tvenkinių; (priimtuvas – Jiesios upė – 54,0 mg/l, 2009 m.) – žemiau tvenkinių. Nežymiai skendinčių dalelių kiekį viršijo ir Šilavoto poskyrio tvenkiniai (priimtuvas – Jiesios upė – 27,0 mg/l, 2009 m.) – žemiau tvenkinių. 2. Nagrinėtuose žuvininkystės tvenkiniuose nei BDS7, nei bendras azotas, nei bendras fosforas neviršijo leistinų normatyvinių rodiklių. Apibendrinus gautus rezultatus peteikiamos sekančios rekomendacijos tvenkininių ūkių vandens kokybei gerinti: 1. Norint išvengti padidintų skendinčių dalelių koncentraciją pageidautina pagal galimybes didžiają paduodamo vandens dalį kaupti tam... [toliau žr. visą tekstą] / The thesis examines four Lithuanian industrial fish farms in releasing pollution (water supply and discharge) by TSS, BDS7, total nitrogen and total phosphorus and recommendations of farm ponds to improve water quality. Working properties: surface water Working methods - evaluating the quality of surface water in the farms above and below the pond (water supply and discharge). Results. Analysis of many fish farms on water quality survey data, the following results: First TSS most contaminated: 1.1. JSC "Daugų Pond: (Receiving - Varėnė River - 38.0 mg / l, 2009.) - below the dams; (Receiving - Zizmai River - 37, 0 mg / l, 2007.) - below the ponds. 1.2. AB Išlaužo Fish Pond: (Receiving - Jiesia River - 47.0 mg / l, 2009.) - above the pond; (Receiving - Jiesia River - 54.0 mg / l, 2009.) - below the ponds. Slightly higher than the amount of suspended solids and Šilavotas subdivision ponds (Receiving - Jiesia River - 27.0 mg / l, 2009.) - Below the ponds. Second INVESTIGATED fishponds than BDS7 than the total nitrogen or total phosphorus exceeded the permissible normative indicators. Summarizing the results peteikiamos next recommendation farm ponds to improve water quality: First to avoid increase of suspended particles concentration preferably by possibilities to a large flow of accumulating a dedicated, larger ponds or specially equipped stores and settle only part of the load of suspended particles continue growing pond filling. Second Extend pond filling period... [to full text]
137

Adsorption of Single-ring Model Naphthenic Acid from Oil Sands Tailings Pond Water Using Petroleum Coke-derived Activated Carbon

Sarkar, Bithun 17 July 2013 (has links)
Petroleum coke-derived activated carbons were prepared and used for the adsorptive removal of a single-ring naphthenic acid (NA) from synthetic oil sands tailings pond water (TPW). The overall adsorption process was found to be intra-particle diffusion-controlled. The Weber-Morris intra-particle diffusion rate constants decreased from 7.43 to 1.23 mg/g min0.5 after activated carbon was post-oxidized with oxygen, suggesting a hindering effect of oxygen surface groups. The Freundlich model fit of the equilibrium adsorption isotherms and the small negative ΔHo pointed to a physisorption-dominated process and the importance of specific surface area. It was estimated that about 2.7 g/L of basic CO2-activated carbon is needed to reduce NA concentration from 120 mg/L to 2.5 mg/L (~98% removal) in synthetic TPW. However, equilibrium adsorption capacity was found to vary significantly after oxygen or nitrogen groups were introduced onto the surface. Therefore, there is a potential for enhanced adsorption by chemical functionalization of carbon.
138

Smoke off the water : determination of mass emission rates from off-gassing surfaces

Rutgers, Gordon W. P. 28 October 2013 (has links)
A flux chamber is an effective and recognized means of sampling off gassing surfaces, such as landfills and settling ponds. Because there has been little discussion on the survey patterns used for deploying flux chambers. This thesis looks into developing a scalable survey pattern as part of a flux chamber test methodology that can accurately give a representative sample of the emission components and the emission rate of the entire area of interest. The test methodology evolved out of literature review and experiences of two case studies which are discussed within this thesis.
139

Adsorption of Single-ring Model Naphthenic Acid from Oil Sands Tailings Pond Water Using Petroleum Coke-derived Activated Carbon

Sarkar, Bithun 17 July 2013 (has links)
Petroleum coke-derived activated carbons were prepared and used for the adsorptive removal of a single-ring naphthenic acid (NA) from synthetic oil sands tailings pond water (TPW). The overall adsorption process was found to be intra-particle diffusion-controlled. The Weber-Morris intra-particle diffusion rate constants decreased from 7.43 to 1.23 mg/g min0.5 after activated carbon was post-oxidized with oxygen, suggesting a hindering effect of oxygen surface groups. The Freundlich model fit of the equilibrium adsorption isotherms and the small negative ΔHo pointed to a physisorption-dominated process and the importance of specific surface area. It was estimated that about 2.7 g/L of basic CO2-activated carbon is needed to reduce NA concentration from 120 mg/L to 2.5 mg/L (~98% removal) in synthetic TPW. However, equilibrium adsorption capacity was found to vary significantly after oxygen or nitrogen groups were introduced onto the surface. Therefore, there is a potential for enhanced adsorption by chemical functionalization of carbon.
140

Effects of the herbicide silvex (PGBEE) on farm pond fishes and invertebrates

Price, Keith Clayton, January 1967 (has links)
Thesis (M.S.)--Louisiana State University. / Vita. Bibliography: leaves 55-56.

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