• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 44
  • 8
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 61
  • 61
  • 33
  • 28
  • 18
  • 16
  • 15
  • 12
  • 12
  • 11
  • 11
  • 10
  • 10
  • 8
  • 8
  • 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.
21

Environmental monitoring of effluent plumes in coastal Newfoundland /

Adams, Sara. January 2005 (has links)
Thesis (M.Eng.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 130-137.
22

Spirulina production in brine effluent from cooling towers

Choonawala, Bilkis Banu January 2007 (has links)
Thesis (M.Tech.:Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xvi, 185 leaves / Spirulina is a blue-green, multicellular, filamentous cyanobacterium that can grow to sizes of 0.5 millimetres in length. It is an obligate photoautotroph and has a pH growth range from 8.3 to 11.0.The large-scale production of Spirulina biomass depends on many factors, the most important of which are nutrient availability, temperature and light. These factors can influence the growth of Spirulina and the composition of the biomass produced by changes in metabolism. Brine effluent from cooling towers of electricity generating plants may provide an ideal growth medium for Spirulina based on its growth requirements, i.e. high alkalinity and salinity. The aim of this research was to optimise brine effluent from cooling towers by supplementing it with salts, in order to use this optimised effluent in a small open laboratory raceway pond in an attempt to increase the biomass production of Spirulina.
23

Infiltration and temperature characterization of a wastewater hyporheic discharge system /

Stewart, Ryan D. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 113-118). Also available on the World Wide Web.
24

Spirulina production in brine effluent from cooling towers

Choonawala, Bilkis Banu January 2007 (has links)
Thesis (M.Tech.:Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xvi, 185 leaves / Spirulina is a blue-green, multicellular, filamentous cyanobacterium that can grow to sizes of 0.5 millimetres in length. It is an obligate photoautotroph and has a pH growth range from 8.3 to 11.0.The large-scale production of Spirulina biomass depends on many factors, the most important of which are nutrient availability, temperature and light. These factors can influence the growth of Spirulina and the composition of the biomass produced by changes in metabolism. Brine effluent from cooling towers of electricity generating plants may provide an ideal growth medium for Spirulina based on its growth requirements, i.e. high alkalinity and salinity. The aim of this research was to optimise brine effluent from cooling towers by supplementing it with salts, in order to use this optimised effluent in a small open laboratory raceway pond in an attempt to increase the biomass production of Spirulina.
25

Ozonizaçãoe peroxização de efluente sanitário proveniente de alagados construídos e reator compartimentado anaeróbio/aeróbio visando reuso / Ozonation and peroxidation of sanitary effluent from constructed westlands and anaerobic baffled reactor/aerobic aiming reuse

Miranda, Nathalie Dyane [UNESP] 02 July 2014 (has links) (PDF)
Made available in DSpace on 2015-03-03T11:52:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-02Bitstream added on 2015-03-03T12:07:00Z : No. of bitstreams: 1 000801776.pdf: 1407087 bytes, checksum: 6fe16dd172219fd42fef9b040a788666 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Esta pesquisa teve por objetivo principal estudar a desinfecção de esgoto sanitário proveniente do tratamento de uma nova configuração de um reator compartilhamentado aneróbio/aeróbio e de alagados construídos, utilizando o ozônio e peroxônio. Avaliaram-se como estes atuam no processo de oxidação e inativação de coliformes totais e Escherichia coli, comparando suas eficiências e a formação do formaldeído, que é principal aldeído formado durante a aplicação de ozônio e peroxônio para desinfecção. A formação de formaldeído foi fortemente da dose de ozônio, porém um tempo de contato maior também favoreceu uma maior formação de formaldeído, mesmo que não significativa segundo os testes estatísticos aplicados. Os ensaios de peroxização com uma dose de 5 mg O3 L-1 promoveram uma média de formação de formaldeído maior que quando apenas aplicando somente a mesma dose de ozônio. Com uma dose de 8 e 10 mg O3 L-1, a formação de formaldeído foi em geral menor que quando aplicada durante somente a mesma dose de ozônio. Ou seja, doses maiores de ozônio durante a peroxização favoreceram uma menor concentração de formaldeído no efluente final. Todos os ensaios de ozonização e peroxização promoveram concentrações de formaldeído que estavam dentro do limite imposto pela OMS (água potável). Tanto para o efluente proveniente dos A.C. quanto do reator compartimentado, doses maiores de ozônio ou um tempo de contato maior não favoreceu uma inativação significativamente maior. A inativação de E. coli, no efluente proveniente do reator compartilhamentado, não foi superior ao se adicionar peróxido de hidrogênio. Já a inativação de coliformes totais foi na maioria dos testes superior aos resultados encontrado quando aplicado somente ozônio, sendo que o consumo de ozônio durante a peroxização foi menor que na ozonização. Pode assim concluir que a adição de peróxido de hidrogênio foi à... / This research was aimed to study the disinfection of wastewater from treatment by a new configuration of an anaerobic/aerobic baffled reactor and by constructed wetlands, using ozone and peroxone. Were avaluated how these processes acted in the oxidation and inactivation of total coliforms and Eschechia coli, comparing their efficiency and formation of formaldehyde, which is the main aldehyde formed during the application of ozone and peroxone for disinfection. The formation of frmaldehyde was strongly depend on the dose of ozone, by a longer contact time also favored an increased in the formation of formaldehyde, even not significant according to the statistical tests applied. Peroxidation tests with a dose of 5 mg O3L-1 promoted a higher average formation of formaldehyde than when applying only just the same dose of ozone. For doses of 8 and 10 mg O3L-1, the formation of formaldehyde was generally smaller than when applied just the same dose of ozone. I.e., higher ozone doses during peroxidation favored a lower formaldehyde concentration in the final effluent. All tests ozonation and peroxidation promoted formaldehyde concentrations that were within the limit imposed by WHO (drinking water). For both the effluent from the C.W. as the anaerobic/aerobic baffled reactor, higher ozone doses or a longer contact time did not favor a significantly higher inactivation. Inactivation of Escherichia coli in effluent from the anaerobic/aerobic baffled reactor was no better when added hydrogen peroxide. The inactivation of total coliforms was higher in most of the tests when applied just ozone, and the consumption of ozone during peroxidation was lower than in ozonation tests. This way, is possible to conclude that the addition of hydrogen peroxide was favorable to the inactivation of total coliforms. For the effluent from the anerobic/aerobic baffled reactor only with the application of ozone was required a dose of 8 mg O3 L-1 for the effluent... / FAPESP: 11/10816-2
26

Estudo da adsorção do corante reativo blue 19 por lama vermelha ativada por tratamento químico e térmico

Souza, Kelli Cristina de [UNESP] 17 August 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:29:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-17Bitstream added on 2014-06-13T18:59:01Z : No. of bitstreams: 1 souza_kc_me_bauru.pdf: 1427333 bytes, checksum: d2af9018310862c2fe34e56e2d8abbd2 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A indústria têxtil é responsável pela geração de efluentes que, normalmente, apresentam um nível indesejável de coloração devido à etapa de tingimento, onde utilizam-se corantes que, quando lançados nos corpos d'água, levam à alteração de sua qualidade e ocasionam efeitos danosos ao meio ambiente e à saúde humana. Em vista disso, este trabalho teve como objetivo utilizar a lama vermelha, resíduo gerado em larga escala na produção de alumínio, como meio adsorvedor do corante Reativo Blue 19, o qual possui grande aplicação industrial e características que dificultam sua remoção em solução aquosa por meio de tratamentos convencionais. Sendo assim, optou-se por ativar a lama vermelha através de tratamento químico (água do mar, nitrato de cálcio e peróxido de hidrogênio) e térmico (400ºC e 500ºC), visando identificar a interferência desses tratamentos no aumento de sua capacidade adsortiva. Para isso, foi realizada a caracterização das amostras de lama vermelha através da determinação do pH, condutividade elétrica, ponto de carga zero (PCZ) difração de raios - x (DRX) e área superficial específica, sendo que a análise granulométrica foi realizada somente para a lama vermelha in natura. Em seguida, visando determinar a capacidade adsortiva da lama vermelha ativada, foram construídas isortermas de adsorção, linearizadas segundo os modelos de Langmuir e Freundlich. Para efeito de comparação, a mesma metodologia foi aplicada ao carvão ativado visando determinar sua capacidade em adsorver o mesmo corante. Foi realizado o estudo da cinética de reação através dos modelos pseudo-segunda ordem, onde todas as amostras obedeceram ao modelo de pseudo - segunda ordem. Os resultados mostraram-se bastante promissores, sendo que a lama vermelha ativada por nitrato de cálcio a 500ºC apresentou uma... / The textile industry is responsible for the generation of effluents usually have an undersirable level of staining due to the step of dyeing, which is used dye which, when thrown into water bodies, leading to alteration of its quality and cause harmful effects the environment and human health. As a result, this study aimed to use the red mud, waste generated on a large scale in the production of aluminum, such as through adsorption of the dye Reactive Blue 19, which has a large industrial application and characteristics that hinder its removal in solution Aqueous by conventional treatments. Therefore, we chose to activate the red mud by chemical treatment (seawater, calcium nitrate and hydrogen peroxide) and thermal (400º C and 500º C) in order to identify the influence of these treatment in increasing its adsorption capacity. For this, we performed the characterization of samples of samples of red mud by determining the pH, electrical conductivity, point of zero charge (PZC) - ray diffraction (XRD) and specific surface area, and the particle size analysis was performed only for red mud in nature. Then, to determine the adsorptive capacity of activated red mud, adsorption isotherms were constructed, according to the linearized Langmuir and Freundlich models. For comparison, the same methodology was applied to activated carbon in order to determine their ability to adsorb the same dye. Was performed to study the kinetics of reaction through the pseudo-first model and pseudo-second order where all samples followed the type of pseudo-second order. The results were very promising, with the red mud activated by calcium nitrate at 500ºC showed a maximum adsorption capacity of 476.02 mg/g at pH 4. The results for the activated carbon did not indicate affinity between the adsorbate and adsorbate material, a factor... (Complete abstract click electronic access below)
27

INDICE DE CONCORDÃNCIA E RISCO FUZZY NA AVALIAÃÃO DO DESEMPENHO DE SISTEMAS DE LAGOAS DE ESTABILIZAÃÃO / Agreement index and fuzzy risk for the evaluation of waste stabilization pond systems

Fernando Josà AraÃjo da Silva 18 October 2010 (has links)
No presente trabalho foi empregada a aritmÃtica fuzzy com NFTs para o cÃlculo do Ãndice de ConcordÃncia Fuzzy (ICF) e do Risco Fuzzy (RF), com fins de anÃlise de aspectos operacionais, desempenho e qualidade dos efluentes de 14 ETEs do tipo lagoas de estabilizaÃÃo (6 lagoas facultativas primÃrias - LFPs e 8 sÃries- LSs) em escala real, tratando esgotos domÃsticos. A lÃgica fuzzy provou ser um recurso eficiente na avaliaÃÃo do desempenho de ETEs e suas compatibilidades ambientais. O estudo propiciou tambÃm uma melhor compreensÃo do funcionamento operacional de lagoas de estabilizaÃÃo. Exceto por dois sistemas (LFP4 e a LS8) o ICF mostrou que as LFPs e LSs operaram em mÃdia 81,3 e 86,3% do tempo, abaixo do valor estipulado em projeto. Nestas seriam possÃveis incrementos mÃdios de vazÃo de 74,7 e 84,5%, respectivamente. Quanto Ãs cargas orgÃnicas afluentes (&#61548;) os valores de ICF mostraram a possibilidade de acrÃscimos de 91,8 e 71,9%, para as LSs e LFPs, respectivamente. Sobre a qualidade dos efluentes, o OD obteve os maiores valores de ICF (LSs = 0,945 e LFPs = 0,867). Os valores de ICF para qualidade do efluente tratado foram mais elevados nas sÃries, com maior concordÃncia fuzzy com as normas ambientais. O risco fuzzy concernente à sobrecarga (orgÃnica e hidrÃulica) foi maior nas sÃries. Individualmente, os sistemas LFP4 e LS8 apresentaram maior risco difuso de sobrecarga, por operarem sob condiÃÃes prÃximas Ãs estabelecidas em projeto. O RF para anÃlise de desempenho mostrou que as ETEs tiveram perfomance um pouco abaixo do que observa a literatura tÃcnica. Os menores valores de RF foram observados nos sistemas em sÃrie. O risco difuso para nÃo atendimento das expectativas de desempenho foi maior em relaÃÃo a SST (0,929 nas LFPs e 0,903 nas LSs), seguido de amostras nÃo filtradas de DQO (0,846 nas LFPs e 0,677 nas LSs). Na violaÃÃo das normas ambientais o RF tambÃm foi maior nas LFPs. Observou-se que nas sÃries, quanto maior o nÃmero de lagoas menor o RF. CorrelaÃÃes lineares positivas (nÃvel de significÃncia de 95%) mostraram que quanto menor o conteÃdo de DBO e DQO (amostras nÃo filtradas), e de SST, menor o risco difuso em relaÃÃo a CTm. No caso do RF para pH e CTm a correlaÃÃo foi negativa. Foi estabelecido um Ãndice de Desempenho Fuzzy (IFD) para lagoas de estabilizaÃÃo, para comparar a qualidade dos efluentes das ETEs. O modelo propÃs uma escala (1 a 18) baseada nos parÃmetros DBOf, DQOf, SST, AMT, OD e CTm. Os resultados apresentaram o seguinte ordenamento: IFD LFP3 (2,09) < IFD LFP2 (2,15) < IFD LFP4 (2,30) < IFD LFP5 (3,49) < IFD LFP1 (3,62) < IFD LFP6 (4,96) < IFD LS5 (9,59) < IFD LS8 (9,67) < IFD LS4 (9,72) < IFD LS3 (10,01) < IFD LS1 (10,38) < IFD LS2 (13,57) < IFD LS6 (15,49) < IFD LS7 (15,69). A anÃlise do RF para ovos de helmintos mostrou que para uma margem e risco difuso de atà 10% seria necessÃrio um TDH de 28,8 dias com oH &#8804; 1,0 ovo/L e 38,0 dias com oH &#8804; 0,1 ovo/L. Em duas sÃries (LS5 e LS8) o cÃlculo de ICF e RF em relaÃÃo à qualidade do efluente de cada lagoa componente permitiu observar distinÃÃes impostas pela configuraÃÃo e condiÃÃo operacional de cada uma dessas ETEs. Nas citadas sÃries os NFTs foram empregados para avaliar &#61548;r de DBO e AMT. As representaÃÃes mostraram taxas de remoÃÃo superficial com valores negativos, que ofereceram uma interpretaÃÃo anÃmala de geraÃÃo de poluente por via fÃsica ou biÃtica. A causa foi a assincronia entre as concentraÃÃes afluentes e efluentes, associadas à flutuaÃÃes nas vazÃes, e, de forma indireta, a fatores climÃticos e hidrÃulica das lagoas. / In the present study fuzzy arithmetic via triangular fuzzy numbers (TFNs) was applied to compute Fuzzy Agreement Index (FAI) and Fuzzy Risk (FR) for the evaluation of operational aspects, performance and effluent quality in 14 full-scale waste stabilization pond plants (6 primary facultative ponds â PFPs and 8 pond series- PSs) treating domestic sewage. Findings showed that fuzzy logic is an attractive approach for the evaluation of the performance of wastewater treatment plants and their environmental compatibilities. The study also provided a better understanding of operational aspects of waste stabilization ponds. Except for two pond systems (PFP4 and PS8) the FAI in PFPs and PSs showed that they operated on average 81.3 and 86.3% of the time below the value stipulated in their original designs. Results indicated average potential increments of 74.7 and 84.5% in influent flow rates to PFPs and PSs, respectively. With respect to organic load (&#61548;) FAI numbers indicated possible increases of 91.8 and 71.9% in PSs and PFPs respectively. In the case of the regulatory standards the FAI applied to effluent quality had best results for DO (PSs = 0.945 and PFPs = 0.867). In general pond series had higher numbers for FAI than PFPs. The fuzzy risk regarded to overloading (organic and hydraulic) was higher in pond series. Comparatively, systems PFP4 and PS8 showed higher fuzzy risk of overloading because these plants operated close to the design numbers. The FR on performance analysis showed that all ponds plants had actual performance slightly below that expected and reported by the literature. The lowest FR values were observed in pond series. On the performance analysis the highest fuzzy risk numbers were for TSS (0.929 in PFPs and 0.903 in PSs), followed by unfiltered COD (0.846 in PFPs and 0.677 in PSs). As expected, fuzzy risk regarded to the violation of environmental standards was higher in PFPs. In pond series by increasing number of cells FR was lower. Positive linear correlations (at a significance level of 95%) showed that lower content of BOD and COD (unfiltered samples), and TSS implied in lower FR with respect to termotolerant coliform concentrations (TTFC). Correlations between FR of pH and TTFC were negative. A Fuzzy Performance Index (FPI) was proposed to compare effluent quality with respect to the environmental standard regulation. The model considered a scale (1-18) based on the following parameters: BODf, CODf, TSS, TAN, DO and TTFC. The results showed the following order: FPI PFP3 (2.09) < FPI PFP2 (2.15) < FPI PFP4 (2.30) < FPI PFP5 (3.49) < FPI PFP1 (3.62) < FPI PFP6 (4.96) < FPI PS5 (9.59) < FPI PS8 (9.67) < FPI PS4 (9.72) < FPI PS3 (10.01) < FPI PS1 (10.38) < FPI PS2 (13. 57) < FPI PS6 (15.49) < FPI PS7 (15.69). The analysis of FR for helminth eggs showed that for a marginal fuzzy risk of 10% pond systems would require a HRT of 28.8 days for oH &#8804; 1.0 egg/L, and 38.0 days for oH &#8804; 0.1 egg/L. In two series (LS5 and LS8) the FAI and FR with respect to effluent quality from each pond component provided distinctions imposed by the configuration and operational status in each of these plants. Along pond cells in these series BOD and TAN surface removal rates (&#61548;r) were represent by TFNs. These fuzzy numbers showed negative surface removal rates. They offered an anomalous interpretation for pollutant generation via physical or biotic means. The probable and reasonable cause was the asynchrony between affluent and effluent concentrations, associated with fluctuations in flow rates. Climatic factors and hydraulic behavior of ponds might also influence this.
28

Effects of hydraulic loading and laundry detergent on the operation of aerobic package treatment systems

Hanna, K. Michael 03 March 2009 (has links)
This study focused on three potential problems with the operation of aerobic package treatment systems: hydraulic retention time, laundry detergents, and hydraulic surges. To determine the effect of hydraulic retention time on system performance, six bench scale activated sludge systems were constructed. Wastewater from an actual residence was collected twice per week and fed to the small activated sludge systems. Two of the systems had a hydraulic retention time of 2 days, two had a hydraulic retention time of 1 day and two had a hydraulic retention time of 0.5 days. Effluent quality was stable and good with regard to chemical oxygen demand (COD) and ammonia (NH)-N) and seemed to be independent of hydraulic retention time. All of the systems performed well, despite considerable variability in influent strength. To study the effect of high concentrations of laundry detergents on the operation of package treatment systems, three of the six laboratory systems were fed high concentrations of detergent. Other than some residual COD from the detergent, no effect on system performance was observed. The final component of the study was the modification of an existing package treatment system to equalize flows from an automatic washing machine. After a month of operation the modified system produced a more constant effluent quality, than did the unmodified system. The field system, with and without modification, had a low mixed liquor suspended solids (MLSS) concentration (35 mg/L). This was probably the result of the long hydraulic retention time. As a result of the low MLSS the system, with and without modification, did not meet Virginia effluent requirements for BODs, TSS or D.O. or generally accepted levels of NH₃-N. / Master of Science
29

The Relative Effectiveness of Drainfield Trenches and Absorption Beds in Disposing of Bacteria, Viruses and Nitrates from Septic Tank Effluent

Collins, Raymond E. 01 January 1984 (has links) (PDF)
No description available.
30

Effects of sewage treatment plant effluents on mollusks and fish of the Clinch River in Tazewell County, Virginia

Goudreau, Stephanie E. 22 June 2010 (has links)
The Clinch River is renown for its rich mollusk and fish assemblages, including many endemic species. New sewage treatment plants (STP's) have recently been constructed along the Clinch River in Virginia, raising concern because of the disappearance of mollusks below existing STP's. Field and laboratory studies were conducted to determine mollusk and fish distribution in proximity to two STP's in Tazewell County, and the tolerance of two mollusk species to mono chloramine and unionized ammonia, the major toxicants in domestic STP effiuent. River reaches up to 3.75 km downstream of the STP outfalls at Tazewell and Richlands were depauperate of mussels. Tolerance to effluent seemed to vary among snails, sphaeriid clams, and the Asiatic clam <i>Corbicula flumineaK</i>. After an initial toxic zone below the Tazewell outfall, abundance of fish appeared to increase by 0.45 km below the outfall. The effluent at Richlands eliminated intolerant species, and more tolerant species were present as far as 0.45 km below the outfall. Laboratory bioassays with glochidia of <i>Villosa nebulosa</i> resulted in 24-h EC₅₀ and LC₅₀ values of 0.042 and 0.084 mg/L monochloramine, respectively, and 24-h EC₅₀ and LC₅₀values of 0.237 and 0.284 mg/L unionized ammonia, respectively. Glochidia rank among the most sensitive invertebrates in their tolerance to these toxicants. The snail <i>Pleurocera unciale unciale</i> was moderately sensitive, with 96-h LC₅₀ values of 0.252 mg/L mono chloramine and 0.742 mg/L unionized ammonia. Comparison of monochloramine and unionized ammonia concentrations monitored at 0.10 km below the outfalls indicated that mono chloramine was the major toxicant likely affecting fauna. / Master of Science

Page generated in 0.0593 seconds