• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 346
  • 175
  • 23
  • 20
  • 5
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 675
  • 202
  • 168
  • 152
  • 135
  • 132
  • 91
  • 90
  • 88
  • 87
  • 77
  • 65
  • 62
  • 55
  • 55
  • 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.
51

Funcionamento atual de solos submetidos ao manejo afeto à cultura da cana-de-açúcar: caracterização para fins de irrigação com efluente de esgoto tratado. Área experimental da Usina Cosan, Piracicaba- SP

Aquino, Aline de [UNESP] 17 October 2008 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-10-17Bitstream added on 2014-06-13T20:36:27Z : No. of bitstreams: 1 aquino_a_me_rcla.pdf: 2664343 bytes, checksum: 2664dac2efd41911b0423e12757905d3 (MD5) / Trata-se do estudo macro, micromorfológico, mineralógico, físico e químico da cobertura de solos de uma área experimental para fins de irrigação com efluente de esgoto tratado. A área localiza-se na cidade de Piracicaba, na Fazenda Taquaral, arrendada à Usina Cosan, para cultivo da cana-de-açúcar. A área cedida pela Usina, unidade Santa Helena, para o experimento foi dividida em 10 parcelas e, tanto essas, quanto o efluente, receberão um determinado tipo de tratamento. Os objetivos deste trabalho foram compreender o funcionamento atual dos solos da área experimental e verificar a possibilidade de influência e/ou modificações da cobertura de solos com a utilização do efluente. A metodologia adaptada para a pesquisa foi a Análise Estrutural da Cobertura Pedológica (BOULET, 1982 a, b). A caracterização dos solos foi feita em uma seqüência de solos e por meio de doze sondagens em cada parcela, de 0 a 100 cm de profundidade. As análises realizadas foram morfológica, física, química e mineralógica, tanto para a seqüência quanto para as sondagens. A análise micromorfológica foi realizada apenas para os solos da seqüência. As características do efluente foram cedidas pelo Departamento de Água e Esgoto de Piracicaba. As análises permitiram classificar o solo da área como Argissolo Vermelho-Amarelo Eutrófico típico, caracterizar e entender o funcionamento atual dos solos, antes da irrigação com o efluente e deduzir as possíveis mudanças do sistema solo a partir do início da irrigação. / The present work is a macro, micromorphological, mineralogical, physical and chemical study in an experimental area with the purpose of irrigation with treated sewage effluent. The area is located in the city of Piracicaba, at Taquaral Farm and leased to Cosan factory for sugar cane cultivation. The area was ceded by the factory for the experiment and divided in 10 parts, in accordance with the kind of treatment to be used with the effluent. This work had the purpose to analyze the soils of the experimental area, to understand its dynamics and to check the possibility of influence and change on the soils’ covering by the usage of effluents. The soil study was based on the methodology of the Structural Analysis of the Pedological Cover (BOULET, et al. 1982. a, b), with adapt. The soil characterization was made in a sequence of soil and through twelve investigations in each part, until 100cm depth. The analysis made were morphological, physical, chemical and mineralogical, for the sequence as well as for the investigations. The micromorphological analysis was made only in the sequence of soil. The effluent characteristics were provided by the Piracicaba Water and Sewage Department. The soil was classified into Typic Hapludults and the analyses were important to characterize and understand the soil’ dynamic before irrigation with treated sewage effluent and deduce the changes in the soil system with the effluent irrigation.
52

Aplicação da técnica de eletrofloculação no tratamento de efluentes têxteis / Application of the technique of eletrofloculation in the treatment of effluent textile.

Alexandre Andrade Cerqueira 10 April 2006 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A poluição dos corpos dágua proveniente dos efluentes têxteis provoca alterações em ciclos biológicos afetando principalmente a fotossíntese. Além disso, algumas classes de corantes podem ser carcinogênicos e/ou mutagênicos. Devido à dificuldade em se tratar estes efluentes, novas tecnologias têm sido investigadas. Neste contexto, a eletrofloculação surge com uma técnica promissora, devido à sua eficiência e possibilidade de reuso da água. O presente trabalho tem como objetivo estudar a aplicação do processo de eletrofloculação no tratamento de efluentes de uma indústria têxtil. O processo de eletrofloculação foi realizado em um reator de batelada utilizando eletrodos de ferro e alumínio. A influência dos seguintes parâmetros foi avaliada: natureza e distância do eletrodo, variação de pH, potencial elétrico aplicado e tempo de operação. Os resultados obtidos indicaram que o processo de eletrofloculação nas condições operacionais estudadas é uma alternativa tecnicamente viável para a remoção de DQO, cor e turbidez, a qual foi, respectivamente, de 87%, 95% e 100%. / The pollution of the stream waters through textille effluents causes alterations in biological cycles affecting the photosynthesis mainly. Moreover, some class of dyes can be carcinogenic and/or mutagenic. Due to difficulty in treating these effluents new technologies have been investigated. In the present work, electrofloculation appears to be a very promising technique, due to relatively high efficiency and possibility of water reuse. The present work emend has objective to study the application of electrofloculation in the treatment of effluents of a textile industry. The process was carried out in a batch reactor using electrodes either iron or aluminum. The influence of the following parameters was evaluated: nature and distance between electrodes, pH, electric potential applied and operation time. The results indicated that the process of electrofloculation in these operational conditions is a technical viable alternative for the removal of COD, color and turbidity, which were, respectively, of 87%, 95% and 100%.
53

Environmental Controls on Clogging in Effluent-Dominated Waterways

January 2012 (has links)
abstract: The Santa Cruz River, in southern Arizona, receives steady inputs of nutrient-enriched treated wastewater (effluent). Previous studies have documented reduced infiltration of surface water in the river. This disruption of hydrologic connectivity, or clogging, can have consequences for groundwater recharge, flows of wastewater in unwanted locations, and potentially even survivorship of floodplain riparian vegetation. Clogging can result from biotic processes (microbial or algal growth), abiotic processes (siltation of interstitial spaces), or both. Little is known about clogging in rivers and the environmental factors that regulate their dynamics, so natural field experiments along the Santa Cruz and San Pedro Rivers were used to answer: 1) Are there spatial patterns of hydraulic conductivity in the riverbed downstream from the effluent point-source? 2) Is there temporal variability in hydraulic conductivity and microbial abundance associated with flooding? 3) Are there environmental variables, such as nutrients or stream flow, related to differences in hydraulic conductivity and microbial abundance? To address these questions, a series of sites at increasing distance from two municipal effluent discharge points with differing water quality were selected on the Santa Cruz River and compared with non-effluent control reaches of the San Pedro River. Physical, chemical, and biological parameters were monitored over one year to capture seasonal changes and flood cycles. / Dissertation/Thesis / M.S. Biology 2012
54

Removal Efficiency of Microbial Contaminants from Hospital Wastewaters

Timraz, Kenda Hussain Hassan 02 1900 (has links)
This study aims to evaluate the removal efficiency of microbial contaminants from two hospitals on-site Wastewater Treatment Plants (WWTPs) in Saudi Arabia. Hospital wastewaters often go untreated in Saudi Arabia as in many devolving countries, where no specific regulations are imposed regarding hospital wastewater treatment. The current guidelines are placed to ensure a safe treated wastewater quality, however, they do not regulate for pathogenic bacteria and emerging contaminants. Results from this study have detected pathogenic bacterial genera and antibiotic resistant bacteria in the sampled hospitals wastewater. And although the treatment process of one of the hospitals was able to meet current quality guidelines, the other hospital treatment process failed to meet these guidelines and disgorge of its wastewater might be cause for concern. In order to estimate the risk to the public health and the impact of discharging the treated effluent to the public sewage, a comprehensive investigation is needed that will facilitate and guide suggestions for more detailed guidelines and monitoring.
55

Mitigating Aquaculture Effluent through Use of Low-Grade Weirs

Flora, Corrin Lee 17 August 2013 (has links)
Water management practices to reduce mass discharge are a major point of concern for aquaculture producers. This study assessed effects of consecutive low-grade weirs on chemical retention and settling of aquaculture pond effluent in a single drainage ditch. Two control and nine treatment discharges were conducted September - October 2012. Control discharge dissolved inorganic phosphorus (DIP) load increased 154%, whereas total inorganic phosphorus (TIP), ammonia, and nitrate loads decreased (47%, 43%, and 63%, respectively). Treatment discharge nutrient loads decreased across all analytes (80% DIP, 86% TIP, 89% ammonia, 89% nitrate). However, control and treatment discharges concentrations of DIP and nitrate increased, whereas TIP and ammonia concentrations decreased. All discharges reduced total and volatile suspended solid loads 72% - 94%, with removal rates of 0.02 ± 0.01 mg/L/min total and 0.02 ± 0.001 mg/L/min volatile suspended solids. Results indicate ditches fit with low-grade weirs may be an innovative management practice.
56

Cultivation of Oleaginous Microorganism Consortium on Municipal Wastewater for the Production of Lipids

Hall, Jacqueline Isonhood 12 May 2012 (has links)
Alternative fuels are necessary to meet the increasing demands for fuels. Alternative fuels such as biodiesel are produced using vegetable oils, which are prominentt in the food industry. An alternate feedstock could be oil-producing microorganisms. These oleaginous microorganisms are defined as accumulating more than 20% of their weight in oil as lipids. Cultivating these microorganisms for oil production is not economical due to the high production costs from the sugars in the culture medium. Municipal wastewater could be a potential growth medium that has not previously been considered for cultivating oleaginous microorganisms. However, municipal wastewater contains a low concentration of carbon, which does not promote oil accumulation in the oleaginous microorganisms. To increase the carbon concentration in the wastewater, lignocellulosic sugars could be added to the municipal wastewater. These sugars are a potential alternative to sugars that are in the food industry. The goal of this research is to determine the efficacy of using municipal wastewater to cultivate a consortium of oleaginous microorganisms, thus, producing oil for biodiesel production. First, a consortium of oleaginous microorganisms was cultivated on autoclaved wastewater to determine if the wastewater contains any inhibiting substances for the microorganisms. In addition to the substances in the wastewater, indigenous microorganisms are possible inhibitors to the consortium. Therefore, to determine the effect these indigenous microorganisms have on the oleaginous microorganisms, the consortium was cultivated on raw municipal wastewater amended with varying amounts of sugar. Since the municipal wastewater can be used as a cultivation medium, the effect of the addition of lignocellulosic sugars was determined. During the production of lignocellulosic sugars, furfural and acetic acid, known microbial inhibitors, are formed. The effect of these inhibitors on the consortium’s growth and oil accumulation ability was ascertained, and inhibition models were developed to describe their impact. With these results, SuperPro Designer v6.0 was used to perform simulations and economic analyses to determine the efficacy of incorporating an oleaginous microorganism consortium in a wastewater treatment facility.
57

Characterization and Treatability Study of the Effluent from a Fish Processing Plant

Riddle, M. J. 01 1900 (has links)
<p> The wastewater from a freshwater fish processing plant was characterized. The plant processed perch and smelt, and thus the wastewater characterized was taken from the perch and smelt processing lines and a combined perch and smelt wastewater. The plant also manufactured fish meal from the fish offal. During this process the offal is pressed to obtain stickliquor. Since this stickliquor is a potential waste product it too was characterized.</p> <p> It was concluded that the wastewater was either of medium strength with large flows or of high strength with low flows.</p> <p> Batch and continuous reactor studies were undertaken to ascertain the degradability of the combined wastewater. It was determined that a reactor with either a detention in excess of 5 days with no sludge recycle or a short detention time reactor (7.5 hours) with sludge recycle would be necessary to effect maximum removal of total BOD5.</p> <p> The effect of physical treatment, flotation, sedimentation and in-plant screening, were also examined in a preliminary manner.</p> / Thesis / Master of Engineering (MEngr)
58

Microparticles in freshwater bivalves chronically exposed to wastewater effluent in the Grand River, Ontario, Canada

Robson, Emily January 2023 (has links)
A thesis submitted to the School of Graduate Studies in partial fulfilment of the requirements for the degree of Master of Science in the graduate academic unit of Biology / Microparticles enter aquatic environments through many sources, including wastewater treatment plants (WWTPs), but their uptake by aquatic organisms is poorly understood. Freshwater bivalves accumulate multiple contaminants, making them potential bioindicators for MP pollution. This study aims to understand the abundance and characteristics of microparticles that accumulate in wild bivalves. Samples were collected from 5 locations along the Grand River (Ontario, Canada) in 2021-2022, including 3 municipal WWTPs where both an upstream and downstream site were sampled. At each site, fingernail clams (Sphaeriidae, n=5 composite samples), flutedshell mussels (Lasmigona costata, n=10), and surface water (n=3) were sampled. Within the mussels, the gill, digestive gland, and hemolymph tissues were targeted and compared. Microparticles were isolated and quantified via stereomicroscopy but have not yet been confirmed as plastic; as such, they will be referred to herein as microparticles. Fibers were the dominant morphology and clear, blue, and black were the most common colours, but there were some differences among sites and sample types. Most microparticles were between 80 μm and 1 mm in length. Fingernail clams contained the highest microparticle counts per mass of tissue at 35.5 ± 29.4 microparticles/g, mussel tissues ranged from 4.3 ± 4.2 microparticles/mL to 6.5 ± 8.1 microparticles/g, and water samples contained the lowest counts at 0.0055 ± 0.0028 microparticles/mL. Elevated microparticle counts at downstream sites were only seen in mussel gills and not other bivalve tissues. Surface water samples did not show elevated counts downstream of the WWTPs and microparticle exposures were similar across sites. This study provides baseline data for future monitoring and informs toxicity studies to fully assess the risk of microparticles to vulnerable freshwater bivalves and other aquatic organisms. It also suggests microparticles in freshwater bivalves are coming from sources in addition to WWTPs and are ubiquitous in the Grand River. / Thesis / Master of Science (MSc) / Microplastics are found in nearly every environment, especially freshwater ecosystems. These plastics come from a variety of sources, and this study focuses on assessing the characteristics of microparticles in freshwater clams and mussels (bivalves) that have been exposed to municipal wastewaters. Bivalves and water samples were collected from 5 locations along the Grand River (Ontario, Canada) in 2021-2022, and microparticles were extracted and analyzed from each sample. Fibers were the most abundant type of microparticle, with colours consisting mostly of clear, blue, and black. Clams had the highest number of microparticles per mass of tissue collected and the lowest counts were found in water samples. Higher microparticle counts were only seen in one (mussel gill) of the four tissues from bivalves collected downstream of wastewater outfalls. This study provides baseline data on microparticle characteristics in freshwater bivalves and will guide future studies on the toxicity of microparticles to these animals.
59

Stormwater Detention Systems with Effluent Filtration

Van de Graaff, Linda M. 01 January 1984 (has links) (PDF)
The growing concern for water quality enhancement of our surface waters has led to changes in detention facility design. Providing a filter media for the effluent water to travel through before discharge into the environment has become an area of interest. Thus, detention facilities may be used for both water quality and quantity control. Different soil medias were studied for the potential of pollutant removal and infiltration rates usable in design work. Both laboratory and field experimentation were performed. A computer program was also developed to model stormwater movement through a swale detention system. This research was performed to examine filter media and to indicate the advisability of designing a combination of detention ponds and berms.
60

Formação de aldeídos e trialometanos da desinfecção por ozonização, cloração e ozonização/cloração de efluente de tratamento anaeróbio de esgoto sanitário / Aldehydes and trihalomethanes formation from desinfection in ozonization, chloration and, ozonation/chloration in anaerobic effluent from sanitary wastewater

Silva, Gustavo Henrique Ribeiro da 09 September 2008 (has links)
O presente trabalho foi realizado em sua maior parte no Brasil. Entretanto, com o intuito de enriquecer a pesquisa, realizou-se coleta de dados por um período de seis meses na Universidade de Wageningen - Holanda. Na etapa realizada no Brasil se propôs: estudar a formação de subprodutos (aldeídos e trialometanos) da desinfecção de efluente de tratamento anaeróbio esgoto sanitário com ozônio, cloro e ozônio/cloro; verificar como os desinfetantes atuam no processo de oxidação; conhecer o grau de toxicidade bem como o efeito do residual do ozônio e cloro empregando Daphnia similis e Danio rerio como organismos-teste e, ainda, analisar a eficiência do ozônio, cloro, ozônio/cloro na inativação de microrganismos. Na etapa da pesquisa realizada na Holanda se propôs: estudar a formação de subprodutos (aldeídos) da desinfecção de efluente de tratamento anóxico com ozônio, ozônio/cloro e ozônio/peróxido de hidrogênio (peroxônio); verificar como os desinfetantes atuam no processo de oxidação; e, ainda, analisar a eficiência do ozônio, ozônio/cloro na inativação de microrganismos indicadores. Nos estudos realizados, pode-se verificar uma expressiva formação de aldeídos com predominância de formaldeído e, principalmente, acetaldeído que apresentou uma maior concentração de formação para os ensaios realizados no Brasil. A formação de aldeídos nos ensaios realizados na Holanda seguiram o mesmo comportamento dos realizados no Brasil, porém, como uma menor formação. Para os ensaios de cloração e ozonização/cloração foi observada a baixa formação de trialometanos. Os testes de toxicidade que usaram como organismo-teste - Daphnia similis - apresentaram toxicidade nos ensaios em que se aplicou 8,0 mg \'O IND.3\'/L, assim como em todas dosagens aplicadas nos ensaios de cloração e, também, para o ensaio de ozonização/cloração para dosagem aplicada de 5,0 mg \'O IND.3\'/L / 10 mg \'CL IND.2\'/L. Em relação ao organismo-teste - Danio rerio - foi detectado toxicidade aguda no ensaio em que se aplicou 5,0 mg \'O IND.3\'/L e tempo de contato 5 minutos e 8,0 mg \'O IND.3\'/L e tempo de contato 15 minutos. / The present work was mostly carried out in Brazil. However, aiming to enhance the research, a six-month data collection was performed at the Wageningen University - the Netherlands. The step carried out in Brazil proposed: to study the formation of by-products (aldehydes and trihalomethanes) from the disinfection of an anaerobic treatment wastewater effluent with ozone, chlorine and ozone/chlorine; to verify how disinfectants act in the oxidation process; to know the degree of toxicity as well as the effects of residual ozone and chlorine employing Daphnia similis and Danio rerio as test-organisms; and, yet, to analyze the efficiency of ozone, chlorine and ozone/chlorine in the inactivation of microorganisms. The step of this research that was carried out in the Netherlands proposed: to study the formation of by-products (aldehydes) from the disinfection of an anoxic treatment effluent with ozone, ozone/chlorine and ozone/hydrogen peroxide (peroxonium); to verify how disinfectants act in the oxidation process; and, to analyze the efficiency of ozone, ozone/chlorine in the inactivation of indicating microorganisms. It was possible to indentify, in the performed studies, an expressive formation of aldehydes with a formaldehyde predominance and, mainly, acetaldehyde that presented a higher formation concentration in the essays carried out in Brazil. The aldehydes formation concentration detected in the essays carried out in The Netherlands followed the same behavior of the ones carried out in Brazil, however with a smaller formation. A low formation of trihalomethanes was observed for the chloration and ozonization/chloration, essays. The toxicity tests that used Daphnia similis as test-organisms presented toxicity in the essays that 8.0 mg \'O IND.3\'/L was applied, as well as for all applied dosages in the chloration essays and, also, for the ozonation/chloration for the applied dosage of 5.0 mg \'O IND.3\'/L / 10 mg \'CL IND.2\'/L. Regarding the Danio rerio test-organism, acute toxicity was detected in the essay in which 5.0 mg \'O IND.3\'/L and contact time of 5 minutes was applied and also for 8.0 mg \'O IND.3\'/L and contact time of 15 minutes.

Page generated in 0.0502 seconds