• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 41
  • 12
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 97
  • 97
  • 97
  • 29
  • 20
  • 15
  • 15
  • 15
  • 14
  • 14
  • 13
  • 12
  • 12
  • 12
  • 10
  • 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.
61

The Synergistic Interaction between White Rot Fungi and Fenton Oxidation: Practical Implication for Bioprocess Design

Van der Made, Julian John Alexander January 2024 (has links)
The metabolism of white-rot fungi has many proposed biotechnological applications. Their unique capability to depolymerize and catabolize lignin, the most recalcitrant component of lignocellulosic biomass, could be instrumental to the sustainable production of fuels, chemical, and materials from waste biomass feedstocks. The non-specific, oxidative nature of this lignin-degrading metabolism of white-rot fungi renders them capable of degrading a wide range of complex refractory organic compounds beyond lignin, including emerging micropollutants such as pharmaceuticals and pesticides which current wastewater treatment processes were not designed to remove. However, harnessing these metabolic capabilities into engineered bioprocesses has proven to be challenging. Common bioreactor design strategies were developed for traditionally-used unicellular bacteria and yeasts and are not necessarily appropriate for the more complex, filamentous white-rot fungi. Due to a lack of specific engineering strategies and other knowledge gaps, the realization of white-rot fungal bioprocesses has been hampered by low process efficiencies and operational challenges. This dissertation aims to expand the engineering toolbox for harnessing the metabolism of white-rot fungi in bioprocesses. Specifically, it proposes the addition of Fenton chemistry as an avenue to unlock the biotechnological potential of white-rot fungi. The production of hydroxyl radicals through the Fenton reaction is generally understood to be part of the lignin-degrading machinery of white-rot fungi and the addition of Fenton chemistry has been shown to synergistically enhance lignin degradation by white-rot fungi. Overall, the research presented here aims to demonstrate that incorporating Fenton chemistry into white-rot fungal bioprocesses not only synergistically increases lignin degradation efficiency, but also offers a potential solution for the operational challenges that have prevented the implementation of white-rot fungal bioprocesses. This dissertation was guided by five objectives aimed at illustrating the utility of coupling Fenton chemistry and white-rot fungi in engineered bioprocesses. The first objective was to demonstrate, optimize, and uncover the underlying mechanisms driving the synergistic degradation of lignin by white-rot fungi and Fenton chemistry. Through this assessment, it was found that lignin degradation increased synergistically from 58.8% to 80.2% in the presence of Fenton chemistry at the optimum concentration. This work also showed that Fe(II)/Fe(III) cycling and the induction of auxiliary ligninolytic pathways mediate this synergistic interaction. The second objective was to elucidate how Fenton chemistry influences the regulating mechanisms of ligninolytic activity in white-rot fungi, specifically C:N ratio. This showed that C:N ratio significantly influences lignin degradation in the absence of Fenton, but that this effect is blunted in the presence of Fenton. The third objective was to investigate how Fenton chemistry modulates the relationship between the concentration of fungal biomass and the extent of lignin. In the absence of Fenton, fungal biomass concentration was strongly correlated to the extent of lignin degradation. While this was also the case in the presence of Fenton chemistry at very low fungal biomass concentrations, this relationship became uncoupled at sufficiently high fungal biomass concentrations. The fourth objective was to evaluate Fenton chemistry as a selective disinfectant to allow for the persistence or enrichment of white-rot fungi in non-sterile settings. The model competitor E. coli became completely inactivated within hours at the optimal concentration of Fenton reagents, whereas the white-rot fungus P. chrysosporium survived and grew. Lastly, the fifth objective was to demonstrate the long-term performance of a continuously-operated bioreactor which integrated Fenton chemistry and white-rot fungal metabolism. A rotating biological contactor (RBC) combined with a rotating cathode electro-Fenton was constructed and a kinetic model based on batch tests was successfully developed and validated. The reactors were operated for over 100 days and reached stable lignin degradation performance at ~55%. Analysis of the microbial ecology of these reactors showed the persistence of the inoculated P. chrysosporium within the biofilms, as well as the enrichment for other lignin-degrading fungi and bacteria with aromatic catabolism and iron-reduction capabilities. Overall, this research provides insight into the potential and practical implications of integrating Fenton chemistry with white-rot fungi in bioprocesses. The lignin-degrading metabolism of white-rot fungi has long been of interest for biotechnological purposes, but attempts to operationalize them have thus far been unsuccessful at scale. In order to consider scaling white-rot fungi to full-scale operations such as wastewater treatment plants, a better understanding and tighter controls on the growth, ligninolytic activity, and ecological interactions of white-rot fungi are needed. This work proposes Fenton chemistry as a synergetic actor, selective promoter and regulator of white-rot fungal biomass and their production of lignin degrading enzymes.
62

A treatment feasibility study of a cellulose acetate manufacturing wastewater

Boyadjian, Dana Mello 08 April 2010 (has links)
Physical-chemical treatment has been shown to be highly successful in treating certain wastewaters and, to some degree, this treatment approach has been promoted as a panacea for all wastewater treatment problems. This project was designed to investigate the best method of treating a wastewater composed primarily of soluble organic material resulting from a cellulose acetate manufacturing process. Both physical-chemical and biological treatment processes were applied to the wastewater to determine whether the performance of the physical-chemical approaches would be less than, equal to, or greater than the performance of the biological treatment system. A further intention of the study was to help in generating guidelines concerning the limitations, if any, of physical-chemical systems. Experimental results showed that chemical treatment using lime or ferric chloride produced only marginal reductions in the COD of the wastewater. From these chemical experiments it was discovered that the wastewater had an extremely high buffering capacity. Adsorption with granular carbon produced a significant reduction in COD provided that a sufficient detention time was allowed. However, final COD values were still too high for discharge under most conditions. In a fairly short aeration period, activated sludge treatment produced an effluent COD value almost one-third the minimum effluent COD value from carbon adsorption. It was therefore concluded that for the wastewater studied t biological treatment was much more efficient than a chemical or physical treatment approach. / Master of Science
63

Selection of the zeo-karb Na and zeo-karb H carbonaceous zeolite system for water treatment at the Virginia Polytechnic Institute power plant

Gudaitis, Peter P. 26 April 2010 (has links)
A number of investigations have been undertaken with the object of replacing the present water treatment system at the Virginia Polytechnic Institute Power Plant. / Master of Science
64

Čištění komunálních odpadních vod v domovních kořenových čistírnách - hygienické aspekty a možnosti využití v podmínkách ČR / Wastewater Treatment Using House Sewage Treatment Plants {--} Hygienic Aspects and Usage in the Czech Republic

FIŠEROVÁ, Alena January 2009 (has links)
Constructed wetlands (CWs) originate from natural wetlands and are used for waste water treatment as an alternative to conventional treatment. This thesis was aimed at providing a literary summary of the types of house sewage water treatment plants and constructed wetlands used in the CR and abroad, of their hygienic aspects, functionality, treatment efficiency, expensiveness and the possibilities of their use in the conditions of the CR and their advantages and disadvantages. It also deals with a proposal of a suitable type of house CW for the conditions of the CR and a list of the necessary steps in construction of a house CW. Quite similar systems are being used for house sewage treatment in the Czech Republic and abroad {--} mostly septic tanks, ground mounds, constructed wetlands, active treatment plants and biodiscs. Alternative water treatment methods are generally not suitable for buildings having (now or in the future) the possibility of connection to municipal sewerage systems. They are on the other hand suitable for buildings not connected to sewerage systems or for seasonal objects, remote places and holiday houses with seasonal waste water production. A system with horizontal subsurface flow is mostly used as a CW in the Czech Republic. This CW type ensures sufficient removal of organic contamination and insoluble substances, but the efficiency of nitrogen and phosphorus removal is relatively low. However it is fully sufficient in the instance of low PE numbers, as the loading rate is usually low and the concentration of contaminants in the output water meets the prescribed limits. Foreign researches show that hybrid systems combining horizontal flow with vertical flow and with recirculation are more suitable for improving efficiency of nitrogen removal. Systems with vertical flow and intermittent waste water dosage showing particularly good results in ammoniac removal are also suitable for nitrogen removal. Special materials with higher iron, aluminium or calcium content are most suitable as filling of a constructed wetland or as additional filters or for improvement of phosphorus removal from waste water as they are able to reach efficiency of up to 90 %. In my thesis I came to a conclusion that a CW with horizontal subsurface flow is the most suitable type of house constructed wetland treatment for the conditions in the CR, mainly because it is the most frequently used and thus best proven CW type with sufficient efficiency of treatment for the substances required by standards.
65

Achieving effective asset management for water and wastewater utilities: A comparison of policy options for a special district and a medium city

Dale, Cari K 01 January 2005 (has links)
This project developed a model for effective asset management drawn from successful programs in the United States, Australia, and New Zealand. Asset management practices were examined at the City of Ontario Utilities Department; a medium sized utility, and also at the Rainbow Municipal Water District, a small sized utility. Gaps between the ideal model and the existing practices were investigated.
66

Determinants of key drivers for potable water treatment cost in uMngeni Basin

Rangeti, Innocent 04 March 2015 (has links)
Submitted in fulfilment of the requirements of the degree of Master of Technology: Environmental Health, Durban University of Technology, 2014. / The study entailed the determination of key water quality parameters significantly influencing treatment cost in uMngeni Basin. Chemical dosage was used as a substitute for treatment cost as the study indicated that cost, in its monetary value, is influenced by market forces, demand and supply, which are both not directly linked to water quality. Chemical dosage is however, determined by the quality of water and thus provides a clear illustration of the effect of pollution on treatment cost. Three specific objectives were set in an effort to determine key water quality parameters influencing treatment costs in uMngeni Basin. The fourth objective was to develop a model for predicting chemical dosages. The first approach was analysis of temporal and spatial variability of water quality in relation to chemical dosage during production of potable water. The trends were explained in relation to river health status. For this purpose, time-series, box-plot, and the Seasonal-Kendal test were employed. The results showed that the quality of water significantly deteriorated from upstream to downstream in relation to algae, turbidity and Escherichia coli (E. coli). High mean range of E. coli (126-1319 colony count/100mL) and turbidity (2.7-38.7 NTU) observed indicate that the quality of water along the basin is not fit for human consumption as these parameters exceeded the target range stipulated in South Africa’s guidelines for domestic use. For water intended for drinking purpose, turbidity should be below 5 NTU, while zero E. coli count is expect in 100 mL. Among the six sampling stations considered along the uMngeni Basin, three dam outflows (Midmar, Nagle and Inanda) showed an improved quality compared with their respective inflow stations. This was expected and could be attributed to the retention and dilution effects. These natural processes help by providing a self-purification process, which ultimately reduces the treatment cost. While considering the importance of disseminating water quality information to the general public and non-technical stakeholders, the second objective of the study was to develop two water quality indices. These were; (1) Treatability Water Quality Index and (2) River Health Water Quality Index. The Treatability Water Quality Index was developed based on the Canadian Council Minister of Environment Water Quality Index (CCME-WQI). The technique is used to determine fitness of water against a set of assigned water quality resource objectives (guidelines). The calculated Harmonised Water Quality Resource Objectives (HWQRO) were used to compare the qualities of the raw water being abstracted at Nagle and Inanda Dam for the purpose of treatment. The results showed that Nagle Dam, which supplies Durban Heights, is significantly affected by E. coli (42% non-compliance), turbidity (20% non-compliance) and nitrate (18% non-compliance) levels. Wiggins Water Treatment Plant which abstracts from Inanda Dam has a problem of high algae (mean 4499 cell/mL), conductivity (mean 26.21 mS/m) and alkalinity (mean 62.66 mg/L) levels. The River Health Water Quality Index (RHWQI) was developed using the Weighted Geometric Mean (WQM) method. Eight parameters, namely, E. coli, dissolved oxygen, nitrate, ammonia, turbidity, alkalinity, electrical conductivity and pH were selected for indexing. Rating curves were drawn based on the target ranges as stipulated in South Africa’s guidelines for freshwater ecosystems. Five classes were used to describe the overall river health status. The results showed that the water is still acceptable for survival of freshwater animals. A comparison of the RHWQI scores (out of 100) depicted that dam inflow station (MDI(61.6), NDI(74.6) and IDI(63.8)) showed a relatively deteriorated quality as compared with their outflows (MDO(77.8), NDO(74.4) and IDO(80)). The third objective was to employ statistical analysis to determine key water quality parameters influencing chemical dosage at Durban Heights and Wiggins Water Treatment Plants. For each of the two treatment plants, treated water quality data-sets were analysed together with their respective raw water data-set. The rationale was to determine parameters showing concentration change due to treatment. The t-test was used to determine the significance of concentration change on each of the 23 parameters considered. Thereafter, the correlations between water quality parameters and the three chemicals used during treatment (polymer, chlorine and lime) were analysed. The results showed that the concentrations of physical parameters namely, algae, turbidity and total organic carbon at both treatment showed a significant statistical (p<0.05) reduction in concentration (R/Ro<0.95). This results implies that such parameters were key drivers for chemical dosage. From the results of the first three objectives, it is recommended that implementing measures to control physical parameter pollution sources, specifically sewage discharges and rainfall run-off from agricultural lands along the uMngeni Basin should assist in reducing the chemical dosage and ultimately cost. The fourth objective was to develop chemical dosage models for prediction purposes. This was achieved by employing a polynomial non-linear regression function on the XLStat 2014 program. The resultant models showed prediction power (R2) ranging from 0.18 (18%) up to 0.75 (75%). However, the study recommends a comparative study of the developed models with other modelling techniques.
67

Environnmental life cycle assessment of potable water production.

Friedrich, Elena. January 2001 (has links)
This study investigates and compares the environmental burdens of two different methods for producing potable water by using the environmental life cycle assessment (LCA). The first method, for the production of potable water, is used by Umgeni Water at their Wiggins Waterworks and it involves conventional processes. The second method is based on a South African membrane technology and currently it is used in three pilot plants around the country. The life cycle concept gives the means understand the environmental impacts associated with a product. process or activity by considering all life-cycle stages, from cradle- to-grave. Formal methodologies for conducting such studies have been developed and in this project the methodological framework endorsed by the International Organisation for Standardisation (ISO) 14040 series of standards has been used. By using this methodology and by tracing all processes involved in the production of potable water, it was found that the main contribution towards the environmental burdens of potable water is due to electricity generation. This conclusion is valid for both methods in vestigated. and as a result the recommendations focus on increasing the energy efficiency of waterworks in order to increase their overall environmental performance. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2001.
68

Diagnóstico dos resíduos gerados em estações de tratamento de água nas bacias dos rios Piracicaba, Capivari e Jundiaí - SP

Vilella, Alexandre Luis Almeida 20 July 2011 (has links)
Made available in DSpace on 2016-06-02T20:00:38Z (GMT). No. of bitstreams: 1 3860.pdf: 7904482 bytes, checksum: fcce0b9ff411b2bc48b7a967806bdb8c (MD5) Previous issue date: 2011-07-20 / The basins of Piracicaba, Capivari and Jundiaí has a territory of 15,304 square kilometers, about 5.2 million inhabitants, 7% of gross national product. However, the scarcity of water resources threatens all this prosperity. The uses of water have led to conflicts because of its multiple and diverse purposes, which require different quantities and qualities. It is against this background that becomes fundamental to understand the current situation of water supply and waste management from the treatment process. The mobilization of society, awareness of public officials and increase the availability of financial resources for the sanitation sector have provided the municipalities to increase their rates of water treatment, through the construction of new structures and technological innovations, however, has aroused another focus attention to the urgent need for the systemic management of waste from water treatment plants, especially the generation, treatment and disposal of sludge and its actual and potential environmental impacts. This research has made diagnosis of generation under the quantitative aspect of the sludge generated in the 89 water treatment plants operating in 58 cities, and identify some experiences about the management. Through various methodological tools, such as the use of questionnaires for data collection to obtain primary data, the paper presents and discusses information about the current generation of waste, existing experiences regarding the disposal and treatment, and the challenges issue requires to be addressed. The results pointed that 9013.20 tons of monthly dry solids are generated, with prominence the one that 70% of plants in operation don't possess any of measurement of the muds system. The realities, front to the service of the effective legislations, training lack and the managers systemic administration and operators on the theme as well as the need of the integration of the sectorial politics with the operation of the systems of water supply that are the great challenges to be overcome. / As bacias hidrográficas dos Rios Piracicaba, Capivari e Jundiaí possuem um território de 15.304 Km², cerca de 5,2 milhões de habitantes, 7% do Produto Interno Bruto Nacional. No entanto, a escassez dos recursos hídricos ameaça toda essa prosperidade. Os usos da água têm gerado conflitos em razão de sua multiplicidade e finalidades diversas, as quais demandam quantidades e qualidades diferentes. É diante desse panorama que se torna fundamental o conhecimento do cenário atual do abastecimento de água e a gestão dos resíduos oriundos do processo de tratamento. A mobilização da sociedade, a conscientização dos gestores públicos e o aumento da disponibilidade de recursos financeiros para o setor de saneamento têm proporcionado que os municípios aumentem os seus índices de tratamento de água, através da construção de novas estruturas e inovações tecnológicas, entretanto, tem despertado a atenção para outro foco, a premente necessidade da gestão sistêmica dos resíduos oriundos das estações de tratamento de água, com destaque a geração, tratamento e disposição dos lodos e seus potenciais e efetivos impactos ambientais. Este trabalho procurou diagnosticar a geração sob o aspecto quantitativo dos lodos gerados em 89 ETAs em operação nos 58 municípios paulistas integrantes da UGRHI n.° 5, além de identificar algumas experiências quanto ao gerenciamento. Através de diversos instrumentos metodológicos, como a utilização de questionários de coleta de dados para obtenção de dados primários, a adoção de métodos teóricos, visitas técnicas, o trabalho apresenta e discute as informações acerca da geração atual desses resíduos, as experiências existentes quanto à destinação final e tratamento, além dos desafios que a temática exige a serem enfrentados. Os resultados apontaram que são gerados 9013,20 toneladas de sólidos secos mensais, com destaque a que 70% das ETAs em operação não possuem sistema algum de medição dos lodos. As realidades, frente ao atendimento das legislações vigentes, carência de capacitação e gestão sistêmica dos gestores e operadores sobre a temática bem como a necessidade da integração das políticas setoriais com a operação dos sistemas de abastecimento de água que se demonstraram como grandes os desafios a serem superados.
69

Segurança e higiene do trabalho em estações de tratamento de agua / Work and hygiene safety in water treatment plants

Causo Neto, João Pedro, 1952- 23 August 2006 (has links)
Orientador: Bruno Coraucci Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-09T18:42:30Z (GMT). No. of bitstreams: 1 CausoNeto_JoaoPedro_M.pdf: 2741267 bytes, checksum: 87cf7d40717c076cc3bf742697e76d87 (MD5) Previous issue date: 2006 / Resumo: Em locais com atividades humanas, tais como nas Estações de Tratamento de Água (ETA), há muitos fatores causadores de acidentes: uso de ferramentas diversas, máquinas ruidosas e sem proteções em partes móveis, substâncias químicas, pisos escorregadios ou irregulares, elementos energizados desprotegidos e ingresso em áreas com oxigênio insuficiente. Estes fatores, se previamente constatados, podem ser controlados, evitando danos à integridade física dos profissionais. Buscou-se, neste estudo, a identificação dos principais riscos no trabalho em ETAs e, através de parâmetros macro, o cumprimento da legislação de saúde e segurança nesta atividade. A metodologia consistiu na aplicação e análise de questionário específico, envolvendo técnicos de 45 empresas operadoras de ETAs no Estado de São Paulo, e em visitas técnicas a nove estações de tratamento. Concluiu-se que grande parte dos acidentes decorre do não atendimento, de forma plena, das obrigações e programas contidos nas normas regulamentadoras existentes na legislação brasileira, e pela necessidade de melhorar o sistema de registro dos acidentes / Abstract: In places with human activities, such as Water Treatment Plants (WTP), there are many factors which can cause accidents: the use of various tools, noisy machinery without protection on mobile parts, chemical substances, slippery or irregular floors, unprotected electric devices, and entrance in unenough oxygenated places. When previously identified, these factors can be manipulated to avoid damages to the physical integrity of professionals. In this study, the identification of the main factors of risk were looked for, while working at WTP, and the compliance with health and safety regulation through the macro parameters. The methodology consisted of an application and analysis of a specific questionnaire, involving technicians of 45 enterprising operators of WTP in the São Paulo State, and in technical visits to nine treatment stations. It was concluded that a major part of accidents happened for lack of attendance, in a overall manner, upon obligations and programs included in the existing regulation norms in the Brazilian legislation, and by the necessity of bettering the system of accidents register / Mestrado / Saneamento e Ambiente / Mestre em Engenharia Civil
70

Étude de l'impact des effluents urbains sur la qualité des eaux de la Garonne estuarienne : application aux composés pharmaceutiques et aux filtres UV / Occurrence and fate of pharmaceuticals and UV filters in urban effluents and in the estuarian Garonne River

Aminot, Yann 06 December 2013 (has links)
Dans le contexte de la contamination quasi-généralisée des eaux de surface par les médicaments, les travaux de cette thèse portent sur l’étude des niveaux de concentration et du devenir de ces micropolluants organiques dans la Garonne estuarienne, recevant les effluents traités de l’agglomération bordelaise. Après le développement et la validation des outils analytiques associés à la détection multi-résidus dans les matrices eau et sédiment, la composition et la variabilité des effluents urbains bordelais ont été caractérisées, avant et après traitement en station d’épuration. La contamination globale des compartiments eau, matières en suspension et sédiment a ensuite été évaluée sur une rivière périurbaine de l’agglomération. Par ailleurs, le suivi réalisé en Gironde montre l’importance relative des apports amont et urbains et met en évidence la dégradation in-situ de certains médicaments, par ailleurs confirmée par une expérience d’incubation d’eau estuarienne réalisée in-vitro. / Ubiquitous presence of pharmaceuticals in the environment is of great concern. In this Ph.D. work, occurrence and fate of these organic contaminants were studied in the estuarine Garonne River, receiving treated effluents of the Bordeaux urban area (France). After developing and validating the analytical methods for multi-residue detection of 53 pharmaceuticals in water and sediment, composition and variability of the Bordeaux wastewater treatment plant influents and effluents were characterized. Presence of analytes in river water, suspended solids and sediments was then investigated on a periurban river located in the suburbs of Bordeaux. Besides, a long-term monitoring of estuarine Garonne River revealed the relative importance of local and upstream inputs and clearly showed a seasonal in-situ degradation of certain pharmaceuticals. This degradation was further confirmed and examined through batch experiments simulating the mixing conditions of wastewater and estuarine river water, highlighting the importance of suspended solid concentration in biodegradation rates.

Page generated in 0.5191 seconds