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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.
1

Investigating the Role of Various Environment and Process Conditions in Wastewater Sludge Odor Generation

Subramanian, Sivarangan Rahul 05 November 2004 (has links)
Dewatered sludges and biosolids generated from wastewater treatment facilities are known to emit malodorous odors causing public inconvenience. The odors typically comprise of reduced organo sulfur based compounds and nitrogen containing compounds. Lime stabilization is a technique which is commonly used in the wastewater industry to produce biosolids having reduced odors that can be safely land disposed. In this research, odors produced from dewatered sludges and lime stabilized biosolids were investigated. Lime dosing and incorporation in sludge play an important role in generation of reduced sulfur and trimethylamine (TMA) odor compounds. Results revealed that poor lime dosing can lead to an increase in odors due to biological generation of volatile sulfur compounds (VSCs) during storage. In this study, a belt filter press gave a higher production of sulfur and TMA odors compared to a vacuum filter for the same sludge, which is attributed to the shear imparted to sludge during the dewatering process. Preliming studies suggested incomplete mixing of lime with sludge led to biological activity. The achievement of the correct pH and its maintenance during storage is considered critical for effective odor management from lime stabilized biosolids. A positive linear relation was obtained between sulfur based odor production and labile protein content in sludge. Furthermore, as the Al/Fe ratio increased, the labile proteins was observed to decrease. Trivalent metals are found to play an important role in binding of labile proteins thus effecting odor potential contained in sludge/biosolids. This was found true for most sludge irrespective of their liming status and independent of upstream process conditions. Further work in this area is needed to be able to provide a better understanding of odor production to aid in development of odor control techniques. Trimethylamine odors, having a characteristic fishy odor, are commonly found in lime stabilized biosolids. Cationic polymers used as dewatering aids are the primary precursors for TMA production. Proteins present in sludge are also associated with odor forming compounds but they produce much lower levels than polymers. These two components under the action of shear present in dewatering devices such as centrifuge are more likely to cause an increase in odor production from lime stabilized biosolids. It was also determined that abiotic polymer degradation to produce TMA either does not occur, or the rate is so slow that TMA production in this way is insignificant for actual field situations. / Master of Science
2

Modeling Volatile Organic Sulfur Compounds In Anaerobic Digestion

Du, Weiwei January 2010 (has links)
Anaerobic digestion is a common process for treatment of wastewater sludge from municipal sewage systems. Volatile sulfur compounds, including volatile organic sulfur compounds (VOSCs) and hydrogen sulfide, have been reported as the most odorous compounds in digestion emissions and impurities which can damage facilities for generation, transportation, storage, and utilization of biogas. There has been no comprehensive study on biological generation and degradation kinetics of VOSC or modeling VOSC behaviors through anaerobic sludge digestion. The goal of the present study was to establish a model for VOSC conversions in anaerobic sludge digestion which could facilitate quantitative analysis of VOSC emissions in anaerobic digestion. VOSCs and methionine were employed in dosed batch tests. VOSC conversion processes in anaerobic methionine digestion have been identified. The kinetics for the identified VOSC degradation and conversion processes were determined at 35 and 55 °C respectively. Mixed-second order kinetics were found to best fit the conversion processes. A model was established based on the identified processes and estimated kinetic constants. To extend the model to VOSC release in anaerobic sludge digestion, mesophilic and thermophilic incubations were conducted with four different sludge samples. The effects of temperature and sludge source on VOSC release patterns were assessed. It was found that an unidentified DMS generation mechanism was triggered in the mesophilic incubation of activated sludge in which iron was dosed. To apply the model which was established based on methionine degradation in sludge digestion, hydrolysis of particulate materials was incorporated. The model simulations for VOSC behavior in thermophilic batch incubation were able to represent the observed VOSC releases. However, the simulations could not well fit the observed VOSC release at 35 ° because the model did not include the unidentified DMS generation mechanism. Application of the model to bench-scale digesters was lack-of-fit. It may have been due to imprecise estimation of the degradable sulfur in the feed sludge. In addition, in the batch tests and digester operation the ratios of the raw and digested sludge were different. This might have resulted in different concentrations of the microorganisms which mediated biotransformations and hence resulted in different kinetic constants.
3

Modeling Volatile Organic Sulfur Compounds In Anaerobic Digestion

Du, Weiwei January 2010 (has links)
Anaerobic digestion is a common process for treatment of wastewater sludge from municipal sewage systems. Volatile sulfur compounds, including volatile organic sulfur compounds (VOSCs) and hydrogen sulfide, have been reported as the most odorous compounds in digestion emissions and impurities which can damage facilities for generation, transportation, storage, and utilization of biogas. There has been no comprehensive study on biological generation and degradation kinetics of VOSC or modeling VOSC behaviors through anaerobic sludge digestion. The goal of the present study was to establish a model for VOSC conversions in anaerobic sludge digestion which could facilitate quantitative analysis of VOSC emissions in anaerobic digestion. VOSCs and methionine were employed in dosed batch tests. VOSC conversion processes in anaerobic methionine digestion have been identified. The kinetics for the identified VOSC degradation and conversion processes were determined at 35 and 55 °C respectively. Mixed-second order kinetics were found to best fit the conversion processes. A model was established based on the identified processes and estimated kinetic constants. To extend the model to VOSC release in anaerobic sludge digestion, mesophilic and thermophilic incubations were conducted with four different sludge samples. The effects of temperature and sludge source on VOSC release patterns were assessed. It was found that an unidentified DMS generation mechanism was triggered in the mesophilic incubation of activated sludge in which iron was dosed. To apply the model which was established based on methionine degradation in sludge digestion, hydrolysis of particulate materials was incorporated. The model simulations for VOSC behavior in thermophilic batch incubation were able to represent the observed VOSC releases. However, the simulations could not well fit the observed VOSC release at 35 ° because the model did not include the unidentified DMS generation mechanism. Application of the model to bench-scale digesters was lack-of-fit. It may have been due to imprecise estimation of the degradable sulfur in the feed sludge. In addition, in the batch tests and digester operation the ratios of the raw and digested sludge were different. This might have resulted in different concentrations of the microorganisms which mediated biotransformations and hence resulted in different kinetic constants.
4

Efeito do tratamento periodontal full-mouth e convencional na redução da halitose / Effect of periodontal treatment full-mouth and conventional in the reduction of halitosis

Léo Guimarães Soares 03 June 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A halitose se caracterizada pela emanação de um odor desagradável onde cerca de 90% de se origina dentro da cavidade oral. Estudos têm demonstrado uma relação direta entre a doença periodontal e o odor ofensivo do hálito. O presente estudo teve como objetivo avaliar a frequência e distribuição de halitose em um grupo de pacientes com doença periodontal em um estudo transversal observacional (n=112) e, em um estudo intervencionista, avaliar o efeito do tratamento periodontal full-mouth e convencional na redução da halitose em um grupo de pacientes com doença periodontal. Os pacientes responderam a uma anamnese, tiveram seu hálito mensurado pelo halímetro e teste organoléptico, além de realizados Índice de placa visível, Índice de sangramento gengival, Índice de saburra lingual e exame periodontal completo. No estudo 2, os pacientes foram submetidos a seis distintas formas de tratamento: terapia periodontal em sessão única, terapia convencional em quadrantes e, um grupo controle, com somente instrução de higiene oral. Todas as modalidades subdivididas: com e sem raspagem lingual diária. No primeiro estudo os resultados mostraram que, tanto para teste organoléptico quanto para o halímetro, houve maior grau de halitose nos grupos de idades mais avançadas, nos que relataram sangramento gengival e escovação menos que três vezes ao dia. Ainda no teste organoléptico a escovação de língua gerou diferença estatística. Não houve diferença estatística entre as medidas de halitose entre teste organoléptico e halímetro. Foram encontrados aproximadamente 75% de pacientes periodontais com halitose. No segundo estudo os resultados mostraram superioridade conforme análise do halímetro para 30, 60 e 90 dias para os grupos de raspagem em sessão única contra raspagem por quadrantes. Sendo todos os grupos superiores ao controle. Não houve diferença na abordagem com ou sem a raspagem de língua. De acordo com o teste organoléptico, não houve diferença entre os quatro tipos de tratamento periodontal comparados aos grupos controle. O mesmo aplica-se ao WTCI, onde os grupos de tratamento foram superiores ao controle, todavia semelhantes entre si. Concluiu-se que a idade e o sangramento gengival, assim como a frequência de escovação podem influenciar no grau de halitose, tanto no teste organoléptico quanto halímetro. A escovação de língua mostrou-se superior apenas na avaliação organoléptica. Quando avaliado através do halímetro o tratamento full-mouth foi superior ao tratamento convencional. Esta diferença não foi observada quando avaliado através do método organoléptico. Todas as modalidades de tratamento periodontal foram superiores aos grupos controle. A raspagem lingual não teve influência nos tratamentos. / Halitosis is characterized by the emission of an unpleasant odor about 90% originates in the oral cavity. Studies have shown a direct relationship between periodontal disease and the offensive odor of breath. The present study aimed to determine the prevalence of halitosis in patients with periodontal disease in an observational cross-sectional study (n = 112) and, in an intervention study, the patients have had six distinct forms of treatment (n = 90) to verify the efficacy of full- vs. partial-mouth disinfection in the control of halitosis. Patients answered an interview, they have had their breath collected by halimeter, they have evaluated by organoleptic test, and visible plaque index, gingival bleeding index, index of tongue coating and periodontal examination. In the second step, patients have been submitted to six different forms of treatment: periodontal therapy in one session, conventional therapy in quadrants, and the control group, with only oral hygiene instruction. All types split: with and without tongue scraping daily. The first study results shown for both organoleptic test as halimeter, a greater degree of halitosis in the older age groups, we have reported that gum bleeding and brushing less than three times per day. Still in organoleptic test brushing of tongue generated statistical difference. There was no statistical difference between the measures between halitosis and organoleptic test halimeter. There was about 75% og periodontal patients with halitosis. In the second study the results shown the superiority analysis as halimeter for 30, 60 and 90 days for groups of scraping in single session against scraping by quadrants. Being all groups superior from control. There was no difference in approach with or without tongue scraping. According to the organoleptic test, there was no difference between the four types of periodontal treatment compared to the control groups. The same applies to WTCI, the treatment groups were superior to the control, but similar to each other. It was concluded that age and gingival bleeding, like brushing frequency can influence the degree of halitosis, both the organoleptic test as halimeter. Brushing the tongue was superior only in organoleptic evaluation. When assessed by halimeter treatment full-mouth was superior to conventional treatment. This difference was not observed when measured by the organoleptic method. All periodontal treatment modalities were superior to control groups. Scraping lingual had no influence on treatments.
5

Efeito do tratamento periodontal full-mouth e convencional na redução da halitose / Effect of periodontal treatment full-mouth and conventional in the reduction of halitosis

Léo Guimarães Soares 03 June 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A halitose se caracterizada pela emanação de um odor desagradável onde cerca de 90% de se origina dentro da cavidade oral. Estudos têm demonstrado uma relação direta entre a doença periodontal e o odor ofensivo do hálito. O presente estudo teve como objetivo avaliar a frequência e distribuição de halitose em um grupo de pacientes com doença periodontal em um estudo transversal observacional (n=112) e, em um estudo intervencionista, avaliar o efeito do tratamento periodontal full-mouth e convencional na redução da halitose em um grupo de pacientes com doença periodontal. Os pacientes responderam a uma anamnese, tiveram seu hálito mensurado pelo halímetro e teste organoléptico, além de realizados Índice de placa visível, Índice de sangramento gengival, Índice de saburra lingual e exame periodontal completo. No estudo 2, os pacientes foram submetidos a seis distintas formas de tratamento: terapia periodontal em sessão única, terapia convencional em quadrantes e, um grupo controle, com somente instrução de higiene oral. Todas as modalidades subdivididas: com e sem raspagem lingual diária. No primeiro estudo os resultados mostraram que, tanto para teste organoléptico quanto para o halímetro, houve maior grau de halitose nos grupos de idades mais avançadas, nos que relataram sangramento gengival e escovação menos que três vezes ao dia. Ainda no teste organoléptico a escovação de língua gerou diferença estatística. Não houve diferença estatística entre as medidas de halitose entre teste organoléptico e halímetro. Foram encontrados aproximadamente 75% de pacientes periodontais com halitose. No segundo estudo os resultados mostraram superioridade conforme análise do halímetro para 30, 60 e 90 dias para os grupos de raspagem em sessão única contra raspagem por quadrantes. Sendo todos os grupos superiores ao controle. Não houve diferença na abordagem com ou sem a raspagem de língua. De acordo com o teste organoléptico, não houve diferença entre os quatro tipos de tratamento periodontal comparados aos grupos controle. O mesmo aplica-se ao WTCI, onde os grupos de tratamento foram superiores ao controle, todavia semelhantes entre si. Concluiu-se que a idade e o sangramento gengival, assim como a frequência de escovação podem influenciar no grau de halitose, tanto no teste organoléptico quanto halímetro. A escovação de língua mostrou-se superior apenas na avaliação organoléptica. Quando avaliado através do halímetro o tratamento full-mouth foi superior ao tratamento convencional. Esta diferença não foi observada quando avaliado através do método organoléptico. Todas as modalidades de tratamento periodontal foram superiores aos grupos controle. A raspagem lingual não teve influência nos tratamentos. / Halitosis is characterized by the emission of an unpleasant odor about 90% originates in the oral cavity. Studies have shown a direct relationship between periodontal disease and the offensive odor of breath. The present study aimed to determine the prevalence of halitosis in patients with periodontal disease in an observational cross-sectional study (n = 112) and, in an intervention study, the patients have had six distinct forms of treatment (n = 90) to verify the efficacy of full- vs. partial-mouth disinfection in the control of halitosis. Patients answered an interview, they have had their breath collected by halimeter, they have evaluated by organoleptic test, and visible plaque index, gingival bleeding index, index of tongue coating and periodontal examination. In the second step, patients have been submitted to six different forms of treatment: periodontal therapy in one session, conventional therapy in quadrants, and the control group, with only oral hygiene instruction. All types split: with and without tongue scraping daily. The first study results shown for both organoleptic test as halimeter, a greater degree of halitosis in the older age groups, we have reported that gum bleeding and brushing less than three times per day. Still in organoleptic test brushing of tongue generated statistical difference. There was no statistical difference between the measures between halitosis and organoleptic test halimeter. There was about 75% og periodontal patients with halitosis. In the second study the results shown the superiority analysis as halimeter for 30, 60 and 90 days for groups of scraping in single session against scraping by quadrants. Being all groups superior from control. There was no difference in approach with or without tongue scraping. According to the organoleptic test, there was no difference between the four types of periodontal treatment compared to the control groups. The same applies to WTCI, the treatment groups were superior to the control, but similar to each other. It was concluded that age and gingival bleeding, like brushing frequency can influence the degree of halitosis, both the organoleptic test as halimeter. Brushing the tongue was superior only in organoleptic evaluation. When assessed by halimeter treatment full-mouth was superior to conventional treatment. This difference was not observed when measured by the organoleptic method. All periodontal treatment modalities were superior to control groups. Scraping lingual had no influence on treatments.
6

Avaliação da relação entre estresse e a concentração de compostos sulfurados volateis no halito bucal

Queiroz, Celso Silva 13 December 1999 (has links)
Orientador: Jaime Aparecido Cury / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-25T22:05:28Z (GMT). No. of bitstreams: 1 Queiroz_CelsoSilva_M.pdf: 4148499 bytes, checksum: a250fc32bc9b3c95e74bc4505b1ca920 (MD5) Previous issue date: 1999 / Resumo: O objetivo do trabalho foi avaliar a relação entre o estresse e a concentração dos compostos sulfurados voláteis (CSV) no hálito bucal. Para tanto, foram avaliadas duas condições estressantes: Estudo I - prova; Estudo II - tensão pré-menstrual (TPM). O Estudo I foi composto de 2 grupos: A e B. O grupo A (34 voluntários), foi subdividido em 18 voluntários com estresse e 16 voluntários sem estresse. As concentrações dos CSV e foram medidas 1 semana antes da prova, no dia e 1 semana após, através do monitor de sulfetos (Halimeter) e o fluxo salivar também foi mensurado. No grupo B (37 voluntários), além dessas análises foram mensurados o pH, "capacidade tampão", cálcio, fósforo e proteína na saliva. O Estudo II foi composto por 50 voluntárias: 27 mulheres sem TPM (controle) e 23 mulheres com TPM. As mensurações dos CSV e do fluxo salivar foram realizadas nos períodos não-menstrual, pré-menstrual e de menstruação. A análise estatística mostrou que tanto no Grupo A (n=34) quanto no Grupo B (n=37) a concentração dos CSV no dia da prova foi maior (p<0,05) enquanto que a taxa de fluxo salivar foi menor (p<0,05). Os voluntários com estresse (n=18) e sem estresse (n=16) também apresentaram maiores concentrações de CSV no dia da prova (p<0,05), enquanto o fluxo salivar foi menor somente nos voluntários não estressados (p<0,05). A análise bioquímica da saliva do Grupo B revelou - que o pH foi menor no dia da prova (p<0,05), e as demais análises não foram diferentes (p>0,05). No Estudo II, as voluntárias sem TPM (n=26) apresentaram maior concentração dos CSV no período menstrual (p<0,05). Enquanto nas voluntárias com TPM (n=23) a concentração dos CSV foi maior (p<0,05) nos períodos menstrual e pré-menstrual. Já o fluxo salivar não mostrou diferenças (p>0,05). Os resultados sugerem que o estresse é um fator pré-disponente da halitose, cujo mecanismo não pode ser explicado somente pela diminuição do fluxo salivar / Abstract:The aim of study was to evaluate the relationship between stress and volatile sulfur compounds (VSC) present in mouth air. Thus, two stressfull conditions were evaluated: Study 1- examination; Study II - premenstrual syndrome (PMS). Study I was composed of 2 groups: A and B. Group A (34 volunteers), was divided in 18 volunteers with stress and 16 volunteers without stress. VSC concentrations were measured a week before, on day and a week after the exam using a sulfide monitor (Halimeter) and the salivary flow was measured. In group B (37 volunteers), others analyisis as pH, "buffer capacity", proteins, calcium and phosphorus, in saliva were performed. In study II, fifty women were selected: 27 women without PMS symptoms (control group) and 23 women with PMS symptoms. The measurements were performed during non-menstrual, PMS and menstrual periods. The statistical results showed in both groups A and B an increase of VSC concentration on the exam day (p<0.05) and the salivary flow was lower (p<0.05). Volunteers with stress (n=18) and without stress (n=16), presented higher VSC concentration on the exam (p<0.05), but there was statistical diferences in the salivary flow rate only in the volunteers without stress (p<0.05). The biochemistry analisys of the saliva in group B showed that pH was lower on the exam day (p<0.05), and others analisys were not statistical differences (p>0.05). In study II, the volunteers without PMS symptoms (n=26) presented higher VSC concentration in the menstrual period (p<0.05). Volunteers with PMS (h=23) showed a greater VSC concentration in both menstrual and PMS periods (p<0.05). Salivary flow rate was not statistically different (p>0.05). The results suggest that stressful conditions can be a predisposing factor for bad breath, and the mechanism cannot be explained only by the decrease of the salivary flow / Mestrado / Fisiologia Oral / Mestre em Odontologia

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