Neste estudo foi avaliado o potencial tóxico de diferentes desinfetantes (cloro, ácido peracético, radiação ultravioleta e ozônio) utilizados na desinfecção de esgotos sanitários. Para tanto, foram realizados ensaios de desinfecção (em diversas concentrações e tempos de contato) com o esgoto doméstico originário da estação de tratamento de esgotos da cidade de Araraquara (SP) e, posteriormente, ensaios de toxicidade a fim de verificar possíveis efeitos agudos e crônicos nos seguintes organismos-teste: Daphnia similis, Ceriodaphnia silvestrii, Chironomus xanthus, Danio rerio e Allium cepa. Todos os desinfetantes, nas condições experimentais testadas, foram capazes de produzir efeitos deletérios aos organismos-teste utilizados nesta pesquisa. O cloro foi considerado o desinfetante mais tóxico, sendo seguido pelo ozônio, ácido peracético e radiação UV. Verificou-se ainda que quando o efluente não desinfetado foi tóxico aos organismos-alvo, sua toxidez foi potencializada com a adição dos diferentes agentes desinfetantes. Os resultados obtidos neste estudo sugerem que a utilização do cloro para desinfecção de esgotos sanitários, sem prévia descloração, deve ser revista, em face da eficiência satisfatória de inativação de bactérias proporcionada por outros agentes de desinfecção potencialmente menos tóxicos (tais como o ácido peracético e a radiação UV). / In this study, it was evaluated the toxic potential of different disinfectant agents (chlorine, peracetic acid, ultraviolet radiation and ozone) used in the disinfection of urban wastewater. For so much, disinfection assays were accomplished (in several concentrations and contact times) with the domestic sewage from Araraquara city (SP) and toxicity bioassays were developed in order to verify possible acute and chronic effects in the following test-organisms: Daphnia similis, Ceriodaphnia silvestrii, Chironomus xanthus, Danio rerio and Allium cepa. All the disinfectants, in the tested experimental conditions, were capable to produce harmful effects to the test-organisms used in this research. Chlorine was considered the most toxic disinfectant, being followed by ozone, peracetic acid and UV radiation. It was noticed that when the effluent, by itself, was toxic to the test-organism, its toxicity was increased with the different disinfecting agents\' addition. The results obtained in this study suggest that the use of chlorine as a wastewater disinfectant, without previous dechlorination, should be reviewed, because it was observed that other disinfection agents (such as peracetic acid and UV radiation) were able to promote satisfactory levels of bacteria inactivation for potentially less toxicity.

Esta pesquisa foi realizada com o objetivo de avaliar a eficácia do ácido peracético ou peroxiacético (APA) a 0,2% na desinfecção de instrumentos contaminados pela microbiota oral. Uma coleta foi realizada com instrumento termolábil usado comumente em alguns procedimentos odontológicos. A coleta foi realizada em quatro sítios da cavidade oral: mucosa jugal (lados direito e esquerdo), palato duro e dorso da língua em trinta pacientes, com quatro instrumentos diferentes para cada local. Cada um dos quatro instrumentos passou por quatro tratamentos diferentes, sendo divididos em quatro grupos: A (sem nenhum tratamento), B (tratamento com APA), C (lavagem com água e detergente) e D (lavagem com água e detergente e tratamento com APA). Após os tratamentos, cada instrumento foi colocado em solução salina estéril para extração dos microrganismos. Diluições da solução salina foram colocadas em placas de Petri contendo meio ágar caseína de soja ou ágar Sabouraud dextrose e incubadas de modo a favorecer, respectivamente, a anaerobiose e aerobiose ou o crescimento de bolores e leveduras. Foi realizada a contagem das unidades formadoras de colônia (UFC) e aplicados o teste ANOVA e o Teorema de Bonferroni para todas as culturas separadamente e conjuntamente para toda a microbiota oral Concluiu-se que o APA foi eficaz na desinfecção desses instrumentos. / This research was realized to evaluate of the of peracetic or peroxiacetic acid (PAA), at 0,2%, efficacy in the disinfection of instruments contaminated by oral microbiota. A collect was realized with heat sensitive instruments used commonly in some procedures in Dentistry in four sites of the oral cavity: buccal mucosa (left and right sides), hard palate and tongue\'s dorsum from thirty patients using four instruments for each site. Each instrument was treated by different methods, and was divided in four groups: A (without any treatment), B (with APA treatment), C (washed by detergent and water) and D (washed by detergent and water and followed by APA treatment). After each treatment, the instruments were put in a sterile salt solution to extract the microorganism. Dilutions of this salt solution were put on Petri plaques with Tryptic soy agar or Sabouraud dextrose Agar and incubated to favor the respective anaerobiosis and aerobiosis or the growing of moulds and yeasts. The units were counted by colonies (CFU) and introduced the ANOVA test and the Theorem of Bonferroni to every separated culture and every oral microbiota. It was concluded that the APA was efficient on the disinfection of the tools instruments.

Foi realizado estudo de desinfecção comparativo, em condições experimentais similares, entre hipoclorito de sódio, ácido peracético, ozônio e o processo de desinfecção seqüencial ozônio/cloro para águas de estudo com características de cor baixa (< 5 uH) e cor elevada (> 100 uH). O desempenho dos desinfetantes foi avaliado segundo a inativação de três microrganismos indicadores, Escherichia coli ATCC 11229, colifagos e Clostridium perfringens ATCC 13124. As concentrações aplicadas de cloro (\'CL IND.2\'), ácido peracético e ozônio (\'O IND.3\') foram de 2,0; 3,0; 4,0 e 5,0 mg/L. A desinfecção seqüencial consistiu das seguintes combinações de concentrações em mg/L: 2,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 3,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 5,0 \'O IND.3\' / 2,0 \'CL IND.2\' e 2,0 \'O IND.3\' / 5,0 \'CL IND.2\'. Os tempos de contato empregados foram de 5, 10, 15 e 20 minutos, tanto para os ensaios individuais, como para a etapa seqüencial. O cloro livre aplicado foi rapidamente transformado em formas de cloro combinado, nos primeiros 5 minutos de contato, para todas as dosagens aplicadas, diminuindo a ação desinfetante do mesmo. Os resultados dos ensaios de desinfecção com ácido peracético indicaram efetiva redução dos microrganismos indicadores empregados, mesmo na presença de elevada concentração de matéria orgânica, proveniente dos meios de cultura. O ozônio foi considerado efetivo para inativação dos três microrganismos indicadores, apresentando melhores resultados que os demais desinfetantes, na inativação dos fagos. Na etapa da desinfecção seqüencial as inativações de E. coli, colifagos e C. perfringens foram substancialmente superiores às inativações obtidas com ozônio e cloro individuais. Ocorreu sinergismo para E. coli e fagos para todas as dosagens e tempos de contato empregados. Em relação à bactéria esporulada C. perfringens tal fenômeno não foi observado para todos as combinações de ozônio e cloro testadas / This is the result of a comparative disinfection study, performed in similar experimental conditions, among hypochlorite of sodium, peracetic acid, ozone and the ozone/chlorine sequential disinfection process for waters of study with low color (< 5 uH) and high color (> 100 uH) features. The disinfectants performance was evaluated according to the inactivation of three indicators microorganisms: Escherichia coli ATCC 11229, coliphages and Clostridium perfringens ATCC 13124. The applied concentrations of chlorine (\'CL IND.2\'), peracetic acid and ozone (\'O IND.3\') were of 2,0; 3,0; 4,0 and 5,0 mg/L. The sequential disinfection consisted of the following concentrations combinations in mg/L: 2,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 3,0 \'O IND.3\' / 2,0 \'CL IND.2\'; 5,0 \'O IND.3\' / 2,0 \'CL IND.2\' and 2,0 \'O IND.3\' / 5,0 \'CL IND.2\'. The different times of contact employed were of 5, 10, 15 and 20 minutes, as for the single test, as for the sequential stage. The free chlorine applied was quickly transformed into combined chlorine forms, in the first 5 minutes of contact, for all the dosages applied, reducing its disinfectant action. The disinfection tests results with peracetic acid indicated an effective reduction of the indicators microorganisms employed, even in the presence of a high concentration of organic matters, deriving from the culture medium. The ozone was considered effective for the inactivation of all the three indicators microorganisms, presenting better results than the other disinfectants for the phages inactivation. In the stage of the sequential disinfection, the inactivations of E. coli, coliphages and C. perfringens were remarkably superior to the inactivations obtained with just ozone and chlorine. It occurred synergism to E. coli and phages for all dosages and times of contact employed. Such a phenomenon was not observed in relation to the sporulated bacteria C. perfringens, for all the combinations of ozone and chlorine tested

<p>For produced biogas to be usable as vehicle fuel it has to be upgraded to a higher energy content. This is accomplished by elevation of the methane concentration through removal of carbon dioxide. Absorption with water wash is the most common upgrading method used in Sweden today. The upgrading technique is based on the fact that carbon dioxide is more soluble in water than methane. Upgrading plants that utilises this method have problems with microbial growth in the system. This growth eventually leads to a stop in operation due to the gradually drop in upgrading capacity.</p><p>The aim of this thesis were to evaluate the possibility to through some kind of water treatment maintain an acceptable level of growth or altogether prevent it in order to maintain an acceptable process capacity and thereby avoid the need to clean. Through collection of literature the implementation possibilities were evaluated with regard to efficiency, economic sustainability and if there would be a release of any harmful substances.</p><p>In order to prevent the microbial growth in the columns the treatment should either focus on removing microorganisms or limit the accessible nutrients. For the single pass system it is concluded that the treatment should reduce the biofilm formation and be employed in an intermittent way. Among the evaluated treatments focusing on the reduction of microorganisms the addition of peracetic acid seems to be the most promising one. For the regenerating system the treatment method could focus on either one. As for the single pass system peracetic acid could be added to reduce the amount of microorganism. To reduce the amount of organic matter an advanced oxidation process could be deployed with the advantage that it also could remove the microorganisms.</p> / <p>För att kunna använda den producerade biogasen som fordonsgas måste dess energiinnehåll höjas. Detta åstadkoms genom avskiljning av koldioxid så att metankoncentrationen ökar. Den vanligaste förekommande uppgraderingstekniken i Sveriges är absorption med vatten, som bygger på att koldioxid är mer lösligt än metan i vatten under tryck. Uppgraderingsanläggningarna har mikrobiell tillväxt på fyllkropparna i absorptionskolonnen, vilket ofrånkommligen orsakar en lägre uppgraderingskapacitet och slutligen är ett stopp i produktionen nödvändig för kunna tvätta fyllkropparna. Anläggningarna som recirkulerar processvattnet kan även ha tillväxt i kolonnen, där den lösta koldioxiden tas bort.</p><p>Syftet med detta arbete var att genom en litteraturstudie undersöka om det vore möjligt att undvika eller åtminstone hålla tillväxten under en acceptabel nivå genom någon typ av vattenrening. De olika reningsmetoderna utvärderades med avseende på möjlighet att implementeras i det befintliga uppgraderings systemet, effektivitet, möjliga utsläpp och ekonomisk hållbarhet.</p><p>För att begränsa tillväxt i kolonnerna ska vattenreningen antingen fokusera på att ta bort mikroorganismer eller begränsa tillgången på näringsämnen för bakterierna som når kolonnerna via biogasen, luften som används för att ta bort koldioxiden från vattnet, eller via vattnet. För uppgraderingsanläggningar där processvattnet bara passerar kolonnen en gång rekommenderas en reningsmetod som fokuserar på reducera bildandet av biofilmen. Av de utvärderade metoderna ter sig perättiksyra som det bästa alternativet. För system med recirkulerande processvatten skulle reningsmetoden fokusera på antingen reduktion av mikroorganismer, organiskt material eller både och. Som för anläggningar med icke-cirkulerande vatten verkar perättiksyra vara det bästa alternativet för reduktion av mikroorganismer. En avancerad oxidationsprocess skulle kunna användas för att reducera mängden mikroorganismer och organiskt material.</p>

For produced biogas to be usable as vehicle fuel it has to be upgraded to a higher energy content. This is accomplished by elevation of the methane concentration through removal of carbon dioxide. Absorption with water wash is the most common upgrading method used in Sweden today. The upgrading technique is based on the fact that carbon dioxide is more soluble in water than methane. Upgrading plants that utilises this method have problems with microbial growth in the system. This growth eventually leads to a stop in operation due to the gradually drop in upgrading capacity. The aim of this thesis were to evaluate the possibility to through some kind of water treatment maintain an acceptable level of growth or altogether prevent it in order to maintain an acceptable process capacity and thereby avoid the need to clean. Through collection of literature the implementation possibilities were evaluated with regard to efficiency, economic sustainability and if there would be a release of any harmful substances. In order to prevent the microbial growth in the columns the treatment should either focus on removing microorganisms or limit the accessible nutrients. For the single pass system it is concluded that the treatment should reduce the biofilm formation and be employed in an intermittent way. Among the evaluated treatments focusing on the reduction of microorganisms the addition of peracetic acid seems to be the most promising one. For the regenerating system the treatment method could focus on either one. As for the single pass system peracetic acid could be added to reduce the amount of microorganism. To reduce the amount of organic matter an advanced oxidation process could be deployed with the advantage that it also could remove the microorganisms. / För att kunna använda den producerade biogasen som fordonsgas måste dess energiinnehåll höjas. Detta åstadkoms genom avskiljning av koldioxid så att metankoncentrationen ökar. Den vanligaste förekommande uppgraderingstekniken i Sveriges är absorption med vatten, som bygger på att koldioxid är mer lösligt än metan i vatten under tryck. Uppgraderingsanläggningarna har mikrobiell tillväxt på fyllkropparna i absorptionskolonnen, vilket ofrånkommligen orsakar en lägre uppgraderingskapacitet och slutligen är ett stopp i produktionen nödvändig för kunna tvätta fyllkropparna. Anläggningarna som recirkulerar processvattnet kan även ha tillväxt i kolonnen, där den lösta koldioxiden tas bort. Syftet med detta arbete var att genom en litteraturstudie undersöka om det vore möjligt att undvika eller åtminstone hålla tillväxten under en acceptabel nivå genom någon typ av vattenrening. De olika reningsmetoderna utvärderades med avseende på möjlighet att implementeras i det befintliga uppgraderings systemet, effektivitet, möjliga utsläpp och ekonomisk hållbarhet. För att begränsa tillväxt i kolonnerna ska vattenreningen antingen fokusera på att ta bort mikroorganismer eller begränsa tillgången på näringsämnen för bakterierna som når kolonnerna via biogasen, luften som används för att ta bort koldioxiden från vattnet, eller via vattnet. För uppgraderingsanläggningar där processvattnet bara passerar kolonnen en gång rekommenderas en reningsmetod som fokuserar på reducera bildandet av biofilmen. Av de utvärderade metoderna ter sig perättiksyra som det bästa alternativet. För system med recirkulerande processvatten skulle reningsmetoden fokusera på antingen reduktion av mikroorganismer, organiskt material eller både och. Som för anläggningar med icke-cirkulerande vatten verkar perättiksyra vara det bästa alternativet för reduktion av mikroorganismer. En avancerad oxidationsprocess skulle kunna användas för att reducera mängden mikroorganismer och organiskt material.

No description available.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1975. / Includes bibliographical references (p. 94-100).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1976. / Includes bibliographical references (p. 112-120).

Thesis (M.S.)--Brigham Young University. Dept. of Microbiology and Molecular Biology, 2007. / Includes bibliographical references (p. 29-31).