Made available in DSpace on 2015-09-25T12:23:34Z (GMT). No. of bitstreams: 1 MyrthisVirginiaAlvesDeAlmeidaReinaldo.pdf: 991886 bytes, checksum: b2a23283e6671d15e111f946866efab9 (MD5) Previous issue date: 2006-02-23 / This research was accomplished with the purpose of studying the acting of a process developed for environmental disinfection, contributing for disinfection of wastewaters from anaerobic treatment systems of sanitary sewers. This process used the heterogeneous photocatalysis, that consists of the oxidation of organic pollutants through the generation of radicals hidroxila ( OH), highly oxidizers, which is gotten with the aid of a semiconductor and a UV radiation source. The semiconductor was the titanium dioxide (TiO2) and the source of energy from artificial luminous source (UV lamp) and natural (Sun) of ultraviolet radiation. Two types of reactors were used: a reactor type concentric tubes containing a 15W bactericidal UV lamp inside, treating wastewaters coming of two systems: UASB and Anaerobic Filter of Chicanes, with a flow of recirculation of 72 L.h-1 for 2 hours. In this reactor was made experiments with and without TiO2 in suspension. And a TiO2 impregnated plate reactor, treating wastewater of the anaerobic filter of chicanes, working in four different flow of recirculation: 13,2L.h-1, 25L.h-1, 42L.h-1 and 75L.h-1, for 4 hours of exposed to the sunlight. For both were evaluated the removal efficiencies of the fecal contamination indicative microorganisms - thermotolerants coliforms, and the rate of bacterial inativation through the study of the kinetic constant (k) and analyzed the physical and chemical parameters corresponding to the variation of the temperature, pH, electric conductivity (CE), total alkalinity and to bicarbonate, total nitrogen Kjeldahl (TNK), ammonia (NH3), total phosphor and orthophosphate, solids and your fractions, volatile greasiest acids (AGV) and removal of the organic matter (QDO). The kinetics study of the bacterial inativation (k) it revealed the best acting, in the concentric tubes reactor, for the experiment with photocatalysis using the anaerobic filter of chicanes wastewater. Already in the impregnated plate reactor, the best acting was observed in the 25L.h-1 flow, with 100% thermotolerants coliforms removed. The experiment with impregnated plate reactor it was shown efficient in the removal of the nitrogen compounds TNK and Ammonia. The smallest removal efficiency of thermotolerants coliforms of the UASB wastewater, in the concentric tubes reactor, was due to the high concentration of solids in suspension of the secondary wastewater, what block the uniformity of the UV radiation penetration. High evaporation rates, frequent in the experiments with the impregnated plate reactor, they caused increase in the final concentration of some parameters. The process of the heterogeneous photocatalysis is an efficient alternative method for the disinfection of tertiary wastewater with low concentration of solids in suspension. / Esta pesquisa foi realizada com a finalidade de estudar o desempenho de um processo desenvolvido para descontaminação ambiental, contribuindo para a desinfecção de efluentes de sistemas de tratamento anaeróbio de esgotos sanitários. Este processo foi o da fotocatálise heterogênea, que consiste na oxidação de contaminantes orgânicos através da geração de radicais hidroxila ( OH), altamente oxidantes, e que é conseguido com o auxílio de um fotocatalisador, no caso um semicondutor, e uma fonte de radiação UV. O semicondutor utilizado foi o dióxido de titânio (TiO2) e a fonte de energia luminosa proveniente de fonte artificial (lâmpada UV) e natural (Sol) de radiação ultravioleta. Foram utilizados dois tipos de reatores: um reator do tipo tubos concêntricos contendo uma lâmpada UV germicida 15W em seu interior, tratando efluentes provenientes de dois sistemas: UASB e filtro anaeróbio de chicanas, com uma vazão de recirculação de 72 L.h-1 durante 2 horas, com os quais foram feitos experimentos com e sem a utilização do TiO2 em suspensão; e um reator de placa impregnada com TiO2, tratando efluente do filtro anaeróbio de chicanas, trabalhando em quatro diferentes vazões de recirculação: 13,2 L.h-1, 25 L.h-1, 42 L.h-1 e 75 L.h-1, durante 4 horas de exposição à luz solar. Para ambos os reatores foram avaliadas as eficiências de remoção dos microrganismos indicadores de contaminação fecal os coliformes termotolerantes, como também a taxa de inativação bacteriana através do estudo da constante cinética (k) e analisados os parâmetros físico e químicos correspondentes à variação da temperatura, pH, condutividade elétrica (CE), alcalinidade total e a bicarbonato, nitrogênio total Kjeldahl (NTK), nitrogênio amoniacal (NH3), fósforo total e ortofosfato, sólidos e suas frações, ácidos graxos voláteis (AGV) e remoção de matéria orgânica (DQO). O estudo da constante cinética de inativação bacteriana (k) revelou o melhor desempenho, no reator de tubos concêntricos, para o experimento com fotocatálise utilizando o efluente do filtro anaeróbio de chicanas. Já no reator de placa impregnada, o melhor desempenho foi observado na vazão de 25L.h-1, com 100% dos coliformes termotolerantes removidos. O experimento com o reator de placa impregnada mostrou-se eficiente na remoção dos compostos nitrogenados NTK e N-amoniacal. A menor eficiência de remoção de coliformes termotolerantes do efluente do reator UASB, no reator de tubos concêntricos, deveu-se à alta concentração de sólidos em suspensão do efluente secundário, o que impede a uniformidade da penetração da radiação UV. Elevadas taxas de evaporação, freqüentes nos experimentos com o reator de placa impregnada, provocaram aumento na concentração final de alguns parâmetros. O processo da fotocatálise heterogênea é um método alternativo eficiente para a desinfecção de efluentes terciários com baixa concentração de sólidos em suspensão.

Este trabalho teve como objetivo estudar a fotocatálise heterogênea com Ti'O IND.2' no tratamento de esgoto sanitário secundário, visando a oxidação da matéria orgânica e desinfecção. A luz solar foi utilizada como fonte de radiação. O reator fotocatalítico consistiu de placa de vidro (aproxidamente 0,48 'M POT.2') sobre a qual foi fixado o catalisador (10 g/'M POT.2'). Foi avaliada a influência de parâmetros operacionais (vazão e ângulo de inclinação do fotorreator) na eficiência do processo. As vazões de estudo foram 15; 22,5 e 30 L/h, e os ângulos de inclinação em relação à horizontal foram 2, 12 e 22 graus. Os experimentos foram realizados com dois tipos de efluentes. O primeiro (efluente 1) foi de reator anaeróbio compartimentado tratando esgoto doméstico e o segundo (efluente 2) de reator anaeróbio/aeróbio de leito expandido com meio suporte constituído de carvão ativado que trata o esgoto do Campus I da USP/São Carlos e de contribuições domésticas. Os ensaios foram do tipo batelada com recirculação do esgoto durante 4 horas. Também foi avaliada a fotólise (ensaio apenas com radiação solar) e adsorção do catalisador (ensaio sem luz e com Ti'O IND.2') na oxidação de matéria orgânica e na desinfecção. Foram avaliadas as remoções de matéria orgânica (DQO e COT) e de microrganismos indicadores de contaminação fecal (Clostridium perfringens, coliformes totais, E. coli e colifagos). Os resultados indicaram que a fotocatálise heterogênea foi mais eficiente como método de desinfecção que a fotólise. A resistência dos microrganismos ao processo Ti'O IND.2'/UV, em ordem decrescente, foi: Clostridium perfringens, coliformes totais, E. coli e colifagos. As melhores condições operacionais para inativação de microrganismos no efluente 1 foram: 'alfa' = 2 graus e Q = 22,5 L/h. O ângulo de inclinação da placa teve maior influência na oxidação de COT do efluente 2 do que a vazão. As características físico-químicas dos efluentes tiveram papel importante no resultado final da fotocatálise heterogênea, tanto na oxidação de matéria orgânica como na desinfecção. A concentração inicial de E. coli exerceu maior influência na desinfecção fotocatalítica do que a radiação solar, para as condições dos ensaios realizados. Os reatores de placa plana com Ti'O IND.2' imobilizado, quando expostos à luz solar, devem ser vedados para evitar evaporação excessiva / The heterogeneous photocatalysis with Ti'O IND.2' and solar radiation in secondary wastewater treatment to remove organic matter and microorganisms was investigated. A glass plate (approximate 0.48 'M POT.2') with immobilized titanium dioxide (10 g/'M POT.2') was operated in different flow rates (15; 22.5 and 30 L/h) and angles in relation to horizontal (2, 12 and 22 degrees). Two effluents were used in the assays. The first (effluent 1) was from an anaerobic reactor treating sewage and the second (effluent 2) from an anaerobic/aerobic granular activated carbon expanded bed reactor which receives the wastewater collected in the Campus of USP/São Carlos and from the surrounding neighborhood of the campus. The assays were carried out in batch with recirculation time of 4 hours. The photolysis (only solar radiation) and the catalyst adsorption (Ti'O IND.2' in the dark) in organic matter removal and disinfection were evaluated. The oxidation of organic matter (COD and TOC) and inactivation of indicators of fecal contamination (Clostridium perfringens, total coliforms, E. coli, and coliphages) were evaluated. The results shows that heterogeneous photocatalysis was more efficient in effluents disinfection than the photolysis. The resistance of the microorganisms to Ti'O IND.2'/UV process was in decreasing order: Clostridium perfringens, total coliforms, E. coli and coliphages. The best operational conditions for microorganisms inactivation in effluent 1 are: 'alfa' = 2 degrees and Q = 22.5 L/h. TOC oxidation in effluent 2 was more influenced by angle than by flow rate. The physical and chemical characteristics of the effluents had an important role in oxidation and disinfection. Initial E. coli concentration was more important than intensity of solar radiation during photocatalytic disinfection in the experimental conditions of this work. The reactors with immobilized Ti'O IND.2' open to solar radiation have to be closed to avoid excessive evaporation

Orientador: Ione Correa / Resumo: Introdução: O bloco cirúrgico ou bloco operatório é classificado como um setor crítico e complexo, com a capacidade de atender as necessidades da prática cirúrgica. Estratégias ambientais são componente essencial para prevenir infecções associadas aos cuidados de saúde. Objetivo: Analisar as evidências científicas sobre a desinfecção de superfícies ambientais em bloco cirúrgico, com uma proposta de construção de um procedimento operacional padrão. Método: Revisão integrativa da literatura com artigos em português, inglês, espanhol nas bases de dados LILACS (via portal Bireme), BDENF, MEDLINE, PubMed, Scopus, SciELO, Web of Science. Os critérios de inclusão foram artigos publicados em periódicos e disponíveis na íntegra, inglês, português ou espanhol que abordassem a temática e sem limitação temporal. Resultados e Discussão: Foram analisados três artigos, dois (66%) foram encontrados na base de dados Medline e um (34%) na Lilacs. Em relação a formação profissional dos autores, dois (66%) eram médicos e um artigo (34%) foi produzido por um enfermeiro. Quanto ao ano de publicação houve uma correlata aproximação de anos. Em relação ao local de estudo, periódico e seu respectivo Qualis, as publicações foram distribuídas em: um (34%) periódico nacional publicado em Uberlândia – MG e dois (66%) periódicos nacionais pulicados em Miami e Texas – USA respectivamente; os três artigos foram publicados em periódicos de grande impacto, sendo o artigo nacional (34%) publicado pela Revista L... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: The surgical block or operative block is classified as a critical and complex sector, with the capacity to meet the needs of the surgical practice. Environmental strategies are an essential component in preventing infections associated with health care. Objective: To analyze the scientific evidence on the disinfection of environmental surfaces in a surgical block, with a proposal to construct a standard operating procedure. Method: Integrative literature review with articles in Portuguese, English and Spanish in the LILACS (via Bireme portal), BDENF, MEDLINE, PubMed, Scopus, SciELO, Web of Science. The inclusion criteria were articles published in periodicals and available in full, English, Portuguese or Spanish that approached the theme and without temporal limitation. Results and Discussion: Three articles were analyzed, two (66%) were found in the Medline database and one (34%) in Lilacs. Regarding the professional training of the authors, two (66%) were doctors and one article (34%) was produced by a nurse. As for the year of publication there was a correlata approximation of years. The publications were distributed in: one (34%) national periodical published in Uberlândia - MG and two (66%) national journals published in Miami and Texas - USA respectively; (34%) published by the Revista Latino Americana de Enfermagem (Revista Latino Americana de Enfermagem) with the stratum indicative of Qualis A1, and the international papers (66%) were published by Infect... (Complete abstract click electronic access below) / Mestre

Dialys är en medicinteknisk teknik som används för att rena blod vid nedsatt njurfunktion. Dialysvätska är en viktig komponent i utrustningen. Syftet med examensarbetet var att utvärdera förbättrade rutiner för kvalitetskontroll av vattnet som används för tillredning av dialysvätskan. Ett program för övervakning av desinfektionseffekt i vattenrenare för dialys har utvecklats i Microsoft Visual Studio, med Windows Forms som plattform och kod skriven i C#. Mjukvaran övervakar konduktivitet, dagar sedan desinfektion, desinfektionseffekt (A₀), aktivitet hos loggningsprogram samt kontrollprogram. Larm skickas via mail vid dåliga värden eller fel, samt visas lokalt på dator i form av en textruta. Ett ytterligare program skapades för att kontrollera att huvudprogrammet är igång, och en varning skickas när aktivitet uteblir under en viss längd. Utöver övervakning skapades även en grafisk del som tillåter visning av loggade data samt beräknade A₀-värden över tid. Analys utförs kring möjligheter att bibehålla mikrobiologisk trend med stabilt låg bakterienivå i vattnet vid minskad desinfektionsfrekvens från tre till två gånger i veckan. Provtagningar tyder på att marginal till gränsvärde inte hotas, men mer data behövs för at bekräfta resultatet. Analys utförs även kring möjligheten att använda beräkning av A₀-värden för att verifiera desinfektionseffekt tidigare än resultat från mikrobiologisk provtagning, vilket resultat från den studie som utförts tyder på är möjligt, med vissa undantag där det inte finns data att förhålla sig till. Vid användning av mjukvaran rekommenderas fortsatta mikrobiologiska provtagningar. / Dialysis is a health technology used for cleaning blood in people with kidney failure. Dialysis fluid is an important component used in the dialysis process. The aim of the project is to evaluate improved quality control routines for the water used in preparation of the dialysis fluid. A program for monitoring disinfection effect in water purification systems for dialysis has been developed in Microsoft Visual Studio, using Windows Forms as platform and the code was written in C#. The software monitors conductivity, days since last disinfection, effect of disinfection (A₀), activity of logging software as well as control software. Warnings are sent by mail for bad results or errors, and a message is shown as a textbox locally on the computer running the software. An additional program was made for monitoring the main programs activity, and a warning is sent after seeing no activity within a time period. Other than monitoring, the software also has a graphical view allowing the user to view logged data and calculated A₀-values over time. An analysis is made regarding the possibility to maintain microbiological trend of low amounts of bacteria in water after reducing the disinfection frequency from three to two times a week. Test results indicate that the margin to the maximum allowed value remains on safe levels, but more data is required to confirm the results. A further analysis is made regarding the possibility to use calculations of A₀-values to verify the disinfection effect earlier than results from microbiological testing. Results from studies indicate that this is possible, but with some exceptions in cases where not enough data is available to draw conclusions. When using the software, continued microbiological testing is recommended.

In the last two decades, Computational Fluid Dynamics (CFD) has shown great potential as a powerful and cost-efficient tool to troubleshoot existing disinfection contactors and improve future designs for the water and wastewater treatment utilities. In the first part of this dissertation two CFD simulation methodologies or strategies for computing turbulent flow are evaluated in terms of the predicted hydraulic performance of contactors. In the LES (large eddy simulation) methodology, the more energetic, larger scales of the turbulence are explicitly computed or resolved by the grid. In the less computationally intensive RANS (Reynolds-averaged Navier-Stokes) methodology, only the mean component of the flow is resolved and the effect of the unresolved turbulent scales is accounted for through a turbulence model. For baffled contactors, RANS performs on par with the LES in predicting hydraulic performance indices. In this type of contactors, hydraulic performance is primarily determined by quasi-steady recirculating (dead) zones within the contactor chambers which are well-resolved in both RANS and LES. Testing of the RANS methodology is also performed for a wastewater stabilization pond leading to prediction of hydraulic performance indices in good agreement with field measurements. However, for column contactors, LES performs better than RANS due to the ability of the LES to resolve unsteady or unstable flow structure associated with spatial transition to turbulence which is important in the determination of the hydraulic performance of the contactor. In the second part of this dissertation the RANS methodology is adapted in order to develop a novel modeling framework for ozone disinfection of drinking water. This framework is unique as it combines CFD with kinetics-based reaction modeling to predict disinfection performance and bromate formation for the first time. Bromate, a human health hazard, is an undesired by-product of the disinfection of drinking water via ozonation. The modeling framework is validated via application to a full-scale ozone contactor. Predictions of ozone and bromate concentrations are consistent with data from physical experiments.

Drinking water is produced from raw water and is either from groundwater or surface water. This thesis aims to find out if the cleaning process of raw water is sufficiently effective. This is important because consumers are otherwise at risk of waterborne infection caused by pathogens. There are three groups of pathogens; bacteria, virus and parasite. These have different characteristics which mean that they require different water treatment to be separated. In addition to normal operation, a number of scenarios were examined. This is to investigate how water treatment would do if they became a reality. The thesis has examined Borg´s waterworks operated by Norrköping Vatten AB. It was defined to cover the distance from water source to the consumer. In the work, the model Quantitative Microbial Risk Assessment (QMRA) was used to perform risk analysis by simulating the normal operation and different scenarios of the water purification process. Thus, knowledge can be obtained about the effectiveness of separation by bacteria, viruses and parasites. However, the QMRA-model is considered to contain some flaws and for that reason the Norwegian model called Good Disinfection Practice (GDP) was also used. GDP is a theoretical model which is based on formulas and tables. The model takes into account the raw water quality and also provides deductions for various measures that the water plant possesses to ensure a good supply of water. The results obtained with both models were similar and showed that the water treatment is sufficient for the bacteria, but not viruses and parasites. Both models were considered to be reliable but viruses and parasites are very difficult to analyze, which has resulted in uncertain literature values and hence in the results. The result also showed that neither viruses nor parasites exceeded the limit by so much that more hygienic barriers to the reduction of them are necessary. The conclusion which may be drawn from the fact that no parasites have been detected in the raw water is that the water treatment still might be sufficient. To determine the effects that an exclusion of various barriers may give, the normal operation was simulated and a purification step at a time was excluded. The result showed that the purification steps which are most important to maintain the treatment process are chemical precipitation followed by rapid filtration, slow filtration and disinfection with chlorine. If any of these cleaning steps were to fail, this introduces a large increase in the risk of waterborne disease. The results showed that the chemical precipitation step gave the greatest separation effect on the virus but also on the parasites. However, the slow filtration gave the largest separation of the parasites. Free chlorine had the greatest effect on bacteria. The investigated scenarios were assumed to be wastewater discharges, sewage discharges in relation to flood the nearby pastures, and sewage overflows due to heavy rainfall. The results of the simulated scenarios were the same when it was only bacteria that in all cases produced a result within the limits of the daily infection probability. Both viruses and parasites exceeded both values. However, there were few studies on these and thus literature values needed to be implemented in the QMRA-model. Hence, the uncertainty of the results was great. The QMRA-model also contained deficiencies in the simulation of the discharge of effluents, where the amount of virus was about 1000-10000 times too much. If this problem as well as more specific data for the investigated area, and more Swedish studies were available, a more credible simulation of the scenarios could be implemented.

Despite extensive preventative efforts, the problem of controlling infections associated with biomedical materials persists. Bacteria tend to colonize on biocompatible materials and form biofilms; thus, novel biomaterials with antibacterial properties are of great interest. In this thesis, titanium dioxide (TiO2)-associated photocatalysis under ultraviolet (UV) irradiation was investigated as a strategy for developing bioactivity and antibacterial properties on biomaterials. Although much of the work was specifically directed towards dental materials, the results presented are applicable to a wide range of biomaterial applications. Most of the experimental work in the thesis was based on a resin-TiO2 nanocomposite that was prepared by adding 20 wt% TiO2 nanoparticles to a resin-based polymer material. Tests showed that the addition of the nanoparticles endowed the adhesive material with photocatalytic activity without affecting the functional bonding strength. Subsequent studies indicated a number of additional beneficial properties associated with the nanocomposite that appear promising for biomaterial applications. For example, irradiation with UV light induced bioactivity on the otherwise non-bioactive nanocomposite; this was indicated by hydroxyapatite formation on the surface following soaking in Dulbecco’s phosphate-buffered saline. Under UV irradiation, the resin-TiO2 nanocomposite provided effective antibacterial action against both planktonic and biofilm bacteria. UV irradiation of the nanocomposite also provided a prolonged antibacterial effect that continued after removal of the UV light source. UV treatment also reduced bacterial adhesion to the resin-TiO2 surface. The mechanisms involved in the antibacterial effects of TiO2 photocatalysis were studied by investigating the specific contributions of the photocatalytic reaction products (the reactive oxygen species) and their disinfection kinetics. Methods of improving the viability analysis of bacteria subjected to photocatalysis were also developed.

Disinfection of the municipal water systems is mostly achieved by means of chlorine addition at water treatment plants known as sources. Thus, there should be an adequate chlorine concentration at the source for an effective disinfection throughout the system by considering upper and lower limits of disinfectant. However, since the disinfectants are reactive and decays through the system, chlorine added at the source may not be enough to maintain desired disinfectant residuals which may lead to water quality problems in the water distribution system. Moreover, the disinfectants such as chlorine has also an effect to be carcinogen due to formation of disinfectant by-products. Thus, the system should balance the amount of disinfectant supplied while minimizing the health risk. In such a case, it is recommended that one or more booster disinfection stations can be located throughout the system. Such a method can provide more uniform distribution of the chlorine concentration while reducing the amount of the disinfectant used. In this thesis, optimum scheduling, and injection rates of the booster disinfection stations have been searched. The objective is to minimize the injected mass dosage rate subjected to the provision of adequate and more uniform residual concentration in the network. Determination of variable network hydraulics and chlorine concentrations is held out by EPANET network simulation sofware. A C++ code was developed to interface with EPANET by means of the EPANET Programmer&#039 / s Toolkit for linear optimization of the disinfectant mass dosage rate applied to the network.

Den största akuta risken inom dricksvattenförsörjningen är vattenburen smittspridning. Dricksvattenrelaterad smittspridning förekommer i störst utsträckning i utvecklingsländer med dåliga sanitära förhållanden. Under 2000-talet har de nordiska länderna drabbats av flertalet dricksvattenburna sjukdomsutbrott vilket har lett till att mikrobiella föroreningar uppmärksammats som ett problem även i Norden. För att säkerställa att det dricksvatten som distribueras är av god mikrobiologisk kvalitet krävs att säkerhetsbarriärerna i vattenverket är tillräckligt effektiva för alla typer av mikrobiella föroreningar. Vissa mikroorganismer har uppmärksammats som mer tåliga mot olika desinfektionsmetoder, till exempel klorering, än vad som tidigare varit känt. För ett säkrare dricksvatten är det därför viktigt att öka kunskapen om mikroorganismers varierande motståndskraft mot olika desinfektionsmedel samt undersöka alternativ till de avskiljnings- och inaktiveringsmetoder som traditionellt används idag. Examensarbetets syfte var att studera de bakterier och virus som har störst relevans för dricksvattenkvaliteten och som tros kunna utgöra ett hot mot nordiskt dricksvatten, att undersöka orsakerna bakom dricksvattenburna utbrott samt att undersöka effektiviteten hos olika avskiljnings- och inaktiveringsmetoder för bakterier och virus. Detta gjordes genom en utförlig litteraturstudie samt en fallstudie. Fallstudiens syfte var att belysa problematiken inom dricksvattenberedning samt distribution i Norden genom verkliga exempel.  Studien visade att vattenburna sjukdomsutbrott normalt orsakas av kontaminering från avloppsvatten till dricksvatten. Detta sker antingen direkt till råvattnet, ofta till följd av kraftig nederbörd, eller under distributionen på grund av driftstörningar. Att kontamineringen tillåts nå konsumenten är ett resultat av inadekvata reningsmetoder i vattenverken. Problematiken inom dricksvattenområdet beror bland annat på användandet av bristfälliga indikatororganismer vilka är mindre tåliga och har sämre överlevnadsförmåga än många sjukdomsalstrande mikroorganismer. Tidskrävande och osäkra analysmetoder utgör också ett stort problem. Svårigheter i att identifiera den orsakande mikroorganismen samt att bekräfta utbrottet som dricksvattenrelaterat har lett till att mörkertalet gällande antalet vattenburna sjukdomsfall är stort. Det finns ett stort behov av ökad kunskap gällande olika mikroorganismers tålighet mot desinfektion samt ett behov av reglering för kontroll av råvattenkvaliteten och den mikrobiologiska säkerheten. Utifrån studien kunde även konstateras att antalet vattenburna utbrott tros öka med kraftigare nederbörd och extremväder till följd av klimatförändringarna. / Waterborne diseases are considered a major problem in the water supply. Spreading of infection through drinking water occurs predominantly in developing countries with poor sanitation. During the 21th century the Nordic countries have been affected by several waterborne outbreaks associated with drinking water. As a result, microbial contamination of drinking water has been recognized as a problem in the Nordic countries as well. To ensure high quality drinking water it is required that the hygienic barriers used in the water treatment plant are efficient in reducing all types of microbial contaminants. Some microorganisms have shown a greater resistance against commonly used disinfectants then previously known. To secure the distribution of safe drinking water it is essential to increase the knowledge regarding the varying resistance of microorganisms and to investigate alternative water treatment processes to those traditionally used in drinking water treatment today.  The objective to this master thesis was to study the bacteria and viruses that are most relevant for drinking water quality and may compose a threat to the drinking water quality in the Nordic countries, to investigate the cause of waterborne outbreaks and to study the effectiveness in reducing bacteria and viruses for various water treatment processes. The study was performed through a thorough literature review and a case study. The purpose of the case study was to illustrate the issues in drinking water treatment and distribution in the Nordic region. The study showed that the majority of the outbreaks are caused by contamination from sewage water to drinking water. The contamination is allowed to reach the consumer as a result of inadequate treatment in the water works. Usage of inappropriate indicator organisms that are less resistant to disinfectants than a lot of pathogens are a big problem in drinking water treatment. Time-consuming and uncertain analytical methods also compose a great issue. Due to difficulties in identifying the causative microorganism and verify the outbreak as drinking water related it is believed that there is a large number of unrecorded cases of illness. There is a great need of increased understanding of the varying resistance of microorganisms to disinfectants and a need for regulation for monitoring raw water quality and microbiological safety. Based on the study it was also found that waterborne outbreaks are believed to increase as a result of extreme weather caused by climate change.

It is well established that water quality is directly linked to health. In-line chlorination is one technology that can be used in the developing world to potentially inactivate pathogens and improve water quality. The purpose of this study was to determine the effectiveness of the Panamanian Ministry of Health's in-line PVC chlorinator under three different operating conditions in a rural water supply system. Free and total chlorine were measured entering the storage tank, leaving the storage tank, and at three households along the transmission line of the water system in the two rural indigenous communities of Calabazal and Quebrada Mina in western Panama during April-August 2011. The Ct method for disinfection was used to compare the measured free chlorine concentration to the concentration required to inactivate common pathogens found in gravity flow water systems in Panama, such as E. coli, Salmonella typhi, Hepatitis A, Giardia lamblia, and E. histolytica, as well as other pathogens of interest to the global health community, such as Vibrio cholerae and Rotavirus. When the chlorine tablet was sealed in a plastic wrapper prior to use to prevent contact with humid surroundings, the chlorine was able to dissolve in seven days instead of three hours into the transmission line. The use of one tablet, sealed in a plastic wrapper before use, was able to obtain the required free chlorine concentration estimated to disinfect E. coli, Vibrio cholerae, Rotavirus, Salmonella typhi, and Hepatitis A. However, it did not achieve a free chlorine concentration above 0.27 mg/L needed to inactivate Giardia lamblia nor above 0.35 mg/L needed to inactivate E. histolytica. The use of three properly stored tablets in the chlorinator was able to provide a free chlorine concentration above 0.35 mg/L for only one day, reaching 0.37 mg/L, before falling below 0.35 mg/L to a level of 0.26 mg/L the next day. The study suggests that with three tablets the in-line PVC chlorinator can be an effective technology if slightly more free chlorine concentration can enter the system. The cost of this technology could be allocated to every owner with a house connection in the communities of Calabazal and Quebrada Mina by increasing their monthly tariff by $1 each month.