| 1. |
- Heinicke, Gerald, 1973, et al.
(författare)
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Application of a QMRA model for surface water treatment to investigate a waterborne outbreak of calicivirus
- 2009
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Ingår i: American Water Works Association, Global Conference on Microbial Contaminants in Drinking Water 2009, 5-8 October, Singapore. ; , s. 7-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The QMRA modelling tool developed by the Swedish Water & Wastewater Association was applied to investigate a probably waterborne outbreak of calicivirus that occurred in the municipality of Lilla Edet, Sweden, after a period with heavy rain. Of the inhabitants that receive water from the municipal water works, 32% reported gastroenteritis in the period investigated. For the QMRA study, the pathogen load in the raw water source was estimated by describing specific discharge events of wastewater upstream the intake of the municipal water works, including dilution and transport time in the river. Estimates of the concentration of norovirus in wastewater, the efficiency of treatment processes in the waterworks, exposure volumes and dose-response relationships were based on literature data that are included in the modelling tool. In a scenario analysis, the probability of infection related to the three discharge events was quantified. The QMRA model estimated probabilities of infection comparable to the proportion of people reported estimated to have fallen ill in the epidemiological study. Sources of uncertainty and potential for improvement were identified for the in-data and for the modelling tool.
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| 2. |
- Lindhe, Andreas, 1981, et al.
(författare)
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Integrated risk analysis from source to tap: Case study Göteborg
- 2008
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Ingår i: The 6th Nordic Drinking Water Conference, Oslo, Norway, 9-11 June, 2008. - 9788241402937 ; , s. 231-241
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To achieve an efficient risk management of a drinking-water system the entire system has to be considered, from source to tap. An important part of risk management is to identify hazards and estimate risks, i.e. to conduct risk analyses. In order to provide a relevant basis for evaluating risks and efficiently prioritising risk reduction options, a risk analysis needs to properly consider interaction between different parts and components of the system. This is especially important in complex systems. Logic tree models have the capability of properly reflect system functionality as well as facilitating quantification of risk levels. A fault-tree model was therefore constructed for an integrated and probabilistic risk analysis of the drinking-water system in Göteborg, Sweden. The main (top) event studied in the analysis was supply failure, which included quantity and quality failures. Quantity failure occurs when no water is delivered to the consumer and quality failure when water is delivered, but unfit for human consumption according to existing water-quality standards. Hard data and expert judgements were used for estimating probabilities of events, consequences and uncertainties of estimates. Monte Carlo simulations were used for the calculations in order to facilitate uncertainty analysis of risk levels. The risk analysis provided information on the probability of failure, rate of failure and mean down time of the system. The number of people affected was also included in the fault tree and risk levels were expressed as Costumer Minutes Lost. The primary aims of this paper were to apply a fault-tree method, for integrated and probabilistic risk analysis of drinking-water systems, on the system in Göteborg and show how the results can be used. The results showed, for example, that the raw water part contributes most to the total risk level and that the distribution part includes frequent failures that most often have a short duration and affect a small number of people. The method was found to facilitate a quantitative and integrated risk analysis of the drinking-water system and the results provide information not only on risk levels, but also on the dynamic behaviour of the system. In addition, the method is capable of relevant handling interaction of system components. Furthermore, it provides transparency and facilitates for formal updating when new information becomes available. Hence, it is concluded that the method provides useful information for discussing and evaluating risks as well as possible risk reduction options.
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| 3. |
- Lindhe, Andreas, 1981, et al.
(författare)
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Verktyg för kvantitativ mikrobiologisk riskbedömning (QMRA) av små avloppsanläggningar nära dricksvattenbrunnar – Manual 2016-03-31
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna manual är avsedd att ge vägledning för att använda ett nyutvecklat verktyg för kvantitativ mikrobiologisk riskbedömning (QMRA) av små avloppsanläggningar nära dricksvattenbrunnar. Som grund för verktyget ligger projektet Verktyg för mikrobiell riskanalys av små avloppsanläggningar nära dricksvattenbrunnar, finansierat av Havs- och vattenmyndigheten inom ramen för anslag 1:12 Åtgärder för havs- och vattenmiljöer. Den teoretiska bakgrunden till detta verktyg (QMRA-verktyget) med redogörelse för antaganden, men även en kortfattad manual, har tidigare redovisats tillsammans med ett fältförsök med bakteriofager i markens mättade grundvattenzon. QMRA-verktyget ska kunna användas av tillsynsmyndigheten för att analysera risken för smittspridning från befintliga avloppsanläggningar men också i planeringssyfte vid bedömning av rimliga säkerhetsavstånd och placering av nya små avlopp och dricksvattenbrunnar. Verktyget är utformat enligt grunderna för kvantitativ mikrobiologisk riskbedömning som inkluderar fyra huvudsteg: faroidentifiering, exponeringsbedömning, dos-respons-bedömning och riskkarakterisering. Modellutvecklingen har framförallt varit inriktad på exponeringsbedömningen och att ta fram en modell som beaktar den barriäreffekt som uppnås via slamavskiljaren, biohuden, transport i markens omättade zon samt transport i markens mättade grundvattenzon. Speciellt fokus har riktats mot transporten och avskiljningen i mättad grundvattenzon. Modellen är fritt tillgänglig som en webb-länk och kräver ingen installation på den egna datorn, även om möjlighet finns till detta.I denna manual beskrivs indata och hur en modellering genomförs, steg för steg. QMRA-verktyget kan ses som ett komplement och fördjupande verktyg i arbetet med att bedöma den smittorisk som små avloppsanläggningar medför. Under hösten 2015 genomfördes utbildningsseminarier under en dag i Uddevalla, Alingsås respektive Norrtälje kommun riktade till miljö- och hälsoskyddsinspektörerna. Under dessa seminarier fick deltagarna dels föreläsningar inom mikrobiologi, riskbedömning och hydrogeologi, dels en presentation av modellverktyget. Deltagarna fick själva testa verktyget på medhavda exempel. Utöver att sprida kunskap om verktyget syftade seminarierna till att generera erfarenhet och underlag för att förbättra verktyget. Den version av QMRA-verktyget som beskrivs i denna manual är en produkt av genomförda seminarier. I ett avslutande kapitel redovisas modelljusteringar samt några av de viktigaste aspekterna som diskuterades vid seminarierna.
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| 4. |
- Lindhe, Andreas, 1981, et al.
(författare)
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Verktyg för mikrobiell riskanalys (MRA) av små avloppsanläggningar nära dricksvattenbrunnar – Modellutveckling och fältförsök
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Föreliggande rapport utgör slutredovisningen av projektet Verktyg för mikrobiell riskanalys av små avloppsanläggningar nära dricksvattenbrunnar, som finansierats av Havs- och vattenmyndigheten inom ramen för anslag 1:12 Åtgärder för havs- och vattenmiljöer. I utlysningen konstateras att små avlopp utgör ett betydande problem och att det därför är viktigt att stimulera fortsatt utveckling inom verksamhetsområdet.Projektet som redovisas i denna rapport fokuserade på smittspridning från små avlopp till närliggande dricksvattenbrunnar. Ett verktyg i form av en datormodell för mikrobiell riskanalys (MRA) anpassad till enskilda avlopp har utvecklats och ett fältförsök har genomförts för att få ökad kunskap om virustransport i grundvatten. Projektet har genomförts i samarbete mellan Chalmers tekniska högskola (DRICKS – Centrum för dricksvattenforskning), Tyréns AB och Sveriges geologiska undersökning. Folkhälsomyndigheten och Norges miljø- og biovitenskapelige universitet (NMBU) har genomfört vattenanalyser. Representanter från Uddevalla kommun, Trollhättans Stad och Alingsås kommun har tillhandahållit synpunkter på den MRA-modell som utvecklats.Författarna vill rikta ett stort tack till Uddevalla kommun och speciellt Tony Grantz som medverkat i projektet och praktiskt bistått i fältförsökets genomförande. Ett stort tack riktas också till Stiftelsen Backamo Lägerplats som upplåtit det aktuella fallstudieområdet.Projektet som presenteras i denna rapport har varit nära knutet till andra pågående projekt vid Chalmers som behandlar mikrobiella risker och grundvattenfrågor, men då med fokus på kommunala grundvattentäkter. Författarna är mycket tacksamma för finansieringen från Havs- och vattenmyndigheten, vilket möjliggjort detta projekt och därmed också en fortsatt utveckling inom området. Förhoppningen är att den utvecklade MRA-modellen, trots kvarstående förbättringsmöjligheter, ska komma till praktisk nytta och underlätta bedömningen av den hälsorisk enskilda avlopp kan utgöra.
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| 5. |
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| 6. |
- Pettersson, Thomas, 1966, et al.
(författare)
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Microbial Contaminants Removal in a Stormwater Pond
- 2010
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Ingår i: Highway and Urban Environment: Proceedings of the 9th Highway and Urban Environment symposium. (Alliance for Global Sustainability Bookseries Science and Technology: Tools for Sustainable Development. Vol 17). - Dordrecht : Springer Netherlands. - 9789048130443 ; , s. 177-185
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Konferensbidrag (refereegranskat)
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| 7. |
- Reischer, G. H., et al.
(författare)
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Performance Characteristics of qPCR Assays Targeting Human- and Ruminant-Associated Bacteroidetes for Microbial Source Tracking across Sixteen Countries on Six Continents
- 2013
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:15, s. 8548-8556
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Tidskriftsartikel (refereegranskat)abstract
- Numerous quantitative PCR assays for microbial fecal source tracking (MST) have been developed and evaluated in recent years. Widespread application has been hindered by a lack of knowledge regarding the geographical stability and hence applicability of such methods beyond the regional level. This study assessed the performance of five previously reported quantitative PCR assays targeting human-, cattle-, or ruminant-associated Bacteroidetes populations on 280 human and animal fecal samples from 16 countries across six continents. The tested cattle-associated markers were shown to be ruminant-associated. The quantitative distributions of marker concentrations in target and nontarget samples proved to be essential for the assessment of assay performance and were used to establish a new metric for quantitative source-specificity. In general, this study demonstrates that stable target populations required for marker-based MST occur around the globe. Ruminant-associated marker concentrations were strongly correlated with total intestinal Bacteroidetes populations and with each other, indicating that the detected ruminant-associated populations seem to be part of the intestinal core microbiome of ruminants worldwide. Consequently tested ruminant-targeted assays appear to be suitable quantitative MST tools beyond the regional level while the targeted human-associated populations seem to be less prevalent and stable, suggesting potential for improvements in human-targeted methods.
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| 8. |
- Sokolova, Ekaterina, 1986, et al.
(författare)
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Decay of Bacteroidales Genetic Markers in Relation to Traditional Fecal Indicators for Water Quality Modeling of Drinking Water Sources
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:2, s. 892-900
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Tidskriftsartikel (refereegranskat)abstract
- The implementation of microbial fecal source tracking (MST) methods in drinking water management is limited by the lack of knowledge on the transport and decay of host-specific genetic markers in water sources. To address these limitations, the decay and transport of human (BacH) and ruminant (BacR) fecal Bacteroidales 16S rRNA genetic markers in a drinking water source (Lake Radasjon in Sweden) were simulated using a microbiological model coupled to a three-dimensional hydrodynamic model. The microbiological model was calibrated using data from outdoor microcosm trials performed in March, August, and November 2010 to determine the decay of BacH and BacR markers in relation to traditional fecal indicators. The microcosm trials indicated that the persistence of BacH and BacR in the microcosms was not significantly different from the persistence of traditional fecal indicators. The modeling of BacH and BacR transport within the lake illustrated that the highest levels of genetic markers at the raw water intakes were associated with human fecal sources (onsite sewers and emergency sewer overflow). This novel modeling approach improves the interpretation of MST data, especially when fecal pollution from the same host group is released into the water source from different sites in the catchment.
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| 9. |
- Sokolova, Ekaterina, 1986, et al.
(författare)
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Estimation of pathogen concentrations in a drinking water source using hydrodynamic modelling and microbial source tracking
- 2012
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1477-8920 .- 1996-7829. ; 10:3, s. 358-370
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Tidskriftsartikel (refereegranskat)abstract
- The faecal contamination of drinking water sources can lead to waterborne disease outbreaks. To estimate a potential risk for waterborne infections caused by faecal contamination of drinking water sources, knowledge of the pathogen concentrations in raw water is required. We suggest a novel approach to estimate pathogen concentrations in a drinking water source by using microbial source tracking data and fate and transport modelling. First, the pathogen (norovirus, Cryptosporidium, Escherichia coli O157/H7) concentrations in faecal contamination sources around the drinking water source Lake Rådasjön in Sweden were estimated for endemic and epidemic conditions using measured concentrations of faecal indicators (E. coli and Bacteroidales genetic markers). Afterwards, the fate and transport of pathogens within the lake were simulated using a three-dimensional coupled hydrodynamic and microbiological model. This approach provided information on the contribution from different contamination sources to the pathogen concentrations at the water intake of a drinking water treatment plant. This approach addresses the limitations of monitoring and provides data for quantitative microbial risk assessment(QMRA) and risk management in the context of faecal contamination of surface drinking water sources.
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| 10. |
- Sokolova, Ekaterina, 1986, et al.
(författare)
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Water quality modelling, monitoring and microbial source tracking for microbial risk assessment of a drinking water source
- 2012
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Ingår i: Åttonde Nordiska Dricksvattenkonferensen, Svenskt Vatten, NordIWA, Stockholm, 18-20 juni 2012. ; , s. 94-98
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To prevent waterborne disease outbreaks, mitigation of faecal contamination of drinking water sources and sufficient treatment of water at the drinking water treatment plant (DWTP) are required. The aim of this study was to combine and apply several tools to investigate the raw water quality and determine the risk for waterborne infections in a drinking water source for the cities of Mölndal and Gothenburg in Sweden, Lake Rådasjön. To identify the major contamination sources around the lake and their contribution to the faecal contamination at the water intakes of DWTPs, monitoring of faecal indicators and pathogens was combined with microbial source tracking and water quality modelling. The microbial source tracking was performed to determine the human or ruminant origin of faecal contamination using host-specific Bacteroidales genetic markers. The decay of these genetic markers in relation to the decay of traditional faecal indicators in water environment was investigated in outdoor microcosm trials performed in different seasons. Using measured concentrations of Bacteroidales genetic markers the pathogen (norovirus and Cryptosporidium) concentrations in faecal contamination sources around the lake were estimated for endemic and epidemic conditions. Afterwards, the fate and transport of faecal indicators and pathogens within the lake were simulated using a three-dimensional coupled hydrodynamic and microbiological model, which was calibrated based on the decay data from the microcosm trials. Based on the obtained results a microbial risk assessment of a conventional DWTP was conducted using two different approaches – optimal disinfection practices (ODP) and quantitative microbial risk assessment (QMRA). The results showed that the on-site sewers were the source that contributed the most to the pathogen concentrations at the water intakes under both endemic and epidemic conditions. The results from both the ODP and QMRA risk assessments indicated that the barrier efficiency against Cryptosporidium and possibly viruses may be too low at a conventional DWTP. This study demonstrated how different approaches and tools can be applied to evaluate the risks for waterborne infections and prioritise mitigation measures related to faecal contamination of surface drinking water sources.
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