| 1. |
- Bondelind, Mia, 1980, et al.
(author)
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Benchmarkingmodell för dricksvattenförsörjning i Sverige
- 2012
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In: Proceedings för Åttonde Nordiska Dricksvattenkonferensen, Stockholm Sverige 2012. ; , s. 36-39
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Conference paper (other academic/artistic)abstract
- The Swedish Water & Wastewater Association has initiated a benchmarking project to assess the quality and quantity, safety and efficiency of drinking water systems in Sweden. An important part of the project is to develop a benchmarking model which provides a useful tool for the municipalities to evaluate the status of their drinking water systems in respect to a safe drinking water quality and quantity. The increased focus on a safe drinking water, in terms of microbiological contaminants, originates from recent outbreaks of waterborne diseases in Östersund and Skellefteå in Sweden. The derived benchmarking model presented in this paper evaluates the safety of the water by a few carefully selected parameters. The model will apply to both small and large drinking water systems and will provide a useful tool for comparison of drinking water systems within Sweden to encourage for a continued improvement of the systems. In addition, the model provides a straightforward and transparent tool for the municipalities to communicate the status of the drinking water systems to the public.
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| 2. |
- Heinicke, Gerald, 1973, et al.
(author)
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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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In: American Water Works Association, Global Conference on Microbial Contaminants in Drinking Water 2009, 5-8 October, Singapore. ; , s. 7-
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Conference paper (other academic/artistic)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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| 3. |
- Lindhe, Andreas, 1981, et al.
(author)
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Integrated risk analysis from source to tap: Case study Göteborg
- 2008
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In: The 6th Nordic Drinking Water Conference, Oslo, Norway, 9-11 June, 2008. - 9788241402937 ; , s. 231-241
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Conference paper (other academic/artistic)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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| 4. |
- Lindhe, Andreas, 1981, et al.
(author)
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Quantitative risk assessment of water supply systems from source to tap
- 2009
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In: TECHNEAU: Safe Drinking Water from Source to Tap. - 1843392755
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Conference paper (other academic/artistic)abstract
- In the 3rd edition of the Guidelines for Drinking-water Quality, the World Health Organisation concludes that an integrated management of risks in source waters, treatment systems and distribution networks is the most efficient way to guarantee safe drinking water to consumers. The integrated approach is fundamental to avoid sub-optimisation of risk-reduction efforts. This paper presents an application of an integrated and quantitative risk model for comparing risk-reduction alternatives to support decisions for reaching specified water safety targets. A fault tree approach is used for structuring the risk analysis and for estimating the risk, expressed as Costumer Minutes Lost (CML). Input information is a combination of hard data and expert judgements. Uncertainties in input information are considerable and modelled by a Bayesian statistical approach. The Göteborg drinking water system is used to exemplify model application. Quantitative safety targets have been confirmed at the political level as a basis for long-term planning of investments and reinvestments. Four different risk-reduction alternatives concerning additional raw water supplies and increased treatment capacity were compared. A combination of increased treatment capacity and additional raw water sources was shown to provide the greatest risk reduction. The paper describes how a structured and thorough analysis of risk-reduction options can facilitate transparency and long-term planning of drinking water systems.
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| 5. |
- Malm, Annika, 1970, et al.
(author)
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Förnyelseplanering av vatten- och avloppsförsörjningsnät i 18 svenska kommuner
- 2009
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In: The 11th Nordic Wastewater Conference, 10-12 November 2009, Odense, Denmark.
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Conference paper (other academic/artistic)abstract
- The water and wastewater pipe net management is of considerable interest. The management influences risk for distribution interruption, health disruptions and environmental safe sewer discharge. There are also huge values involved. The renewal of the pipe networks is the major question, each municipality has to handle. There is a lot of knowledge among the water administrations in the municipalities; however the knowledge is often in the mind of the employees. Water engineers in 18 Swedish municipalities of various categories have been interviewed. Most municipalities are in short of a systematic renewal planning, such as risk analysis or cost calculated goals. The interviewed municipalities felt that there renewal rate should be higher, but they have no structural instrument to show the reasons. Priorities were done as “worst first”, and the selection of “worst” were built on experience. There is a need of structure in order to assist the municipalities to rely on their work, and to express to politicians and others the future rehabilitation needs.
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| 6. |
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| 7. |
- Rosen, Lars, 1962, et al.
(author)
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Comparing Raw Water Options to Reach Water Safety Targets Using an Integrated Fault Tree Model
- 2008
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In: International Water Association Conference, Water Safety Plans: Global Experiences and Future Trends, Lisbon, Portugal, 12-14 May, 2008.
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Conference paper (other academic/artistic)abstract
- In the 3rd edition of the Guidelines for Drinking-water Quality, the World Health Organization (WHO) concludes that an integrated management of risks in source waters, treatment systems and distribution networks is the most effective way to guarantee safe drinking water to consumers. The integrated approach is fundamental to avoid sub-optimisation of risk reduction efforts. This paper presents an application of an integrated and quantitative risk model for comparing risk-reduction alternatives to support decisions for reaching specified water safety targets. A fault tree approach is used for structuring the risk analysis and for estimating the risk, expressed as Costumer Minutes Lost. Input information is a combination of hard data and expert judgements. Uncertainties in input information are considerable and modelled by a Bayesian statistical approach. The Göteborg drinking water system is used to exemplify model application. Quantitative safety targets have been confirmed at the political level as a basis for long-term planning of investments and reinvestments. Four different risk reduction alternatives were compared and increased treatment capacity in combination with additional raw water supply was shown to provide the greatest risk reduction. The paper describes how a structured and thorough analysis of risk reduction options can facilitate transparency and long-term planning of drinking water systems.
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| 8. |
- Sokolova, Ekaterina, 1986, et al.
(author)
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Hydrodynamic Modelling of Microbial Water Quality in a Drinking Water Source
- 2013
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In: Urban Environment. Proceedings of the 11th Urban Environment Symposium (UES), held in Karlsruhe, Germany, 16-19 September 2012. - Dordrecht : Springer Netherlands. - 9789400777552 ; , s. 517-526
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Conference paper (peer-reviewed)abstract
- The presence of faecal contamination in drinking water sources can cause waterborne disease outbreaks. The aim of this article was to study the influence of wastewater discharges from a wastewater treatment plant on microbial water quality in a drinking water source—the river Göta älv in Sweden. To fulfil this aim, the fate and transport of the faecal indicators E. coli and somatic coliphages in the river Göta älv were simulated using a three-dimensional hydrodynamic model. The validation of the hydrodynamic model confirmed a good model performance: the correlation coefficient was 0.99; the absolute mean difference between the simulated and measured water surface elevation was 0.03 m, which is 11.1 % of the standard deviation of the measured data. The modelling results revealed that during overflow events at the wastewater treatment plant, discharges of untreated wastewater contributed more to the concentrations of faecal indicators at the water intake than discharges of treated wastewater. The hydrodynamic modelling of microbial water quality proved to be a useful tool to estimate the contribution of different sources to the total contamination of raw water used for drinking water supply and, therefore, to provide decision-support information for preventive and mitigative risk-reduction measures.
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| 9. |
- Sokolova, Ekaterina, 1986, et al.
(author)
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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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In: Åttonde Nordiska Dricksvattenkonferensen, Svenskt Vatten, NordIWA, Stockholm, 18-20 juni 2012. ; , s. 94-98
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Conference paper (other academic/artistic)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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| 10. |
- Åström, Johan, 1977, et al.
(author)
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Kvantitativ mikrobiell källspårning med Bacteroidales qPCR för bedömning och åtgärder av patogenrisker i en ytvattentäkt
- 2010
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In: Den 7. Nordiske Drikkevandskonference, 7.-9. juni 2010, DGI-byen, Köpenhamn, Danmark. - 8790455983
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Conference paper (other academic/artistic)abstract
- Flera viktiga vattenburna patogener i Norden kan smitta mellan djur och människor, exempelvis parasiten Cryptosporidium. Det finns flera skäl för dricksvattenproducenter att inkludera mikrobiologisk källspårning i kartläggningen av sina råvattentäkter, och EU:s ramdirektiv för vatten tar upp principen om att åtgärda vid föroreningskällan och att förorenaren betalar. Vi har använt kvantitativ PCR (qPCR) för att detektera genetiska markörer av ordningen Bacteroidales från människor och idisslare i vattenprov från Rådasjön, en dricksvattentäkt för mer än 500 000 invånare i Västsverige. Den humana markören återfanns på alla provpunkter omkring sjön och vid råvattenintaget på 16 m djup, generellt i högre halter än E. coli, vilken bekräftar en tydlig avloppspåverkan. Idisslarmarkören återfanns mer sporadiskt, med högst halter invid en strandbetesmark där ungdjur vistats under sommarhalvåret. Resultat från provtagningar vid regnhändelser i en bäck nära råvattenintaget bekräftade human förorening från uppströms liggande enskilda avlopp, medan idisslarmarkören på motsvarande sätt återfanns vid regnhändelser vid strandbetesmark. Den fekala kontamineringen vid råvattenintagen till följd av olika riskhändelser vid Rådasjön (sannolikhet) har sammanvägts med litteraturangiven potential hos olika genotyper av Cryptosporidium att orsaka infektion (konsekvens) i en riskmatris. Sammanvägningen visar att avloppsrelaterade riskhändelser vid denna sjö står för en avsevärt större risk för kryptosporidieinfektion än idisslarrelaterade riskhändelser. Resultaten visar att qPCR-detektion av genetiska markörer kan kasta nytt ljus över ursprunget till fekal förorening i ytvattentäkter, men bör kombineras med en bedömning av riskhändelser i det aktuella området.
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